Selected Instructional Course Lectures

SelectedInstructional Course Lectures

THE AMERICAN ACADEMY OF ORTHOPAEDIC SURGEONS*

FRANKLIN H. SIM, Editor, Vol. 50

COMMITTEE

JAMES H. BEATY, ChairmanFRANKLIN H. SIM

S. TERRY CANALE

DONALD C. FERLIC

DAVID L. HELFET

EX OFFICIO

FRANKLIN H. SIM, Editor, Vol. 50DEMPSEY S. SPRINGFIELD, Deputy Editor of

The Journal of Bone and Joint Surgeryfor Instructional Course Lectures

JAMES D. HECKMAN, Editor-in-Chief,The Journal of Bone and Joint Surgery

*Printed with permission of the American Academy of Orthopaedic Surgeons. This article, as well as otherlectures presented at the Academy’s Annual Meeting, will be available in March 2001 in Instructional CourseLectures, Volume 50. The complete volume can be ordered online at www.aaos.org, or by calling 800-626-6726(8 A.M.-5 P.M., Central time).

1328 THE JOURNAL OF BONE AND JOINT SURGERY

Primary Total Hip ArthroplastyAfter Acetabular Fracture*†

BY DANA C. MEARS, M.D., PH.D.‡, AND JOHN H. VELYVIS, M.D.§

An Instructional Course Lecture, American Academy of Orthopaedic Surgeons

After a displaced acetabular fracture, a patient maybe predisposed to the development of symptomaticposttraumatic degenerative arthritis of the hip joint oravascular necrosis of the femoral head. In selected pa-tients, a total hip arthroplasty may eventually be neces-sary irrespective of the method of initial management1-3.On the basis of a review of the results described byLetournel and Judet2 and Matta4 and on the basis ofour experience, we determined that the likelihood thattreatment will culminate in an arthroplasty is related tothe initial type of fracture; the magnitude of the provoc-ative force; the age and weight of the patient; and, whenthe initial management of the fracture was open reduc-tion and internal fixation, the duration of the delay fromthe injury to the surgical procedure. When the initialacetabular deformity is relatively minor and when theacetabulum unites, especially following nonoperativetreatment, a conventional arthroplasty is likely to leadto an uncomplicated recovery and a satisfactory out-come. Nevertheless, in selected cases, one or morecomplicating factors may be encountered. Followingnonoperative treatment of an acetabular fracture, resid-ual displacement may hamper a subsequent arthro-plasty because of an occult or frank nonunion of theacetabulum or possibly because of a malunion or amalaligned nonunion5. When the initial management ofan acetabular fracture was surgical, a belated arthro-plasty performed to manage posttraumatic arthritis may

be impeded by dense scar tissue, heterotopic bone, avas-cularity of the hip muscles or the acetabulum, obstruc-tive hardware, or occult infection6. On the basis of areview of the few prior studies in the literature7-10, wefound that the overall prognosis for a patient managedwith a total hip arthroplasty after an acetabular fractureis less favorable than that for one managed with an ar-throplasty performed because of primary degenerativearthritis. In the present study, we address the principalconcerns regarding management with total hip arthro-plasty after initial treatment of an acetabular fracturewith closed or open reduction.

In view of the principal shortcoming of acute man-agement with total hip arthroplasty following an acetab-ular fracture — namely, the vulnerability to prematurefailure and the subsequent need for one or more sur-gical revisions — the potential therapeutic alternativesmerit serious consideration. For example, young male la-borers or other young, exceptionally active individualsare highly susceptible to premature failure of an arthro-plasty11. In such patients, one therapeutic alternative isarthrodesis of the hip, which is mainly indicated if thereis relative preservation of the osseous architecture of thehip joint. The other criteria for an arthrodesis — namely,a normal contralateral hip, normal knees, and an asymp-tomatic lower back — also must be met12. Currently,most individuals in North America are reluctant to con-sider arthrodesis. When a patient has avascular necrosisof the femoral head, loss of acetabular bone stock,marked osteoporosis, or a persistent acetabular non-union that impairs the mechanical stability of a hip fu-sion and hampers the healing of the bone, the likelihoodof achieving a solid fusion is considerably compromised.In such complex cases, the main practical alternative is aresection arthroplasty, with or without the use of a ce-ment spacer13.

Certain other symptomatic acetabular fractures maybe associated with secondary problems that can be ad-dressed by reconstruction of the hip, thus preserving thehip as a functional joint. Examples of the problems in-clude heterotopic bone leading to hip stiffness; symp-

*Printed with permission of the American Academy of Ortho-paedic Surgeons. This article, as well as other lectures presented at theAcademy’s Annual Meeting, will be available in March 2001 inInstructional Course Lectures, Volume 50. The complete volume canbe ordered online at www.aaos.org, or by calling 800-626-6726 (8 A.M.-5 P.M., Central time).

†No benefits in any form have been received or will be receivedfrom a commercial party related directly or indirectly to the subjectof this article. No funds were received in support of this study.

‡Department of Orthopaedic Surgery, Johns Hopkins BayviewMedical Center, 4940 Eastern Avenue, Baltimore, Maryland 21224-2780. E-mail address: [email protected].

§Division of Orthopaedic Surgery, Albany Medical Center, 47New Scotland Avenue, Suite A300A, Albany, New York 12208-3479.E-mail address: [email protected].

PRIMARY TOTAL HIP ARTHROPLASTY AFTER ACETABULAR FRACTURE 1329

VOL. 82-A, NO. 9, SEPTEMBER 2000

toms related to the hardware; a symptomatic nonunionor malunion of the acetabulum and/or hemipelvis; and,occasionally, a localized and indolent infection. In eachof these situations, all relevant diagnostic clinical andradiographic methods are used in an attempt to deter-mine whether the hip joint has intact and congruentbearing surfaces. Whenever it is technically possible,and especially in a younger patient, every attempt shouldbe made to salvage a functional hip joint14.

Clinical Assessment

The typical presenting symptoms of posttraumaticarthritis or avascular necrosis of the femoral head in-clude local or referred pain, a limp, and a decreasedlevel of activity. If the acetabulum, or another site in thepelvic ring, has a persistent nonunion, the patient maycomplain of pelvic instability with gross motion of thenonunion site or sites. A marked deformity of the pelvicring can be an associated complicating factor, but this israre. After an open reduction of the acetabulum, partic-ularly when an extensile exposure has been used, stiff-ness may develop secondary to extensive heterotopicbone. Young obese men who sustain a closed head in-jury in addition to the acetabular fracture are notori-ously susceptible to this problem.

During the physical examination, a shortened leg oran antalgic or stiff-hipped gait may be evident. Tender-ness about the hip and the presence of a surgical scar,along with a flexion or other type of contracture andstiffness, are commonly observed. The ipsilateral lowerextremity is examined carefully for subtle findings of asciatic nerve palsy, such as hypoesthesia of the foot ormotor weakness. When a patient has these findings,even a slight intraoperative injury to the sciatic nervecreates a substantial risk for the development of a post-operative complete footdrop because of the extraordi-nary susceptibility of a peripheral nerve to a secondinjury, or “double crush syndrome” as described byOsterman15.

When open reduction of the acetabulum culminatesin a chronically painful hip, the potential for a deepwound infection needs to be considered. Most such in-fections are occult, with such subtle clinical findings thathematological, bacteriological, and radiographic stud-ies, and even an aspiration arthrogram, may not confirmthe diagnosis. In an exceptional case, a frank wound in-fection with an open sinus tract may complicate the pre-sentation of grossly infected bone. From the time ofpresentation, the patient should be managed with suit-able antibiotic therapy, and surgical planning shouldinclude multiple débridements, techniques for plasticcoverage of the wound, and consideration of a belatedarthroplasty.

Radiographic Assessment

When a minimally displaced acetabular fractureprogresses to posttraumatic arthritis, the preparation for

a total hip arthroplasty may be adequately accomplishedby scrutiny of standard anteroposterior pelvic and frog-leg lateral radiographs. In more complex cases, addi-tional pelvic radiographs may be helpful2,3. Forty-five-degree inlet and outlet radiographs reveal pelvic ringdeformities, including central protrusion and vertical orposterior displacement of a hemipelvis. The 45-degreeobturator oblique radiograph highlights deformities ofthe anterior column and the posterior wall, while thecorresponding iliac oblique radiograph depicts the pos-terior column and the anterior wall. A computed tomo-graphic scan may provide the optimal view of an occultnonunion and of incarcerated hardware such as a screw.When a patient has an exceptional deformity that in-volves the entire pelvic ring, a three-dimensional com-puted tomographic scan may help the surgeon to identifythe sites and vectors of the deformity16. When there is ex-tensive heterotopic bone formation, a combination ofimaging modalities merits consideration in order to fullycharacterize the magnitude of the problem. A computedtomographic scan along with Judet oblique radiographsare crucial to fully ascertain the extent of the anteriorand posterior heterotopic ossification17.

