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Acetabular Fracture ORIF - Posterior Wall

Comprehensive surgical technique guide for posterior wall acetabular fracture ORIF via the Kocher-Langenbeck approach for FRCS exam preparation

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By OrthoVellum Medical Education Team

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High Yield Overview

POSTERIOR WALL ACETABULAR FRACTURE ORIF

Kocher-Langenbeck Approach | Most Common Acetabular Fracture Pattern

Critical Yield Data
40%Wall loss threshold for instability
50%Have marginal impaction
70%Associated with hip dislocation
5-10%AVN rate (higher if delayed reduction)

Indications and Contraindications

Unstable Hip Joint

  • Posterior wall involvement >40% (dynamic or static instability)
  • Positive dynamic stress test under fluoroscopy
  • Subluxation on static imaging
  • Failed closed reduction of hip dislocation

Articular Incongruity

  • Intra-articular fragments preventing concentric reduction
  • Marginal impaction requiring elevation
  • Step >2mm on CT
  • Gap >2mm between fragments

Mechanical Block

  • Incarcerated labral tissue
  • Osteochondral fragments blocking reduction
  • Associated femoral head fracture (Pipkin)

Critical Danger Structures - Kocher-Langenbeck Approach

Sciatic Nerve

Injury rate 5-15% (mostly neuropraxia). Exits greater sciatic notch, runs 2-3cm medial to acetabular rim, deep to piriformis. Protection: Identify early, vessel loop, flex hip/knee, limit retraction to 60 minutes continuously.

Superior Gluteal NVB

Life-threatening haemorrhage if injured. Exits greater sciatic notch ABOVE piriformis. Supplies gluteus medius/minimus and TFL. Protection: No retraction above piriformis, stay inferior to notch.

Inferior Gluteal Artery

Major bleeding risk. Exits greater sciatic notch BELOW piriformis with sciatic nerve. Protection: Careful dissection at notch, identify before retracting, have vascular clamps ready.

Medial Femoral Circumflex Artery

Primary blood supply to femoral head. Runs along inferior hip capsule. Protection: Limit anterior capsular dissection, preserve retinacular vessels, gentle femoral head manipulation.

Pre-operative Planning

History

  • Mechanism: Dashboard injury, fall from height, pedestrian vs vehicle
  • Time since injury (AVN risk increases after 6-12 hours dislocation)
  • Pre-injury mobility and functional status
  • Comorbidities affecting anaesthesia and healing

Examination

  • Hip position: Shortened, flexed, internally rotated = posterior dislocation
  • Neurovascular status: SCIATIC NERVE - document peroneal and tibial components
  • Associated injuries: Knee (PCL), femoral shaft, spine
  • Skin integrity over posterior approach

Timing Considerations

  • Hip dislocation: EMERGENCY REDUCTION < 6 HOURS (AVN risk)
  • Definitive ORIF: 3-10 days (allows swelling resolution, prevents callus)
  • >3 weeks: Significantly increased difficulty
Mnemonic

WALLWALL - Posterior Wall Assessment

Equipment

Implants

  • 3.5mm pelvic reconstruction plates
  • 3.5mm cortical screws (various lengths)
  • 4.5mm screws for larger fragments
  • Spring plates for comminution
  • Absorbable screws (alternative for small fragments)

Instruments

  • Pelvic reduction set
  • Ball spike pushers
  • Pointed reduction clamps
  • Schanz pins (5mm)
  • Plate bending irons
  • Bone graft instruments (if impaction)

Adjuncts

  • C-arm fluoroscopy (essential)
  • Cell saver
  • Surgical headlight
  • Radiolucent table
  • Vessel loops for nerve protection
  • Bone graft (autograft or allograft)

Anaesthesia and Positioning

Anaesthetic Considerations

Preferred: General anaesthesia with muscle relaxation

Key Points:

  • Cell saver recommended (blood loss 500-1500mL typical)
  • Induced hypotension may be used (MAP 60-70mmHg)
  • Adequate IV access for potential massive transfusion
  • Arterial line for monitoring

