Review Article A new classification for complex lumbosacral injuries Ronald A. Lehman, Jr., MD a,b, * , Daniel G. Kang, MD a , Carlo Bellabarba, MD c,d a Department of Orthopaedics and Rehabilitation, Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889, USA b Division of Orthopaedics, Department of Surgery, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd, Bethesda, MD 20814, USA c Department of Orthopedics and Sports Medicine, Harborview Medical Center, University of Washington School of Medicine, 325 Ninth Ave, Seattle, WA 98104, USA d Department of Neurological Surgery, Harborview Medical Center, University of Washington School of Medicine, 325 Ninth Ave, Seattle, WA 98104, USA Received 3 September 2011; revised 24 December 2011; accepted 22 January 2012 Abstract BACKGROUND CONTEXT: The optimal classification and treatment algorithm for complex lumbosacral injuries, in particular high-energy sacral fractures and lumbosacral dissociation (LSD) injuries, remains controversial. Currently used classification systems are largely descriptive, lacking validity, reproducibility, treatment considerations, and prognostic information. PURPOSE: We set out to develop a comprehensive, yet practical, classification system for com- plex lumbosacral injuries that assists in clinical decision making. STUDY DESIGN: We developed a new classification system for complex lumbosacral injuries de- rived through literature review, expert opinion, and our clinical experience treating combat casual- ties over the past 10 years. We have seen an increased incidence of complex sacral fractures and LSD injuries after high-energy blast trauma, motor vehicle collisions, and aircraft crashes. METHODS: We performed an extensive literature review and discussed the proposed classifica- tion with spinal trauma surgeons from a variety of institutions familiar with the treatment of com- plex high-energy sacral fractures and LSD injuries. We identified the significant clinical and radiographic variables encountered in the decision-making process for the treatment of complex lumbosacral injuries. Existing classification systems were reviewed in light of these essential char- acteristics, and their limitations were defined and addressed with the new system. RESULTS: A new classification system called lumbosacral injury classification system (LSICS) was devised based on three injury characteristics: injury morphology, posterior ligamentous com- plex integrity, and neurologic status. A composite injury severity score was calculated by summing a weighted score from each category, allowing patients to be stratified into surgical and nonsurgical treatment groups based on threshold values. Modifiers to determining appropriate selection for op- erative treatment include systemic injury load and physiological status of the polytraumatized pa- tient, soft-tissue status, and expected time to mobility. Finally, an algorithm was developed to determine the optimum operative technique based on the previously outlined injury characteristics. CONCLUSIONS: The LSICS provides a comprehensive and practical approach for evaluating in- jury severity and guiding clinical decision making. This system provides common language for sur- geons to communicate various injury patterns and formulate treatment modalities. Further studies are necessary to determine the reliability and validity of this new classification system. Published by Elsevier Inc. Keywords: Lumbosacral dissociation; Spinopelvic dissociation; Transverse sacral fracture; U-type sacral fracture; Classifi- cation system FDA device/drug status: Not applicable. Author disclosures: RAL: Grants: DARPA (G, Paid directly to institu- tion/employer), DMRDP (H, Paid directly to institution/employer). DGK: Nothing to disclose. CB: Speaking/Teaching Arrangements: Synthes (B); Relationships Outside the One Year Requirement: Synthes (Speaking/ Teaching Arrangements, B). The disclosure key can be found on the Table of Contents and at www. TheSpineJournalOnline.com. The views expressed in this manuscript are those of the authors and do not reflect the official policy of the Department of Army, Department of Defense, or US government. Authors are employees of the US govern- ment. This work was prepared as part of their official duties, and as such, there is no copyright to be transferred. * Corresponding author. Department of Orthopaedic Surgery and Reha- bilitation, Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889, USA. Tel.: (202) 390-3892; fax: (301) 295-4141. E-mail address: [email protected](R.A. Lehman) 1529-9430/$ - see front matter Published by Elsevier Inc. http://dx.doi.org/10.1016/j.spinee.2012.01.009 The Spine Journal 12 (2012) 612–628
Transcript
The Spine Journal 12 (2012) 612–628
Review Article
A new classification for complex lumbosacral injuries
Ronald A. Lehman, Jr., MDa,b,*, Daniel G. Kang, MDa, Carlo Bellabarba, MDc,d
aDepartment of Orthopaedics and Rehabilitation, Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889, USAbDivision of Orthopaedics, Department of Surgery, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd, Bethesda, MD 20814, USA
cDepartment of Orthopedics and Sports Medicine, Harborview Medical Center, University of Washington School of Medicine, 325 Ninth Ave, Seattle,
WA 98104, USAdDepartment of Neurological Surgery, Harborview Medical Center, University of Washington School of Medicine, 325 Ninth Ave, Seattle, WA 98104, USA
Received 3 September 2011; revised 24 December 2011; accepted 22 January 2012
Abstract BACKGROUND CONTEXT: The optimal c
FDA device/drug
Author disclosure
tion/employer), DMR
Nothing to disclose. C
Relationships Outsid
Teaching Arrangemen
The disclosure key
TheSpineJournalOnlin
1529-9430/$ - see fro
http://dx.doi.org/10.10
lassification and treatment algorithm for complexlumbosacral injuries, in particular high-energy sacral fractures and lumbosacral dissociation(LSD) injuries, remains controversial. Currently used classification systems are largely descriptive,lacking validity, reproducibility, treatment considerations, and prognostic information.PURPOSE: We set out to develop a comprehensive, yet practical, classification system for com-plex lumbosacral injuries that assists in clinical decision making.STUDY DESIGN: We developed a new classification system for complex lumbosacral injuries de-rived through literature review, expert opinion, and our clinical experience treating combat casual-ties over the past 10 years. We have seen an increased incidence of complex sacral fractures andLSD injuries after high-energy blast trauma, motor vehicle collisions, and aircraft crashes.METHODS: We performed an extensive literature review and discussed the proposed classifica-tion with spinal trauma surgeons from a variety of institutions familiar with the treatment of com-plex high-energy sacral fractures and LSD injuries. We identified the significant clinical andradiographic variables encountered in the decision-making process for the treatment of complexlumbosacral injuries. Existing classification systems were reviewed in light of these essential char-acteristics, and their limitations were defined and addressed with the new system.RESULTS: A new classification system called lumbosacral injury classification system (LSICS)was devised based on three injury characteristics: injury morphology, posterior ligamentous com-plex integrity, and neurologic status. A composite injury severity score was calculated by summinga weighted score from each category, allowing patients to be stratified into surgical and nonsurgicaltreatment groups based on threshold values. Modifiers to determining appropriate selection for op-erative treatment include systemic injury load and physiological status of the polytraumatized pa-tient, soft-tissue status, and expected time to mobility. Finally, an algorithm was developed todetermine the optimum operative technique based on the previously outlined injury characteristics.CONCLUSIONS: The LSICS provides a comprehensive and practical approach for evaluating in-jury severity and guiding clinical decision making. This system provides common language for sur-geons to communicate various injury patterns and formulate treatment modalities. Further studiesare necessary to determine the reliability and validity of this new classification system. Publishedby Elsevier Inc.
