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Posterior Column and Wall Acetabular Fracture ORIF

Surgical technique guide for Posterior Column and Wall Acetabular Fracture ORIF via Kocher-Langenbeck approach - FRCS exam preparation

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By OrthoVellum Medical Education Team

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High-yield overview

Kocher-Langenbeck approach | Sciatic nerve protection | Marginal impaction | 40% wall rule | Buttress plating

Absolute Indications

  • Posterior wall fracture >40% of acetabulum (instability)
  • Posterior column or wall fracture with >2mm displacement
  • Incongruous hip joint on imaging
  • Incarcerated intra-articular fragments
  • Associated femoral head fracture (Pipkin)
  • Hip instability despite closed reduction

Relative Indications

  • Posterior wall fracture 20-40% with marginal impaction
  • Non-concentric hip reduction
  • Young, active patient with any displacement
  • Associated posterior column fracture
Mnemonic

PGOQG

Short External Rotators (Superior to Inferior)

Mnemonic

WALL

Posterior Wall Fracture Key Principles

Critical Danger Structures

Sciatic Nerve

Location: Exits greater sciatic notch 20-30mm medial to posterior acetabular rim. Runs on deep surface of gluteus maximus. Protection: Identify BEFORE releasing rotators. Hip/knee flexion 45°/90°. Vessel loop. Limit retraction <2hr.

Superior Gluteal Bundle

Location: ONLY structure exiting ABOVE piriformis at greater sciatic notch. At risk: Extended approaches, excessive superior retraction. Contains superior gluteal artery, vein, and nerve.

Inferior Gluteal Artery

Location: Exits BELOW piriformis. Supplies gluteus maximus. At risk: Splitting gluteus maximus, deep dissection near greater sciatic notch.

Medial Femoral Circumflex Artery

Location: Courses posteriorly at base of femoral neck, deep branch supplies femoral head. Protection: Careful capsulotomy, avoid damage to femoral head blood supply (AVN risk).

Surgical Anatomy

Posterior Column and Wall Anatomy

Posterior Column:

  • Extends from posterior ilium to ischial tuberosity
  • Forms posterior support of hip joint
  • Visualized on ILIAC oblique view (Judet)

Posterior Wall:

  • Posterior lip of acetabulum
  • Critical for hip stability - prevents posterior dislocation
  • Visualized on OBTURATOR oblique view (Judet)

Fragment-Size "Rules" and Their Limits

The "percentage of wall" thresholds come from two different sources and are often conflated in exams — know the distinction:

  • Cadaveric biomechanics (Vailas, 1989): fragments involving 25% or less of the wall do NOT destabilise the hip; fragments of 50% or more are always unstable; the 25-50% "transitional zone" depends on the integrity of the posterior capsule and labrum.
  • CT-based clinical estimates (Calkins, Moed): a practical operative threshold of roughly 40-50% wall involvement (or roof-arc and CT subchondral-arc measurements) is widely quoted as the cut-off above which fixation is mandatory.

Pragmatic global synthesis:

  • Wall involvement under 20%: usually stable
  • 20-50% ("transitional"): stability is UNRELIABLE on size alone - this is the group in which an examination under anaesthesia (EUA) with dynamic fluoroscopic stress is decisive
  • Over 50%: unstable - fixation required

Key teaching point: fragment size is a guide, not a verdict. Marginal impaction, comminution, capsular/labral disruption, and an associated column fracture all reduce stability independently of percentage. When in doubt, perform an EUA before committing to non-operative care.

Assessment: CT with 3D reconstruction and subchondral-arc measurement, supplemented by dynamic stress fluoroscopy.

Marginal Impaction

  • Present in 30-50% of posterior wall fractures
  • Depressed articular segment at weight-bearing dome
  • Caused by femoral head impacting wall during dislocation
  • MUST be addressed - elevation + bone graft
  • Failure to recognize causes residual incongruity → arthritis

Sciatic Nerve Anatomy

  • Largest nerve in body (L4-S3)
  • Exits pelvis through greater sciatic foramen BELOW piriformis
  • Lies 20-30mm medial to posterior acetabular rim
  • Hip flexion + knee flexion relaxes nerve by 20-30%
  • At highest risk during external rotator release

Positioning and Preparation

Patient Position: Lateral decubitus (most common - 95% of surgeons), affected hip up. Secured with beanbag or pelvic posts. Hip must be free to flex/extend/rotate for reduction maneuvers.