When an occult deep wound infection is suspectedafter a prior open acetabular reduction, either an aspi-ration arthrogram or a technetium-99m bone scan maybe helpful. An infection is a causative factor for hetero-topic bone formation18. Ironically, when a patient hasflorid heterotopic bone, an aspiration arthrogram maybe impossible and a technetium-99m bone scan maylose much of its sensitivity in the detection of infection.In addition to a complete blood-cell count with differen-tial and a determination of the erythrocyte sedimenta-tion rate and C-reactive protein level, a gallium-67citrate scan or an indium white blood-cell scan may bevaluable, but only in rare cases19,20.

Preoperative Planning for theTotal Hip Arthroplasty

When the clinical and radiographic assessments arecomplete, the specific focal problems of the patient arecarefully analyzed to plan the arthroplasty. A discrete

TABLE ICLASSIFICATION OF ACETABULAR DEFICIENCIES IN

TOTAL HIP ARTHROPLASTY ACCORDING TO THE SYSTEMOF THE AMERICAN ACADEMY OF ORTHOPAEDIC SURGEONS21

Type Deficiency

I Segmental deficienciesIA PeripheralIB Central (medial wall absent)

II Cavitary deficienciesIIA PeripheralIIB Central (medial wall intact)

III Combined deficiencies

IV Pelvic discontinuity

V Arthrodesis

THE JOURNAL OF BONE AND JOINT SURGERY

1330 D. C. MEARS AND J. H. VELYVIS

acetabular defect may arise from the site of a displacedacetabular fragment following surgical removal of aloose fragment or from an area of marginal or centralimpaction. The defect may vary widely in size, fromminute to structurally important. As a general rule, adefect with a diameter of less than ten millimeters is notstructurally important, a defect with a diameter of ten totwenty-five millimeters is moderately important, and adefect with a diameter of greater than twenty-five milli-meters is very important (Figs. 1-A, 1-B, and 1-C). Suchdefects can be characterized by one of the availableclassification schemes, such as the system of the Ameri-can Academy of Orthopaedic Surgeons21 and that ofGross et al.22 (Tables I and II). Most of the availableclassification schemes distinguish isolated cavitary le-sions from segmental defects. The more structurally im-portant segmental group can be subdivided into defectsinvolving a wall or a rim as opposed to a column or, ulti-mately the most sinister form, a transverse dissociationor nonunion. These types of defects represent progres-sively more challenging reconstructive problems. Irre-spective of its size, such a defect may possess a wellcircumscribed boundary or a highly irregular one, andits borders may have well vascularized or avascularbone. All of these factors have profound implicationsfor the therapeutic plan.

A wide variety of deformities of the acetabulum andthe pelvic ring may be encountered. When a late defor-mity is present, it may involve a limited portion of theacetabulum, such as the anterior or posterior column orthe medial wall. This type of deformity may be evidentas a linear step-off. Alternatively, after an unreducedfracture of both columns, a “secondary incongruity”may represent a malrotation of each portion of the ace-tabulum, manifesting as a protrusion of the fragmentsaround the imploded femoral head2. Nevertheless, inthis situation, while the center of rotation of the femoralhead is somewhat altered biomechanically, there is notrue focal acetabular defect. This deformity, therefore, isreadily addressed with use of a standard cementless cupof a somewhat enlarged size, or a so-called jumbo cup23

(Figs. 2-A and 2-B).At the time of a total hip arthroplasty for posttrau-

matic arthritis following an acetabular fracture, a non-

union is particularly likely to be encountered after aposterior wall or column injury. However, after an injurypattern such as a transverse fracture or a fracture of bothcolumns, a nonunion is an uncommon problem that oc-curs primarily when florid displacement is uncorrected.Preoperative multiplanar imaging of the acetabulum isparticularly helpful to characterize the magnitude, site,and vector of displacement of the nonunion. The degreeof malalignment of an acetabular nonunion has con-siderable therapeutic implications and can be broadlysubdivided into three categories that correspond to the

TABLE IICLASSIFICATION OF ACETABULAR DEFICIENCIES

IN TOTAL HIP ARTHROPLASTY ACCORDINGTO THE SYSTEM OF GROSS ET AL.22

Type Deficiency

I Contained cavitary defect (protrusio)

II Uncontained (structural rim defect)

IIA Minor column (shelf defect) with >50%of cup coverage

IIB Major column (acetabular defect) with>50% loss of cup contact and loss ofone or both columns

FIG. 1-A

Figs. 1-A, 1-B, and 1-C: The structural importance of acetabular de-fects is related to their size, location, and characterization as a cavi-tary or segmental lesion.

Fig. 1-A: Oblique three-dimensional computed tomographic scan,made one year after a fracture-dislocation of the posterior wall, show-ing a large segmental defect of the posterior wall secondary to failedfixation.

FIG. 1-B

Anteroposterior radiograph of a hip, made two years after a trans-tectal transverse fracture that was treated nonoperatively, showing acentral segmental defect of moderate size with a principal axis ofmore than ten millimeters but less than twenty-five millimeters.



magnitude of the acetabular defect. When the nonuniongap is less than ten millimeters, it can be readily obliter-ated by packing it with autograft harvested from thefemoral head. Alternatively, the fracture fragments maybe sufficiently mobile to approximate the fracture sur-faces with use of suitable bone-holding forceps. The fix-ation of the fragments can be achieved with use of lagscrews, a plate, a cup with multiple screws, or a ring.When a nonunion defect is ten to twenty-five millime-ters, scar tissue, heterotopic bone, or fracture callus mayconsiderably impede an attempted open reduction. Thegap can be obliterated with morselized or bulk autograft.For structural augmentation, one of several strategiesmay be considered. Fine stainless-steel or titanium meshcan be used to buttress the acetabulum to facilitate im-paction grafting24. Alternatively, a cup inserted withmultiple screws can be used as a form of a hemispheri-cal plate. For defects that are larger than twenty-five mil-limeters, one of several specialized devices may be used.A cage or ring combined with a cemented cup can beemployed to immobilize multiple acetabular bone frag-ments and to obliterate the acetabular defect25,26. To filla superior acetabular defect, a bilobed cup can be uti-lized. As an alternative strategy, when the nonunion gapexceeds twenty-five millimeters, serious considerationshould be given to realignment and reapproximation ofthe acetabulum5. Otherwise, a technical failure with apersistent nonunion, premature loosening of the cup, orother complication is likely to ensue. During preopera-tive preparation for such a case, a three-dimensionalcomputed tomographic scan is helpful to optimally char-acterize the pelvic deformity.

Optimal Timing of the Arthroplasty

After initial management of an acetabular fracture,total hip arthroplasty is typically considered when a pa-tient is seen with evidence of secondary degenerativechange one or more years after the initial injury. By thattime, the acetabulum is usually united, even thoughthere may be a defect or a deformity. Occasionally, a se-rious problem with the hip (for example, an early sec-ondary displacement of the fracture, possibly with failedinternal fixation) is recognized within a few days orweeks after the initial injury and following either non-operative or operative treatment.

An unacceptable deformity often is not adequatelyappreciated radiographically. For instance, when a pa-tient has a displaced transverse or posterior fracture-dislocation and osteopenia, the femoral head typicallyundergoes rapid abrasive wear that may culminate inthe loss of 50 percent or more of its surface area. Like-wise, late recognition of marginal or central acetabularimpaction may not be consistent with a realistic capa-bility to achieve a satisfactory belated surgical correc-tion. Unfortunately, both conventional radiography andcomputed tomography may fail to provide a realisticrepresentation of a hip with an extraordinary amount ofloss of surface area of the femoral head or extensive ac-etabular impaction.

When a total hip arthroplasty is indicated, a ques-tion may arise about the need to delay the procedureuntil the acetabular fracture has fully united so that thecup can be inserted into a stable osseous bed. The bestsolution depends on the severity of the particular ace-tabular deformity and the experience of the surgeon.

FIG. 1-C

Anteroposterior radiograph of a pelvis, made two years after a transtectal T-type fracture that was treated nonoperatively, showing progres-sion to a large central segmental defect with a principal axis of approximately fifty millimeters.



There are potential advantages to undertaking a totalhip arthroplasty as soon as the hip has been shown ra-diographically to have incongruent articular surfacesand thus an overwhelming potential for a rapid onset ofpain. The foremost advantage is minimization of the de-lay between the acute fracture and the recovery fromthe arthroplasty. Also, when an unacceptable deformityof the acetabulum is recognized soon after the injury, ei-ther as a failure to achieve an acceptable reduction or asa delayed displacement, the defect can typically be ade-quately minimized or even fully corrected at the time ofa promptly executed arthroplasty.

For some hips with a displaced fracture, open reduc-tion and internal fixation needs to be considered whenan incongruity has been recognized early14. In the ab-sence of marked impaction or abrasion of the articularsurfaces, and especially in a young adult who has a sim-ple fracture pattern, delayed open reduction is pre-ferred. In an inactive elderly or otherwise infirm patient,in whom comminution and impaction secondary to os-teoporosis can be anticipated, acute management with

an arthroplasty may be a more realistic endeavor. Whenit is difficult to predict the extent of irreversible damageradiographically, consent for open reduction with a pos-sible total hip arthroplasty is obtained and the appropri-ate resources are organized for both procedures.

