rifa 14

Journal of the American Academy of Orthopaedic Surgeons54

Of all types of acetabular fractures,the posterior-wall fracture is themost common and the seeminglyeasiest to treat. In Letournels seriesof 940 acetabular fractures, 24%were isolated posterior-wall frac-tures, and another 26% involved afracture of the posterior wall as partof a more complex fracture pattern.1The familiarity of the posteriorapproach to the hip and the simplic-ity of the fracture pattern lead manysurgeons to treat posterior-wallfractures when they might other-wise refer more complicated acetab-ular fractures.

Despite the routine nature of pos-terior-wall fractures, poor outcomesoccur frequently. In Epsteins long-term follow-up of 150 posterior-wall fractures, 88% of patientstreated in a closed manner had anunsatisfactory result, but so did37% of patients who underwent

early open reduction and internalfixation.2 A recent study reporteda 30% failure rate within the firstyear after fixation.3 Letournel1 andMatta4 achieved perfectly anatomicreductions of posterior-wall acetab-ular fractures in 94% to 100% oftheir cases, and they have indepen-dently demonstrated that residualdisplacements greater than only 1mm after fixation of most types ofacetabular fractures are associatedwith clinically significant jointdeterioration when patients areassessed at long-term follow-up.

The purpose of this article is toreview the assessment and man-agement of the isolated posterior-wall acetabular fracture, emphasiz-ing the factors influencing outcomethat the treating physician can con-trol. Associated fracture patternsthat involve the posterior wall willnot be discussed.

Etiology

Most fractures are the result of thesudden deceleration of an unre-strained occupant during a motorvehicle crash. Force is transmittedfrom the floorboard to the foot orfrom the dashboard to the flexedknee through the femur to thefemoral head. With the hip flexedand in varying degrees of adduc-tion and internal rotation, as thefemoral head dislocates, it fracturesthe posterior wall. The specificlocation of the fracture can be pre-dicted from the position of theextremity at impact.1 Generally,the shape of the acetabular fracturemade by the femoral head is an arcof varying size with a radius of cur-vature that approximates that ofthe head.

Because of the indirect nature ofthe fracturing force, it is unusual tosee significant direct soft-tissueinjury in the area of the hip, butassociated injuries to the extremityare common. Major knee ligament

Dr. Baumgaertner is Associate Professor andChief of the Orthopaedic Trauma Service,Department of Orthopaedics and Rehabili-tation, Yale University, School of Medicine,New Haven, Conn.

Reprint requests: Dr. Baumgaertner, Depart-ment of Orthopaedics and Rehabilitation, YaleUniversity School of Medicine, PO Box208701, New Haven, CT 06520.

Copyright 1999 by the American Academy ofOrthopaedic Surgeons.

Abstract

Only 30% of posterior-wall acetabular fractures involve a single large frag-ment. The majority are multifragmentary or have areas of impaction.Unsatisfactory clinical results occur in more than 80% of patients treated non-surgically. Operative management usually offers the best chance of preservinglong-term joint function, but only if an anatomically reconstructed acetabulumcan be achieved without complication. The keys to surgical success includemaintaining the viability of the fracture fragments and the femoral head itself,using bone grafts and buttress plating to support elevated and comminutedfragments, and protecting the neurovascular structures at risk. Complicationscan include sciatic nerve injury (incidence, 3% to 18%), heterotopic ossification(7% to 20%), and osteonecrosis of the femoral head (5% to 8%). Despite therelative simplicity of this acetabular fracture, unsatisfactory outcomes after sur-gical repair of the posterior wall occur in at least 18% to 32% of cases, resultsthat are worse than for most of the other more complex acetabular fracture pat-terns.

J Am Acad Orthop Surg 1999;7:54-65

Fractures of the Posterior Wall of the Acetabulum

Michael R. Baumgaertner, MD


Vol 7, No 1, January/February 1999 55

(e.g., posterior cruciate) injuries,osteochondral lesions, and footinjuries can be missed unless theremainder of the extremity is care-fully assessed. The physicianshould critically evaluate the statusof the sciatic nerve before and afterattempts at closed reduction. Aneurologic injury occurs in 18% to22% of patients who sustain poste-rior-wall fracture-dislocations.1,5Awareness and documentation of amotor or sensory deficit (even aminor one) avoids postoperativeconfusion and allows appropriatepreoperative counseling.

