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Acetabular Fracture ORIF - Ilioinguinal Approach

Complete surgical technique guide for the ilioinguinal approach to acetabular fractures - the three-window anterior approach for anterior column, anterior wall, and both-column fracture patterns. FRCS exam preparation.

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High Yield Overview

ILIOINGUINAL APPROACH TO THE ACETABULUM

Letournel's Three-Window Approach | Anterior Column Access | Advanced Trauma

Indications

Fracture Patterns Requiring Ilioinguinal:

  • Anterior column fracture - displaced more than 2mm articular step or 5mm gap
  • Anterior wall fracture - displaced with hip instability
  • Anterior column + posterior hemitransverse - classic pattern for this approach
  • Both-column fracture - when anterior displacement predominates
  • Transverse fracture - when significant anterior displacement (rare indication)
  • Transverse + posterior wall - combined approach if anterior component displaced

Radiographic Criteria:

  • Articular step-off greater than 2mm on CT
  • Displacement greater than 5mm at pelvic brim
  • Loss of secondary congruence in both-column patterns
  • Medial roof arc angle less than 45 degrees

Pre-operative Planning

History:

  • Mechanism of injury (high-energy: MVA, fall from height; low-energy in elderly: hip fracture equivalent)
  • Associated injuries (head, chest, abdomen, spine - polytrauma common)
  • Pre-injury mobility and function (independent vs dependent)
  • Comorbidities (DVT risk, bleeding disorders, anticoagulation)

Examination:

  • Neurovascular status - document femoral, sciatic, obturator function
  • Morel-Lavallee lesion - check for soft tissue degloving (delays surgery)
  • Abdominal examination - bladder, bowel injury
  • Associated pelvic ring assessment - pubic symphysis, SI joint
  • Skin condition - abrasions, lacerations, open fracture wounds

EXAM KEY: "I document detailed neurological examination pre-operatively as the approach places femoral nerve at risk, and I need baseline to compare post-operatively."

Equipment

Implants

  • 3.5mm pelvic reconstruction plates (12-16 hole)
  • 3.5mm cortical screws (20-60mm lengths)
  • 4.5mm cortical screws for iliac wing
  • Infrapectineal buttress plates
  • Spring plates for posterior column
  • 2.7mm screws for comminution

Instruments

  • Large pelvic reduction set
  • Pointed reduction forceps (Weber, Jungbluth)
  • Ball spike pushers
  • Large Hohmann retractors (blunt)
  • Vessel loops / Penrose drains
  • Pelvic C-clamp (for ring control)
  • Long drill bits (150mm)

Adjuncts

  • Fluoroscopy (C-arm)
  • Cell saver (blood loss 500-2000ml typical)
  • Foley catheter (mandatory)
  • Radiolucent table
  • 4 units PRBC crossmatched
  • TXA 1g IV at induction

Anaesthesia and Positioning

Type: General anaesthesia (mandatory)

  • Prolonged procedure (3-4 hours) precludes regional alone
  • Muscle relaxation essential for reduction
  • Consider arterial line for haemodynamic monitoring

Adjuncts:

  • Tranexamic acid 1g IV at induction, repeat at 3 hours
  • Cell saver for blood conservation
  • Hypotensive anaesthesia (MAP 60-70) if tolerated
  • Warming blanket (forced air)

Considerations:

  • Avoid nitrous oxide (bowel distension impairs access)
  • Antibiotic prophylaxis: Cefazolin 2g IV within 60 minutes of incision
  • Repeat antibiotics every 4 hours or 1.5L blood loss

Surface Anatomy and Landmarks

Critical Surface Landmarks

EXAM KEY: "I mark the incision from a point 2cm below the iliac crest at the level of ASIS, extending medially along the crest for 8-10cm, then curving distally parallel to and 2cm above the inguinal ligament toward the pubic tubercle. The LFCN typically exits 1-2cm medial to ASIS and must be identified early."

Surgical Approach - The Three Windows

Letournel's Three-Window Technique

The ilioinguinal approach provides access to the entire anterior column through three anatomically safe windows. Each window has specific boundaries that must be respected to avoid neurovascular injury.