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Introduction injuries, and mobility status of the patient. In addition to
In a young healthy individual, a high-energy injurymechanism is necessary to cause a complex lumbosacral in-jury. The lumbosacral region has significant surroundingosseoligamentous structures, which provide protection toimportant neural elements controlling lower extremityfunction, as well as bowel, bladder, and sexual function.Unfortunately, there has been no consistent or reliable clas-sification or treatment algorithm for complex lumbosacralinjuries and is largely because of the low incidence and het-erogeneous nature of these injuries. A particular complexlumbosacral injury is lumbosacral dissociation (LSD),which is frequently associated with falls from height, crushinjuries, and high-speed motor vehicle collisions. Thisunique injury pattern was first described by Purser [1] in1969 and later characterized by Roy-Camille et al. [2] asinvolving a transverse fracture of the upper sacrum as partof a more complex sacral fracture pattern and termed the‘‘suicide jumper’s fracture.’’ Recently, Helgeson andLehman et al. [3] reported the largest series of LSD injuriesin 23 service members and described an increased inci-dence of significantly complex LSD injuries after high-energy blast trauma sustained during combat. Lumbosacraldissociation injuries generally comprise a transverse sacralfracture with associated bilateral vertical fracture compo-nents, resulting in instability because of a lack of contiguityof the cephalad body and end plate of S1 with the ilium,which results in an obligatory anatomic separation of thepelvis from the spinal column [2–5]. Although LSD injuriesare relatively rare, there have been several case reports andretrospective reviews concerning the evaluation and treat-ment of these complex injures [2–4,6–8]. However, therehas been no widespread agreement on terminology, andother descriptions of LSD include lumbopelvic dissociation[6], spinopelvic dissociation [9–12], spondylopelvic disso-ciation/instability [9,13], and lumbosacral fracture disloca-tion [14–24]. Along with this confusion, there has been noagreement on the optimal classification and treatment ofcomplex high-energy sacral fractures and LSD injuries.
Several classification systems have emerged to describelumbosacral injuries [25–27], with particular paradigms in-cluding those by Sabiston and Wing [28], Denis et al. [29],Roy-Camille et al. [2], Strange-Vognsen and Lebech [30],and Isler [11]. These unique sacral injuries have also beencharacterized through simple descriptive terms of the frac-ture morphology, such as U type, H type, Y type, andlambda type [7]. However, these classification systems arelimited by several fundamental problems, such as being pri-marily descriptive, lacking validity, reproducibility, treat-ment considerations, and prognostic information. Also,many systems fail to include certain anatomic or physiolog-ical factors important to clinical decision making, such asthe amount of deformity or comminution, neurologic statusof the patient, integrity of the posterior ligamentous com-plex (PLC), systemic injury load, associated soft-tissue
complicating clinical decision making and treatment, thiscreates obvious barriers to communication between mem-bers of the multidisciplinary trauma team, as well as the ed-ucation of surgical fellows and residents. As a result of thecontroversy surrounding the classification of sacral injuries,most treatment decisions rely on anecdotal surgeon experi-ence, retrospective postulation of injury mechanism, andnonvalidated predictors of spinal deformity and neurologiccompromise. Recent advances in the classification systemsfor thoracolumbar spine (thoracolumbar injury classifica-tion and severity score) [31] and subaxial cervical spine(subaxial cervical spine injury classification system) [32]injuries have demonstrated that a clinically relevant classi-fication system should take into account the natural historyof an injury pattern, guide clinical decision making based ona simple algorithm with consistent radiographic and clinicalcharacteristics, stratify injury severity to suggest prognosis,provide a common language to describe injury pattern, andbe easy to remember and apply in clinical practice [31,32].These principles were used as a foundation as we set out todevelop a comprehensive, yet practical, classification sys-tem for complex lumbosacral injuries that assists in clinicaldecision making.
Methods
A review of PubMed from 1910 to 2011 was performedwith various keyword search terms related to different sa-cral fracture patterns, lumbosacral injury, LSD, spinopelvicdissociation, lumbosacral subluxation, lumbosacral disloca-tion, and sacral injury classification. Results of English andnon-English literature were extensively reviewed and se-lected for their relevance, level of medical evidence, sound-ness of their methodology, and popular acceptance amongspine and orthopedic trauma communities, and 43 relevantarticles were reviewed [31] (Table 1). The data were dis-cussed among spine surgeons and orthopedic trauma sur-geons familiar with the treatment of complex high-energysacral fractures and LSD injuries. Civilian experts wereidentified primarily from academic research contributionsto the published literature regarding complex lumbosacralinjuries, and one of us (CB) was chosen as the civilian rep-resentative to determine specific variables important toexpert surgeons at civilian Level 1 trauma centers in thetreatment of complex lumbosacral injuries. Experts also in-cluded military spine surgeons highly experienced in treat-ing blast-related injuries and consisted of two militarymedical centers with the highest volume of combat casualtycare from the current overseas conflicts. The proposed clas-sification was discussed with both civilian and militaryexperts, and we identified the significant clinical and radio-graphic variables encountered during the decision-makingprocess for current standard-of-care treatment of complexlumbosacral injuries. All existing sacral injury classification
Table 1
Literature review
Author, year Level of evidence No. of patients Variable
Purser, 1969 [1] 4 1 Fracture morphology
Roy-Camille et al., 1985 [2] 4 13 Fracture morphology
Helgeson et al., 2011 [3] 4 23 Fracture morphology—blast/shear type
Neurologic status
Soft-tissue status
Immobility
Schildhauer et al., 2006 [4] 4 18 Fracture morphology
Neurologic status
Bellabarba et al., 2006 [5] 4 19 Neurologic status
Soft-tissue status
Degree of comminution/deformity
Nork et al., 2001 [6] 4 19 Fracture morphology
Neurologic status
Carl et al., 1985 [8] 4 1 Fracture morphology
Neurologic status
Bents et al., 1996 [9] 4 1 Fracture morphology
Neurologic status
Hunt et al., 2002 [10] 4 4 Fracture morphology
Immobility
Isler, 1990 [11] 4 193 Classification of lumbosacral injury
Markel et al., 1993 [12] 4 1 Fracture morphology—rotation/translation type
Vresilovic et al., 2005 [13] 4 2 Fracture morphology
Cruz-Conde et al., 2003 [14] 4 1 Traumatic lumbosacral dislocation
Herron and Williams, 1984 [15] 4 1 Lumbosacral fracture dislocation
Naude et al., 1992 [16] 4 1 Lumbosacral fracture dislocation
Veras del Monte et al., 2000 [17] 4 1 Traumatic lumbosacral dislocation
Marcus and Hansen, 1984 [18] 4 1 Fracture morphology—rotation/translation type
Van Savage et al., 1992 [20] 4 1 Lumbosacral fracture dislocation
Kaplan et al., 1999 [21] 4 1 Lumbosacral fracture dislocation
Verlaan et al., 2001 [22] 4 1 Traumatic lumbosacral dislocation
Fountain et al., 1977 [58] 4 6 Fracture morphology
Neurologic status
Phelan et al., 1991 [59] 4 4 Fracture morphology
Neurologic status
Kim et al., 2001 [60] 4 7 Fracture morphology
Neurologic status
Ebraheim et al., 2001 [65] 3 N/A Fracture morphology—cadaveric study
Hessmann and Rommens, 2002 [67] 4 2 Fracture morphology
Neurologic status
Yasuda et al., 1990 [68] 4 1 Fracture morphology
Savolaine et al., 1991 [69] 4 1 Fracture morphology
Neurologic status
(Continued)
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Table 1
(Continued )
Author, year Level of evidence No. of patients Variable
Suzuki and Mochida, 2001 [70] 4 1 Fracture morphology
Neurologic injury
Schildhauer et al., 2002 [72] 3 40 Fracture morphology
Vilela et al., 2007 [77] 4 1 Fracture morphology
Neurologic status
N/A, not applicable; PLC, posterior ligamentous complex.