Classification

The posterior-wall fracture is oneof the elementary fracture patternsof the acetabular fracture classifica-tion system proposed by Letourneland co-workers in 1964.6 Althoughslightly modified subsequently,this system has been validated by30 years of observation and hasgained virtually universal accep-tance by acetabular-fracture sur-geons. In an attempt to create aunified classification system for allfractures, the Orthopaedic TraumaAssociation recently codified Le-

tournels classification into a for-mat that is consistent with the AOComprehensive Classification ofFractures, allowing computerizedcategorizing of posterior-wall frac-tures.7,8

In this system, there are threebasic patterns of posterior-wallfractures (Fig. 1). The simplest pat-tern is a fracture line that creates asingle posterior fragment. Single-fragment posterior-wall fracturesoccurred in 30% of fractures inLetournels series.1 They can occurin the posterosuperior aspect of thejoint and involve the roof, or weight-bearing dome, of the joint. Whenthese fractures occur posteroinferi-orly, they take in a varying amountof ischium.

The second variant is the multi-fragment posterior-wall fracture.This pattern is seen in about a thirdof cases and can be further classi-fied on the basis of the number andlocation of fragments.

The third type of wall fracture isthe one considered to be the mostcomplex and difficult to treat. Inaddition to a single-fragment ormultifragment wall fracture, someof the articular surface remainingmedial to the primary fracture lineis impacted into the cancellous

bone of the posterior column by thedislocating femoral head, rotatingan osteochondral fragment out ofits anatomic plane. The mecha-nism and resulting joint incongru-ency are similar to those seen whenthe lateral femoral condyle createsa split-depression fracture of thetibial plateau. Termed marginalimpaction by Letournel1 andacetabular depression fracture byBrumback et al,9 this type is report-ed to occur in approximately onefourth of all posterior-wall frac-tures.

Posterior hip fracture-dislocationscause a spectrum of osseous in-juries. The large, isolated single-fragment posterior-wall fracture isrelatively uncommon; the surgeonmust expect and be prepared toanatomically reduce and stabilizethe marked comminution andimpaction of the posterior wall thatis frequently found if the patient isto benefit from open treatment.

Radiologic Diagnosis

The anteroposterior (AP) radio-graph of the pelvis is an essentialdiagnostic test in most blunt-traumaevaluation protocols. Provided the

Fig. 1 The three subgroups of posterior-wall fractures. In the first type, a fracture line creates a single posterior fragment. The secondtype is a multifragment fracture. The third type (also called a marginal impaction or acetabular depression fracture) is a single-fragmentor multifragment wall fracture in which some of the articular surface medial to the primary fracture line has been impacted into the can-cellous bone of the posterior column by the dislocating femoral head, rotating the osteochondral fragment out of its anatomic plane.

Type 1 Type 2 Type 3

Posterior-Wall Acetabular Fractures


film is of good quality, most ace-tabular fractures can be recognizedon this view. If the hip has notbeen reduced, the wall fragment isusually seen to be displaced withthe femoral head, and the defect inthe posterior wall is readily appar-ent (Fig. 2, A). It is impossible tocompletely assess a posterior-wallfracture on an AP radiograph, butthis view is very helpful in exclud-ing other fracture patterns.

Of the six fundamental radio-graphic landmarks of the acetabu-lum described by Letournel,1,6 fivewill be seen to be intact and unaf-fected by an isolated posterior-wallfracture. Only the posterior rimwill be disrupted, although oncethe dislocation is reduced, the over-

lying femoral head may make thisfinding subtle. To exclude an asso-ciated acetabular fracture thatincludes a fracture of the posteriorwall, the other landmarks (anteriorrim, iliopectineal line, ilioischialline, tear drop, and acetabular roof)should be confirmed to be intact.Marginal impaction, if present, canoften be recognized on the AP radio-graph as a curved, dense subchon-dral line that is out of anatomicposition (Fig. 2, B). All radiographicviews, but particularly the AP view(which has the opposite hip forcomparison), should be scrutinizedto confirm that a concentric reduc-tion with a normal clear spaceexists between the femoral headand the remaining acetabulum and

that no incarcerated fragment ispreventing complete anatomicreduction.

