Acetabular Fracture ORIF - Comprehensive Approach Selection

Examiner Question: "What determines whether a transverse fracture needs K-L alone or a combined approach?"

Model Answer: "The key determinant is anterior column displacement. Most transverse fractures can be managed through K-L because: (1) The posterior column is the larger fragment and reduces first; (2) The anterior column typically follows as the columns are linked through the dome. However, if there is significant anterior displacement that won't reduce indirectly after posterior column fixation, I would consider staging an ilioinguinal approach 3-7 days later. I would NOT use extended iliofemoral due to its high morbidity (50%+ HO rate)."

Examiner Question: "You've fixed the anterior column through ilioinguinal but the posterior column has 4mm residual displacement. What do you do?"

Model Answer: "This is an important decision point. I would NOT convert to an extended iliofemoral approach due to its high morbidity (50%+ HO). Instead, I would: (1) Close the ilioinguinal wound; (2) Stage a Kocher-Langenbeck approach 3-7 days later when soft tissues have recovered; (3) Through K-L, I can then directly reduce and fix the posterior column. This staged approach provides equivalent access to extended iliofemoral with significantly lower complication rates. If the patient cannot tolerate a second surgery, I would accept the imperfect reduction but counsel regarding accelerated arthritis."

Examiner Question: "When would you choose Modified Stoppa over standard ilioinguinal for a both-column fracture?"

Model Answer: "I would favor Modified Stoppa when there is significant quadrilateral surface medialization that requires direct buttress plating. The key advantages are: (1) Direct intrapelvic visualization of the quadrilateral surface through the Space of Retzius; (2) Easier infrapectineal plate placement for buttressing the medial wall; (3) Can combine with a lateral window for complete anterior column access. I would use standard ilioinguinal when the quadrilateral surface is minimally displaced or when I need superior access to the iliac crest and SI joint area."

Examiner Question: "A patient with a T-type fracture has significant displacement of both columns. How do you decide between same-day combined versus staged approaches?"

Model Answer: "I would generally favor a staged approach unless there are specific factors making a second surgery risky. The decision factors are: (1) Patient fitness - if unable to tolerate second anesthetic, consider same-day combined; (2) Soft tissue condition - extensive bruising favors staging; (3) Blood loss management - combined approaches have more bleeding; (4) Operative time - staging keeps each procedure shorter (less HO). My typical approach: Ilioinguinal first, then assess posterior reduction on fluoroscopy. If residual >2mm, stage K-L at 3-7 days. Same-day combined requires position change (supine to lateral) adding complexity and time."

Examiner Question: "A patient has an acetabular fracture with 2.5mm dome displacement. Why would you operate?"

Model Answer: "Displacement >2mm at the weight-bearing dome is an absolute indication for surgery. This threshold is based on biomechanical and outcome data showing: (1) Increased contact pressure - every mm of incongruity significantly increases articular stress; (2) Matta's outcome data - anatomic reduction (0-1mm) achieves 83% good outcomes versus 50% for poor reduction (>3mm); (3) Weight-bearing dome - this is where peak loads occur, making perfect reduction essential. At 2.5mm, the risk of accelerated osteoarthritis without surgery exceeds the risks of operative intervention."

Examiner Question: "How do you measure roof arc angles and what do they tell you?"

Model Answer: "Roof arc angles assess dome integrity on three views: AP, obturator oblique, and iliac oblique. For each view: (1) Draw a vertical line through the center of the femoral head; (2) Draw a second line from the center to where the fracture exits the acetabulum; (3) Measure the angle between these lines. If the angle is <45° on any single view, there is insufficient weight-bearing dome coverage, and non-operative management will likely fail. This is because the dome is the primary load-bearing surface. All three views must have angles >45° to consider non-operative treatment."

Examiner Question: "What is secondary congruence and when can you rely on it?"