Surgical Approaches

Depending on the focal anatomical and pathologicalproblem, such as heterotopic ossification, one of severalstandard surgical approaches may be preferred26-31 (Figs.3-A through 3-D). Typically, when posttraumatic arthri-tis develops after an acetabular fracture has healed withminimal deformity, either a conventional anterior Har-dinge approach31 or a posterior approach is highly suit-able. When there is a substantial acetabular deformity orheterotopic bone, a modified or alternative exposuremay be preferred. If a fractured posterior wall or columnrequires an extensive surgical field, then a full Kocher-Langenbeck incision2 is utilized. For adequate visualiza-tion of both the anterior and the posterior aspect of theacetabulum and the adjacent hip joint, a triradiate inci-sion with preservation of the greater trochanter is highlyappropriate. When the entire hemipelvis is involved in

FIG. 2-B

Anteroposterior radiograph made after the total hip arthroplasty,showing the large defect obliterated by a jumbo cup.

FIG. 2-A

Figs. 2-A and 2-B: A forty-eight-year-old man sustained a T-typeacetabular fracture, which was managed with limited internal fixa-tion. Subsequent symptomatic posttraumatic arthritis was compli-cated by an excessively large superocentral acetabular defect andnecrotic bone in the roof. Three years after the injury, as part of a to-tal hip arthroplasty, the necrotic bone was removed and a structuralautograft from the femoral head was used to obliterate the acetabulardefect.

Fig. 2-A: Anteroposterior radiograph of the right hip, made threeyears after the injury, showing the large acetabular defect.



the deformity and needs a corrective osteotomy as partof the arthroplasty, then an extended iliofemoral ap-proach may be used. In this situation, we prefer a modi-fied or limited extended iliofemoral approach wherebythe gluteal tendons and adjacent greater trochanter aswell as the piriformis tendons are preserved intact. Ifthe ipsilateral sacroiliac joint is displaced, typically inexternal rotation, open reduction can be achieved bymeans of a variety of exposures. With the extended il-iofemoral or triradiate approach, a release of the inser-tions of the external oblique muscle from the iliac crestand the iliacus muscle from the internal iliac fossa pro-vides a suitable access. Alternatively, if the arthroplastyis performed with a conventional anterior or posteriorapproach to the hip, a second incision along the anterioriliac crest can be used to approach the sacroiliac joint.Whenever a secondary deformity of the pelvic ring cul-minates in malalignment of the acetabulum by morethan 25 degrees in a single plane, initial correction ofthe pelvic ring is usually indicated prior to the total hiparthroplasty. Otherwise, after insertion of the cup, aniatrogenic deformity would ensue as the pelvic ring de-formity was corrected. For deformities that involve bothhemipelves, the multiple corrective osteotomies and thearthroplasty may be undertaken as a combined sequen-tial procedure (Figs. 4-A, 4-B, and 4-C) or as separateprocedures at two different times. The relevant deter-minants include the experience of the surgeon, the mag-nitude and complexity of the deformities, the presenceof heterotopic bone, and the potential comorbidities ofthe patient. Some of the principal determinants and thecorresponding therapeutic strategies are outlined in Ta-ble III.

Preparation of the Acetabulum

After routine resection of the femoral neck andhead, the acetabulum is debrided of residual fibrocarti-

lage and granulation tissue. The acetabulum is carefullyexamined for a defect, deformity, or nonunion. If sucha site is identified, its osseous surfaces are meticulouslydenuded so that the structural problem can be carefullyassessed. The subsequent stages depend on the natureof the problem. If the acetabulum displays necrotic bone,then the dead bone is removed until a uniformly bleed-ing bed is achieved. Subsequently, the acetabulum isreamed to restore a hemispherical concavity that is suit-able for the insertion of a cementless cup. A large so-called jumbo cup may be needed to obliterate a residualacetabular recess (Figs. 2-A and 2-B).

Contained Defects

For a small contained defect, impaction grafting withmorselized bone from the femoral head is preferred24,33-36.When a defect is twenty-five millimeters or more in itslargest dimension, a structural autograft should be con-sidered. In some instances, a femoral head-and-neckautograft can be shaped to fit precisely into the defect(Fig. 5). If it is slightly oversized, it may be impacted toachieve a stable fit. In other instances, fixation with sup-plementary lag screws or a plate may be necessary. Whenthe cup is placed on a bed of autograft, a cementless cupis the most appropriate choice. When the bed consists ofallograft, and especially when it involves the weight-bearing surface, use of a cemented cup is preferred37. Ifthe defect greatly exceeds twenty-five millimeters in itslargest dimension, another useful option is a ring or cage.

Use of a Ring or Cage

Historically, a ring or cage was used in conjunctionwith a cemented polyethylene cup (Figs. 6-A and 6-B).The more recent designs include the availability of ametal-backed polyethylene liner that is mechanicallysecured to the cage so that the use of bone cement isunnecessary. A wide variety of cages with diverse exten-

TABLE IIIGUIDELINES FOR SURGICAL STRATEGIES TO ADDRESS PELVIC AND

ACETABULAR DEFORMITIES AS PART OF A TOTAL HIP ARTHROPLASTY

Type of Defect Treatment

Intrinsic acetabular defectsSmall superior acetabular defect Morselized impaction grafting if contained defect, supplementary

mesh if uncontained defect, cementless cupLarge superior acetabular defect Structural or morselized grafting, cementless cup, jumbo cup,

bilobed cup, protrusio cageMedial acetabular defect Central mesh, morselized impaction grafting, cagePosterior acetabular defect Structural or morselized grafting, posterior plate, mesh, standard

cup, cage

Associated deformities of pelvic ringIliac defect, nonunion, malalignment Open reduction and internal fixation of ilium, standard cupExternal rotational deformity of ipsilateral

or contralateral sacroiliac joint Open reduction and internal fixation of sacroiliac joint, standard

cupUnstable, windswept pelvis Open reduction and internal fixation of both sacroiliac joints,

standard cupVertical defect

Ipsilateral Reduction of hemipelvis, long-stemmed componentContralateral Reduction of hemipelvis, standard cup



sion plates are available for special problems25,26,28 (Figs.7-A, 7-B, and 7-C). The principal advantage of the cageis the potential to utilize a device with a predictableshape to obliterate a highly irregular defect. Frequently,

supplementary bone graft is needed to fill any gaps thatremain between the outer surface of the cage and the in-tact pelvis. The cage may function as a type of fixationplate that immobilizes the site of a transverse nonunion.

FIG. 3-BFIG. 3-A

Figs. 3-A through 3-D: Illustrations showing the surgical approaches commonly used in total hip arthroplasty for late reconstruction of ace-tabula with various defects and accompanying deformities.

Fig. 3-A: The modified Hardinge (anterolateral) incision is useful for hips with posttraumatic arthritis, cavitary lesions, or most limited seg-mental defects, including ones that involve the posterior wall. Our preferred modification of the approach includes an orientation of 30 degreesfrom the long axis of the limb so that more direct visualization of the acetabulum is achieved with a shorter incision.

Fig. 3-B: The Kocher-Langenbeck incision is useful for fractures involving the posterior wall and column.

FIG. 3-C

Fig. 3-C: The modified triradiate incision, with preservation of the greater trochanter, is an extensile approach that is useful for complete vi-sualization of both the anterior and posterior columns and the hip joint. The incision is appropriate for exposure of a large central defect, a dis-placed ipsilateral sacroiliac joint, or a hip with grade-IV heterotopic bone that completely surrounds the hip joint.

Fig. 3-D: The limited extended iliofemoral incision is an extensile approach that is useful for visualization of the entire hemipelvis and allowsfor a corrective pelvic osteotomy. The approach is modified by extending the incision to the posterior inferior iliac spine and by preserving theinsertions of the gluteal muscles and piriformis tendons on the greater trochanter.

FIG. 3-D



Nevertheless, despite its current popularity, a cage hascertain shortcomings. The foremost problem is a poten-tial for loosening when its anchoring screws are insertedin osteopenic bone. Where there is a nonunion and os-teopenic bone, failure to achieve a rapid union of the ac-etabulum contributes greatly to premature loosening ofthe cage. A shortcoming that pertains to previous de-signs in which the cup was attached to the cage withbone cement is late deterioration of this interface, withsubsequent loss of fixation of the cup. This problem isnot uncommon after a period of five to ten years. Anadditional shortcoming of the various cages with a su-perior or inferior flange or hook is the anatomical con-figuration of such devices. Typically, such a cup does notfit properly in a highly deformed acetabulum. Mostcages are too thick to permit realistic contouring withstandard bending instrumentation. A review of the indi-cations for the use of a variety of these devices is sum-marized in Table IV.

Intermediate or Uncontained Defects

The most common site of an intermediate or uncon-tained defect is the posterior wall (Figs. 8-A, 8-B, and8-C). In this situation, the displaced and ununited frag-ment of wall typically is maintained, by scar tissue, in ahighly displaced location with superior and posteriormalalignment. To achieve a nearly anatomical reduction,the surfaces attached by scar tissue must be fully mobi-lized, which inevitably provokes extensive avascularity.As an alternative technique, we prefer to denude thedeep, former articular surface of the displaced fragmentso that it contacts the structural graft and provides a po-tential source of blood supply.