The obturator oblique view,obtained by rotating the patient 45degrees onto the unaffected side,displays the obturator ring as near-ly circular and uncovers the poste-rior aspect of the acetabulum fromthe anterior wall and the femoralhead. It usually shows the fullextent of the fracture fragment, theamount of displacement, and thedefect in the acetabulum (Fig. 2, C).Incarcerated fragments in the ante-rior aspect of the joint are best seenon this view. The opposite obliqueview (the iliac oblique) is obtainedby rotating the patient 45 degreesonto the side of the fracture. The

Fig. 2 Images of a 37-year-old womanwith a left-hip fracture-dislocation. A, Thehip is dislocated with the femur adductedand internally rotated. Note the defect inthe posterior acetabular border and thewall fragment above the displaced femoralhead. B, After closed reduction, a walldefect remains, and there is evidence ofmarginal impaction (arrow) but theamount of posterior-wall fracture-displace-ment is not obvious. C, The obturatoroblique radiograph shows the wall frag-ment clearly. D, Axial CT image demon-strates significant marginal impaction andan inadequately reduced wall fracture.

C D

BA



unbreached borders of the greaterand lesser sciatic notches confirmthat the posterior column is intact,but the wall fracture is usuallyobscured.

Computed tomography (CT) isprobably the single most valuabletool in assessing posterior-wallacetabular fractures, provided indi-vidual images through the joint arecontiguous and not more than 3 to 5 mm thick (Fig. 2, D). It is alwayshelpful to include the contralateralacetabulum for comparison. Ifclosed management is being consid-ered, CT scanning utilizing 3-mmoverlapping sections is mandatoryto definitively exclude incarceratedfragments and subtle joint incon-gruity that can be missed on plainradiographs (Fig. 3, A and B).

During dislocation, the ligamen-tum teres frequently avulses a smallbone fragment, which appears as afree fragment on the CT scan. Aslong as it is small, low in the joint,and restricted to the confines of thecotyloid fossa, such a fragment isnot in itself an indication for openmanagement.

Computed tomography greatlyfacilitates the assessment of frac-ture comminution and residual dis-placement. It is the ideal study for

identifying posteromedial marginalimpaction in a fragment that isrotated externally. However, supe-rior impaction of the lateral aspectof the roof, which can occur in theplane of the axial CT section, maybe more clearly appreciated on anAP radiograph or with CT recon-structions. With thin sections, in-creased bone density can be seenwhere impaction into the cancellousbed has occurred (Figs. 2, D; 3, C).In addition, CT is frequently usedto quantify the amount of posteriorwall that remains after fracture byallowing comparison of the frac-tured side with the intact contralat-eral wall.10-12

Management Options

Although Epstein2 recommendedprimary open reduction for all pos-terior-fracture dislocations, mostprotocols employ urgent closedreduction with the use of adequatesedation and muscle relaxation.Reduction is immediately followedby clinical assessment of hip stabil-ity performed by cautiously flex-ing and slightly adducting the hipwhile feeling for subluxation.Sciatic nerve function should be re-

assessed and documented. Subse-quently, the adequacy of thereduction and the size and dis-placement of the fragments areassessed radiographically.9 Abso-lute operative indications includedeteriorating sciatic nerve functionafter attempted closed reductionand the presence of an incarceratedfragment that prevents congruentreduction of the head to the intactacetabulum. Inability to achieve aclosed reduction and the presenceof a femoral neck fracture are alsoabsolute indications for open man-agement.