Nerve Protection Setup: Plan for hip flexion 45°/knee flexion 90° throughout case.

Surgical Approach: Kocher-Langenbeck posterior approach.

Incision: From PSIS curving over greater trochanter to lateral thigh (15-20cm).

Key Setup:

  • Radiolucent table for fluoroscopy
  • Test AP, obturator oblique, iliac oblique views BEFORE draping
  • Cell saver available
  • Neuromonitoring optional but useful for complex cases

Operative Technique

Step 1: Position Patient in Lateral Decubitus

  • Secure with beanbag or posts (anterior chest, posterior sacrum)
  • Affected hip UP
  • Adequate padding all pressure points
  • Hip must be free to flex, extend, and rotate
  • Test fluoroscopy before draping (AP, obturator oblique, iliac oblique)

Clinical Pearl

EXAM KEY: Lateral decubitus allows gravity-assisted reduction and easier fluoroscopy than prone. Hip/knee flexion 45°/90° relaxes sciatic nerve - maintain throughout case.

Step 2: Make Kocher-Langenbeck Incision

  • Mark incision from PSIS curving over greater trochanter to lateral thigh
  • Total length 15-20cm
  • Incise skin and subcutaneous tissue
  • Identify and protect posterior cutaneous nerve of thigh
  • Develop plane to gluteal fascia

Clinical Pearl

EXAM KEY: Adequate length essential - short incision causes excessive retraction → nerve injury. Extensile approach can extend for complex fractures or THA if needed.

Step 3: Split Gluteus Maximus in Line with Fibers

  • Identify fiber direction (superolateral to inferomedial)
  • Blunt dissection with fingers or scissors along fibers
  • Fiber-splitting is internervous plane (inferior gluteal nerve enters deep)
  • Place self-retaining retractor
  • Expose underlying short external rotators

Clinical Pearl

EXAM KEY: Fiber-SPLITTING (not cutting) preserves innervation and blood supply. Gluteus maximus reflection (trochanteric slide) is alternative for extensile approach.

Step 4: Identify and Protect Sciatic Nerve

CRITICAL STEP:

  • Sciatic nerve runs along deep surface of gluteus maximus
  • Crosses short external rotators
  • PALPATE nerve BEFORE releasing any structures
  • Place vessel loop for gentle retraction
  • Maintain hip flexion 45°/knee flexion 90° throughout

Sciatic Nerve Protection

Identification is MANDATORY before proceeding. Flexing hip/knee relaxes nerve by 20-30%. Palsy rate 2-8% but permanent <1% with meticulous protection. Avoid traction and limit retraction time.

Step 5: Release External Rotators (PGOQG)

  • Identify each muscle: Piriformis → Gemellus superior → Obturator internus → Gemellus inferior → Quadratus femoris
  • Release tendons 5-10mm from greater trochanter insertion
  • TAG each tendon with heavy non-absorbable suture (#2 Ethibond)
  • Sciatic nerve lies on deep surface - PROTECT during release

Clinical Pearl

EXAM KEY: Tag for repair - unrepaired external rotators cause instability. Some preserve piriformis and superior gemellus to protect superior gluteal nerve.

Step 6: Perform Posterior Capsulotomy

  • T-shaped or cruciate capsulotomy
  • Longitudinal limb along posterior femoral neck
  • Transverse limbs at acetabular rim
  • Visualize femoral head and acetabular surfaces
  • Remove hematoma and loose fragments from joint

Clinical Pearl

EXAM KEY: Capsulotomy allows DIRECT articular visualization for reduction assessment. Remove all loose fragments - they cause mechanical block and chondral damage.

Step 7: Expose and Assess Fracture Pattern

  • Clear fracture site of hematoma
  • Assess posterior COLUMN (greater sciatic notch to ischial tuberosity)
  • Assess posterior WALL fragments (simple vs comminuted)
  • Identify MARGINAL IMPACTION (depressed articular segment)
  • Note any anterior column involvement (transverse pattern)

Clinical Pearl

EXAM KEY: Marginal impaction present in 30-50% - appears as depressed articular segment at weight-bearing dome. Requires elevation and bone graft to restore congruity.