Antibiotic Prophylaxis:

  • Cefazolin 2g IV within 60 minutes of incision
  • Redose at 4 hours or 1500mL blood loss
  • Clindamycin 900mg IV if penicillin allergy

Patient Positioning

Lateral Decubitus Position

  1. Affected side UP
  2. Beanbag or pegboard for stability
  3. Axillary roll to protect brachial plexus
  4. All bony prominences padded:
    • Fibular head (peroneal nerve)
    • Lateral malleolus
    • Greater trochanter (contralateral)

Position Checklist:

  • Pelvis perpendicular to floor
  • Hip and knee can flex/extend freely (to relax sciatic)
  • C-arm access confirmed (AP and lateral)
  • Table radiolucent

Exam Pearl

Exam Tip: Flexing the hip and knee relaxes the sciatic nerve and improves visualization. The ability to manipulate the leg during surgery is a key advantage of lateral positioning for this approach.

Surface Anatomy and Landmarks

Key Surface Landmarks

Incision: Curved incision from PSIS toward greater trochanter, then distally along posterior femoral shaft. Total length 15-20cm.

Surgical Approach - Kocher-Langenbeck

Step 1: Incision and Superficial Dissection

Incision

  • Start at PSIS
  • Curve toward greater trochanter (apex at trochanter)
  • Continue distally along posterior femur
  • Total length: 15-20cm

Superficial Dissection

  1. Incise skin and subcutaneous tissue
  2. Identify fascia lata and gluteus maximus fibres
  3. Split gluteus maximus BLUNTLY in line with fibres
    • Fibres run superolateral to inferomedial
    • Proximal: between upper 1/3 and lower 2/3
    • Distal: posterior to IT band

Superior Gluteal Nerve Warning

The superior gluteal nerve enters gluteus maximus 4-5cm above greater trochanter. Stay inferior to this level when splitting the muscle to avoid denervation of the superior portion.

Step 2: Deep Dissection and Nerve Identification

Sciatic Nerve Identification (CRITICAL STEP)

  1. Palpate greater sciatic notch
  2. Identify piriformis tendon (most superior rotator)
  3. Sciatic nerve exits BELOW piriformis
  4. Lies 2-3cm medial to acetabular rim
  5. Protect with vessel loop throughout case

Short External Rotator Exposure

  • Identify from superior to inferior:
    1. Piriformis - most superior
    2. Superior gemellus
    3. Obturator internus
    4. Inferior gemellus
    5. Quadratus femoris - most inferior
Mnemonic

PGOGOQPGOGOQ - Short External Rotators

Rotator Management

  • Tag each tendon with heavy suture (for later repair)
  • Divide tendons 1cm from trochanteric insertion
  • Preserve muscle belly for vascularity
  • Flex and internally rotate hip to relax structures

Exam Pearl

Exam Tip: The sciatic nerve is intimately related to the obturator internus - it lies just inferior and medial. When dividing the obturator, always visualise the nerve to avoid iatrogenic injury.

Step 3: Capsulotomy and Fracture Exposure

Posterior Capsulotomy

  1. Palpate femoral head through intact capsule
  2. Perform T-shaped or inverted-L capsulotomy
  3. Extend along acetabular rim and down femoral neck
  4. Limit ANTERIOR capsular dissection (preserves MFCA)

Fracture Visualization

  • Identify posterior wall fragment(s)
  • Assess comminution pattern
  • Extract intra-articular fragments and debris
  • Assess for marginal impaction (present in 50%)

Retractor Placement

  • Cobra retractor on ischium (inferior)
  • Hohmann on ilium (superior)
  • Avoid excessive traction on sciatic nerve

Marginal Impaction - Critical Assessment

Marginal impaction is cartilage-covered bone depressed at the fracture edge. Present in 50% of posterior wall fractures. If missed and not elevated, leads to rapid post-traumatic arthritis. Look for a subtle step at the articular margin.