With the widespread use of CTscanning, the amount of the poste-rior wall that is fractured or im-pacted (and therefore cannot supportthe femoral head) can be accuratelydetermined before surgery. Severalauthors have attempted to definehow much of the posterior wall isneeded to maintain hip stability.10-12There is general agreement that frac-tures involving 50% or more of theposterior wall are unstable and de-mand surgical repair, whereas frac-tures involving 20% or less are gen-erally stable and can be managed byactivity restriction with carefulobservation. Vailas et al10 demon-strated no hip subluxation at 90

Fig. 3 Images of a 65-year-old man with a right posterior-wall fracture. A, After closed reduction, it is difficult to appreciate the extent ofthe fracture on the AP radiograph. B, CT image shows an incarcerated osteochondral fragment in the joint (arrow), a comminuted rimfragment, and a completely deficient posterior wall. C, Another, more distal CT scan shows marginal impaction.

A B C



degrees of flexion, 20 degrees ofinternal rotation, and 20 degrees ofadduction in cadaver hemipelveswith fractures involving 25% of theposterior wall if the posterior capsulewas intact. Of the 9 hips with a com-plete capsulectomy, only 1 (11%)was unstable.

There is no consensus on treat-ment of fractures that are clinicallystable but involve 20% to 50% of theposterior wall. For these fractures,treatment decisions should bebased on the patients clinical situa-tion (age, activity level, expecta-tions, other injuries) as well as thelikelihood that the surgeon canachieve the desired surgical resultwithout complications. Althoughthe long-term effect on joint biome-chanics of reducing the contact areaof the posterior wall has not beenadequately studied, Olson et al13demonstrated near doubling of thecontact force on the superior aspectof the acetabulum after simulatedposterior-wall fracture in cadavers.Subsequently, they showed thateven small rim fractures that wouldnot cause clinical instability greatlyaltered joint-contact characteris-tics.14

If the hip is stable and closedmanagement is elected, bed rest isinstituted until the acute pain of thefracture-dislocation subsides. Mostauthors believe that skeletal trac-tion is not indicated. Historically, aprolonged period of bed rest withor without traction has been recom-mended, but the need for this hasnever been documented.12,15 Re-strictions against provocativeranges of motion (total hip precau-tions against adduction, internalrotation, and excessive flexion)until capsular healing occurs cer-tainly appear appropriate, but bedrest longer than that necessary forcomfort is not justified by any avail-able data.16 Weight bearing shouldbe limited until there is evidence offracture healing.13,17 It is impera-tive to monitor very closely any

patient who is managed nonopera-tively with the use of only activityrestrictions. Radiographs (andrepeat CT scanning if evidence ofinstability exists) should be ob-tained 1, 3, 6, and 12 weeks afterfracture, at the minimum.

Surgical Treatment

For isolated injuries, if the hip isreduced and nerve function is sta-ble, emergency operation is notwarranted. Surgery should pro-ceed as soon as the patient, theoperating suite, and the surgicalteam are prepared, usually within72 hours of injury. Maintaining thehip in mild abduction and externalrotation should obviate the needfor preoperative skeletal traction.If there is gross instability or ifthere are bone fragments withinthe joint, skeletal traction to neu-tralize the joint reaction force isindicated to prevent secondarymechanical damage to the articularcartilage.

Most of the instruments andimplants necessary to manage aposterior-wall fracture are availablein general orthopaedic operatingrooms. Small-fragment (3.5-mm)cortical screws of standard lengths

are used with reconstruction platesthat allow contouring in all threeplanes. A spiked-ball pusher tomanipulate and reduce wall frag-ments and a T-handled universalchuck mounted with a Schanzscrew, which can be inserted intothe greater trochanter to distractthe femoral head, are helpful acces-sories (Fig. 4). As blood loss israrely less than 700 to 1,000 mL,intraoperative red blood cell salvagesystems are usually an effectiveadjunct to minimize transfusionrequirements.

Use of somatosensory evokedpotentials to monitor sciatic nervefunction intraoperatively remainscontroversial. The technique is rec-ommended by some authors tohelp minimize the risk of iatrogenicnerve insult,5,18 but others considerit unnecessary and have reportedvery low rates of neurologic com-plications without the addedexpense and surgical time associat-ed with monitoring.19

An operating table that allowsunrestricted multiplanar and ob-lique fluoroscopic visualization ofthe pelvis is preferred over a stan-dard operating table or a fracturetable because it greatly facilitatesintraoperative assessment of thereduction and fixation. The C arm

Fig. 4 Instruments andimplants for treatment ofposterior-wall fractures:from left to right, spiked-ballpusher, T-handled universalchuck with Schanz screw,implant template, 3.5-mmreconstruction plates, recon-struction plate bendingirons, and pliers.



is positioned to be brought perpen-dicular to the table on the sideopposite the surgeon. With combi-nations of table tilt and C-arm cantand rotation, AP and Judet viewscan be obtained, as well as individ-ual oblique views that show screwsend-on or in perfect profile to con-firm exact length and position rela-tive to the joint and pelvic cortices.