Mnemonic

Lateral, Middle, MedialLMM - Window Order

Lateral Window

Boundaries:

  • Lateral: Detached abdominal wall musculature
  • Medial: Elevated iliacus muscle on iliopsoas tendon
  • Superior: Iliac crest
  • Inferior: Pelvic brim

Access Provides:

  • Inner table of iliac wing
  • SI joint (up to 3cm posterior)
  • Iliac crest and anterior column proximally
  • Greater sciatic notch (limit of safe dissection)

Structures at Risk:

  • Superior gluteal neurovascular bundle (exits above piriformis, 3-4cm from notch)
  • L5 nerve root (at sacral ala)
  • Iliac crest bleeding

Development Technique:

  1. Detach external oblique, internal oblique, transversus abdominis from anterior iliac crest
  2. Elevate iliacus subperiosteally from inner iliac fossa
  3. Identify and protect LFCN (exits 1-2cm medial to ASIS)
  4. Expose from anterior iliac crest to pelvic brim
  5. Identify greater sciatic notch - do not dissect beyond

Middle Window

Boundaries:

  • Lateral: Iliopsoas muscle (with femoral nerve on surface)
  • Medial: External iliac vessels
  • Superior: Continuation of lateral window dissection
  • Inferior: Inguinal ligament/lacunar ligament

Access Provides:

  • Pelvic brim from ASIS to pectineal eminence
  • Mid-portion of anterior column
  • Quadrilateral plate (limited view)

Structures at Risk:

  • Femoral nerve (lies on iliopsoas, 2-3cm lateral to artery)
  • External iliac artery and vein
  • Corona mortis (crosses superior ramus)

Development Technique:

  1. Identify external iliac vessels deep to transversalis fascia
  2. Identify iliopsoas muscle with femoral nerve on its surface
  3. Mobilise vessels medially using vessel loops (Penrose drains)
  4. NEVER use sharp retractors on vessels
  5. Identify and LIGATE corona mortis before fracture manipulation

Medial Window

Boundaries:

  • Lateral: Iliopsoas muscle
  • Medial: Spermatic cord (male) or round ligament (female)
  • Superior: Pectineal eminence
  • Inferior: Pubic symphysis

Access Provides:

  • Superior pubic ramus
  • Pectineal eminence
  • Quadrilateral plate (good view)
  • Symphysis pubis

Structures at Risk:

  • Spermatic cord/round ligament
  • Bladder (lies medially)
  • Obturator nerve and vessels (deep to ramus)
  • Corona mortis (if not already ligated)

Development Technique:

  1. Identify spermatic cord entering inguinal canal
  2. Gently retract cord medially with Penrose tape
  3. Expose superior pubic ramus and pectineal eminence
  4. Identify obturator foramen and canal
  5. Protect bladder with gentle medial retraction

Critical Danger Structures

CORONA MORTIS - Crown of Death

Anatomy and Significance

Corona Mortis is an aberrant vascular anastomosis between the external iliac (or inferior epigastric) vessels and the obturator vessels. Present in 30-50% of patients.

  • Location: Crosses superior pubic ramus 4-6cm from symphysis
  • Calibre: Can be arterial (10%) or venous (70%) or both (20%)
  • Danger: If injured during fracture manipulation or fixation, causes massive haemorrhage that is difficult to control in the pelvis

EXAM KEY: "I identify corona mortis in the medial window BEFORE fracture manipulation. I ligate it between clips or ties. If injured, it causes torrential haemorrhage - the name means 'crown of death' in Latin."

Structures at Risk by Window

Operative Technique

Step-by-Step Procedure

Step 1: Positioning and Preparation

  1. Position supine on radiolucent table
  2. Insert Foley catheter (mandatory - decompresses bladder)
  3. Arms on boards or tucked
  4. Prepare from costal margin to mid-thigh, symphysis to contralateral ASIS
  5. Mark incision before prep
  6. Confirm fluoroscopy: AP pelvis, inlet, outlet, both Judet obliques

Exam Pearl

Technical Pearl: "The Foley catheter is not optional - the distended bladder lies directly in the surgical field and is at risk of injury. I confirm fluoroscopy capability before draping."

Step 2: Incision

  1. Begin incision at ASIS level, 2cm below iliac crest
  2. Extend medially along iliac crest for 8-10cm
  3. Curve distally, running parallel to and 2cm above inguinal ligament
  4. Continue toward pubic tubercle (total length 20-25cm)
  5. Divide skin and subcutaneous fat
  6. Identify and preserve LFCN (exits 1-2cm medial to ASIS)

LFCN Management

The lateral femoral cutaneous nerve injury rate is 15-25%. Options:

  • Preserve: Identify and protect throughout (preferred)
  • Divide: If preservation impossible, divide sharply and bury proximal end in muscle to prevent neuroma
  • Consequence: Meralgia paresthetica (anterior thigh numbness) - usually transient

Step 3: Develop Lateral Window

  1. Incise external oblique aponeurosis along iliac crest
  2. Detach internal oblique and transversus from crest with diathermy
  3. Enter between transversalis fascia and peritoneum (extraperitoneal plane)
  4. Elevate iliacus subperiosteally from inner table of ilium
  5. Continue posteriorly to greater sciatic notch (DO NOT exceed)
  6. Identify pelvic brim and sacroiliac joint

Exam Pearl

Technical Pearl: "The lateral window is developed entirely subperiosteally on the inner iliac fossa. I do NOT dissect beyond the greater sciatic notch as this risks the superior gluteal neurovascular bundle which exits above piriformis."