Operative Technique

Step 4: Fracture Reduction

Reduction Principles

  • Goal: Anatomic reduction <2mm step or gap
  • <1mm = 88% good outcome
  • >2mm = 45% good outcome

Technique

  1. Clear fracture surfaces of soft tissue and clot
  2. Identify marginal impaction if present
  3. Use Schanz pins in ilium/ischium as joysticks
  4. Ball spike pushers for fine manipulation
  5. Pointed reduction clamps for provisional fixation

Marginal Impaction Management

  1. Make window in wall fragment if needed
  2. Use curved osteotome to elevate depressed cartilage
  3. Bone graft the defect (autograft or allograft)
  4. Support with subchondral screws if needed

Exam Pearl

Exam Tip: The classic sign of marginal impaction on CT is a double-density sign at the posterior wall margin - the depressed fragment appears as a separate line parallel to the acetabular surface.

Step 5: Provisional Fixation and Lag Screws

Provisional Fixation

  • Apply pointed reduction clamps across fracture
  • Multiple clamps may be needed for comminuted fractures
  • Confirm reduction with direct vision AND fluoroscopy

Lag Screw Technique

  1. Drill perpendicular to fracture plane
  2. Overdrill near cortex (glide hole)
  3. Measure depth, tap far cortex only
  4. Insert 3.5mm cortical screw achieving compression
  5. Typical: 2-4 lag screws for posterior wall

Safe Zone for Screws

  • Aim from posterior toward anterosuperior
  • 45° cranial trajectory
  • Avoid intra-articular penetration (palpate joint surface)

Intra-articular Screw Penetration

Risk 5-15% if not carefully assessed. Prevention: Check with fluoroscopy in MULTIPLE views (AP, obturator oblique, iliac oblique) AND directly palpate the articular surface through the capsulotomy before final tightening.

Step 6: Buttress Plate Application

Plate Selection

  • 3.5mm pelvic reconstruction plate (standard)
  • Pre-contoured posterior wall plates available
  • Spring plates for small or comminuted fragments

Plate Positioning

  • Functions as BUTTRESS (prevents posterior displacement)
  • Lag screws provide compression; plate prevents migration

Fixation Points

  • Proximal: 3-4 bicortical screws in ilium above fracture
  • Distal: 3-4 screws in ischium below fracture
  • Additional screws through plate holes into wall fragment

Contouring

  • Plate must match posterior column anatomy
  • Use bending irons to achieve precise contour
  • Poor contour = loss of reduction when tightening screws

Exam Pearl

Exam Tip: The plate functions as a BUTTRESS, not a compression device. The lag screws provide interfragmentary compression across the fracture. The plate prevents secondary displacement. This is a key concept for viva discussions.

Step 7: Final Assessment

Reduction Assessment

  1. Remove provisional clamps
  2. Palpate articular surface through capsulotomy
  3. Stress test hip - should be stable through ROM

Fluoroscopic Views (All MANDATORY)

  • AP pelvis: Concentric reduction, no roof step
  • Obturator oblique: Posterior wall reduction (best view)
  • Iliac oblique: Column integrity
  • Lateral: Femoral head concentricity

Stability Testing

  • Flex hip to 90°
  • Apply posterior force with internal rotation
  • Hip should not subluxate
  • If unstable - reassess reduction, consider larger plate

Step 8: Closure

Capsular Repair

  • Repair posterior capsule with interrupted #1 absorbable sutures
  • Capsular closure adds stability to construct

Short External Rotator Repair

  • Use tagged sutures placed during exposure
  • Repair to greater trochanter with heavy non-absorbable (#2 Ethibond)
  • Anatomic repair sequence: piriformis → obturator/gemelli → quadratus
  • This reconstructs posterior hip stability

Layer Closure

  1. Deep drain in posterior hip region (19Fr)
  2. Gluteus maximus fascia - interrupted absorbable
  3. Fascia lata - interrupted absorbable
  4. Subcutaneous - running absorbable
  5. Skin - staples or subcuticular

Exam Pearl

Exam Tip: Meticulous short external rotator repair is essential - these muscles are dynamic stabilisers of the hip. Failure to repair increases posterior instability risk and may worsen heterotopic ossification.