Step 8: Reduce Posterior Column

If posterior column displaced:

  • Ball spike pusher in ischium and greater sciatic notch
  • Schanz pin in ischial tuberosity for joystick control
  • Farabeuf clamps or pointed reduction forceps across fracture
  • Reduce INFERIOR fragment (ischium) to SUPERIOR stable reference (ilium)

Clinical Pearl

EXAM KEY: Column reduction restores pelvic ring stability. Always reduce UNSTABLE fragment to STABLE reference. Confirm reduction on fluoroscopy before definitive fixation.

Step 9: Address Marginal Impaction

If marginal impaction present:

  • Use curved osteotome or curette to elevate depressed segment
  • Support with bone graft (iliac crest autograft preferred)
  • Pack subchondral void completely to prevent re-depression
  • Hold elevated segment with K-wire temporarily

Marginal Impaction

MUST be addressed - failure to elevate causes residual articular incongruity and accelerated arthritis. Bone graft prevents collapse. This is frequently tested in exams.

Step 10: Reduce Posterior Wall Fragments

  • Reduce large fragments anatomically with reduction clamps
  • Small fragments may need to be captured with plate only
  • K-wire provisional fixation
  • Ensure articular surface is congruent (<1mm step)

Step 11: Provisional Fixation and Confirmation

  • Hold reduction with 2.0mm K-wires or provisional screws
  • Visually confirm articular reduction through capsulotomy (<1mm step)
  • Obtain fluoroscopy: AP, obturator oblique, iliac oblique
  • Do NOT proceed to plating until confirming ANATOMIC reduction

Clinical Pearl

EXAM KEY: Obturator oblique shows posterior WALL best. Iliac oblique shows posterior COLUMN best. Both views mandatory - fracture involves both structures.

Step 12: Apply Posterior Column Plate

If column fracture present:

  • 3.5mm or 4.5mm reconstruction plate along posterior column
  • Pre-contour to match anatomy
  • Minimum 3 screws above fracture (ilium), 3 below (ischium)
  • Bicortical screws for maximum purchase
  • Screws directed anteriorly - must NOT penetrate joint

Clinical Pearl

EXAM KEY: Plate position critical - too anterior risks joint penetration, too posterior loses bone contact. Pre-contouring essential or plate will displace reduction when tightened.

Step 13: Apply Buttress Plate for Posterior Wall

  • Large fragments: lag screws first if geometry allows
  • Then apply BUTTRESS plate (reconstruction or spring plate)
  • Position to prevent posterior displacement
  • Multiple screws into stable posterior column
  • Plate spans from stable column across ALL wall fragments

Clinical Pearl

EXAM KEY: Buttress plate prevents re-displacement but doesn't compress. Spring plate contours to posterior wall anatomy. Ensure ALL marginal fragments captured.

Step 14: Check Hip Stability and Final Imaging

  • Remove provisional K-wires
  • Gently rotate and translate hip - should be stable through full ROM
  • Final fluoroscopy: AP and both Judet views
  • Arc image intensifier through joint to check for screw penetration
  • Posterior wall coverage should be >60% for stability

Clinical Pearl

EXAM KEY: Stability test confirms adequate fixation. If unstable, need revision or augmentation. Posterior wall coverage <60% may need constrained liner or THA.

Step 15: Repair External Rotators and Close

External Rotator Repair:

  • Heavy non-absorbable suture (#2 or #5 Ethibond)
  • Repair PGOQG to posterior capsule and greater trochanter
  • Create bone tunnels if needed
  • Robust repair critical for stability

Closure:

  • Meticulous hemostasis (gluteal muscles bleed significantly)
  • Irrigate 3-6L saline
  • 14Fr drain deep to gluteus maximus
  • Close gluteal fascia (0-Vicryl), subcutaneous (2-0 Vicryl), skin (staples)

Postoperative Protocol:

  • Touch weight-bearing × 6 weeks, progressive to full by 12 weeks
  • Posterior precautions if stability concern (no flexion >90°, no IR, no adduction) × 6-12 weeks
  • DVT prophylaxis: LMWH or DOAC × 35 days
  • HO prophylaxis: Indomethacin 75mg daily × 6 weeks
  • X-rays: 6 weeks, 12 weeks, 6 months, 12 months

Complications

Complications: Recognition, Prevention, and Management

Clinical Decision Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"How do you protect the sciatic nerve during the Kocher-Langenbeck approach?"