Model Answer: "Secondary congruence is a phenomenon unique to both-column fractures where the femoral head remains congruent with the fractured acetabulum despite both columns being detached. The head 'medializes' with the medial column fragments, maintaining articular congruency. To rely on it: (1) Roof arc >45° on all three views (AP, obturator, iliac obliques); (2) Concentric femoral head on traction radiographs; (3) No posterior wall component; (4) Patient can comply with 6-12 weeks TTWB. Even with true secondary congruence, I counsel that outcomes are slightly inferior to anatomic reduction, particularly in young active patients."

Examiner Question: "What are the advantages and disadvantages of prone versus lateral positioning for K-L approach?"

Model Answer: "Lateral decubitus is most common because: (1) Easier hip manipulation for reduction; (2) Familiar positioning for most surgeons; (3) Can dislocate hip for wall fixation. Prone positioning has advantages: (1) Reduced venous bleeding due to lower abdominal pressure; (2) Better access to posterior column superiorly; (3) Gravity assists exposure. However, prone makes hip dislocation difficult and limits manipulation. I would choose lateral for most cases, considering prone for posterior column fractures where dislocation is not required."

Examiner Question: "Describe the internervous plane of the Kocher-Langenbeck approach."

Model Answer: "The K-L approach utilizes two internervous intervals. Superficially: between gluteus maximus (inferior gluteal nerve) and gluteus medius (superior gluteal nerve) - we split maximus in line with its fibers rather than taking the interval. Deeply: between the short external rotators and the posterior hip capsule. The key landmark is the piriformis muscle - the sciatic nerve exits the pelvis below it. By releasing the short rotators from the greater trochanter (piriformis, superior gemellus, obturator internus, inferior gemellus), we can retract them posteriorly with the sciatic nerve, protecting it while exposing the posterior column."

Examiner Question: "When do you need to dislocate the hip during a K-L approach, and how do you do it safely?"

Model Answer: "Hip dislocation is required for posterior wall fractures to directly visualize and reduce the wall fragments. For isolated posterior column fractures, dislocation is usually NOT required. Safe dislocation technique: (1) Release short rotators completely; (2) Complete capsulotomy; (3) Flex hip to 90°, adduct, and internally rotate; (4) Lever femoral head posteriorly over acetabulum. To protect femoral head blood supply: minimize dislocation time, maintain reduction with provisional fixation, repair capsule at end. Prolonged dislocation increases AVN risk."

Examiner Question: "Why do you tilt the pelvis during ilioinguinal approach?"

Model Answer: "A 10-15° bolster under the ipsilateral buttock serves multiple purposes: (1) Improves access to the iliac wing and SI joint area through the lateral window; (2) Reduces venous congestion compared to flat supine; (3) Facilitates visualization of the pelvic brim and quadrilateral surface. For both-column fractures or when Modified Stoppa is planned, I may position flat or with minimal tilt as this improves access to the true pelvis. The key is ensuring C-arm can still obtain all required views."

Examiner Question: "Describe the middle window and how you protect the corona mortis."

Model Answer: "The middle window lies between the external iliac vessels medially and the iliopsoas muscle laterally. This is the most dangerous window because of the corona mortis - an anastomosis between the obturator and external iliac vessels present in 30% of patients. To protect it: (1) Identify systematically - look on the posterior aspect of the superior pubic ramus; (2) Ligate prophylactically - clip or tie before dividing; (3) If bleeding occurs - direct pressure, then suture ligation on the ramus. The external iliac vessels are protected with vessel loops and retracted gently medially. I use malleable retractors padded with moist swabs."

Examiner Question: "How do you develop the three windows of the ilioinguinal approach?"

Model Answer: "After skin incision, I: (1) Identify LFCN 1cm medial to ASIS and protect; (2) Incise external oblique aponeurosis along inguinal ligament; (3) Lateral window first - elevate iliacus from iliac fossa, the femoral nerve is safe on the muscle surface; (4) Identify spermatic cord/round ligament and protect with vessel loop; (5) Middle window - identify external iliac vessels, place vessel loops, search for and ligate corona mortis on posterior pubic ramus; (6) Medial window - between vessels and spermatic cord, access symphysis. Sequential development prevents disorientation."