Step 4: Develop Middle Window

  1. Identify external iliac artery and vein deep to transversalis fascia
  2. Identify iliopsoas muscle with femoral nerve visible on its surface
  3. Create window BETWEEN vessels (medially) and iliopsoas (laterally)
  4. Mobilise vessels with vessel loops or Penrose drains
  5. NEVER use sharp retractors or excessive traction on vessels
  6. Release retractors every 15 minutes to prevent nerve injury

KEY STRUCTURES:

  • Femoral nerve lies on iliopsoas, 2-3cm lateral to artery at inguinal ligament
  • External iliac vessels must be mobilised medially with extreme care
  • This window exposes pelvic brim from ASIS to pectineal eminence

Step 5: Develop Medial Window and Ligate Corona Mortis

  1. Identify spermatic cord (male) or round ligament (female) at internal inguinal ring
  2. Gently retract cord medially with Penrose tape
  3. Expose superior pubic ramus and pectineal eminence
  4. CRITICAL: Identify corona mortis - crosses superior ramus 4-6cm from symphysis
  5. Ligate corona mortis between clips before ANY fracture manipulation
  6. Expose quadrilateral plate and symphysis region

Corona Mortis Protocol

Present in 30-50% of patients. ALWAYS identify before fracture reduction:

  1. Look for vessel crossing superior pubic ramus
  2. Ligate between clips or ties (both ends)
  3. If not visible, assume it exists deep - careful dissection
  4. If injured: immediate pressure, then ligation of both ends

Step 6: Fracture Reduction - Proximal to Distal

Principle: Work from stable (iliac crest) to unstable (symphysis)

  1. Clear fracture haematoma and fibrous tissue from all lines
  2. Begin reduction at iliac wing (stable reference point)
  3. Use ball spike pushers and pointed reduction forceps
  4. Hold provisional reduction with 2.0mm K-wires
  5. Progress distally along pelvic brim
  6. Address quadrilateral plate displacement last

Reduction Aids:

  • Schanz pins in anterior column for manipulation
  • Jungbluth clamps across pelvic brim
  • Farabeuf clamps for symphysis

Exam Pearl

Technical Pearl: "I reduce fractures from proximal to distal - the intact ilium is my stable reference. I aim for anatomic reduction at the pelvic brim (less than 1mm step) as this is the primary weight-bearing path through the anterior column."

Step 7: Definitive Fixation

Pelvic Brim Plate:

  • 3.5mm reconstruction plate along entire pelvic brim
  • Contour to match pelvic brim anatomy
  • Position on INTERNAL aspect (best biomechanical position)
  • Minimum 3 bicortical screws each side of fracture
  • Check screw lengths - avoid joint penetration (iliac oblique view)

Iliac Wing Plate (if needed):

  • External surface of ilium through lateral window
  • 4.5mm reconstruction plate for comminution
  • Spans from intact ilium to pelvic brim

Quadrilateral Plate (if fractured):

  • Infrapectineal buttress plate through medial window
  • Prevents medial displacement of femoral head
  • Alternative: posterior column screws from anterior for indirect support

Symphyseal Plate (if required):

  • 3.5mm plate on superior pubic surface
  • Minimum 6-8 cortices each side
  • Consider two plates for unstable patterns

Step 8: Final Assessment

Fluoroscopy Views:

  1. AP pelvis - overall reduction
  2. Inlet (25-degree caudal) - pelvic ring, anterior displacement
  3. Outlet (45-degree cranial) - vertical displacement, sacrum
  4. Obturator oblique - anterior column profile
  5. Iliac oblique - posterior column profile

Confirm:

  • Anatomic reduction (less than 2mm step, less than 5mm gap)
  • No intra-articular hardware
  • No joint penetration
  • Adequate fixation of all fragments
  • No vascular compression

Exam Pearl

Technical Pearl: "Intra-operative fluoroscopy misses 20-30% of intra-articular screw penetration. Post-operative CT is MANDATORY to confirm reduction and hardware position."

