Comprehensive surgical technique guide for Anterior Column Acetabular Fracture ORIF via Ilioinguinal Approach - FRCS exam preparation
Reviewed by OrthoVellum Editorial Team
Orthopaedic clinicians and medical editors • Published by OrthoVellum Medical Education Team
Ilioinguinal Approach (Three-Window Technique) | Advanced Pelvic Trauma
Exam Pearl
Examiner Question: "How do you determine if the weight-bearing dome is involved?"
Model Answer: "I use Matta's roof arc measurements. On AP and both oblique views, I draw a vertical line through the femoral head center, then measure the angle from this line to where the fracture exits the articular surface. If ANY of the three roof arc angles is less than 45°, the weight-bearing dome is involved and surgery is indicated. Additionally, on CT, I look at cuts through the dome - the superior 10mm of acetabulum carries 90% of load."
| View | What It Shows | Key Measurements |
|---|---|---|
| AP Pelvis | Overall alignment, both columns, teardrop | Roof arc angles (Matta): >45° medial/anterior/posterior |
| Obturator Oblique (45°) | Anterior column + posterior wall | Anterior column displacement, posterior wall size |
| Iliac Oblique (45°) | Posterior column + anterior wall | Posterior column alignment, anterior wall involvement |
| CT with 3D | Fracture pattern, comminution, fragments | Dome impaction, marginal impaction, loose bodies |
| CT Axial Cuts | Quadrilateral plate, femoral head | Medial wall displacement, head congruency |
Exam Pearl
Matta Roof Arc Measurements: Draw vertical/horizontal lines through femoral head center on AP and obliques. Measure angle from fracture to weight-bearing dome. If ALL three arcs >45°, non-operative management may be considered.
Expected Outcomes:
Specific Risks to Discuss:
| Complication | Incidence | Key Points |
|---|---|---|
| LFCN injury | 70% | Usually temporary numbness anterolateral thigh |
| Femoral nerve | 1-3% | Usually neuropraxia, recovers 6-12 months |
| Vascular injury | <1% | External iliac - catastrophic if occurs |
| Corona mortis bleed | 5-10% | Ligate prophylactically |
| DVT/PE | 5-10% | Extended prophylaxis required |
| Infection | 2-3% superficial, <1% deep | Higher with Morel-Lavallée |
| Heterotopic ossification | 20-50% | Prophylaxis reduces to 5-10% |
| Post-traumatic arthritis | 20-30% | Despite anatomic reduction |
| Nonunion | ~5% | Higher with comminution |
Step 1: Skin and Subcutaneous
Step 2: External Oblique and LFCN
The LFCN is the most commonly injured structure (70% temporary neuropraxia). Look for it early under the external oblique fascia, 1-2cm medial to ASIS, running obliquely over iliacus. Protect with vessel loop or sacrifice with informed consent.
LATERAL WINDOW (Iliac Wing)
MIDDLE WINDOW (Pelvic Brim)
Exam Pearl
Corona Mortis: Present in ~30% of patients. An aberrant connection between external iliac/inferior epigastric and obturator vessels. If avulsed during subperiosteal dissection, causes significant bleeding that is difficult to control. Always actively look for it 2-3cm from symphysis and ligate before avulsion.
MEDIAL WINDOW (Superior Pubic Ramus)
Key Principle: Restore pelvic brim continuity FIRST (middle window) as reference for remaining reduction
Exam Pearl
Examiner Question: "What fluoroscopy views do you obtain for acetabular fracture ORIF and what does each show?"
Model Answer: "I obtain three views: (1) AP pelvis - shows both columns, teardrop integrity, overall alignment; (2) Obturator oblique (45° affected side DOWN) - shows anterior column profile and posterior wall en face - best view for posterior wall reduction; (3) Iliac oblique (45° affected side UP) - shows posterior column profile and anterior wall en face. Each view shows one column in profile and the opposite wall en face. I must achieve all three to assess complete reduction."
Exam Pearl
Examiner Question: "What is your reduction sequence for anterior column fractures?"
Model Answer: "I follow the principle of restoring the pelvic brim first as the reference for remaining reduction. Sequence: (1) Debride haematoma from all windows; (2) Identify fracture pattern and key fragments; (3) Reduce pelvic brim in middle window using Farabeuf clamps - this is the 'keystone'; (4) Reduce superior fragments through lateral window; (5) Reduce inferior fragments through medial window. I verify with fluoroscopy (AP, obturator oblique, iliac oblique) before definitive fixation."
Reduction Verification:
Anatomic reduction (<2mm articular displacement) is critical for outcome. Matta's data: Anatomic reduction = 85-90% good/excellent outcome. Non-anatomic = 50% poor outcome. Do not accept malreduction.
Exam Pearl
Examiner Question: "How do you confirm your K-wires are not intra-articular?"