Examiner Question: "How do you safely enter the Space of Retzius?"

Model Answer: "The Space of Retzius (retropubic space) is a preperitoneal plane between the bladder and pubic symphysis. To enter safely: (1) Foley catheter must be in place to decompress bladder; (2) Through Pfannenstiel or midline incision, identify rectus fascia; (3) Incise fascia in midline between rectus muscles; (4) Blunt finger dissection to develop the space - the peritoneum and bladder fall posteriorly; (5) Place a Deaver retractor to retract bladder posteriorly; (6) Corona mortis will be on the posterior pubic ramus - identify and ligate. The key is staying in the preperitoneal plane - if you see bowel, you've entered the peritoneum."

Examiner Question: "How do you combine Modified Stoppa with a lateral window, and when would you do this?"

Model Answer: "The 'Stoppa + lateral window' approach provides complete anterior hemipelvis access. Indication: both-column fractures requiring both quadrilateral surface buttressing AND iliac wing/SI joint access. Technique: (1) Perform Stoppa through Pfannenstiel; (2) Add a separate lateral incision along the iliac crest; (3) Develop the lateral window between iliacus and abductors; (4) This avoids the extensive inguinal dissection of traditional ilioinguinal while accessing both areas. The advantage is avoiding inguinal canal dissection, reducing hernia risk while maintaining full access."

Examiner Question: "Why do you reduce the posterior column before the anterior through K-L approach?"

Model Answer: "Through the K-L approach, I reduce the posterior column first because: (1) It is the larger, stronger fragment - provides a stable foundation; (2) The intact ilium (sciatic buttress) serves as the reference point; (3) The anterior column is indirectly linked through the acetabular dome - when posterior reduces, anterior often follows; (4) If I tried to reduce anterior first through K-L, I have no direct access to manipulate it. For both-column via ilioinguinal, the sequence reverses - anterior first with posterior reducing indirectly in 60-70% of cases."

Examiner Question: "What fluoroscopic views do you use to assess reduction and what does each show?"

Model Answer: "I use four views intraoperatively: (1) AP pelvis - overall alignment, femoral head concentricity; (2) Obturator oblique (45° toward affected side) - shows anterior column as a profile and posterior wall en face; (3) Iliac oblique (45° away from affected side) - shows posterior column as a profile and anterior wall en face; (4) Inlet/outlet views if pelvic ring involvement. For reduction assessment, I look for: step-off <2mm, gap <2mm, concentric femoral head, and smooth articular contour. Any intra-articular hardware must be removed and redirected."

Examiner Question: "You've achieved a 3mm step at the dome. What are your options?"

Model Answer: "A 3mm step is not acceptable - Matta's data shows only 50% good outcomes versus 83% with anatomic reduction. My options: (1) Reassess reduction technique - am I pulling in the correct direction? Is there interposed soft tissue or marginal impaction blocking reduction? (2) Change clamp position - may need different reduction point; (3) Address marginal impaction - if impacted bone blocking reduction, must elevate and graft; (4) Consider staging additional approach - if this approach cannot achieve reduction; (5) Accept only if absolutely no alternative - after exhausting all options, document limitation and counsel patient. I would spend significant time optimizing reduction before accepting imperfection."

Examiner Question: "What is your HO prophylaxis protocol after K-L approach, and what if the patient has renal impairment?"

Model Answer: "For K-L approach, HO prophylaxis is mandatory given the 20-30% risk without it. My first-line is indomethacin 25mg TDS for 6 weeks, starting within 24-72 hours. If the patient has renal impairment (eGFR <30) or NSAID contraindication (PUD, aspirin-sensitive asthma, anticoagulation), I use single-dose radiation 700cGy within 72 hours post-op. Radiation is equally effective but more logistically complex. For patients on aspirin for cardiovascular protection, I discuss the risk-benefit - often the HO risk outweighs a brief NSAID course, but this requires MDT input."