After curettage, whenever feasible, the defect is pre-pared with conventional acetabular reamers. Likewise,the true acetabulum is reamed in a conventional man-ner. The resected femoral head is denuded of residualcartilage with use of cup arthroplasty reamers or so-called reverse acetabular reamers and is used as a struc-tural autograft. A v-shaped notch is made in the femoralhead so that the notch interlocks into the damaged sec-tion of the posterior wall. The autograft is anchoredwith use of three 3.5 or 4.0-millimeter fully threadedscrews. Then, the acetabulum is reamed again to the op-

timal diameter. Any persistent small defect at the junc-tion between the graft and the residual acetabulum isfilled with morselized cancellous bone. Then, a metalbacking for a cementless cup in an appropriate size isimpacted into the acetabular recess and is anchoredwith two or three cancellous screws.

Large Uncontained Defects

Large uncontained defects present a principal struc-tural problem in the posterior, superior, or central aspectof the acetabulum. Some reconstructive recommenda-tions are described for each type of defect.

When a patient has a large defect in the posteriorpart of the acetabulum that involves the wall and the ad-jacent column, perhaps the most formidable mechanicalchallenge is the transfer of the patient from the bed toa chair. Thus, a highly stable configuration of the re-construction is essential. Historically, the most popularform of reconstruction has been the application of aposterior plate with the use of a structural autograft(Figs. 5, 8-A, 8-B, and 8-C). Alternative potential solu-tions include the use of a cage or a mesh, which is an-chored around the rim of the defect with screws. Then,impaction grafting of the defect is performed with autol-ogous bone in order to create a suitable bed for the cup.

Another option is the fabrication of a custom im-plant that is designed on the basis of a three-dimensionalcomputed tomographic scan or a corresponding modelof the hip (Figs. 9-A and 9-B). While this method permitsthe use of an unlimited variety of shapes to address trulyunique structural problems, it possesses several short-comings. Not only is this technique costly, but only a sin-gle implant design can be available during the procedure.If an unanticipated defect within an avascular bed isidentified during the operation, so that additional bonehas to be excised, then the custom implant no longer fitsprecisely into the defect. In this situation, structural au-tograft or, suboptimally, allograft is needed to restore thestructural stability of the reconstruction.

A viable solution for a defect in the superior aspectof the acetabulum that includes a corresponding seg-ment of wall is a bilobed or oblong cup38. One newermodular model permits the application of a lobe ofthree different sizes for obliteration of the correspond-

TABLE IVDEVICES TO MANAGE A LARGE DEFECT AND INDICATIONS FOR THEIR USE

Device Indication

Mesh Superior or middle central defect or superior posterior wall defect(remaining acetabulum must be intact)

Bilobed cup Superior wall and dome defect

Müller ring Central, superior defect

Ganz ring with hook inobturator foramen

Nonunion of transverse fracture

Burch-Schneider cage Large superior and central defect; nonunion of transverse, T-type fracture;large posterior defect; transverse dissociation with central bone loss toanterior inferior iliac spine



ing defects (Fig. 10). The principal shortcoming of a bi-lobed cup is the need to orient it so that the lobe isdirected superiorly. If a defect is posterosuperior, the

lobe cannot be redirected or the articular portion of thecup will be malaligned and provoke instability of the to-tal hip prosthesis.

FIG. 4-A

Figs. 4-A, 4-B, and 4-C: A forty-one-year-old pilot sustained a displaced iliac-wing, or so-called crescent, fracture of the left hip and a T-typeacetabular fracture of the right hip in a free fall in his helicopter from 200 feet (sixty-one meters). Two years after nonoperative treatment, hewas referred to us with bilateral pelvic pain and a persistent and highly displaced nonunion of both the left iliac fracture and the right acetabu-lar fracture. A partial realignment and stabilization of the left hemipelvis was performed with a right total hip arthroplasty and open reductionand internal fixation of the right acetabulum. In order to improve the patient’s sitting balance, the right ischial tuberosity was osteotomized andpartly resected so that his weight rested on the inferior end of the posterior column.

Fig. 4-A: A three-dimensional computed tomography scan, made at the time of presentation, showing a persistent vertical and rotational de-formity of the left hemipelvis and a displaced nonunion of the right T-type acetabular fracture with distal displacement of the inferior half ofthe acetabulum.

FIG. 4-B

Postoperative anteroposterior radiograph showing a partial correction of the left pelvic deformity and a right cementless total hip replace-ment with immobilization of the acetabulum.



For repair of a defect in the central aspect of theacetabulum, use of a structural autograft, a cage, or a cen-tral mesh should be considered39 (Figs. 11-A, 11-B, and11-C). For the latter two methods, morselized autograftinitially is placed into the base of the defect prior to in-sertion of the hardware. If a central mesh is used, a five toten-millimeter-thick layer of morselized cancellous bonegraft is impacted in place after insertion of the mesh.

If the defect is exceedingly large, a bed of mor-selized cancellous bone graft is inserted into the acetab-ulum to a thickness of approximately five millimeters. Alayer of mesh that obliterates the entire defect is placedinside the bone graft and is supported by the adjacentintact acetabulum. Extra-articular screws may be in-serted to anchor the periphery of the mesh to the lateralwall of the acetabular rim. Additional bone graft is im-pacted into the mesh until a continuous layer that is fiveto ten millimeters thick has been established. A secondlayer of mesh is inserted into the acetabulum with twoadditional extra-articular anchoring screws. An addi-tional layer of impacted bone graft is used to cover thesecond mesh. Then, a cup is cemented into the bonegraft. In this construct, the secondary layer of meshserves to compartmentalize the bone graft and therebyto inhibit late subsidence.

Nonunion

When a partial union of a displaced acetabular frac-ture creates a gap of as much as twenty-five millimeters,the fracture gap is usually managed with débridementand obliteration with autograft. If a mobile nonunion is

FIG. 4-C

Anteroposterior radiograph of the right hip, made eleven years af-ter the arthroplasty, showing a successful long-term result. The pa-tient had no pain.

FIG. 5

A T-type fracture of the posterior wall that initially was managed nonoperatively progressed to a nonunion with deformity and degenerativechange. Two years later, the posterior column was stabilized, through a Kocher-Langenbeck approach, with a reconstruction plate while the de-fective wall was replaced with a precisely fitting structural autograft and lag screws. This intraoperative photograph was made after a metal-backed cup was secured to the pelvis while the autograft was secured with multiple screws.



encountered, the opposing surfaces are approximatedand immobilized with appropriate fixation. Any resid-ual fracture gaps are obliterated with bone graft. Thepreferred strategies for fixation of a nonunion site in-clude the use of lag screws or the insertion of a cup as ahemispherical plate, both of which avoid exposure ofthe posterior column, which is the most suitable site forplate fixation. The application of a plate to the posteriorcolumn in the setting of a nonunion is likely to result inavascular necrosis of the acetabulum as the periostealblood supply is compromised by the elevation of soft tis-sues and revascularization is impeded by the plate.

Another technique of fixation is the use of cablesaround the acetabulum40 (Figs. 12-A, 12-B, and 12-C).This method is particularly suitable for a transversefracture pattern. The cable is passed around the innerpelvic wall with a standard or modified Statinski vascu-lar clamp. We have procured custom-made modifiedclamps that are stiffer and have jaws designed to rigor-ously grip the end of a two-millimeter cable. The advan-tages of this method include minimal denuding anddevascularizing of the hemipelvis and prolonged integ-rity of the fixation in osteopenic bone, where screws arevulnerable to a rapid onset of loosening. The principalliability of the cabling technique is the potential for aneurovascular injury during the passage of the cablealong the inner pelvic table.

Insertion of the Femoral Stem

Currently, the optimal design of a cemented or ce-mentless femoral stem remains highly controversial41. As

FIG. 6-A

Figs. 6-A and 6-B: A twenty-eight-year-old man sustained a transverse fracture of the posterior wall of the left acetabulum. Open reductionand internal fixation was performed with use of a triradiate incision. Within two weeks, the posterior wall fragment had displaced; subse-quently, the hip progressed to posttraumatic arthritis with grade-IV heterotopic bone formation. Two years later, a total hip arthroplasty wasperformed and augmented with a Müller ring to stabilize the wall defect.

Fig. 6-A: Anteroposterior radiograph, made two years after the open reduction and internal fixation, showing grade-IV heterotopic boneformation and a fusion of the hip.

FIG. 6-B

Anteroposterior radiograph, made five years after the total hip ar-throplasty, showing stable fixation of the ring along with a cementedpolyethylene cup and a cementless stem.



a general rule, in the United States, a cementless designis favored for use in younger adults. In the few previousreports in the literature on total hip arthroplasty per-formed after an acetabular fracture, some investigatorsacknowledged an exceptionally high prevalence of pre-mature loosening of cementless stems6,7,42,43. They de-scribed the development of a relative osteopenia of theproximal part of the femur even in young men. Thisobservation has been interpreted to mean that the pe-riod of inactivity and limited weight-bearing that imme-diately follows the acute injury, combined with theadditional period of limited weight-bearing that accom-panies the onset of posttraumatic arthritis of the hipbefore the total hip arthroplasty, culminates in disuse os-teoporosis. In such a patient, the application of a ce-mented stem merits consideration.