The Kocher-Langenbeck poste-rior approach is always used forisolated posterior-wall acetabularfractures. The patient can be in thelateral or prone position with theinvolved extremity draped freely.Although lateral positioning ismore familiar to most surgeons, theprone position is preferred if thereis an extensive posterior-wall frac-ture with gross instability or if thefracture involves the roof of theacetabulum, because prone posi-tioning tends to slightly extend andabduct the hip, thus helping tokeep the femoral head reduced. Inaddition, the hip extension afford-ed by prone positioning (alongwith knee flexion) decreases therisk of stretch injury to the sciaticnerve.

It is important to appreciate thatthe approach for repair of a posterior-wall acetabular fracture is not thesame as a posterior approach fortotal hip arthroplasty. Anatomicplanes are blurred due to muscularhematoma from the recent trauma,and landmarks that are normallyeasily identified may be absent ormarkedly distorted. The sciaticnerve is directly at risk as it passesthrough the zone of injury andshould be visually identified inevery case, as it is immediatelysuperficial to where implants mustbe placed. Perhaps the most im-portant difference between fracturesurgery and replacement arthro-plasty is that the viability of thewall fragments and the femoralhead itself must be maintained; dis-section must proceed with thiscaveat in mind.

The skin and fascial incisions arecentered at the posterosuperioraspect of the greater trochanter andextend distally along the shaft andproximally toward, but not entirelyto, the posterior superior iliac spine.The gluteus maximus muscle issplit proximally until the first cross-ing branches of the inferior glutealnerve are reached (further dissec-tion will denervate the part of themuscle anterosuperior to the inci-sion). The osseous insertion of thegluteus maximus onto the femur isroutinely released about 1 cm fromits attachment to facilitate atrau-matic posterior retraction.

Careful posteromedial dissectionon the superficial surface of thequadratus femoris will identify thesciatic nerve, which is frequently intwo physically separate trunks atthis level. The lateral edge of thenerve is then followed proximallythrough the fracture zone to whereit exits the pelvis through thegreater sciatic notch, deep to thepiriformis muscle. With the nerveidentified and freed from imping-ing bone fragments, any blood-filled bursal tissue or avulsed mus-culature can be safely debrided.

The interval between the inferiorgemellus and the quadratus femorisis identified to avoid any inadver-tent dissection into the quadratus,which would risk injury to themedial femoral circumflex arterysupplying the femoral head. Thetendons of the piriformis and obtu-rator internus are identified andcarefully elevated off the joint cap-sule before sectioning. This allowsthe fractured wall fragments tomaintain their capsular attach-ments, which are frequently theironly remaining blood supply. Thetendons are cut in midsubstance,and the muscle ends are tagged.Retraction on these muscles allowsexposure of the retroacetabular sur-face posteriorly to the border of thegreater sciatic notch and the bursaaround which the obturator inter-

nus tendon exits the inner pelvisthrough the lesser notch. This ten-don can be sutured to the gluteusfascia to create a soft-tissue slingthat retracts and protects the sciaticnerve from the edge of a blunt-tipped nerve retractor maintainedin the lesser notch. Nerve retractorsin the greater notch, where thenerve is unprotected, should beused cautiously or not at all.

If further inferior exposure isnecessary, the origin of the quadra-tus femoris as well as the ham-strings can be taken down off theischium. The pudendal nerve ismedial to the field and is not at risk.Hip extension and knee flexion aremaintained throughout the proce-dure, and the sciatic nerve is inter-mittently inspected for inadvertentcompromise.