PRACTICAL APPROACH
Sciatic nerve protection is my primary concern throughout this approach. It starts with patient positioning - I maintain hip flexion of 45 degrees and knee flexion of 90 degrees throughout the case, which relaxes the nerve by 20-30% and reduces traction injury risk. After splitting the gluteus maximus along its fibers, I palpate to identify the nerve BEFORE releasing any structures - this is mandatory. The sciatic nerve runs along the deep surface of gluteus maximus and crosses the short external rotators. I place a vessel loop around the nerve for gentle retraction using a dedicated sciatic nerve retractor if needed. During release of the external rotators, I work from the greater trochanter side where I can see the nerve, maintaining constant visualization. I avoid cautery near the nerve and limit total retraction time to less than 2 hours. If the case is prolonged, I release retraction periodically to allow nerve recovery. With these precautions, the transient palsy rate is 2-8% but permanent injury is less than 1%. Importantly, the peroneal division is more susceptible to stretch injury than the tibial division, so foot drop is the most common presentation if palsy occurs.
CLINICAL SCENARIOStandard

CLINICAL PROMPT

"Explain the posterior wall 40% rule and how you assess wall involvement"

PRACTICAL APPROACH
The 40% rule is based on biomechanical studies that demonstrated posterior wall fractures involving more than 40% of the acetabulum result in hip instability with risk of subluxation or dislocation. This is because the posterior wall is the primary restraint to posterior translation of the femoral head, especially in hip flexion. With less than 20% wall involvement, the hip is usually stable. Between 20-40%, stability is variable and requires stress testing. Above 40%, the hip is definitively unstable and requires surgical stabilization. I assess wall involvement using CT with 3D reconstruction, measuring the arc of wall loss compared to the total posterior wall arc. On plain radiographs, I can estimate this on the obturator oblique view, which best profiles the posterior wall, but CT is more accurate. Intraoperatively, I assess stability by gently rotating and internally rotating the hip at 90 degrees flexion - this position stresses the posterior wall maximally. If the hip subluxates, the wall involvement is significant regardless of the percentage measurement. After fixation, I repeat this stability test - the hip should be stable through full range of motion, and posterior wall coverage should be greater than 60% for reliable stability.
CLINICAL SCENARIOStandard

CLINICAL PROMPT

"What is marginal impaction and why is it critical to address?"

PRACTICAL APPROACH
Marginal impaction is depression of the articular surface at the weight-bearing dome of the acetabulum. It occurs in 30-50% of posterior wall fractures and is caused by the femoral head impacting against the posterior wall during the injury mechanism, typically during posterior hip dislocation. On CT, it appears as a depressed segment of subchondral bone at the junction between the stable dome and the displaced wall fragment. It is clinically critical because if not addressed, it causes persistent articular incongruity even if the wall fragments are perfectly reduced - the depressed segment remains below the normal articular surface. This incongruity leads to point loading on the remaining cartilage, accelerated wear, and post-traumatic arthritis. In my surgical technique, I identify marginal impaction by visualizing through the capsulotomy and correlating with the preoperative CT. I address it by using a curved osteotome or curette to elevate the depressed segment back to the level of the surrounding articular surface. Crucially, this creates a subchondral void that must be filled - I pack this with bone graft, preferably iliac crest autograft, to prevent the segment from re-depressing. The elevated segment is then held with the buttress plate along with the wall fragments. Failure to recognize and treat marginal impaction is one of the most common causes of poor outcomes after technically successful wall fixation.

