in other joints, grade I represents pain without plain ra-diographic changes, but with magnetic resonance imag-ing, evidence of a loss of vascularity. Grade II demon-strates an area of radiographic sclerosis and loss ofcirculation on both plain radiograph and magnetic reso-nance imaging without subchondral collapse. Grade III isevidenced by an area of similar findings with subchondralcollapse. Grade IV demonstrates subchondral and articu-lar collapse. Grade V (end-stage disease) represents biar-ticular arthrosis of the humeral head and glenoid(Fig. 1).
Classic symptoms include pain, stiffness, loss of mobility,night pain, and decreased function. Management of AVN ofthe proximal humerus has been separated into nonoperativeand operative approaches. Nonoperative approach, includ-ing observation, has been relegated only to those early cases
in grade I or II where no significant subchondral collapse has
Figure 1 Stages of humeral head avascular necrosis (AVN). Stage I: Radiograph appears normal, and magnetic resonanceimaging (MRI) shows early fascial necrosis. Stage II: Radiograph and MRI show areas of subchondral sclerosis. Stage III:Subchondral collapse is observed in both plain radiographs and MRI. Stage IV: Articular degeneration is noted abovearea of necrosis and collapse of the humeral head. Stage V: Biarticular degeneration is noted involving both the humeral
head and glenoid.
Figure 2 (A) Stemmed humeral head replacement arthroplasty restores articular congruity but removes substantial bonestock. (B) Cup resurfacing arthroplasty preserves humeral head bone stock while resurfacing the entire humeralarticular surface. (C) “Hemi-Cap” arthroplasty replaces only the focally diseased area of articular surface while preserv-
ing healthy surrounding cartilages.
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62 W.H. Seitz, Jr and A. Miniaci
been noted. Surgical management has included core decom-pression and bone grafting of various techniques.2 With sub-hondral or articular collapse, some form of prosthetic re-lacement arthroplasty, however, is needed to restore motionnd function, while relieving pain.
Classically, prosthetic replacement has required extensiveone resection with large stemmed implants being either ce-ented or pressed-fit to restore normal congruity to the hu-eral head, providing a stemmed a metal implant, which can
rticulate with a relatively intact and healthy glenoid surface.his, however, has required the removal of a subsequentonsiderable amount of proximal humeral bone stock, laterevision of such a procedure if glenoid erosion were to occur,equiring total shoulder arthroplasty, has required extensiveissection.More recently, subtotal final techniques for localized
esurfacing of the humeral articular surface without signif-cant removal of bone stock has demonstrated significantdvances in preservation of natural anatomy, allowinginimal bone removal while providing an environment,hich allows simpler more straightforward revision to to-
al shoulder arthroplasty should that at a later date beequired.3-5
Clearly, the degree of AVN should dictate the degree ofprosthetic replacement. This article will focus on the indica-
Figure 3 Symptomatic grade III AVN (A) has been treatviable surrounding articular cartilage while resectingonline.)
tions for focal resurfacing (“hemi-cap”), management of en-
tire humeral head involvement with total resurfacing or “cuparthroplasty” of the humeral head, conservative resurfacingof both articular surfaces of the humeral head and glenoid,and indications when formal total shoulder arthroplasty witha stemmed implant with or without total shoulder resurfac-ing is indicated.
Historically, humeral head replacement arthroplasty, asdesigned by Neer, has evolved from monoblock implantsand has given way to modular designs, which allow abilityto match stemmed implants to the diameter of the humeralcanal and articular surfaces to the anatomy of the humeralhead. However, use of these stemmed implants requiresubstantial bone resection, which, in fact, make revisionchallenging. Cup arthroplasty, as pioneered by Copeland,resurfaces the entire articular surface of the humeral head,but in doing so, preserves humeral head intramedullarycanal integrity using a localized fixation stem and a cen-tered “ongrowth” surface, which bonds to the humeralhead.6 This preserves humeral head and intramedullaryanal integrity and allows relatively easy revision surgery.5
The concept of a “hemi-cap” has only recently evolved.1
This procedure replaces only the focally diseased articularsurface, preserves the surrounding articular cartilage (as-suming it is intact and healthy), restores the surface geom-
h focal “hemi-cap” arthroplasty (B and C), preservingal bone stock. (Color version of figure is available
ed witminim
etry that is being replaced, and allows easy revision should
Avascular necrosis of the humeral head 63
this be necessary at a later date. This process, however, istechnically challenging because it requires precise realign-ment of the focal implant with the surviving articular car-tilage (Fig. 2).
The question that arises is When is it most appropriate to usewhich of the options to manage symptomatic AVN?
The authors have worked out a process for approaching
Figure 4 (A and B) Radiographic and MRI appearanceextensive (75%) subchondral collapse, but adequate boof figure is available online.)
AVN as follows:
Grade 2-3: “Focal, less than 30%” hemi-cap replacement(Fig. 3).
Grade 2-4: 30%-50% articular surface involvement,with good bone stock cup arthroplasty resurfacing ofthe entire humeral head (Fig. 4).
Grade 2-4: With poor bone stock, regardless of the de-gree of head involvement, a stemmed hemi-arthro-
es 3-4 AVN. (C and D) Intraoperative findings revealk to support cup resurfacing (E and F). (Color version
of gradne stoc
plasty (Fig. 5).
dictated stemmed hemiarthroplasty humeral head replacement.