Strategies to Address Anticipated Problems

When a total hip arthroplasty is performed after anacetabular fracture, problems may arise that need spe-cial consideration and an appropriate alteration of the

technique. Infrequently, a concomitant fracture of theproximal part of the femoral shaft or an intertrochan-teric fracture is an additional problem that may lead to asecondary malunion, retained metal, the developmentof heterotopic bone, or a nonunion in rare cases44-49. Theprincipal factors that are most likely to influence ace-tabular reconstruction are sciatic nerve injury, obstruc-tive hardware, heterotopic ossification, occult infection,and avascular necrosis.

Sciatic Nerve Injury

After initial operative management of a posteriorfracture-dislocation of the acetabulum, the sciatic nerveusually becomes attached to the site of the posterior fix-ation with scar tissue. The extent of the scar tissue variesconsiderably and may progress to its most sinister form,in which supplementary heterotopic bone is encoun-tered. When a total hip arthroplasty is performed after aposterior fracture-dislocation has been initially managedwith an operation, we prefer to use an anterolateral ora modified Hardinge approach31 (Fig. 3-A). In this way,the need for posterior dissection is minimized. In manycases, some degree of contusion of the sciatic nerve ac-companies the initial traumatic injury. At the time of thearthroplasty, the sciatic nerve is particularly vulnerableto a clinically important secondary injury as a manifesta-tion of the “double crush syndrome,” which may resultfrom a seemingly trivial retraction15. Whenever possible,the principal posterior fixation is left in situ, although notinfrequently one or two obstructive screws may need to

FIG. 7-C

Burch-Schneider cage with large superior and inferior flanges foranchoring screws.

FIG. 7-B

Ganz ring with a superior flange and an inferior hook for anchor-age in the obturator foramen.

FIG. 7-A

Figs. 7-A, 7-B, and 7-C: Drawings showing multiple designs of cageswith diverse extension plates that are available for use with a ce-mented cup.

Fig. 7-A: Müller ring with a smaller posterosuperior flange.



be entirely or partly removed. In certain cases in which apersistent nonunion or malunion of the posterior col-umn or a retained plate needs to be exposed, a completeexposure of the relevant segment of the sciatic nerveshould precede the osseous reconstruction or metal re-moval. In order to minimize the tension on the nerve, theknee is maintained in a position of more than 90 degreesof flexion during the remainder of the arthroplasty ex-cept for the brief period when the hip is being reduced.

In an attempt to monitor the function of the sciaticnerve during a surgical procedure, both somatosensoryevoked potentials and continuous electromyographicmeasurements have been utilized. Some early reportsexpressing enthusiasm for measurements of somatosen-sory evoked potentials have been published50-52. Never-theless, a disturbing trend, which we have documented,has been a prevalence, albeit a low one, of false-positiveand false-negative results50,53,54. The latter is a particularproblem that undermines the confidence of the surgeonin the reliability of this method. Other problems includea substantial latent period, which may be exacerbatedby the complexities in the interpretation of the results.Recent evaluations of continuous electromyographicmonitoring have indicated that this method has more ad-vantages than the former one55,56. Unlike somatosensory-

evoked-potential recordings, electromyographic mea-surements represent virtually instantaneous changes innerve function. Also, electromyographic measurementsare technically less demanding to obtain and require lesssophisticated and less costly instrumentation. While themethods can be used in combination, it appears that iso-lated use of motor-nerve monitoring is the most practicaloption.

Intraoperative spontaneous electromyographic re-cordings are obtained with use of sterile needle elec-trodes from the muscles innervated by the commonperoneal nerve (tibialis anterior and peroneus longusmuscles) and the posterior tibial nerve (abductor hallu-cis and flexor hallucis longus muscles). Unlike the situa-tion with somatosensory-evoked-potential monitoring,a neurotechnologist is not needed to evoke electromyo-graphic activity. The data are continuously recordedfrom the muscles; any mechanical or thermal irritationof the sciatic nerve results in a burst or train of neuro-muscular discharges, which usually persists until the of-fending stimulus is removed55.

Obstructive Hardware

In many patients who have a total hip arthroplastyafter open reduction and internal fixation of an acetab-ular fracture, some of the hardware is directly visual-ized once the articular surface of the acetabulum isexposed. This problem may be indicative of loose orbroken hardware that has migrated, or it may be a se-

FIG. 8-A

Figs. 8-A, 8-B, and 8-C: A fifty-three-year-old man who had a frac-ture of the posterior wall was managed with an acute open reductionand internal fixation with use of a plate. Within two weeks, the fixa-tion failed, with the initiation of rapid, abrasive destruction of thefemoral head. When the patient was referred to us four weeks afterthe injury, a hybrid total hip arthroplasty was performed with a struc-tural autograft from the femoral head to buttress the posterior wall.

Fig. 8-A: Anteroposterior radiograph of the right hip, made at thetime of the injury, showing the fracture-dislocation of the posteriorwall.

FIG. 8-B

Transaxial computed tomographic scan, made four weeks after theinjury, showing erosive damage to more than 30 percent of the femo-ral head. This finding was not visualized on plain radiographs made atthat time.



quela to an eroded osseous surface or a malpositionedimplant. Generally, appropriate preoperative imagingallows this problem to be recognized or at least sus-pected so that a suitable preoperative plan can be made.When a plate on the posterior column is directly visual-ized within the acetabulum, or when the plate or its as-sociated screw is struck by an acetabular reamer, thefeasibility of leaving the plate in situ needs to be consid-ered. The potential problems that may be encounteredduring an attempt to remove the entire plate includethe risk of an iatrogenically induced injury to the sciaticnerve, the inevitable blood loss, and the extensive oper-ative time needed to remove the plate. Occasionally,with certain patterns of acetabular malunion in thepresence of a thick layer of heterotopic bone, most ofthe structural integrity of the posterior column is pro-vided by the heterotopic bone. On removal of the het-erotopic bone and the underlying plate, the residualacetabulum may be weakened to a substantial degree,even to the point where a fracture occurs through theremaining defective bone6. Once this problem arises, asuccessful arthroplasty necessitates structural replace-ment of the posterior column, which is a formidable

technical challenge. We recommend that, wheneverfeasible, impaction grafting of the acetabulum withmorselized femoral-head autograft be performed tocover the exposed bottom surface of the plate and to re-store a five to ten-millimeter-thick osseous supportivelayer for the cup. If a segment of a protruding screw oranother nonstructural portion of hardware intrudes intothe acetabulum, it may be trimmed with a diamond burrwithout compromising the structural integrity of theposterior column.

Heterotopic Ossification

When a lateral exposure (especially an extended lat-eral approach) was used for the fixation of an acetabularfracture, some degree of heterotopic bone is typicallyseen5. Occasionally, clinically important heterotopic ossi-fication develops after a Kocher-Langenbeck approach,whereas it rarely develops after an ilioinguinal exposure.While the amount of heterotopic ossification may belimited, an extensive region of dense scar tissue usuallysurrounds the radiographically demonstrable area. Thisarea may be impregnated with multiple small deposits ofbone that are radiographically invisible. Such tissue mustbe excised to permit dislocation of the hip and subse-quent completion of the total hip arthroplasty. If the pre-operative radiographs display extensive grade-III or IVheterotopic bone according to the system of Brooker etal.57, a rigorous characterization of the extent of theproblem is essential. Both supplementary iliac and obtu-rator oblique radiographs are needed to determine themagnitude of the anterior and posterior extent of theheterotopic ossification17. A computed tomographic scanis useful to document that the hip capsule and adjacentmuscles are intact, which indicates that excision of theheterotopic ossification is feasible. Prior to the removalof the heterotopic ossification, the precise distribution ofthe bone, the optimal approaches to the sites, and the po-tential anatomical hazards are reviewed. One typicalpattern involves heterotopic ossification that is limitedto the site of the hip capsule and does not extend into theadjacent hip muscles or femoral head. In this situation,removal of the heterotopic ossification during the totalhip arthroplasty may be highly successful (Figs. 6-A and6-B). The opposite extreme involves circumferential het-erotopic bone that infiltrates radially from the femoralhead and neck to pervade the capsule and the adjacentmuscles, with associated osseous bars that anchor the en-tire proximal part of the femur to the pelvis. Almost allof these more florid cases are encountered in patientswho have had a closed head injury, particularly youngobese men. Despite the use of postoperative radiationtherapy, the likelihood for recurrent formation of mas-sive heterotopic ossification is great53. With the loss ofthe normal tissue planes and mobile interfaces, resectionof heterotopic ossification when there is such extensiveinvolvement is a formidable undertaking. Considerableblood loss can be anticipated, and arrangements for

FIG. 8-C

Iliac oblique radiograph, made after the total hip arthroplasty,showing the structural autograft secured with two cancellous screws.



transfusion and intraoperative salvage of blood areneeded.