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systems were also reviewed, and their methodologies andmajor limitations were carefully considered and used to pro-vide a framework for a new comprehensive lumbosacral in-jury classification system (LSICS). We also modeled thenew classification system using previously published para-digms for spinal trauma of the thoracolumbar spine (thora-columbar injury classification and severity score) andsubaxial cervical spine (subaxial cervical spine injury clas-sification system) [31,32]. These have recently gained pop-ularity in the spinal trauma community with enthusiasm fortheir validity and reliability and their use of injury character-istics important in identifying, managing, and predictingtreatment and outcomes of spinal trauma. Therefore, thisnew paradigm for characterizing complex high-energy sa-cral fractures and LSD injuries was a synthesis of the bestsacral fracture classification parameters produced throughextensive literature review and expert clinical experienceand modeled after recent comprehensive injury classifica-tion systems for the thoracolumbar and subaxial cervicalspine [31,32].
Results
We devised a new classification system called LSICSbased on three injury characteristics: injury morphologyas determined by the pattern of sacral injury on availableimaging studies, PLC integrity, and neurologic status ofthe patient. These characteristics were identified as criticalto clinical decision making in recent thoracolumbar andsubaxial cervical spinal trauma classification systems andaccordingly recognized to be appropriate for LSD injurieswith slight modifications. The three variables were alsodetermined to be the principal independent predictors ofclinical outcome, and each category was further dividedinto subgroups arranged from least to most significant. Acomposite injury severity score (CISS) was calculated bysumming a weighted score from each category, allowingpatients to be stratified into surgical and nonsurgical treat-ment groups based on threshold values. Modifiers to deter-mining appropriate selection for operative treatmentinclude systemic injury load and physiological status ofthe polytraumatized patient, soft-tissue status, and expectedtime to mobility. Finally, an algorithm was developed to de-termine the optimum operative technique based on the pre-viously outlined injury characteristics.
Classification system
The new classification system is used to assess complexhigh-energy sacral fractures and specifically LSD injuriesthat involve an anatomic separation of the pelvis from thespinal column. These injuries involve two primary fracturefragments, one consisting of the lumbar spine and centralsacral fragment and the other consisting of the peripheralsacral fragment and the pelvis. Another variant of LSDinjury includes lumbosacral dislocation, also termed trau-matic lumbosacral spondylolisthesis, which is a rare andhighly unstable injury pattern characterized by a translationof the lumbar spine on the sacrum. This is also an injury pat-tern that we have seen as a result of high-energy blast mech-anisms in our current conflicts in Iraq and Afghanistan.Therefore, the LSICS should be applied to complex lumbosa-cral injuries involving a transverse fracture with associatedbilateral longitudinal fracture components (often describedas U-type, H-type, Y-type, and lambda-type fracture pat-terns), significant comminution of the upper sacral levels(S1–S3), a traumatic spondylolisthesis involving the lumbo-sacral junction (L5–S1), or a vertically unstable sacral frac-ture. Although also the result of high-energy trauma,a unilateral impaction sacral fracture associatedwith a lateralcompression pelvic ring injury should not be evaluated usingthe LSICS.
Injury morphology
Injury morphology for LSD injuries has been previouslydescribed through a retrospective review and cadaveric studyby Roy-Camille et al. [2] and later modified by Strange-Vognsen and Lebech [30]. These previous classification sys-tems were largely used to determine the subgroups for injurymorphology of the new classification system that includeflexion compression, axial compression, translation/rotation,and blast/shear. The fourth subgroup takes into account ourrecent military experience, described by Helgeson andLehman et al. [3], of unique LSD injuries after combat-related high-energy blast trauma, typically involving severecomminution or segmental bone loss. Injury morphology isdetermined by careful review of plain radiographs (includinga lateral view of the sacrum), high-resolution (2-mm slice)reconstructed computed tomography (CT) imaging, andmagnetic resonance imaging (MRI). Our experience hasfound it imperative to have multimodal imaging of the
pression injury with mild kyphosis and no displacement.
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lumbosacral complex to ascertain a complete appreciationfor the fracture morphometry. Having said this, many ofour combat casualties after blast-related trauma presentwith metallic fragmentary wounds, vascular shunts, inferiorvena cava filters, and significantly impaired physiologicalstatus, which often preclude the ability to obtain an MRI(Table 2).
Flexion compressionThe flexion compression morphology is used to describe
an LSD injury that occurs with an axial load applied to theupper sacrum with the lumbar spine in flexion or kyphosis.This imparts a deforming flexion force on the superior frac-ture fragment (lumbar spine and attached upper sacral verte-brae). This is based on the Roy-Camille Type 1 sacralfracture, which describes a flexion fracture with a simple an-terior bending of the upper sacrum fragment [2] (Fig. 1). Thissubcategory of flexion compression injuries can vary fromminimal angulation to severe kyphosis of the superior frac-ture fragment. Sacral kyphosis is measured as the anglesubtended by a line drawn along the posterior cortex ofthe sacral body above and below the transverse fracturecomponent on lateral sacral radiographs or reconstructedsagittal CT images [4]. Kyphotic deformity in the presenceof an LSD injury is because of deforming forces of theiliopsoas muscle and the pull of gravity, causing the ceph-alad portion of the spine or sacrum to rotate into flexionrelative to the pelvis, even when the patient is nonambula-tory [3,4]. The long-term complications associated witha posttraumatic kyphotic deformity at the lumbosacraljunction include increased local degenerative changes,lumbago, and lumbar muscle weakness, as well as diffi-culty with sitting and gait efficiency [3]. As a result ofour experience with combat-related LSD injuries, and aspreviously reported by Nork et al. [6], we found that pa-tients treated nonoperatively with more than 20� of kypho-sis had progression of sacral deformity and representeda subset of patients with increased instability, thereforewarranting operative fixation [3,5,6]. We do not includethe Roy-Camille Type 2 fracture in this subcategory, whichis also characterized by a flexion deformity but has
� Axial compression (comminution of upper sacrum)B Without sacral canal or neuroforaminal encroachment 2B With sacral canal or neuroforaminal encroachment 3
� Translation/rotational 3B Anterior or posterior translation of upper sacrumB Lumbosacral facet injury or dislocationB Vertical translation or instability
� Blast/shear (severe comminution or segmental bone loss) 4
associated posterior displacement of the superior fracturefragment, best visualized on the reconstructed sagittal CTimages or sagittal MRI. We believe that displacement indi-cates a more severe injury pattern with increased instabilityand is therefore placed in the translation/rotation morphol-ogy subgroup.