64 W.H. Seitz, Jr and A. Miniaci
Figure 6 (A and B) Grade V AVN with complete head collapse and arthritic glenoid degeneration has required biarticular
Figure 5 (A and B) MRI revealing grade IV involvement, with extensive collapse of supporting subchondral bone has
total shoulder replacement arthroplasty (C and D).
Avascular necrosis of the humeral head 65
Figure 7 (A-J) As demonstrated in this “saw-bones” model, the surgical technique for “hemi-cap” resurfacing requiresidentification of the focal defect, central guide-wire placement, bed preparation, and confluent implant placement. Thisgrade II lesion has been managed with focal surface replacement with a “hemi-cap” implant (H, I and J). (Color version
of figure is available online.)
y(
nsu
66 W.H. Seitz, Jr and A. Miniaci
Grade 5: With biarticular disease, total shoulder arthro-plasty (Fig. 6).
Surgical TechniquesHemi-cap focal or “spot” resurfacing of the humeral head isperformed by localizing the area of degeneration and sub-chondral collapse, ensuring that the peripheral support boneand articular surface is healthy, diseased surface excision,debridement of unhealthy subchondral bone, preparationof a bed for insertion of a confluent focal resurfacing im-plant using a “hemi-cap.” This requires identification ofthe area of decay, central placement of guide wires, surfacedebridement, templating of a trial implant, and ultimately,insertion of a definitive implant to fill the defect and becongruent with the existing peripheral articular cartilagesurface (Fig. 7). This technique is applicable for defectsranging from 25-mm (in diameter) to full-head lesions.The implants increase in size from 5 mm to 40 mm. Anydevice larger than 40 mm will now cover the entire hu-
Figure 8 (A and B) Grade III AVN following IM Rodinwithout rod removal by complete articular replafollow-up (C-F).
meral head. The largest device that can resurface the entire f
humeral head is an aspherical design, thus one can matchthe exact humeral anatomy.
Cup Arthroplasty Resurfacing
Total resurfacing allows a metallic surface to replace the en-tire articular surface. This new metallic surface is bonded tothe humeral head through cintered ongrowth fixation. It pre-serves most of the surrounding bone stock of the humeralhead and provides restoration of a normal smooth articularsurface, while burning no bridges with regard to bone stockremoval, preserving potential for later uncomplicated revi-sion surgery.7,8 This technique is extremely applicable inoung patients who have good bone stock and a stable jointFig. 8).
If these last 2 parameters are not present, this technique isot applicable. Contraindications to both of these bone-pre-erving procedures include poor underlying bone stock, annstable joint, or inadequate peripheral support, such as in a
umeral shaft fracture has been successfully managedt using a cup arthroplasty seen here at 3-year
g for hcemen
racture.
(
hrera
). (Colo
Avascular necrosis of the humeral head 67
For grade V AVN where both sides of the joint are degen-erated, if there is enough healthy bone support to allow re-surfacing of the humeral head, then a fascial resurfacing ofthe glenoid, as described by Burkhead,9 can be performedFig. 9).
If, however, there is too much collapse and the humeralead will not support application of a focal or entire cupesurfacing implant, then a stemmed implant should be usedither with fascial resurfacing or with a more formal syntheticesurfacing of the glenoid as in a standard total shoulderrthroplasty.
ConclusionsFocal (hemi-cap) or complete resurfacing (cup resurfacing) is aconservative means of restoring articular congruity to the hu-meral head. These techniques remove little bone, burn fewbridges, offer pain relief, a smooth articular surface for enhancedmotion, and provide for easy ability to perform later revisionarthroplasty as needed. Stemmed implants require removal of asignificant amount of bone but can be effective to provide ahumeral head resurfacing with or without glenoid resurfacing asneeded depending on the extent of the disease.
An understanding of the indications for these surgical pro-
Figure 9 In young patients with early glenoid erosion (staga layer of glenohumeral capsule and securing it over the glewith the cup arthroplasty resurfacing the humeral head (B
cedures is paramount in using the most appropriate tech-
nique to the degree of pathology presented in this challeng-ing spectrum of patients.
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Ischemia and Necrosis of Bone. New York, NY, Lippincott Williams &Wilkins, 1980, p 171
2. Nakagawa Y, Ueo T, Nakamura T. A novel surgical procedure for osteo-necrosis of the humeral head: Reposition of the joint surface and boneengraftment. Arthroscopy 15:433-438, 1999
3. Scalise JJ, Miniaci A, Iannotti JP: Resurfacing arthroplasty of the hu-merus: Indications, surgical technique, and clinical results. Tech Shoul-der Elbow Surg 8:152-160, 2007
4. Seitz WH Jr: Cup arthroplasty for shoulder resurfacing: Technical tipsand “pearls,” Semin Arthroplasty 18:33-41, 2007
6. Levy O, Copeland SA: Cementless surface replacement arthroplasty(Copeland CSRA) for osteoarthritis of the shoulder. J Shoulder ElbowSurg 13:266-271, 2004
7. Bigliani LU, Bell R, Boselli K, et al: What would you do? Challenges inshoulder surgery. Semin Arthroplasty 21:209-216, 2010
8. Mariscalco MW, Patterson RW, Seitz WH Jr: Cup arthroplasty forrotator cuff tear arthropathy. Tech Hand Up Extrem Surg 15:2-5,2011
9. Burkhead WZ Jr, Hutton KS: Biologic resurfacing of the glenoid withhemiarthroplasty of the shoulder. J Shoulder Elbow Surg 4:263-270,
ascial glenoid resurfacing can be performed by separating). This provides a buffering soft-tissue surface to articulater version of figure is available online.)