Model Answer: "I confirm with all three fluoroscopy views (AP, obturator oblique, iliac oblique). The key is that a K-wire may appear extra-articular on one view but penetrate joint on another. I look for: (1) Wire tip relationship to the teardrop on AP; (2) Wire relationship to the posterior wall on obturator oblique; (3) Wire relationship to the anterior wall on iliac oblique. If any doubt, I remove and reposition. An intra-articular wire causes chondrolysis and rapid arthritis."
Anterior Column Plate (Pelvic Brim):
Exam Pearl
Safe Screw Trajectory: Screws along pelvic brim should be directed POSTERIORLY toward posterior column, NOT medially. Medially-directed screws risk external iliac vessels (10-20mm medial) and obturator vessels. Posterior direction is safe for 30-50mm screws.
Exam Pearl
Examiner Question: "When do you add a quadrilateral plate and how do you position it?"
Model Answer: "I add quadrilateral plate buttress for: (1) Medial wall comminution; (2) Elderly osteoporotic bone; (3) Central head protrusion. Positioning: Place the plate INFRAPECTINEAL (below the pectineal line) along the quadrilateral surface. Screws are directed posteriorly 30-40° into the posterior column - this avoids the hip joint. The plate acts as a buttress preventing the femoral head from medializing. Pre-contoured quadrilateral plates are now available and simplify this step."
Exam Pearl
Examiner Question: "What are you looking for on your final fluoroscopy images?"
Model Answer: "On final fluoroscopy, I systematically verify: (1) Reduction quality - <2mm step-off in weight-bearing dome on all views; (2) No intra-articular hardware - check each screw on all 3 views, a screw may look extra-articular on one view but penetrate joint on another; (3) Screw purchase - bicortical where possible, not protruding posteriorly; (4) Joint congruency - concentric femoral head, no subluxation; (5) Overall alignment - pelvic brim restored, no gapping. I save images for the operative record."
External Iliac Vessel Injury
Corona Mortis Bleeding
Exam Pearl
Examiner Question: "You encounter sudden profuse bleeding from the middle window. What do you do?"
Model Answer: "I immediately apply direct pressure with a laparotomy pack and call for help. I suspect external iliac vessel injury. Steps: (1) Maintain pressure while team activates massive transfusion protocol; (2) Call vascular surgery immediately; (3) Extend incision if needed for proximal control; (4) Once vascular surgeon arrives, obtain proximal and distal control with vessel loops or clamps; (5) Identify injury - primary repair if clean laceration, interposition graft if complex; (6) Check distal pulses post-repair; (7) Fasciotomies if ischaemia time >4-6 hours."
| Fracture Pattern | Weight-bearing | Duration |
|---|---|---|
| Simple anterior column | Toe-touch | 6-8 weeks |
| Anterior + PHT | Toe-touch | 8-10 weeks |
| Both column | Toe-touch | 10-12 weeks |
| With comminution | Toe-touch | 12 weeks |
Practice these scenarios to excel in your viva examination
"A 35-year-old motorcyclist presents after a high-speed collision with displaced anterior column acetabular fracture. CT shows 8mm displacement at the pelvic brim with quadrilateral plate involvement. How would you manage this patient?"
"Describe the corona mortis. Why is it clinically significant and how do you manage it?"
"How do you assess acetabular fracture reduction quality, and what is the evidence for anatomic reduction?"
Classification: Draw all 10 Judet-Letournel patterns - 5 elementary (anterior wall, anterior column, posterior wall, posterior column, transverse) + 5 associated (T-type, posterior column + wall, transverse + posterior wall, anterior column + PHT, both column)
Surgical Indications: Roof arc <45°, dome impaction, posterior wall >40%, displaced through weight-bearing dome >2mm, brim >5mm
Three Windows:
Danger Structures with Distances:
Outcomes Data:
High-Yield Exam Summary
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):1632-45.
Letournel E, Judet R. Fractures of the Acetabulum. 2nd ed. Springer-Verlag; 1993.
Giannoudis PV, et al. Operative treatment of displaced fractures of the acetabulum: a meta-analysis. J Bone Joint Surg Br. 2005;87(1):2-9.
Tile M, et al. Fractures of the Pelvis and Acetabulum: Principles and Methods of Management. 4th ed. Thieme; 2015.
Tornetta P 3rd, Matta JM. Outcome of operatively treated unstable posterior pelvic ring disruptions. Clin Orthop Relat Res. 1996;(329):186-93.
Karunakar MA, et al. Iatrogenic nerve palsy after acetabular surgery. J Orthop Trauma. 2003;17(2 Suppl):S19-25. [LFCN injury data]
Okcu G, Erkan S. The corona mortis: a systematic review. Surg Radiol Anat. 2004;26(6):475-81.