Axial compressionThe axial compression morphology is used to describe
an LSD injury that occurs with an axial load applied tothe upper sacrum with the lumbar spine in neutral position,causing a comminuted fracture of the upper sacrum, withno displacement or translation relative to the lower fracturefragment. This injury morphology is based on the Roy-Camille Type 4 sacral fracture, which was a modificationby Strange-Vognsen and Lebech to the original classifica-tion [2,30]. The severity of the axial compression subcate-gory is determined by the presence of sacral canal orneuroforaminal encroachment. We believe that this is a lesssevere injury pattern compared with recently describedhigh-energy blast trauma casualties with severely commi-nuted and displaced LSD injuries.
Translation/rotationalThe translation/rotational injury morphology is the result
of a significant shear or torsional force and is based on radio-graphic evidence of an LSD injury with anterior or posteriortranslation of the superior fracture fragment, similar toRoy-Camille Type 2 and 3 sacral fractures [2] (Figs. 2 and3). We also include in the translation/rotational morphologya variant of LSD injury, which involves significant shear or
Fig. 2. Sagittal reconstructed computed tomography image translation/rotational injury with severe kyphosis and posterior displacement.
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torsional forces at the lumbosacral junction (L5–S1) result-ing in lumbosacral facet injury. Lumbosacral junction injurymay be present even in the absence of a transverse fractureline, with L5–S1 instability as a consequence of a verticalsacral fracture causing facet joint disruption [7]. Isler [11]first classified injuries of the lumbosacral facet and de-scribed significant lumbosacral instability with a verticaltransforaminal sacral fracture either medially or directlythrough the S1 articular process, or Isler Type 2 and 3 in-juries, respectively. The author demonstrated that a fractureline lateral to the S1 articular process, or Isler Type 1 injury,is not associated with instability because the L5–S1 articu-lation remains continuous with the stable fracture compo-nent of the sacrum [11]. A more severe form oflumbosacral facet injury involves lumbosacral dislocation,also termed traumatic lumbosacral spondylolisthesis, whichis a rare and often fatal lesion with only approximately 30cases reported in the literature [13,18–24,33]. This transla-tion/rotational injury results in anterolisthesis of L5 on S1as a result of bilateral dislocations or fracture dislocationsof the L5–S1 facet joints and can involve mild anterior trans-lation or complete dislocation of the lumbar spine anterior tothe sacrum. Also included in the translation/rotational injurymorphology is a high-energy sacral fracture involving verti-cal translation or instability [34–36].
The lumbosacral junction is considered a nonconstrainedarticulation, and the stability of this transition area islargely determined by other osteoligamentous constraints.Failure through a translation/rotational injury morphologyat the lumbosacral junction requires significant destruction
of normal anatomy and imparts considerably more instabil-ity than failure from flexion or axial compression [31]. Thesacrum has variable kyphosis, ranging from 0 to 90� of an-gulation, and contributes to the pelvic tilt and sacralinclination angle of the superior end plate of S1 [31,37].Consequently, the compensatory lordosis of the lumbarspine and the forward inclination of the superior end plateof the S1 predisposes the L5 vertebra, and the entire lumbarspine, to slide anteriorly down the slope [7,38]. However,there are significant anatomic restraints to forward transla-tion and rotation provided by the anatomy of this transitionarea and include the L5–S1 facet joint, the facet joint cap-sule, and the strong PLC of the lumbosacral junction. Thebony anatomy of the L5–S1 facet joint provides the mostsignificant resistance to forward translation and rotation be-cause the facet joint is oriented 45� to the sagittal plane.The PLC has considerable strength, and the tension sus-tained through the iliolumbar ligaments is evident in thesize of the L5 transverse processes, which are significantlylarger and thicker compared with other lumbar levels[7,38,39]. Therefore, a sacral fracture involving the lumbo-sacral facet joint or a lumbosacral dislocation is usuallycomplex and inherently unstable and therefore warrants op-erative fixation [7,11]. However, meaningful outcome dataare limited, and untreated lumbosacral facet injuries orlumbosacral dislocations can lead to a residual facet incon-gruence that may contribute to clinically relevant symptomssuch as posttraumatic arthrosis and late lumbosacral pain[7]. The translation/rotational injury morphology is bestrecognized and evaluated using the sagittal CT
/rotational injury with mild kyphosis and anterior displacement.
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reconstruction, which provides the details necessary to vi-sualize disruption of the lumbosacral facet and lumbosacraljunction. An axial CT reconstruction may demonstratea shift in the midline sagittal plane across the lumbosacraljunction, and any translation or rotation unrelated to degen-erative causes is considered a translation/rotational injurymorphology.
Blast/shearThe blast/shear morphology is primarily identified by
the evidence of significant comminution and displacementof the upper sacrum, often with segmental bone loss(Figs. 4–6). Essentially, if the fracture of the upper sacrumis exceedingly complex and cannot be placed into the pre-vious subgroups, it is considered a blast/shear morphology.In the community setting, LSD injuries are frequently theresult of motor vehicle collisions or falls from height, withenergy transferred from the lower extremities through theacetabulae into the pelvis and spine. However, Vresilovicet al. [13] recently reported two cases of traumatic spondy-lopelvic dissociation injury and characterized this complexinjury pattern as involving significant fracture comminu-tion and severe instability in the cephalad direction. Theauthors described the mechanism as a direct blow to theposterior part of the sacrum, resulting in an extremelyhigh-energy fracture pattern with associated extensivesoft-tissue damage, hemorrhage, and visceral injury.
Fig. 4. Sagittal reconstructed computed tomography image blast-shear in
Schildhauer et al. [40] also proposed a Type 5 shear injuryto the Roy-Camille classification, which was described asa direct loading mechanism such as impalement or ballistictrauma. The authors reported a case report of patient whosustained an unusually complex multisegmental sacral in-jury with severe comminution that did not fit any existinginjury type [40].
We have experienced a high incidence of similar high-energy injuries after combat-related trauma [3], with theblast injury morphology being the result of an extremelylarge blast force through the bottom of a vehicle, causinga substantial superiorly directed force on the seated com-batant and subsequently imparting a significant amountof energy directly to the bottom of the pelvis and sacrum.We believe that this injury morphology represents the mostsevere LSD injury pattern, and these highly complex sacralinjuries result in a great degree of anatomic disruption andinstability, frequently necessitating soft-tissue managementand a more complex level of decision making with regardto operative intervention. Additionally, because the zone ofinjury is extensive and not limited to the lumbosacral re-gion in these blast injuries, several of our combat casual-ties have experienced open LSD, adding an additionallayer of complexity to the management of these injuries.Additionally, we have found that many injuries have asso-ciated dural tears, which further compromise the care ofthe patient.
jury with severe comminution and complete anterior displacement.