Closure

  1. Release all vessel loops and retractors gently
  2. Inspect for active bleeding - control with diathermy or clips
  3. Check for hematoma formation in retroperitoneum
  4. Confirm distal pulses before closure

Intra-operative Complications

Structures: Corona mortis, external iliac vessels, obturator vessels

Recognition:

  • Sudden profuse bleeding
  • Hypotension
  • Visible vessel injury

Prevention:

  • Ligate corona mortis prophylactically
  • Vessel loops on external iliacs
  • Blunt retractors only
  • Screw lengths less than 20mm through superior ramus

Management:

  • Immediate pressure
  • Call vascular surgery if major vessel
  • Corona mortis: ligate both ends (may retract into pelvis)
  • Pack and resuscitate if unstable
  • Have cell saver running throughout

Post-operative Care

Monitoring:

  • HDU if significant blood loss or comorbidities
  • Neurovascular observations every 2 hours for 24 hours
  • Monitor for abdominal compartment syndrome if large retroperitoneal hematoma
  • Urine output monitoring (minimum 0.5ml/kg/hour)

Medications:

  • DVT prophylaxis: LMWH (Enoxaparin 40mg daily) from day 1
  • HO prophylaxis: Indomethacin 25mg TDS for 6 weeks (if no contraindications)
  • Alternative HO prophylaxis: Single fraction radiation 700cGy within 72 hours
  • Analgesia: PCA then oral, target pain less than 4/10

Drains:

  • Remove when output less than 30ml per 8-hour shift
  • Typically 48-72 hours

Viva Scenarios

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"You are performing an ilioinguinal approach and encounter brisk bleeding from a vessel crossing the superior pubic ramus. What is this and how do you manage it?"

EXCEPTIONAL ANSWER
This is injury to the corona mortis - an aberrant anastomosis between the external iliac or inferior epigastric vessels and the obturator vessels. It is present in 30-50% of patients and crosses the superior pubic ramus typically 4-6cm from the pubic symphysis. The name means 'crown of death' in Latin, reflecting the potentially catastrophic haemorrhage if injured. My immediate management would be: 1. Apply direct pressure with a gauze swab to control haemorrhage 2. Suction to clear the field and identify the bleeding source 3. Ask anaesthesia to give fluid resuscitation and check crossmatch is available 4. The vessel often retracts into the pelvis, so I need to extend my exposure if necessary 5. Once I can visualise the vessel, I apply clips or ties to BOTH ends as it is an anastomotic vessel with blood supply from two directions 6. If I cannot control with clips, I may need to ligate the feeding vessel more proximally Prevention is better than cure - I always identify and ligate corona mortis prophylactically when developing the medial window, BEFORE any fracture manipulation. I look for a vessel crossing the superior pubic ramus in the 4-6cm zone from the symphysis and ligate it between clips regardless of whether it appears to be a significant calibre. In terms of vessel type, corona mortis can be arterial (10%), venous (70%), or both (20%). The venous variant is more common but the arterial variant causes more dramatic bleeding. Either way, the management is the same - control with pressure and ligate both ends.
VIVA SCENARIOStandard

EXAMINER

"Describe the boundaries of the three windows in the ilioinguinal approach and what structures each window gives you access to."

EXCEPTIONAL ANSWER
The ilioinguinal approach, developed by Emile Letournel in the 1960s, provides access to the entire anterior column of the acetabulum through three anatomically safe windows. Each window has specific boundaries that must be respected to avoid injury to neurovascular structures. **Lateral Window:** The boundaries are: lateral - the detached abdominal wall musculature (external oblique, internal oblique, transversus abdominis), medial - the elevated iliacus muscle on the iliopsoas tendon. This window provides access to the inner table of the iliac wing from the anterior border to the greater sciatic notch posteriorly, the sacroiliac joint (up to about 3cm posterior), and the proximal anterior column at the pelvic brim. The danger structures here are the superior gluteal neurovascular bundle which exits the pelvis above the piriformis muscle about 3-4cm from the sciatic notch - I never dissect beyond the notch for this reason - and bleeding from the iliac crest. **Middle Window:** The boundaries are: lateral - the iliopsoas muscle with the femoral nerve running on its surface, medial - the external iliac artery and vein protected with vessel loops. This window provides access to the pelvic brim from the ASIS to the pectineal eminence, the mid-portion of the anterior column, and limited visualisation of the quadrilateral plate. The danger structures are the femoral nerve lying on the iliopsoas about 2-3cm lateral to the femoral artery, the external iliac vessels, and the corona mortis crossing the superior pubic ramus. **Medial Window:** The boundaries are: lateral - the iliopsoas muscle, medial - the spermatic cord in males or round ligament in females. This window provides access to the superior pubic ramus, pectineal eminence, the quadrilateral plate (best visualisation), and the pubic symphysis. The danger structures are the spermatic cord (handle gently to avoid testicular ischaemia), the bladder lying medially, and the obturator nerve and vessels deep to the superior ramus. The internervous plane is only truly present in the lateral window - between the territory of the femoral nerve (L2-4) supplying iliacus and the gluteal nerves (L4-S1) supplying the gluteal muscles. The middle and medial windows are developed between structures rather than in internervous planes.
VIVA SCENARIOStandard