The gluteus minimus is elevatedoff the capsule and ilium as neces-sary. It is important to cautiouslyelevate near the superior border ofthe sciatic notch to avoid lacerationof the superior gluteal nerve, artery,or vein, which may lie directly onbone at this level. Anterior andsuperior exposure is facilitated byhip abduction, which relaxes themuscle and protects the superiorgluteal nerve from traction palsy.The field can be maintained byplacing Steinmann pins into thesuperolateral ilium.

The first step in the reductionand fixation stage is always toinspect the joint. The wall frag-ments are rotated back on their cap-sular attachments, and the fracturesurfaces are debrided of clot andcallus. A Schanz screw placed intothe trochanter is usually adequateto distract the femoral head, allow-ing examination of both articularsurfaces, removal of incarceratedfragments, and flushing of debrisfrom the joint. The size and shapeof any free cartilaginous fragmentsshould be noted before they are dis-carded. Free osteochondral frag-ments of significant size are marked



for orientation and set aside forlater reconstruction. If sustaineddistal retraction is desired, thefemoral distractor can be used effec-tively with one pin in the ilium andthe other in the trochanter.

After joint cleansing, the femoralhead is reduced to the intact acetab-ulum, and the quality of the jointreduction is evaluated. An anatomicreduction is implied if only theedge of intact acetabular articularsurface is seen through the fractureplane, and it is concentric and per-fectly satisfied by the femoral head.Marginal impaction exists if there isany acetabular cartilage that doesnot anatomically cup the reducedfemoral head but instead is rotatedto face toward the plane of the frac-ture. If not corrected, not only willthis aspect of the joint be incongru-ent, but the displaced articularosteochondral segment will preventanatomic reduction of the overlyingwall fragment. Therefore, frag-ments that are marginally impactedmust be recognized, elevated, andsupported with bone graft beforeaddressing other wall fragments.

The concentrically reduced fem-oral head acts as a template to guidethe reduction. A narrow Cobb eleva-tor can be used to create a planealong the cortex of the quadrilateralsurface, deep to the depressed articu-lar surface and underlying cancellousbone, and then to rotate the frag-ments en bloc to elevate the depres-sion (Fig. 5). Any free osteochondralfragments are reoriented andreduced to the head as well. To sup-port the reduced joint surface, a bonegraft from the greater trochanter ispacked into the defect that is createdbehind the elevator. The femoralhead prevents overelevation butallows aggressive impaction of thegraft into the defect such that afterthe procedure, the grafted areaappears more dense than the sur-rounding cancellous bone (Fig. 6).

Reduction and fixation of poste-rior-wall rim fragments that are at-

tached to the capsule is attemptedonly after the correction of any mar-ginal impaction, as this step preventsfurther unobstructed inspection ofthe articular surface. Slight abduc-tion and external rotation relaxes the

capsule and allows the fragments tobe manipulated. A spiked-ball push-er is helpful in completing and main-taining the reduction. Alternatively,temporary fixation can be achievedwith small Kirschner wires directed

Fig. 5 Technique for dealing with marginal impaction and a free osteochondral fragment.A, With the femoral head concentrically reduced to the intact acetabulum, the wall frag-ment with attached capsule (W) is reflected with a dental pick to reveal the marginalimpaction (I) and the free osteochondral fragment (F), which is temporarily removed. B,After harvesting of cancellous autograft (G) from the greater trochanter, an elevator is usedto undermine and derotate the impacted fragment. The femoral head guides the reductionand prevents overelevation. The autograft is impacted into the defect created by elevation.C, After repositioning and support of the osteochondral free fragment with additionalgraft, the wall fragment is finally repositioned. As the joint is no longer visible, the reduc-tion must be judged from the retroacetabular fracture line. D, The reconstructed posteriorwall is supported by a buttress plate and an appropriately directed lag screw.

A B

C D

I

F

W G

IF

WG



away from the joint. The quality ofthe joint reduction must frequentlybe inferred from the reduction of theretroacetabular cortical fracture linesand the continuity of the posteriorrim.