Complications

Incidence: 5-15% (mostly neuropraxia; 1-3% permanent)

Recognition

  • Foot drop (peroneal more common than tibial)
  • Sensory loss: Peroneal = dorsum of foot; Tibial = sole
  • Document motor/sensory function preoperatively

Prevention

  • Identify nerve early and protect with vessel loop
  • Flex hip and knee to relax nerve tension
  • Limit continuous retraction to <60 minutes
  • Use padded retractors only
  • Avoid posterior screw penetration toward notch

Management

  • Document new deficit immediately postoperatively
  • Consider re-exploration if:
    • Complete deficit (not present preop)
    • Expanding haematoma
    • Suspected screw impingement
  • Most neuropraxia recovers 6-18 months
  • AFO for foot drop during recovery
  • EMG/NCS at 6 weeks to assess severity
  • Tendon transfer if no recovery by 12-18 months

Post-operative Care

Immediate Post-operative

Recovery Room

  • Neurovascular check documented (sciatic nerve function)
  • AP pelvis X-ray to confirm reduction and hardware position
  • Pain control: PCA or regional anaesthesia

Day 0-1

  • Mobilise with physiotherapy when stable
  • Toe-touch weight bearing (TDWB) with frame/crutches
  • DVT prophylaxis: LMWH or DOAC per protocol
  • Drain removal when output <30mL per 8 hours (usually 24-48hr)

Heterotopic Ossification Prophylaxis

MANDATORY in all patients

Option 1: Indomethacin

  • 75mg daily (or 25mg TDS) for 6 weeks
  • Start within 24 hours postoperatively
  • Monitor for GI side effects

Option 2: Radiation

  • 7-8 Gy single dose
  • Within 72 hours of surgery
  • Reserved for NSAID contraindications

Exam Pearl

Exam Tip: HO prophylaxis reduces Brooker 3-4 HO from 25% to 5-10%. In exam discussions, always mention prophylaxis when discussing posterior approach to acetabulum - it's a key examiner expectation.

Rehabilitation Protocol

Weight Bearing

  • Weeks 0-6: Toe-touch weight bearing (TDWB)
  • Weeks 6-8: Partial weight bearing (PWB) if healing on XR
  • Weeks 8-12: Progress to full weight bearing (FWB)

Range of Motion

  • Week 1-2: Gentle passive ROM
  • Week 3+: Active-assisted ROM
  • No active hip flexion >90° for 6 weeks (protects rotator repair)
  • No resisted external rotation for 6 weeks

Hip Precautions

  • Avoid combined flexion + adduction + internal rotation
  • Use abduction pillow for 6 weeks
  • Avoid low chairs, crossing legs

Follow-up Schedule

  • 2 weeks: Wound check, staple removal
  • 6 weeks: XR (AP pelvis + Judet views), assess union
  • 12 weeks: XR, assess for FWB
  • 6 months: Clinical and radiological review
  • 1 year: Assess for arthritis, AVN
  • Annual: Long-term surveillance for arthritis

Viva Scenarios

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 35-year-old man presents after a motor vehicle accident with a posterior hip dislocation. The hip has been reduced in ED. CT shows a posterior wall fracture involving approximately 35% of the wall with a small area of marginal impaction. How do you manage this patient?"