Fig. 5. Postoperative radiographs blast-shear injury from Fig. 4 after L4-to-ilium posterior spinal fusion.
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Integrity of the PLC
The anatomic components of the PLC in the lumbosa-cral region include the supraspinous ligament, interspinousligament, ligamentum flavum, iliolumbar ligament, laterallumbosacral ligament, and the facet joint capsule. ThePLC provides significant restraint against deforming forces,particularly anterior translation and flexion deformity. Thisallows for movement under normal physiological load andhas been termed the ‘‘posterior tension band.’’ The integrity
Fig. 6. (Top) Axial and (Bottom) sagittal reconstructed computed tomography im
anterior translation of fracture fragment.
of the PLC is thought to be directly proportional to spinalstability [31]. This is important for fracture classificationand clinical decision making because soft-tissue healingof this ligamentous complex is less predictable than bonehealing and generally necessitates operative stabilization.If a PLC injury is unrecognized or inappropriately treated,progressive deformity and instability could potentially leadto catastrophic long-term disability. Therefore, assessmentof the PLC integrity is a critical and independent
ages blast-shear injury with severe comminution, segmental bone loss, and
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component of clinical decision making and is categorizedas intact, indeterminate, or disrupted. Assessment of PLCintegrity is made through available imaging, including plainfilms, reconstructed CT images, and MRI. Translation/rotational injury morphology is almost always associatedwith some degree of PLC compromise. The facet joint cap-sule and bony anatomy of the facet joint are the strongestcomponents of the PLC; these determine stability and resis-tance against forward displacement. Therefore, any abnor-mal facet alignment, including unilateral or bilateral facetfracture, subluxation, or dislocation, is considered an abso-lute indication of PLC disruption [32]. Another indirect indi-cator of PLC disruption is fracture of the L5 transverseprocess, which represents a functional disruption of the ilio-lumbar ligament [41]. The iliolumbar ligaments are of par-ticular importance because they prevent forward translationof the L5 vertebra relative to the sacrum and also resist tor-sional forces [38,42–45]. When the evidence of PLC disrup-tion is subtle or the injury is sustained as a result of significanthigh-energy trauma, the integrity of the ligaments is recordedas indeterminate (Table 3).
Neurologic status
Neurologic function has not been a component of widelyrecognized trauma classification systems, despite the factthat neurologic injury is the major determinant of a patient’squality of life after spinal trauma [7,46]. In a report byBellabarba et al. [5], the predominance of complaints aftercomplex lumbosacral injuries was the result of persistentneurologic deficits causing bowel and bladder dysfunction,sexual dysfunction, and dysethesias in the lumbosacralplexus distribution. Significant neurologic injury is also animportant indicator of instability and the severity of spinalcolumn injury, as disruption of the strong osseoligamentousanatomy of the sacrum protecting the cauda equina, lumbo-sacral plexus, and sacral plexus requires an extremely severehigh-energy trauma. In addition, neurologic status may bethe single most important aspect of patient evaluation andsurgical decision making, as the presence of progressiveneurologic deficit necessitates a decompressive procedureto improve the likelihood of functional neurologic recovery.Gibbons et al. [26] described a classification for sacral neuro-logic injury, which we modified as the basis for characteriz-ing severity of neurologic injury in our new classificationsystem. The neurologic status is described in increasingorder of urgency: neurologically intact, paresthesias, lower
In each of the three categories, points are assigned to re-flect the degree of injury severity and the potential impacton mechanical stability or functional neurologic outcome.A CISS is calculated by summing the score from each cat-egory, allowing patients to be stratified into nonoperative oroperative treatment groups based on threshold values. If thetotal score is from 1 to 3, nonoperative treatment may berecommended. If the total is greater than or equal to 5, op-erative treatment is recommended. Our definition of opera-tive treatment consists of reduction (indirect decompressionusually through ligamentotaxis), direct neurologic decom-pression, and/or stabilization.
Injury morphologyA flexion compression injury is assigned one point. If
there is more than 20� of kyphosis, an additional point(1þ152 points) is assigned. An axial compression injuryis assigned two points, and if sacral canal or neuroforami-nal encroachment is present, an additional point (2þ153points) is assigned. Translation/rotational injuries are as-signed three points and include variants of lumbosacralfacet injuries and dislocations. The most severe injury isblast/shear morphology and is assigned the maximum pos-sible four points. Only the most severe or the highest scoreinjury morphology is used to calculate the injury severityscore (Fig. 7).
Integrity of PLCAn intact PLC is assigned no points. Definite PLC dis-
ruption (as indicated by significant flexion/translation, com-minution, facet joint injury, lumbosacral dislocation, oriliolumbar ligament injury) is assigned two points. WhenPLC integrity is indeterminate (ie, mild flexion deformity,MRI signal change), one point is assigned.
Neurologic statusA patient with no neurologic deficit is assigned zero
points. A patient is assigned one point for exhibiting onlysensory deficits/paresthesias, two points for lower extrem-ity motor deficits, and three points for complete caudaequina injury (bowel and bladder dysfunction). If there is
Table 4
LSICS neurologic status
Severity Points
Intact 0
Paresthesias only 1
Lower extremity motor deficit 2
Bowel/bladder dysfunction 3
Progressive neurologic deficit 4
Fig. 7. Illustration of lumbosacral injury fracture morphologies: (A) flexion compression, (B) axial compression, (C) translation/rotation, and (D) blast/shear.
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a progressively worsening neurologic deficit, the patient isscored four points.
Clinical modifiers
Although the use of a CISS objectively addresses lumbo-sacral injuries and assists in clinical decision making, a vari-ety of other factors can significantly influence treatment.These clinical modifiers should be considered for all com-plex high-energy sacral injuries before acting exclusivelyon the injury severity score, including systemic injury loadand hemodynamic stability of the polytrauma patient (ie,physiological status), soft-tissue status (ie, open fracturesand known dural tear), and expected mobility status (ie, ifa patient is going to be at bed rest for 3 months, consider-ation may be given to nonoperative treatment of acceptablyaligned fractures if there is no neurologic deficit).
When considering the systemic injury load and hemody-namic stability of the polytrauma patient, timing of surgicalintervention should be chosen based on treatment goals andinvasiveness of the surgical procedure. Aggressive attemptsat early surgery can lead to risk of significant intraoperativeblood loss, cardiopulmonary compromise, soft-tissue break-down, and unacceptable risk for infection in the meta-bolically challenged trauma patient [7]. Clinical decisionmaking should also take into consideration other associatedsystemic injuries or musculoskeletal injuries, severe trau-matic brain injury, osteoporosis, obesity, patient’s physiolog-ical age and previous general health condition. However,significant delay in decompression of compromised neuralelements, usually more than 2 weeks, may adversely affectthe optimal chance for functional neurologic recovery[7,29]. An additional factor is that many of the war-injuredpatients present with multiple extremity injuries and ampu-tations and are systemically anticoagulated because of a pro-longed medical evacuation process from the combat theaterto the definitive treatment facility or Echelon V facility (ie,Walter Reed Army Medical Center) and often present withknown deep vein thrombosis or pulmonary embolus.