Following such an extensive procedure, the risk of aserious deep wound infection is considerable. If such aninfection does develop, it has been our experience that,despite the use of multiple surgical débridements, forma-tion of scar tissue usually progresses to a virtual fusion ofthe hip. Alternatively, a resection arthroplasty may be-come necessary to control the infection. This measure isreserved solely for infections that culminate in extensivenecrosis of the involved bone and neighboring soft tis-sues. After adequate débridements of bone and soft tis-sue, a cement spacer is inserted to obliterate the deadspace and to provide a temporary reservoir of a suitableantibiotic. It has been our experience that, when the re-sidual viable tissues have been extensively covered withscar tissue in the aftermath of the infection, the late func-tional outcome of a resection arthroplasty with a cementspacer often is functionally equivalent to that of a sec-ondarily performed total hip arthroplasty with regard topain relief, stability, and mobility. In fact, after a resec-tion arthroplasty with a cement spacer, many patients

refuse to consider additional surgery even if a surgeonrecommends conversion to a total hip replacement.

Once the amount and the site of distribution of theheterotopic ossification have been characterized, theoptimal surgical approach can be selected. Althoughgrade-I or II heterotopic ossification does not materi-ally influence the approach, grade-III or IV heterotopicossification has an impact on the surgical plan. If het-erotopic ossification is localized solely to the posterioraspect of the hip joint, the use of a Kocher-Langenbeckapproach is recommended (Fig. 3-B). If heterotopicossification is both anterior and posterior to the hipjoint, we prefer to use a triradiate incision with preser-vation of the greater trochanter and the adjacent glu-teal insertions30.

The excision of two patterns of heterotopic ossifica-tion is especially challenging. In some patients with ma-ture heterotopic ossification, the extra bone is virtuallyindistinguishable from the intact pelvis. Furthermore,the soft-tissue boundaries, such as the capsule, may bewholly or substantially lost, as they have been replacedby bone. In contrast, progressive removal of heterotopicossification in a patient who has preservation of the soft-

FIG. 9-A

FIG. 9-B

Figs. 9-A and 9-B: A thirty-five-year-old man sustained a fractureof the posterior wall and posterior column of the right acetabulumand was managed initially with limited internal fixation. The fixationrapidly failed, which provoked secondary degenerative change. Twoyears later, the patient was referred to us with marked erosive dam-age to the femoral head, an absent posterior wall, and a partial defectof the posterior column. A total hip arthroplasty with a custom cupthat had a large posterior flange with drill-holes to permit effectivescrew fixation to the pelvis was performed.

Fig. 9-A: Transaxial three-dimensional computed tomographic re-construction with a template of the custom cup.

Anteroposterior radiograph of the right hip, made six years afterthe total hip arthroplasty, showing continued stable fixation of thecup in a superior position.



tissue intervals can be documented by visualization ofconspicuous osseous landmarks, such as the anterior in-ferior iliac spine and the junction between the femoralneck and the greater trochanter. The other challengingpattern of heterotopic ossification is ossification that in-filtrates deeply into the adjacent soft tissues such as thegluteus minimus. At the time of the initial cutaneous in-cision, the first hint of this pattern is typified by evidenceof bone in the deep fascia. To dislocate the hip, resectionof the involved portion of the gluteus minimus may benecessary. Other local muscles that are likely to containossified portions include the indirect head of the rectusfemoris, the iliopsoas, and the short external rotators.

During resection of heterotopic ossification aroundthe superior portion of the hip joint, the insertions ofthe gluteal muscles into the trochanteric region mustbe carefully preserved. The exposure of a fixation plateon the posterior column or an isolated screw is a valu-able landmark for identifying the surface of the intactpelvis. As a rule, such hardware is left in situ. In thisway, if another approach to the hip subsequently be-comes necessary, possibly for a revision arthroplasty,the hardware continues to serve as a marker of the nor-mal pelvic surface, so that overenthusiastic removal ofrecurrent heterotopic bone does not progress to a cata-strophic resection of the acetabulum. In cases with themost extensive heterotopic ossification, the anteriorinferior iliac spine is an additional useful anterior land-mark. Supplementary image intensification can be usedto delineate the position of the acetabular rim. Duringtotal hip arthroplasty, the femoral neck is provisionallydivided in its midportion with a power saw. Sufficientheterotopic ossification is removed so that the proxi-mal part of the femoral shaft can be placed in approxi-mately 90 degrees of external rotation. Afterward, thestandard cut at the base of the femoral neck is madewith the use of an alignment guide. Once the hetero-topic ossification has been completely removed, the re-mainder of the arthroplasty continues in a conventionalfashion.

Often, the most extensive cases of heterotopic bonearound the hip are encountered in patients with an ace-tabular fracture and an associated fracture of the proxi-mal or midpart of the femur who had combined internalfixation performed through contiguous surgical fields.In the most florid cases, the heterotopic bone can ex-tend from the iliac crest to the distal femoral metaphysisso that both the hip and the ipsilateral knee are anky-losed. A suitable release of the hip and knee involvesboth a resection of the massive amount of bone and acomplete quadricepsplasty. Despite the use of post-operative radiation therapy and/or treatment with in-domethacin, recurrent heterotopic ossification is almosta certainty53,58. Nevertheless, the patient may be gratefulfor a moderate functional improvement in gait and theability to transfer.

In some cases of massive heterotopic ossification,

the findings on preoperative radiographs are consistentwith some degree of posttraumatic degenerative arthri-tis of the hip. Even with an adequate computed tomo-graphic scan, the surgeon may be unable to determinewhether complete removal of the heterotopic ossifica-tion will permit a functional restoration of a mobile andpainless hip joint. The patient’s preoperative consentand the corresponding discussion may be directed to-ward surgical resection of the heterotopic ossification,with a possible supplementary total hip arthroplasty, iffeatures of severe degenerative changes in the hip jointare observed during the procedure.

Following a total hip arthroplasty that is accompa-nied by the removal of extensive heterotopic ossification,the use of one or more postoperative prophylactic mea-sures is recommended53. Radiation therapy with a dose of700 centigray on the first postoperative day is a standardrecommendation59. Alternatively, the use of indometha-cin for a period of at least six weeks has been advised. Ina recent randomized, prospective study to assess the for-mation of heterotopic ossification after open reductionof acute acetabular fractures, Matta and Siebenrock58 re-ported that indomethacin had no therapeutic beneficialeffect as prophylaxis against heterotopic ossification.Other surgeons have used a combination of radiationtherapy and indomethacin60. Despite the use of prophy-lactic regimens, the formation of clinically important het-erotopic ossification or a complete recurrence of it afterresection is not unlikely in hips with florid heterotopicossification following a closed head injury. It has beenour experience that this sobering event may transpireeven though years of “maturation” of the heterotopic os-

FIG. 10

Photograph showing the modular bilobed cup (Mars; Biomet, War-saw, Indiana), which allows application of a lobe of three differentsizes to obliterate corresponding acetabular defects. The polyethyleneliner is secured mechanically to the bilobed cup, in contrast to thecase with a conventional cage.



sification may ensue after the acetabular fracture andprior to the total hip arthroplasty.

Occult Infection

An occult infection may be a source of chronic painin the hip after open reduction and internal fixation ofthe acetabulum, and it may be the cause of deteriora-tion of the joint surfaces. Certain circumstances shouldheighten suspicion of an occult infection. The use of anextended lateral approach for the initial treatment ofan acetabular fracture is a risk factor, particularly whenthe dissection is undertaken along both the inner andthe outer pelvic table. Another factor is heterotopic os-sification, which may be provoked in part by the infec-tion itself. Additional factors include morbid obesity, animmunocompromised patient, and previous radiationtherapy to the pelvis.

While clinical, hematological, radiographic, or otherfindings may indicate an infection, clear evidence of aninfection is typically not available until the arthroplastyis performed. When dense scar tissue or heterotopicbone is anticipated, a preoperative aspiration or even atrephine biopsy of the hip may fail to confirm the in-fection. At the time of the arthroplasty, specimens ofjoint fluid should be sent to the laboratory for analysis,including a gram stain and a histological scrutiny forwhite blood cells. A highly reliable method is intraop-erative examination of a frozen section obtained frommembrane or pericapsular granulation tissue. The pres-ence of ten white blood cells per high-power field ispresumptive evidence of an infection61. If the hip is in-fected, our preferred method is to perform a thoroughdébridement, including resection of the femoral headand neck and any necrotic acetabular bone. Followingpulsatile jet lavage and antibiotic irrigation, a cementspacer that has been impregnated with an antibiotic,typically gentamicin, is inserted into the acetabulum62-64.The wound is closed in layers over a suction drain. Post-operatively, after the identification of the pathogen, ap-propriate intravenous antibiotics are given for at leastsix weeks. Upon the cessation of antibiotic therapy, atrephine biopsy of the hip is performed under image in-tensification. If the specimen is sterile, insertion of thetotal hip prosthesis is considered. If the specimen re-veals a persistent infection, multiple surgical débride-ments with replacement of the cement spacer andcontinued intravenous antibiotic therapy are under-taken until the infection is eradicated.