Examiner Question: "Do you give HO prophylaxis after ilioinguinal approach?"

Model Answer: "HO prophylaxis is recommended but not mandatory after ilioinguinal approach because the baseline risk is lower (5-15% vs 20-30% for K-L). I would give prophylaxis in specific situations: (1) Complex patterns with extensive dissection; (2) Combined or staged approach including K-L; (3) Prior history of HO; (4) Prolonged operative time with significant soft tissue trauma. When used, the protocol is the same: indomethacin 25mg TDS for 6 weeks or radiation 700cGy if NSAID contraindicated. For straightforward anterior column fractures with minimal dissection, I may omit prophylaxis."

Examiner Question: "A patient wakes up with a foot drop after K-L approach. How do you manage this?"

Model Answer: "Post-operative sciatic nerve palsy after K-L occurs in 5-15% and is usually neurapraxia from retraction. My management: (1) Immediate examination - document motor/sensory function, distinguish peroneal (foot drop, dorsum numbness) from tibial division; (2) Ankle splint - prevent equinus contracture; (3) Observation initially - 70-90% recover over 12-18 months; (4) EMG at 3-4 weeks - baseline study to assess injury severity; (5) Serial clinical exam - monthly initially; (6) Consider exploration ONLY if: complete transection suspected (open injury), worsening despite time, no recovery signs by 4-6 months with EMG showing complete denervation. Most cases recover with observation."

Examiner Question: "You encounter brisk arterial bleeding from the middle window during ilioinguinal approach. Talk me through your management."

Model Answer: "Brisk arterial bleeding in the middle window is likely corona mortis (obturator-external iliac anastomosis) or external iliac vessel injury. My immediate management: (1) Direct pressure with finger or packing - maintain for 5 minutes; (2) Call for help - senior colleague, vascular surgery standby, blood bank; (3) Improve exposure - suction, lighting, additional retractors; (4) Identify source - if on superior pubic ramus, likely corona mortis; (5) Corona mortis management - clamp, ligate with 2-0 silk on the bone; (6) If external iliac - maintain pressure, DO NOT clamp blindly, await vascular surgery; (7) Resuscitation - cell saver, crossmatch blood products. Prevention is key - always look for and ligate corona mortis prophylactically."

Examiner Question: "When would you excise heterotopic ossification after acetabular surgery?"

Model Answer: "I would consider HO excision for Brooker grade III-IV causing functional limitation. Key principles: (1) Wait for maturity - typically 12-18 months post-surgery; (2) Confirm maturity with bone scan (cold scan = mature) or serial X-rays showing no change; (3) Pre-operative planning - CT to delineate HO extent and relationship to vessels/nerves; (4) Approach - usually through previous incision; (5) Post-operative prophylaxis - mandatory radiation (700cGy within 24-72 hours) AND indomethacin; (6) CPM and aggressive physiotherapy - maintain motion gains. Without maturity, recurrence rates approach 100%."

Examiner Question: "A patient develops fever and wound erythema 10 days after acetabular ORIF. How do you manage this?"

Model Answer: "This presentation suggests surgical site infection, a serious complication after acetabular surgery. My management: (1) Clinical assessment - wound inspection, systemic signs, neurological exam; (2) Investigations - FBC, CRP, blood cultures, wound swab for culture; (3) Imaging - X-ray to assess implant position, consider MRI if deep infection suspected; (4) Early operative debridement - within 24-48 hours of diagnosis, thorough washout, deep tissue cultures, consider implant retention if fixation stable; (5) Antibiotics - empirical IV (flucloxacillin + gentamicin), then culture-directed; (6) Multidisciplinary input - infectious diseases, consider suppressive antibiotics; (7) Follow-up - serial inflammatory markers, wound review. Early aggressive management preserves fixation and reduces long-term morbidity."