Evaluation of soft-tissue status is also extremely impor-tant for patients with complex high-energy lumbosacralinjuries because the presence of an open fracture substan-tially affects treatment and prognosis [31]. The thin poste-rior soft-tissue envelope of the presacral area consists ofa thin layer of multifidus muscle and the lumbosacral fas-cia, which has a limited ability to withstand blunt traumaand tolerate prominent posterior instrumentation [31].Most open lumbosacral fractures can be described as Type3-A, according to the Gustilo-Anderson classification sys-tem [47]. However, combat casualties have frequently ex-perienced more severe open and degloving soft-tissueinjuries of the presacral and gluteal areas as a result ofhigh-energy blast trauma [3]. Helgeson et al. [3] reportedan overall 13% infection rate for combat-related LSD in-juries, which rose to 33% when open injuries were ana-lyzed separately. The authors noted that in cases of openinjury, particularly with large gluteal wounds and compro-mised presacral tissues, nonoperative management was ul-timately chosen in most patients in this cohort. Patientsshould also be carefully assessed for more significant openinjuries involving violation of the rectal or vaginal vault orcontamination from associated urogenital injury [39]. Al-though fecal diversion is not routinely indicated in patientswith open injuries, wounds near the rectum may benefitfrom colostomy [40,48,49]. Other soft-tissue injuries thatcan complicate operative management include superficialor deep burn wounds, as well as a closed injury with exten-sive lumbosacral fascial degloving similar to a Morel-Lavellee injury. Therefore, in any case with compromisedsoft tissue about the presacral and gluteal area, operativeintervention and technique should be carefully plannedand timed [50].
Clinical decision making also depends on the mobilitystatus of the patient. This modifier has become particularlyimportant with our experience in the treatment of themultiple-injured combat casualty, with significant systemicinjury load or compromised posterior soft tissue, and othersubstantial associated injuries that prevent the patient fromearly weight bearing.
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Treatment algorithm
The LSICS and CISS, in conjunction with the three mod-ifiers for systemic injury load, soft-tissue status, and mobil-ity status, can be used to guide clinical decision making(Fig. 8). Nonoperative management should be consideredin patients whose expected immobility or nonweightbearingis more than 3 months, which is typically the time necessaryfor early fracture consolidation. With the sacrum beingcomposed of mostly cancellous bone, we have seen manyLSD fractures consolidated over this time frame without fix-ation. Other clinical factors that should persuade the sur-geon toward nonoperative management include significantsystemic injury load with multiple associated injuries or co-morbidities and compromised soft-tissue status preventingsafe operative stabilization. However, in a patient with sig-nificant deformity with unfavorable pelvic incidence [51],acute realignment and stabilization should be considered,because after fracture consolidation the chance to reliablycorrect alignment may be lost, and there is significant mor-bidity with late sacral realignment/osteotomy procedures.
Operative stabilization promotes healing and earlier mo-bilization but can result in significant perioperative risk.When operative treatment is indicated, clinical decisionmaking should incorporate clear and realistic attainable
Fig. 8. Treatment algorithm for complex lumbosacral
goals, including fracture stabilization and lumbosacralalignment, early mobilization to facilitate rehabilitation,optimization of neurologic recovery, adequate debridementof open injuries and compromised tissues, and minimiza-tion of additional morbidity [7]. Operative techniques canrange from minimally invasive techniques to comprehen-sive posterior decompression with open reduction internalfixation or segmental iliolumbar fixation.
The surgeon should consider stand-alone bilateral percu-taneous sacroiliac screw fixation in patients without sig-nificant deformity or comminution and when expectedimmobility is between 6 and 12 weeks. A report by Gribnauet al. [46] demonstrated that early postoperative mobiliza-tion was frequently delayed by associated injuries. A fre-quent reason was the presence of calcaneal fractures, withnearly all their patients sustaining bilateral injuries, causingnonweight bearing for 8 to 12 weeks after fixation [46].This minimally invasive technique has limited biomechan-ical stiffness and requires an attempt at early closed reduc-tion. However, only a minimal amount of reduction isattainable through closed means and made considerablymore difficult as the time from injury increases. Also, thereis risk to neural, vascular, and visceral structures as a resultof screw or drill misplacement, which has been rarely
injuries. CISS, composite injury severity score.
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described and dramatically increases when there is signifi-cant displacement or deformity because of the narrowing ofthe safe zone for iliosacral screw placement. Alternatives topercutaneous sacroiliac screw placement should be consid-ered when there is anomalous transitional lumbosacral anat-omy, when closed reduction is inappropriate, unsuccessful,if there is severe comminution, or if unable to obtain accept-able fluoroscopic visualization [4,6,7,52]. Minimally inva-sive fixation is also typically inappropriate for translation/rotation and blast/shear injury morphologies, where the of-ten significant displacement, comminution, or instability atthe lumbosacral junction precludes reliable closed reductionand adequate decompression and stabilization. Nork et al.[6] reviewed a series of 13 patients using in situ percutane-ous sacroiliac screw fixation for U-type sacral fractureswithout decompression. In this select series of patients withminimal comminution and relatively minor deformity, theauthors found that all fractures healed clinically and radio-graphically. Most (77%) patients with initial neurologic def-icits and no neural pathway debris had resolution of sacralnerve root dysfunction, and all screws demonstrated accu-rate placement without neuroforaminal or sacral spinal ca-nal violations [6].
If immediate mobility is expected and the patient’s anat-omy or injury morphology prevents safe percutaneous fixa-tion [53], the surgeon should perform stabilization withposterior lumbopelvic instrumentation, with indirect de-compression via fracture reduction, as well as direct sacralnerve root decompression when appropriate. Urgent reduc-tion or surgical intervention should be considered for a dis-placed sacral fracture causing skin tenting or impendingdorsal soft-tissue compromise, as well as progressive neu-rologic deficit. All information pertaining to the patient’sinjuries and medical condition should be considered duringclinical decision making to weigh the associated risks andbenefits of various treatment options. The literature has alsoreported that patients treated with posterior lumbopelvicinstrumentation frequently complain of prominent instru-mentation, occasionally with associated skin ulceration,and recommend the recessing of iliac screw to reduce pro-minence as a routine technique of lumbopelvic fixation[4,5,36]. However, the most frequent complication relatedto lumbopelvic fixation has been fracture of the connectingrods (31%) and wound-related problems (26%) such as in-fection, hematoma, and seroma [4,5]. There is no classifica-tion system or treatment algorithm that can supersedea surgeon’s experience and clinical acumen in prioritizingand integrating a multitude of complex clinical variables.However, if an unstable LSD injury or complex sacral frac-ture is left untreated, either intentionally or because of lackof recognition, painful progressive deformity or worseningneurologic dysfunction may occur, with late corrective sur-gery being generally more complex and associated withworse outcomes [2,4,29,54].