Posterior Column and Wall Acetabular Fracture ORIF - Exam Summary

Clinical summary

Key Evidence

Accuracy of reduction predicts clinical outcome (foundation evidence)

Level III
Matta JM • J Bone Joint Surg Am
Clinical Implication: Anatomic articular reduction (1mm or less of step/gap) is the single modifiable determinant of outcome - this underpins the whole rationale for ORIF rather than non-operative care.
Verify on PubMed (PMID 8934477)

Cadaveric basis of posterior wall stability - the true fragment-size data

Level V
Vailas JC, Hurwitz S, Wiesel SW • J Trauma
Clinical Implication: The popular '40% rule' is a pragmatic radiographic cut-off, not the original biomechanical finding. Mid-range fragments are capsule-dependent, which is why dynamic examination under anaesthesia - not size alone - should decide borderline cases.
Verify on PubMed (PMID 2585559)

Postoperative CT detects malreduction missed on plain films

Level III
Moed BR, Carr SE, Gruson KI, Watson JT, Craig JG • J Bone Joint Surg Am
Clinical Implication: Plain radiographs systematically overestimate reduction quality; a postoperative CT is the most reliable way to confirm a truly anatomic posterior wall and to detect occult marginal incongruity.
Verify on PubMed (PMID 12637440)

Long-term hip survivorship after acetabular ORIF (benchmark)

Level III
Tannast M, Najibi S, Matta JM • J Bone Joint Surg Am
Clinical Implication: Posterior wall involvement and marginal impaction are independent drivers of late hip failure - reinforcing meticulous wall reconstruction and obligatory elevation/grafting of impaction.
Verify on PubMed (PMID 22992846)

Meta-analysis of operative acetabular fracture outcomes

Level III
Giannoudis PV, Grotz MRW, Papakostidis C, Dinopoulos H • J Bone Joint Surg Br
Clinical Implication: Across thousands of cases, the surgeon-controllable variables (early referral, correct approach, anatomic reduction) are what separate good from poor results - the message to take into the viva.
Verify on PubMed (PMID 15686228)

References

  1. Letournel E, Judet R. Fractures of the Acetabulum. 2nd ed. Springer-Verlag; 1993. The definitive text on acetabular fracture classification and management.

  2. Matta JM. 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. 1996;78(11):1632-1645.

  3. Moed BR, Carr SE, Watson JT. Open reduction and internal fixation of posterior wall fractures of the acetabulum. Clin Orthop Relat Res. 2000;(377):57-67. PMID: 10943185.

  4. Moed BR, Carr SE, Gruson KI, Watson JT, Craig JG. Computed tomographic assessment of fractures of the posterior wall of the acetabulum after operative treatment. J Bone Joint Surg Am. 2003;85(3):512-522. PMID: 12637440.

  5. Vailas JC, Hurwitz S, Wiesel SW. Posterior acetabular fracture-dislocations: fragment size, joint capsule, and stability. J Trauma. 1989;29(11):1494-1496. PMID: 2585559.

  6. Calkins MS, Zych G, Latta L, et al. Computed tomography evaluation of stability in posterior fracture dislocations of the hip. Clin Orthop Relat Res. 1988;227:152-163. (Original CT-arc stability work; predates routine PubMed indexing of CORR - cited from primary literature.)

  7. Brooker AF, Bowerman JW, Robinson RA, Riley LH Jr. Ectopic ossification following total hip replacement: incidence and a method of classification. J Bone Joint Surg Am. 1973;55(8):1629-1632.

  8. Giannoudis PV, Grotz MR, Papakostidis C, Dinopoulos H. Operative treatment of displaced fractures of the acetabulum: a meta-analysis. J Bone Joint Surg Br. 2005;87(1):2-9. PMID: 15686228.

  9. Briffa N, Pearce R, Hill AM, Bircher M. Outcomes of acetabular fracture fixation with ten years' follow-up. J Bone Joint Surg Br. 2011;93(2):229-236. PMID: 21282764.

  10. Hak DJ, Olson SA, Matta JM. Diagnosis and management of closed internal degloving injuries associated with pelvic and acetabular fractures: the Morel-Lavallée lesion. J Trauma. 1997;42(6):1046-1051.

  11. Tannast M, Najibi S, Matta JM. Two to twenty-year survivorship of the hip in 810 patients with operatively treated acetabular fractures. J Bone Joint Surg Am. 2012;94(17):1559-1567. PMID: 22992846.