Avascular Necrosis of the Acetabulum

Another potential complicating factor is avascularnecrosis of the acetabulum65. Following a single exten-sile approach or two simple approaches for acute recon-struction of an acetabular fracture, the blood supply tothe acetabular bone may be heavily compromised for aprolonged period of years. At the time of a belated ar-throplasty, necrotic acetabular bone may thwart the in-

sertion of the cup and may predispose the patient topremature acetabular loosening. When a total hip ar-throplasty is being considered for a patient with post-traumatic arthritis after an extended lateral approach ora two-incision approach, the surgeon is advised to re-view the prior operative report to determine whether anextensive intraoperative dissection on the inner andouter pelvic tables was performed. A helpful, althoughsubtle, radiographic sign of acetabular necrosis is an in-creased radiodensity, especially in the region of thedome (Fig. 13). If the cup is inserted into an avascularbed, a serious potential complication is an insidious pro-trusion of the cup through the medial acetabular wall. Inthe most florid case, a transverse dissociation may occur(Figs. 14-A, 14-B, and 14-C).

The optimal method of addressing acetabular avas-cular necrosis is to reduce its potential for developmentat the time of the initial open reduction; for instance,use of the extended lateral approach should be mini-mized, and the blood supply to all of the major acetab-ular fragments should be maintained. At the time ofthe arthroplasty, if a cementless cup is used, it must beplaced on viable bone. Even if a cemented cup is se-lected, a viable osseous bed markedly improves thelongevity of the fixation. When the preoperative radio-graphs indicate an extensive area of periacetabularavascular necrosis, the feasibility of successfully anchor-

FIG. 11-A

Figs. 11-A, 11-B, and 11-C: A fifty-six-year-old man who had failureof fixation of a transverse acetabular fracture of the right hip wasmanaged with a total hip arthroplasty with use of central mesh, mor-selized bone graft, and lag screws.

Fig. 11-A: Anteroposterior radiograph, made before the total hiparthroplasty, showing failure of internal fixation solely with lag screwsand marked abrasive destruction of the femoral head.



ing the cup on viable bleeding and structurally soundbone must be carefully reviewed. In exceptional cases, aresection arthroplasty may provide a superior and morepredictable outcome than a total hip arthroplasty.

After a thorough inspection of the preoperative im-ages, the feasibility of reconstructing a stable acetabu-lum needs to be determined. For a particularly largeacetabular defect that is further complicated by a suspi-cion of extensive avascular bone, a frank discussion withthe patient about the magnitude of the problem and thepotential need for resection arthroplasty may be advis-

able before embarking on the procedure. If the poten-tial for acetabular reconstruction remains unclear to thesurgeon, a review of the clinical and radiographic fea-tures with an orthopaedist who is highly experiencedwith this problem may be beneficial.

Salvage of Complex Late Cases

A limited spectrum of acetabular fractures, after fail-ure of the initial open reduction and internal fixation,have a heterogeneous mixture of complicating factors. Apatient may have a serious deep wound infection, possi-

FIG. 11-B

Schematic drawings of the central mesh and morselized impacted bone chips.

FIG. 11-C

Obturator oblique radiograph, made after the hybrid total hip arthroplasty, showing a central mesh and a metal-backed cup secured withthree screws.



bly with persistent drainage through a sinus tract. Thegluteus medius and minimus muscles may have beendamaged by an injury to the superior gluteal nerve, het-erotopic bone formation, or avascular necrosis, or theymay even have been injured secondary to a life-savingembolic occlusion of a traumatic laceration of the inter-nal iliac artery. Substantial acetabular bone loss mayhave occurred as a result of avascularity or infection oroccasionally other factors. In some of these situations, atotal hip arthroplasty may be feasible, even if a multi-staged reconstruction is necessary. Nevertheless, in cer-tain situations, such as complete loss of the posteriorcolumn (Fig. 15), a total hip arthroplasty may be techni-cally unrealistic. Furthermore, the functional outcome ofa total hip arthroplasty with respect to pain relief anddurability may not be any better than that of the princi-

pal surgical alternative, a resection arthroplasty with orwithout the insertion of a cement spacer66-69.

Acute Management with TotalHip Arthroplasty After AcetabularFracture in Highly Selected Patients

Fractures in elderly individuals represent the mostrapidly growing spectrum of acetabular trauma70-72. Thespecific indications for acute management with total hiparthroplasty after a displaced acetabular fracture haveyet to be clearly defined but may include marked impac-tion, extensive abrasion or fracture of the femoral head,a completely displaced femoral neck fracture, marginalor central impaction of the acetabulum involving morethan 30 percent of its surface area, and extensive acetab-ular comminution in the presence of osteopenic bone.Other relative indications include delayed presentation,substantial medical comorbidities, morbid obesity, andadvanced age. We have been encouraged by our earlyexperience with total hip arthroplasty in the treatmentof selected acute fractures40.

Postoperative Management

After the total hip arthroplasty, a patient is managedwith an abduction bolster or split Russell traction for

FIG. 12-B

Photograph of an intact anatomical pelvic model, showing the posi-tion of a cable on the outer pelvic table.

FIG. 12-A

Figs. 12-A, 12-B, and 12-C: Cables can be used for reconstruction ofthe inner pelvic table in a so-called geriatric acetabular fracture pat-tern in which the quadrilateral plate is displaced medially. As dis-played in Fig. 1-C, a sixty-two-year-old woman with osteopenic bonesustained a T-type acetabular fracture with marked displacement ofthe posterior column, including most of the quadrilateral surface. Fol-lowing nonoperative treatment, she was seen two years later withmarked protrusion of the femoral head through the site of the non-union. Cables were used to reduce and immobilize the displaced pos-terior column and to buttress the quadrilateral surface. After theapplication of a structural femoral head autograft, a hybrid total hiparthroplasty was performed.

Fig. 12-A: Photograph of an intact anatomical pelvic model, show-ing the position of the cables on the inner pelvic table.



twenty-four hours to minimize the risk of postoperativedislocation. In general, bed-to-chair transfers are initi-ated on the first postoperative day, with touch-down orlight partial weight-bearing beginning on the second day.Substantial partial weight-bearing is begun at four to sixweeks after the arthroplasty, with full weight-bearing atsix to eight weeks. When an elderly patient who has com-promised strength, agility, and balance compared with ayounger adult is managed with a total hip arthroplasty,partial weight-bearing or weight-bearing as tolerated isalmost essential or the risk of a fall becomes excessive.Therefore, the acetabular repair requires sufficient struc-tural integrity so that some degree of immediate weight-bearing is feasible.

Whenever practical, vigorous progressive resistanceexercises of the hip abductors, quadriceps, and ham-strings as well as active range-of-motion exercises, includ-ing flexion, extension, and abduction of the hip joint, areencouraged6,73. A program of continuous passive motionmay be used at the discretion of the surgeon. Prophy-lactic intravenous antibiotics with a second-generationcephalosporin are used routinely for forty-eight hours.Prophylaxis against thromboembolism includes the ap-plication of elastic stockings, sequential compression de-vices, and an appropriate course of anticoagulation withwarfarin (Coumadin) or low-molecular-weight heparin.

Patients who have previously had open reductionand internal fixation of an acetabular fracture and whohad grade-I or II heterotopic ossification and/or anextended lateral approach prior to the belated totalhip arthroplasty are managed with low-dose radiation

FIG. 12-C

FIG. 13

Anteroposterior radiograph made after total hip arthroplasty withtwo cables that buttress the crucial quadrilateral surface.

Increased radiodensity of the acetabular roof on the left side is a subtle but important finding of acetabular avascular necrosis. This twenty-eight-year-old woman sustained a transverse fracture that was managed acutely with open reduction and was managed one year later withremoval of the metal. Three years after the injury, a total hip arthroplasty was performed to manage posttraumatic arthritis. Within anothertwo-year period, the patient complained of recurrent hip pain, and an aspiration arthrogram confirmed an aseptically loose cup. This antero-posterior radiograph shows superior migration of the failed cup into the necrotic acetabular roof.



(a single dose of 700 centigray). Alternatively, indo-methacin can be used in younger female patients inwhom radiation exposure should be avoided. Whenindomethacin and anticoagulation with low-molecular-weight heparin or warfarin are used concomitantly, ap-propriate medical supervision is needed to minimizethe risk of a coagulopathy.

Clinical Outcome of Total HipArthroplasty After Acetabular Fracture

According to a few prior studies on the late out-come of a belated total hip replacement after closed oropen treatment of an acetabular fracture7,8,43,80, the clini-cal outcome is generally less favorable than that aftertotal hip arthroplasty performed to manage degenera-tive arthritis. Undoubtedly, the outcome of belated totalhip arthroplasty after acetabular fracture is best whenthe fracture pattern is one of minor displacement withunion, especially following nonoperative treatment. Inearlier published reports, such as one by Boardman andCharnley76, even when open reduction of the acute ace-tabular fracture had been performed, the indication forthe late total hip arthroplasty typically was a posterior

fracture-dislocation, such as a posterior wall fracture,for which an isolated posterior surgical approach wasused to achieve fixation with lag screws or a single plate.In contrast to the simple-pattern fractures of the pos-terior column, posterior wall, and transverse fractures,few of the more complex patterns, such as a fracture ofboth columns, a T-type fracture, or an anterior column-posterior hemitransverse fracture, were managed sur-gically until recently. For example, Boardman and Charn-ley76, in a study of the outcomes of sixty-eight Charnleylow-friction arthroplasties, reported that fifty-five ofthe acute acetabular fractures were managed nonop-eratively and the remaining thirteen were treated withprimary open reduction and internal fixation. After arelatively short period of follow-up (an average of 3.5years), the patients had good results with respect topain and function. Waddell and Morton77, in a study ofthirty-four patients, reported that twenty-nine weremanaged initially with open reduction. Satisfactoryrates of success were noted after an average follow-upperiod of two years. Earlier studies by multiple authorshave described comparable rates of success over simi-larly brief follow-up periods, regardless of whether theinitial management of the diverse patterns of the ace-tabular fractures was open or closed8,10,75,78,79.