EXCEPTIONAL ANSWER
This is a borderline case for surgical indications. The 35% posterior wall involvement is below the classic 40% threshold for instability, but the presence of marginal impaction is concerning. My management would be as follows: First, I would perform a dynamic stress examination under general anaesthesia with fluoroscopy. With the patient supine, I would flex the hip to 90 degrees and apply a posteriorly directed force while internally rotating the hip. This simulates the position of instability. If the hip subluxates on fluoroscopy during this manoeuvre, the hip is unstable and requires operative fixation regardless of the percentage involvement. If the stress test is positive, I would proceed with ORIF via a Kocher-Langenbeck approach. During surgery, I must specifically address the marginal impaction - this is cartilage-covered bone depressed at the fracture edge, present in 50% of posterior wall fractures. I would elevate the impacted segment using a curved osteotome through a window in the posterior wall fragment, bone graft the resulting void, and support with subchondral screws if needed before reducing and plating the posterior wall. Failure to address marginal impaction leads to early post-traumatic arthritis even with anatomic wall reduction. If the stress test is negative, I would consider non-operative management with protected weight bearing for 6 weeks, close clinical follow-up, and serial radiographs. However, given his young age, high functional demands, and the presence of marginal impaction, I have a low threshold for operative intervention in this case. Post-operatively, I would institute mandatory heterotopic ossification prophylaxis with indomethacin 75mg daily for 6 weeks, DVT prophylaxis, and toe-touch weight bearing for 6 weeks progressing to full weight bearing by 12 weeks based on radiographic healing.
VIVA SCENARIOStandard

EXAMINER

"During ORIF of a posterior wall fracture, you have difficulty achieving reduction. What are the potential causes and how would you address each?"

EXCEPTIONAL ANSWER
Difficulty achieving reduction of a posterior wall fracture can have several causes, and I approach each systematically: First, INTERPOSED SOFT TISSUE is a common problem. Capsule, labrum, or muscle can become trapped in the fracture or between the femoral head and acetabulum. I would carefully inspect the fracture surfaces and the joint through my capsulotomy, removing any interposed tissue. An incarcerated labrum sometimes requires partial resection. Second, MARGINAL IMPACTION may be preventing congruent reduction. The depressed articular cartilage and subchondral bone act as a block to reduction. I would identify the impacted segment, create an access window if needed, elevate the fragment using a curved osteotome until it is flush with the native articular surface, then bone graft the resulting cavity to prevent subsidence. Third, INTRA-ARTICULAR FRAGMENTS - loose osteochondral pieces in the joint can prevent concentric femoral head reduction. I would systematically extract all loose fragments through the capsulotomy, using irrigation to flush small debris. Each fragment should be inspected - large articular pieces may occasionally be fixable. Fourth, MALREDUCTION OF ASSOCIATED COLUMN FRACTURE - if there is an associated posterior column component that I haven't addressed, it may prevent wall reduction. I would reassess my CT images and extend my reduction to include the column component. Fifth, COMMINUTION of the posterior wall with multiple fragments requires sequential reduction starting from the most stable reference point - usually the intact acetabulum superiorly. I would provisionally fix each fragment in sequence using small pointed reduction clamps, building the reduction progressively. Sixth, CALLUS FORMATION - if there has been significant delay (>2-3 weeks), early callus may need to be removed with osteotomes to allow mobilisation of fragments. If despite all measures reduction remains difficult, I would consider the TROCHANTERIC FLIP OSTEOTOMY to improve visualization, or accept a slightly imperfect reduction in an elderly patient where THA may ultimately be needed anyway.
VIVA SCENARIOStandard

EXAMINER

"Post-operatively, your patient with posterior wall ORIF develops a foot drop on day 1. How do you assess and manage this?"