The patient’s neurologic status should also guide clinicaldecision making. The benefits of nonoperative versus
operative decompression for neurologic deficit have yet tobe established and remain controversial [4,26,54–57]. Thedifficulty in determining treatment is largely because ofthe difficulty in diagnosing the extent of sacral nerve rootinjury [54]. Neurologic dysfunction may be related to nerveroot contusion, compression, or stretching caused by frac-ture angulation/displacement, neuroforaminal encroach-ment, or even by transection of the nerve root. Neurologicimprovement has been reported in up to 80% of sacral frac-tures regardless of treatment, even in the presence oflumbopelvic instability [4–6,26–28,36,58–60]. However,recent case series have described better neurologic outcomewith surgical treatment, particularly in patients with boweland bladder dysfunction [4,5,29,55]. Denis et al. [29] re-ported no improvement in bowel/bladder function in allthree patients with a transverse sacral fracture treated non-operatively, whereas all five patients treated surgically hadcomplete return of bowel/bladder control. Fountain et al.[58] reported similar results for five of six patients withtransverse sacral fractures, who had gradual improvementof bowel and bladder dysfunction within 4 to 6 months afterposterior sacral laminectomy and decompression. More re-cently, Schildhauer and Bellabarba et al. [4] demonstratedgood outcomes after lumbopelvic fixation and decompres-sion in 19 patients who all had neurologic deficits affectingbowel and bladder function, with loss of anal sphinctertone. The authors found that 83% of patients had improve-ment in bowel and bladder function, with 56% of patientswith complete nerve root injuries recovering full boweland bladder function. Conversely, patients with transectionor avulsion injury of any lumbosacral nerve root (even innerve roots not responsible for bowel and bladder function)were unlikely to have significant improvement, probablybecause of the greater degree of neurotrauma sustained. Ifsuch situations can be reasonably anticipated preoperatively,decompression should be avoided. Otherwise, we recom-mend operative decompression if there is a reasonablechance of restoring even unilateral sacral nerve root functionthat is often sufficient for voluntary bowel and bladder con-trol [7,61].
Huittinen in a postmortem study [62] found that trans-verse sacral fractures were associated with a 35% rate of sa-cral nerve root transection. Nerve root transection injurieshave also been frequently associated with Roy-CamilleType 3 LSD injuries, whereas lumbosacral plexus avulsionswere associated with severely displaced Denis Zone II‘‘vertical shear’’ type injuries [2,26,36]. Unfortunately,there is currently no ability to identify the extent of sacralnerve root or lumbopelvic plexus injury based on imagingmodalities or electrophysiological testing. We have also ex-perienced difficulty in determining neurologic status in ourpolytrauma combat casualties who are intubated or ob-tunded, have severe traumatic brain injury, complex uro-genital injuries, and complex lower extremity injuries oramputations. The multiple studies arguing for nonoperativetreatment versus decompression have both had significant
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limitations with regard to cohort size, selection bias, hetero-geneous injury patterns, poor documentation of neurologicstatus and severity of neuroforaminal encroachment, andconsistency in the type and timing of surgical interventionand decompression [7]. Along with this controversy, thereis no specific recommendation concerning the optimal tim-ing of decompression surgery, although the potential benefitsof early surgical intervention include functional neurologicrecovery and patient mobilization. However, these must beweighed against the increased risk of hemodynamic instabil-ity, hemorrhage, wound complications, and cerebrospinalfluid leak in the physiologically compromised polytraumapatient. Prolonged delay of surgical decompression in pa-tients with canal encroachment and concordant neurologicdeficit may negatively influence functional neurologic out-come and should be treated within a 48-hour to 2-week timeframe [27,29,55,63,64]. Also, delayed decompression afterfracture healing may be complicated by epineural fibrosisand increased scarring of the central canal and foramina[39,55].
Again, there have not been any prospective randomizedtrials that demonstrate a proven early decompression andan improved neurologic outcome after sacral fracture.We have also found that most combat casualties with com-plex lumbosacral injuries after blast trauma have neuro-logic deficits that are proportional to the energy of injuryand degree of initial fracture displacement. Many of ourpatients after blast injury have had gradual improvementof neurologic function within 1 year regardless of treat-ment and therefore operative exploration and decom-pression should be individualized based on the patient’sinjury morphology and associated injuries [3]. Also, thesepatients often have open wounds with contamination thatrequire obligatory operative debridement, and any bonefragments causing neural compression should be removedand associated dural tears appropriately repaired to preventpseudomeningocele.
In summary, we recommend that the earlymanagement ofcomplex lumbosacral injuries should begin with an attemptat the least invasive possible means for reduction and stabi-lization. If the patient has worsening neurologic status or sig-nificant neuroforaminal or spinal canal compromise, a focallimited decompression should be performed within 2 weeksof injury, with a limited midline exposure and fluoroscopi-cally guided focal laminectomy [7]. However, if closed re-duction and percutaneous stabilization cannot reasonablyaccomplish the desired goals, a comprehensive posterior de-compression and stabilization should be performed. Thetreatment of complex high-energy sacral injuries may alsorequire the assistance and expertise of orthopedic traumasurgeons, who are generally more experienced with sacroil-iac screw insertion and sacral plating but may have lessexperience with neural decompression and pedicle screwplacement for lumbopelvic instrumentation [37]. In thesame context, various surgical approaches may be usedsuccessfully in the treatment of LSD injuries and complex
sacral fractures. Like many aspects of patient care, con-tinuous communication between all members of the multi-disciplinary trauma team is paramount to a successfuloutcome for the patient.
Discussion
The necessity of a clinically relevant sacral injury clas-sification was brought to the forefront by our increasing ex-perience with complex combat-related sacral injuries andLSD injuries. After an extensive review of the literature,in addition to substantial combined clinical experience,the authors have proposed a set of criteria and an injury se-verity score for the evaluation and clinical decision makingof complex lumbosacral injuries, in particular LSD injuries.
Our institutional experience from combat-related LSDinjuries has brought about unique challenges in the treat-ment of these complex sacral fractures. One of the reasonsthat we have seen a much higher preponderance of this in-jury pattern than in the civilian community is because ofthe force imparted by the blast mechanism. This occursmainly from two different injury mechanisms in the mili-tary population. The V-shaped hull of the current Mine Re-sistant Ambush Protected vehicle deflects the majority ofthe blast wave laterally around the bottom of the vehicle.However, until this modification was implemented, a highincidence of LSD injuries occurred as the vehicles weresubjected to a violently vertically directed axial force,which lifted the vehicles off the ground and then subjectedto a secondary axial force with gravity assistance on returnto the ground. Furthermore, improperly or unrestrained ve-hicle occupants would oftentimes be subjected to strikingthe roof of the vehicle, resulting in a third axial blow. Ob-viously, the position of the body is paramount, as one canonly surmise the soldier’s position (eg, axial flexion, neu-tral, and extension) by a thorough understanding of thefracture mechanism and morphometry.