EXAMINER

"A 45-year-old man sustains an anterior column fracture with posterior hemitransverse component. Two weeks post-ilioinguinal approach and ORIF, he has weakness of knee extension and absent knee jerk. How do you assess and manage this?"

EXCEPTIONAL ANSWER
This presentation suggests femoral nerve injury, which occurs in 2-5% of ilioinguinal approaches. The femoral nerve lies on the surface of the iliopsoas muscle in the middle window, approximately 2-3cm lateral to the femoral artery at the level of the inguinal ligament, and is at risk from retraction injury during the procedure. **Assessment:** My clinical assessment would include: 1. Detailed motor examination: hip flexion (iliopsoas - L2,3), knee extension (quadriceps - L3,4), and comparison with the other side. I would grade power on the MRC scale. 2. Sensory examination: anterior thigh and medial leg (saphenous nerve distribution) 3. Reflexes: knee jerk (L3,4) - assess both sides for comparison 4. Documentation of findings in the notes for comparison with pre-operative baseline I would also want to review my operative notes to assess: retraction time, any direct trauma to the nerve, and whether any steps were taken to protect it. Prolonged retraction greater than 15 minutes without release is a risk factor for traction neuropraxia. **Investigations:** 1. Nerve conduction studies and EMG at 6 weeks post-injury - this will help differentiate between neuropraxia, axonotmesis, and neurotmesis, and provide prognostic information 2. MRI of the femoral nerve if there is concern about structural lesion (rarely needed) **Management:** The majority (90%) of femoral nerve injuries after ilioinguinal approach are neuropraxias from retraction injury. These typically recover over 6-12 months. My management would be: 1. **Reassurance and counselling:** Explain the likely mechanism and expected recovery timeline 2. **Physiotherapy:** Quadriceps exercises to maintain muscle bulk, gait training 3. **Falls prevention:** The patient is at risk of falls due to knee giving way - may need locked knee brace initially 4. **Serial clinical assessment:** Monthly review of power and function 5. **Repeat EMG at 3-6 months** if not improving to assess for reinnervation potentials If there is no improvement by 6 months with EMG showing no reinnervation, I would consider: - MRI to assess nerve continuity - Neurosurgical referral for possible nerve exploration - However, direct repair is rarely possible and outcomes of exploration are guarded For the patient in this scenario at 2 weeks, it is too early to make definitive prognostic statements. I would reassure him that recovery is expected in most cases, arrange physiotherapy, and plan review with EMG at 6 weeks.

Key Exam Points

Ilioinguinal Approach - FRCS Quick Reference

High-Yield Exam Summary

References

Key Literature

Original Description:

  • Letournel E. Acetabulum fractures: classification and management. Clin Orthop Relat Res. 1980;(151):81-106. Classic paper describing the ilioinguinal approach and Judet-Letournel classification

Anatomical Studies:

  • Tornetta P 3rd, Hochwald N, Levine R. Corona mortis: incidence and location. Clin Orthop Relat Res. 1996;(329):97-101. Found corona mortis in 34% of cadavers
  • Darmanis S, Lewis A, Mansoor A, Bircher M. Corona mortis: an anatomical study with clinical implications. Clin Anat. 2007;20(4):433-439. Venous variant more common than arterial

Outcomes:

  • 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. Landmark outcomes study - anatomic reduction correlates with clinical outcome
  • 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.

Complications:

  • Liebergall M, Mosheiff R, Low J, Goldvirt M, et al. Acetabular fractures: clinical outcome of surgical treatment. Clin Orthop Relat Res. 1999;(366):205-16.
  • Letournel E, Judet R. Fractures of the Acetabulum. 2nd ed. Berlin: Springer-Verlag; 1993. Definitive textbook on acetabular fractures