EXCEPTIONAL ANSWER
Post-operative sciatic nerve palsy after Kocher-Langenbeck approach occurs in 5-15% of cases, and I take this seriously. My assessment and management approach is as follows: IMMEDIATE ASSESSMENT: First, I would compare to the documented pre-operative examination - was there any sciatic dysfunction before surgery? This is crucial baseline information. I would perform a detailed neurological examination documenting both peroneal and tibial components. Peroneal division is more commonly affected due to its lateral position and limited blood supply. I would test: - Motor: Ankle dorsiflexion, toe extension (peroneal); plantarflexion, toe flexion (tibial) - Sensory: Dorsum of foot (peroneal); sole of foot (tibial) - Classify as complete or partial deficit DETERMINE THE CAUSE: Several mechanisms are possible: 1. HAEMATOMA - expanding collection compressing nerve. I would check drain output, examine wound for tension/swelling 2. RETRACTOR INJURY - direct compression during surgery (usually neuropraxia) 3. SCREW IMPINGEMENT - hardware penetrating near sciatic notch 4. TRACTION INJURY - from positioning or manipulation 5. DIRECT TRAUMA - though this is rare with careful technique INVESTIGATIONS: - Urgent AP pelvis and Judet view XRays to assess hardware position, particularly any posterior screws near the sciatic notch - If concern for haematoma - urgent ultrasound or CT MANAGEMENT DECISION: If there is a COMPLETE NEW DEFICIT (not present preoperatively) with suspicion of haematoma or screw impingement, I would discuss urgent re-exploration. At re-exploration, I would evacuate haematoma, decompress the nerve, and remove or revise any offending hardware. If the deficit is PARTIAL or there is no expandinng haematoma or screw concern, I would manage expectantly as most represent neuropraxia from retraction. Management includes: - AFO for foot drop to prevent equinus contracture - Physiotherapy for strengthening and gait training - EMG/NCS at 6 weeks - this helps differentiate neuropraxia (good prognosis) from axonotmesis or neurotmesis - Serial clinical examinations documenting recovery PROGNOSIS: Most neuropraxia recovers over 6-18 months. I would counsel the patient that recovery can be slow. If no clinical or electrical evidence of recovery by 12-18 months, I would consider tendon transfer (tibialis posterior transfer for foot drop) rather than nerve surgery, as the distance from sciatic notch to foot muscles is too great for successful nerve repair.

Key Exam Points

Posterior Wall Acetabular Fracture ORIF - Exam Summary

High-Yield Exam Summary

References

Key Literature - Posterior Wall Acetabular Fractures

Multiple
Finding: Foundation literature for posterior wall acetabular fracture management
Source: Compiled Evidence

  1. Matta JM (1996). Fractures of the acetabulum: accuracy of reduction and clinical results in patients managed operatively within three weeks after the injury. J Bone Joint Surg Am 78(11):1632-45.

    • Landmark study establishing reduction quality thresholds (<1mm = 88% good outcome)

  2. Letournel E, Judet R (1993). Fractures of the Acetabulum. 2nd ed. Berlin: Springer-Verlag.

    • Definitive classification and surgical approach atlas

  3. Keith JE Jr, Brashear HR Jr, Guilford WB (1988). Stability of posterior fracture-dislocations of the hip. Quantitative assessment using computed tomography. J Bone Joint Surg Am 70(5):711-14.

    • Established 40% posterior wall threshold for instability

  4. Vailas JC, Hurwitz S, Wiesel SW (1989). Posterior acetabular fracture-dislocations: fragment size, joint capsule, and stability. J Trauma 29(11):1494-96.

    • Dynamic stress testing methodology for borderline cases

  5. Kreder HJ, et al (2006). Determinants of functional outcome after simple and complex acetabular fractures involving the posterior wall. J Bone Joint Surg Br 88(6):776-82.

    • Identified marginal impaction as key predictor of poor outcome

  6. Matta JM, Tornetta P 3rd (2000). Internal fixation of unstable pelvic ring injuries. Clin Orthop Relat Res (329):129-140.

    • Surgical technique refinements and outcomes

  7. Brooker AF, et al (1973). Ectopic ossification following total hip replacement. Incidence and a method of classification. J Bone Joint Surg Am 55(8):1629-32.

    • Classification system still used today

  8. Burd TA, et al (2001). Heterotopic ossification prophylaxis with indomethacin increases the risk of long-bone nonunion. J Bone Joint Surg Br 83(5):651-54.

    • Caution with concomitant long-bone fractures