FIG. 14-A

Figs. 14-A, 14-B, and 14-C: A twenty-four-year-old woman sus-tained a fracture of both columns of the left acetabulum, which wasinitially treated with open reduction through a triradiate approachand dissection on the outer and inner pelvic tables. Six years later,she underwent a total hip arthroplasty without cement to manageposttraumatic arthritis. Within two years, severe aseptic osteolysis ofthe acetabulum culminated in a transverse dissociation.

Fig. 14-A: Anteroposterior radiograph made ten months after theopen reduction and internal fixation.

FIG. 14-B

Anteroposterior radiograph made soon after the total hip arthro-plasty and six years after the initial injury.



Romness and Lewallen7, in a longer-term evaluationof fifty-five belated arthroplasties performed after anacetabular fracture, observed that the rate of radio-graphic acetabular loosening at an average of 7.5 yearspostoperatively was 52.9 percent; the loosening wassymptomatic in 27.5 percent, and it progressed to a revi-sion in 13.7 percent. In contrast, Stauffer9, in a ten-yearfollow-up study of 231 hips in which a Charnley arthro-plasty had been performed for degenerative arthritis,reported that 36.8 percent had features of radiographicloosening and the rate of revision was 8.2 percent. Therates of radiographic loosening of the femoral compo-nent (29 percent), symptomatic loosening (16 percent),and revision (8 percent) were remarkably similar in thetwo series. When the two series were compared withrespect to the results in patients who were more thansixty years old, the rates of loosening of the femoralcomponent were similar; however, the rate of looseningof the acetabular component was 38.5 percent in the se-ries described by Romness and Lewallen comparedwith approximately 4.8 percent in the series reportedby Stauffer. Romness and Lewallen concluded that thefourfold to fivefold increase in the rate of failure of totalhip arthroplasty after an acetabular fracture was prima-rily attributable to damage or loss of acetabular bonestock. They recommended an initial open reduction as away to reconstruct the osseous anatomy, even if that

procedure fails to prevent posttraumatic degeneration.In contrast, Carnesale et al.80, in a study of fifty-six hipswith an acetabular fracture, including eleven that weretreated operatively, discouraged open reduction as theinitial choice of treatment for an acetabular fracture be-cause of the corresponding deterioration of the out-come after belated arthroplasty.

More recently, Mears and Ward81 evaluated a seriesof thirty-six patients who underwent a total hip arthro-plasty after previous open reduction and internal fixa-tion of the acetabulum. Most patients (83 percent) hadhad a triradiate extended lateral surgical exposure withdissection along the inner and outer pelvic walls. Therate of radiographic loosening was 58 percent, and therate of surgical revision was 36 percent within two yearsafter the primary arthroplasty. The high rate of pre-mature technical failure was, in part, a reflection of theuse of an unsatisfactory design of a cementless femoralstem. Nevertheless, at the time of the revision arthro-plasties, multiple acetabular biopsies confirmed the highlikelihood of widespread avascular necrosis in the cen-tral aspect of the acetabulum that correlated with theinitial dissections along the inner and outer pelvic walls.

Weber et al.43 reported on sixty-three patients whowere followed for an average of 9.6 years after a primarytotal hip arthroplasty following failed open reduction ofan acetabular fracture. The ten-year rate of survival of

FIG. 14-C

Iliac oblique radiograph, made two years after the total hip arthroplasty, showing a completely loose cup and a transverse dissociation sec-ondary to marked osteolysis of the anterior and posterior columns.



the components was 78 percent, and the rate of revision,which was performed mainly because of aseptic loosen-ing of one or both components, was 51 percent. Notablerisk factors for revision included an age of less than fiftyyears, a weight of greater than eighty kilograms, andlarge residual combined segmental and cavitary defi-ciencies in the osseous acetabulum. Mont et al.11 also ob-served a poorer outcome after total hip arthroplastiesperformed in younger patients, who generally are moreactive and have an increased body weight comparedwith older individuals.

For many reasons, the use of extensile or multiplepelvic incisions has diminished greatly during the pastdecade. Nevertheless, there is currently no convincingdocumented evidence that acute management with openreduction and internal fixation improves the success of asubsequent total hip arthroplasty performed for post-traumatic arthritis. Ironically, it has been our experiencethat the best late results of total hip arthroplasty afteracetabular fracture have been documented when the ar-throplasties were performed acutely. In a series of fifty-seven patients managed with an acute total hip arthro-plasty after acetabular fracture, the principal problemswere postoperative dislocation in two hips (3.5 percent),one of which progressed to a revision of the cup, and asymptomatic loose cup in one hip (1.6 percent), whichwas revised at three years74,82. In one other hip, grade-IVheterotopic bone developed after the acute total hiparthroplasty. The heterotopic ossification was resected,

and there was no recurrence at twenty months after thearthroplasty. There were no deep wound infections andno cases of radiographic or symptomatic femoral loosen-ing. The discussion of these results is not meant to be arecommendation for total hip arthroplasty for more thanan exceptional acetabular fracture, especially in elderlypatients. Nevertheless, an analysis of the results of openreduction and internal fixation of acute acetabular frac-tures highlights a therapeutic dilemma. Even in the mostexperienced hands, as Letournel and Judet2 meticulouslydocumented, certain patterns of acetabular fracture havean abysmal prognosis.

A small group of patterns of displaced acetabularfractures and clinical scenarios have a low likelihood for afavorable outcome after open reduction and internal fix-ation, and an open reduction of such fractures may com-promise the outlook for a successful subsequent total hiparthroplasty. These fracture patterns include abrasion,impaction, or fracture of the femoral head; a displacedfracture of the femoral neck; acetabular impaction; cer-tain comminuted fractures; multiple associated fractures;and osteopenic bone. The clinical scenarios include ad-vanced patient age, morbid obesity, substantial medicalcomorbidities, and a delay between the injury and thesurgery. In certain patients who have several of thesecomplicating factors, some alternative method of primarymanagement seems to be preferable. When the primaryfactor is comminution and impaction with relativelyminor displacement, most surgeons may lean toward

FIG. 15

Three-dimensional computed tomographic scan of the hip of a seventy-three-year-old woman who had complete, traumatic loss of the poste-rior acetabular column. This acetabular defect presents one of the most challenging reconstruction problems, as it can be very difficult toachieve a stable acetabular component that will resist the forces that are imposed by sitting and sitting transfers as well as standing and walking.



nonoperative treatment. When a patient has substantialdisplacement, especially an elderly patient with osteo-penic bone, acute total hip arthroplasty merits more care-ful consideration.

Overview

In most cases, when total hip arthroplasty is per-formed after an acetabular fracture, it is done to managesecondary degenerative change or, possibly, avascularnecrosis of the femoral head. Secondary complicatingfactors may be encountered during the total hip arthro-plasty. After initial nonoperative treatment of an acetab-ular fracture, an occult or frank acetabular nonunion andmalunion are not uncommon and may extend to the re-sidual pelvic ring. After operative treatment, intrusivehardware, heterotopic bone, dense scar tissue, ischemicmuscle or bone, and occult infection are additional haz-ards that may be encountered. When acute sciatic nervepalsy, whether induced traumatically or iatrogenically,accompanies the initial acetabular injury, the palsy islikely to be exacerbated during a subsequent total hip ar-throplasty. A careful clinical and radiographic evalua-tion is needed, along with the formulation of a detailedsurgical strategy. The need for specialized arthroplastyinstruments, fixation devices, and autograft or, occasion-ally, allograft has to be identified.

When heterotopic bone is evident, an extensile ap-proach may be needed to allow adequate exposure forits complete removal. After a bone defect and/or a non-union with displacement has been characterized, one ormore strategies for obliteration of the defect are consid-ered; these include the use of impaction grafting, a struc-tural graft, a cup inserted with multiple screws, mesh, ora suitable ring or other fixation device.

Evaluation of results has shown that, overall, the lateoutcome of total hip arthroplasty after acetabular frac-ture is inferior to that of arthroplasty performed becauseof degenerative arthritis. Although open reduction andinternal fixation of an acute acetabular fracture was pre-viously hypothesized as an effective way to improve theanticipated late outcome of total hip arthroplasty by theelimination of a large fracture gap or the prevention of apotential nonunion, current observations do not supportthat hypothesis. An initial open reduction may compro-mise the outcome of a subsequent total hip arthroplastyby compromising the blood supply of the acetabulumand by initiating the formation of scar tissue, heterotopicbone, or an occult or frank infection.

For a highly selected group of especially severe ace-tabular fractures, particularly those in elderly patients,total hip arthroplasty appears to be a promising thera-peutic alternative.

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