We combined our military war time experience with theclinical expertise of civilian spine and orthopedic traumasurgeons to produce a classification system that objectivelydelineates the severity of the recent injuries after blasttrauma. There are several different sacral injury classifica-tions that incompletely characterize fracture patterns andmechanisms of injury [2,11,28–30]. The numerous classifi-cations demonstrate the difficulty at efforts to understandand communicate complex lumbosacral injuries, as wellas determining optimal treatment and prognosis [31]. Thesedescriptive noncomprehensive classification systems havebeen inconsistently used and resulted in a large body of lit-erature with few scientifically based insights, causing con-fusion in the approach to individual patients, particularlythe polytrauma patient with significant associated injuries.This has been compounded by the relative rarity and het-erogeneous nature and treatment of complex sacral frac-tures and dislocations, with even the most experienced
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orthopedic trauma surgeons and spine surgeons having lim-ited exposure to these injuries [7].
In addition to the confusing recommendations for man-agement of complex high-energy sacral fractures and LSDinjuries, most studies have been necessarily retrospective innature, with small heterogeneous cohorts, significant selec-tion bias, little to no documentation of preoperative andpostoperative neurologic examination, highly variable sur-gical technique and timing of intervention, and limitedreports of outcome measures such as pain and pelvic insta-bility [7]. The literature has multiple case reports and smallclinical series that infrequently report the measurements orfactors determining instability and offer little to guide clin-ical decision making. Therefore, the current literature hasa fundamental inadequacy preventing the ability to drawconcrete conclusions concerning the optimal managementof complex lumbosacral fractures, the ideal operative ap-proach for a given injury pattern, and the indications fordifferent operative techniques. These difficulties have re-sulted in confusion among orthopedic trauma surgeonsand spine surgeons, as well as researchers, residents, andmedical students.
The most widely recognized classification system for sa-cral fractures is the Denis three-zone descriptive classifica-tion, which was introduced in 1988 [29]. Denis et al. [29]performed a retrospective review of 236 patients over 11years and characterized sacral fractures based on the loca-tion of the vertical fracture line component in relation toinvolvement of the neuroforamina and the sacral canal.The authors determined a correlation between a more me-dially located fracture line to a higher energy injury mech-anism and increased prevalence of neurologic injury. Thissystem’s greatest strength of simplicity and reproducibilityleads to its greatest weakness of being noncomprehensiveand lacking clinical application. There has been limited ap-plication of this classification to complex sacral fractureswith multiplanar fractures or significant comminution, withmost complex injuries being characterized merely as Zone3 injuries. The Denis classification makes an attempt atproviding prognostic information concerning neurologicinjury; however, the paradigm fails to differentiate moresevere injury patterns, such as transverse fractures or sig-nificant comminution, and associated higher rate of boweland bladder dysfunction with more severe injury patterns[55,58,62].
Denis Zone 3 injuries [29] were differentiated by Roy-Camille et al. [2] in 1985, describing the injury morphologyof transverse sacral fractures and termed the injury patterna ‘‘suicide jumper’s’’ fracture. A transverse sacral fracturehas been commonly described after a fall from height orafter motor vehicle accidents and is by definition a complexDenis Zone 3 injury [60,65–68]. However, advances inimaging technique and wide-spread use of CT after high-energy trauma have demonstrated that most transversesacral fractures are frequently associated with bilateraltransforaminal vertical sacral fractures that extend to the
lumbosacral junction [69]. Therefore, Roy-Camille et al.[2] was the first to attempt classification of LSD injuries,describing his experience with a retrospective review of13 patients sustaining a transverse fracture of the uppersacrum, as well as a cadaveric experiment, to developa descriptive classification based on the position of thelumbar spine during injury. Types 1 and 2 were caused byimpact of the lumbar spine in the flexed position and Type3 with the lumbar spine and hips in extension. The authorsalso conducted a cadaveric study in conjunction with theirretrospective review to verify the proposed mechanisms ofinjury and positioning of the lumbar spine. There was asubsequent modification to this classification by Strange-Vognsen and Lebech with a Type 4 injury that was postulatedto be from an axial compression force with the spine ina neutral position [2,30]. Roy-Camille et al. provided rudi-mentary treatment recommendations based on their pro-posed classification; however, the proposed algorithm wasneither based on fracture stability nor on patient outcome.Also, advances in segmental spine fixation and increasedexperience with lumbopelvic instrumentation have signifi-cantly altered the treatment algorithm for LSD injuries[4,5,34,35,70–80].
None of the classification systems published to date haveintegrated injury morphology with specific treatment algo-rithms for the care of patients with complex lumbosacral in-juries. The multiple limitations of previous classificationsystems have been addressed with the LSICS, which is in-structive as to the severity of injury severity despite thecomplex biomechanical environment of the lumbosacralspine. We provide a treatment algorithm based on clinicalfactors relevant to the injured patient and incorporate a com-prehensive injury severity score using three criteria thatrepresent a high-risk injury pattern for instability and sub-optimal clinical outcome if left untreated.
Reliability and validation
Audige et al. [81] outlined a three-phase process for val-idating a new classification system. Our current descriptionof the LSICS is Phase 1, in which the classification is pro-posed based on literature review and expert opinion, withidentification of specific variables that influence clinical de-cision making and outcome. To bridge Phase 1 and Phase 2,the authors recommend a pilot reliability study to detect ob-vious inconsistencies between evaluators, thereby allowing
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the classification to be appropriately modified early in thedevelopment [81,82]. Phase 2 involves a multicenter multi-surgeon assessment for inter- and intraobserver reliability.Finally, Phase 3 involves a true validation of the classifica-tion system through a prospective observational clinicalstudy involving a heterogeneous group of surgeons, usingthe paradigm on a wide variety of patients to assess its clin-ical usefulness [81,82].
A pilot reliability study was performed using two primaryclassification developers and one spine surgeon newly intro-duced to the classification. Statistical analysis with intra-class correlation coefficient (ICC) was calculated usingSPSS 18.0 for Windows (SPSS, Inc., Chicago, IL, USA)to assess the inter- and intraobserver reliability of the evalu-ators. Acceptable agreement was defined a priori as an IC-C of more than 0.60 and poor agreement defined as#0.20, fair50.21 to 0.40, moderate50.41 to 0.60,good50.61 to 80, and excellent 0.81 to 1.00. We found goodto excellent ICC for inter- and intraobserver reliability(Tables 5 and 6).
Conclusion
We propose a novel classification, termed the LSICS,which provides a comprehensive and practical approachfor evaluating lumbosacral injury severity and guiding clin-ical decision making. Controversy remains in the area of sa-cral injury diagnosis, treatment, and determining prognosis.However, the LSICS reflects established clinical indicatorsand radiographic variables, cited in the literature and basedon expert consensus, important for predicting instability,progressive deformity, neurologic deterioration, and patientoutcome. We think the LSICS provides a significant im-provement over previous classification systems because ofits simplicity, standardization, and by taking into account rel-evant clinical factors. This should improve communicationfor complex high-energy sacral fractures and LSD injuriesbetween different members of the multidisciplinary traumateam and facilitate collaboration in treatment of this infre-quent and unique injury pattern. Ultimately, the LSICSmay also prove useful as a research tool to conduct prospec-tive studies to further our understanding on the outcomesafter various treatments for complex sacral injuries. Furtherstudies are necessary to determine the reliability and validityof this new classification system and justify its use in everyday clinical practice [81,82].
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