Definitive fixation of the wallfracture generally requires buttressplating. Very rarely, a large singlefragment can be adequately stabi-lized with three to five lag screws.Goulet et al17 demonstrated thatthe combination of a buttress plateand lag screws provided a fourfoldincrease in local effective stiffness(P



Additionally, the surgeon shouldpalpate and listen for any gratingof the joint with motion, suggest-ing misplaced hardware. It is veryhelpful to manipulate the positionof the table and the C arm so thatscrews near the joint are viewedend-on and appear as a circle onthe monitor. If the projectionshows the implant outside the jointclear space, the screw is unques-tionably safe (Fig. 9). Any muscleof questionable viability should beresected before the torn capsuleand the tendons of the short rota-tors and gluteus maximus inser-tion are repaired anatomically.The fascia and dermis are thenclosed in routine fashion. Hard-copy film of the key fluoroscopicimages as well as an AP view ofthe pelvis should be obtained be-fore the patient leaves the operat-ing room.

Postoperatively, patients com-plete their perioperative antibioticregimen and continue thromboem-

bolism prophylaxis.23 Before dis-charge, a complete set of pelvicradiographs should be obtained inthe radiology suite unless the intra-operative films are of excellentquality. If any question remainsregarding the quality of the reduc-

tion or the position of the hard-ware, a postoperative CT scan canbe obtained. Fracture healing andthe status of the joint should bemonitored radiographically withan AP view of the pelvis 6 weeks,12 weeks, and 6, 12, and 24 monthsafter surgery (Fig. 10).

Motion restrictions against ad-duction, internal rotation, and ex-cessive flexion are maintained for 4to 6 weeks. Even though the fixa-tion rarely involves the area of thejoint that resists the resultantforces of weight bearing, touch-down weight bearing should bemaintained for a period of at least6 to 8 weeks. Olson et al13 haveshown that even perfect anatomicreduction and rigid internal fixa-tion of a simple posterior-wall frac-ture does not restore normal loadtransfers across the joint. In an-other study, Goulet et al17 noted asmall margin of safety betweenconstruct strength and expectedphysiologic loads.17

Strengthening exercises shouldstart at 6 weeks and continue for atleast 6 months. Dickinson et al24examined patients an average of 21months after posterior-wall acetab-ular surgery (minimum, 6 months)and reported a 43% reduction in

A B

Fig. 8 Images of a 20-year-old man with a multifragment posterior-wall fracture. A, CTscan demonstrates marginal impaction, wall comminution, and a peripheral rim fragmentattached to the posterior capsule. B, Follow-up radiograph obtained 1 year after surgeryshows the rim fragment captured by a spring plate. The plate lies under the buttress plateand is fixed additionally by a screw.

Fig. 9 Intraoperative oblique fluoroscopic images obtained before buttress-plate applica-tion suggest (left) and confirm (right) safe screw placement by showing the two lag screwsend-on and outside the joint clear space.



abductor strength in patients whohad satisfactory reductions andwho had completed a postopera-tive physical therapy program.They postulated that the weaknesswas permanent and was related tothe amount of exposure and theforce of retraction on the superiorgluteal neurovascular bundle dur-ing surgery.

Complications

Hematoma and infection are rare butserious complications that are bestmanaged prophylactically. Theiroccurrence necessitates prompt sur-gical drainage. Like thromboem-bolism, they are not unique toacetabular fractures; therefore, theirdiagnosis and treatment will not bediscussed further.

Iatrogenic injury to the sciaticnerve is related not only to fracturepattern and approach but also tothe preoperative status of the nerve

and the experience of the surgicalteam.5 Letournel and Judet1 re-duced the rate of sciatic palsy from18% in their first 126 cases in whichthe Kocher-Langenbeck approachwas used to 3.3% in the subsequent211 cases. Almost invariably, theperoneal division is injured with orwithout some tibial compromise,and although the prognosis forimprovement is good, it is uncom-mon to regain completely normalmuscle and sensory function. Al-though the primary means used toavoid nerve injury are visualizationof the nerve and positioning of theextremity to minimize tension dur-ing retraction, somatosensoryevoked potential monitoring hasbeen used to identify nerve com-promise so that corrective actionscan be taken before irreversiblechanges occur.5,18

Osteonecrosis following opera-tive management of acetabularfractures is generally overdiag-nosed. When Kocher-Langenbeck

approaches have been used, ratesas high as 42% within the firstyear after surgery have beenreported.25 Rapid mechanicaldestruction of the femoral headcan occur from the injury itself,due to osteochondral impaction orcartilage crushing, or can be theresult of inadequate reduction,loss of reduction with recurrentinstability, or violation of the jointby inadvertently retained bonefragments or screws. These diag-noses should be excluded beforeconsidering a diagnosis of post-traumatic osteonecrosis of thefemoral head, which does not pre-sent until at least several monthsafter injury. Epstein2 identifiedosteonecrosis in 5.3% of surgicallytreated posterior-wall fractures.Letournel and Judet1 reported a7.5% incidence of osteonecrosis in227 fractures that included a pos-terior dislocation and that weretreated surgically within 21 daysof injury.

A B

Fig. 10 A, Postoperative obturator oblique view of same patient shown in Figures 3 and 6 demonstrates the reconstructed posterior wall,the plate contour, and the diverging screw pattern. B, Intermediate follow-up AP radiograph obtained at 30 months shows well-preserved joint space.



Heterotopic bone formationoccurs less frequently after aKocher-Langenbeck approach fora posterior-wall acetabular frac-ture than after an extensile ap-proach for associated fractures.Nevertheless, it still occurs in 20%of patients who have not receivedprophylactic therapy and is clini-cally significant (Brooker grade IIIor IV) in more than 7%.1 Male sexand head injury are factors thattend to increase the risk. Treat-ment with indomethacin (25 mgthree times a day, starting on theday of surgery and continuing for4 to 6 weeks) has been recom-mended as effective, safe, andinexpensive prophylaxis againstheterotopic ossification26,27; how-ever, a recent randomized pro-spective study by Matta andSiebenrock28 questions the efficacyof this method. Low-dose periop-erative irradiation (700 to 1,000cGy within 48 hours of surgery) iseffective in reducing the incidenceand severity of heterotopic ossifi-cation after acetabular fracture,29,30but the unknown potential for latecomplications from radiation dis-courage treatment with this mo-dality for the isolated posterior-wall fracture in the typicallyyoung patient.

Outcome

Patients with posterior hip disloca-tions that are associated with mini-mal acetabular rim fractures dowell provided reduction is promptand atraumatic.16 There is no ques-tion that unstable fracture-disloca-tions that receive delayed treatmenthave dismal clinical outcomes, withfailure rates approaching 90%.1,2,16It is in the light of these extremesthat the results of acute stabilizationshould be viewed. In the study ofPantazopoulos et al,31 more than90% of patients who had under-gone anatomic reduction of a poste-rior-wall fracture had a very goodclinical result 2 to 15 years (average,7 years) postoperatively, comparedwith only 50% of patients whosereductions had 1 to 3 mm of resid-ual displacement.

In Letournels series,1 19 (16%)of 119 perfectly reduced posterior-wall fractures were found to havedeveloped significant osteoarthro-sis at follow-up, which was as longas 25 years. The rate of posttrau-matic arthrosis after a perfectlyreduced posterior-wall fracturewas higher than the 10% rate forall types of acetabular fracturesthat had an anatomic reduction,but was much lower than the 38%

rate of arthrosis for posterior-wallfractures that were not reducedanatomically. Overall, Letournelreported an 18% rate of unsatisfac-tory outcome for posterior-wallfractures.

Femoral head impaction, carti-lage necrosis, and posterior-wallresorption can lead to arthrosiseven after anatomic reconstructionof the acetabulum. Despite achiev-ing perfect reductions in all 22 posterior-wall fractures treated,Matta had a 32% clinical failurerate in this group, higher than thatfor any other fracture pattern in hisseries of 262 fractures.4

Summary

Patients who sustain an unstableposterior-wall acetabular fracturehave a guarded prognosis. Ananatomic reduction is achievable inthe great majority of cases and is aprerequisite to long-term hip sur-vival. Although not even a perfectsurgical reconstruction of a joint willguarantee long-term function, thatgoal must be the mind-set of sur-geons who choose to treat this injury,because the results of imperfect orunstable reductions are clearly infe-rior and usually unsatisfactory.

References

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