Smith-Petersen / Iliofemoral Extensile Approach to the Acetabulum and Anterior Column

What this approach delivers. The Smith-Petersen (iliofemoral) approach is the classical anterior exposure of the hip and hemipelvis. When extended by subperiosteal reflection of muscle from both iliac tables, it becomes the iliofemoral extensile approach of Letournel and Judet, giving simultaneous access to the anterior column of the acetabulum, the inner (internal iliac fossa) and outer (gluteal) tables of the iliac wing, the iliac crest, and - distally - the anterior hip capsule. It is one of the three standard operative approaches to the acetabulum taught at fellowship-exam level, alongside the ilioinguinal (anterior, intrapelvic) and the Kocher-Langenbeck (posterior).

Primary indications. - Anterior column acetabular fractures requiring direct visualisation and plating

• Anterior wall acetabular fractures
• Both-column fractures in which the anterior column component dominates (the extended variant addresses both columns)
• Selected T-type and combined fractures where the anterior limb requires fixation
• Delayed presentation and malunions of the anterior column (where the extensile reflection is most useful)
• Pelvic and periacetabular osteotomies: Salter innominate, Bernese periacetabular (Ganz), triple (Tonnis), Chiari medial displacement
• Paediatric hip exposure: Salter, Pemberton and Dega osteotomies for developmental dysplasia; open reduction
• Iliac and acetabular tumour resection and reconstruction, and biopsy or curettage of iliac lesions
• Anterior hip capsulotomy when open intra-articular access is required Contraindications and limitations. - Posterior column or posterior wall fractures as the dominant injury - use Kocher-Langenbeck instead
• Skin compromise or infection over the iliac crest or anterior thigh
• Severe obesity in which exposure of the iliac crest and safe identification of the lateral femoral cutaneous nerve become difficult
• It does not give safe access to the low anterior column at the quadrilateral surface as directly as the ilioinguinal approach, and it does not reach the posterior column without conversion to the extended variant How it differs from related approaches. The position and the columns reached are the first discriminators examiners look for. Anterior column or anterior wall fractures are fixed anteriorly (this approach or the ilioinguinal); posterior wall or posterior column fractures need the Kocher-Langenbeck; both-column fractures with a dominant anterior limb use the ilioinguinal for the quadrilateral surface, while complex or delayed both-column injuries may need the extended iliofemoral for simultaneous two-column access.

Position and landmarks. The patient is placed supine on a radiolucent (flat or Jackson) table so intra-operative fluoroscopy (obturator and iliac oblique views) is unobstructed. A small sandbag or roll under the ipsilateral buttock tilts the pelvis forward and lifts the iliac crest toward the surgeon; the entire hemipelvis and the whole lower limb are prepped and draped free so the leg can be flexed, rotated and tractioned, and the arm on the operated side is placed across the chest to keep it out of the fluoroscopic field. A urinary catheter and cell saver are routine for acetabular work given potential blood loss from the iliac surfaces. Palpate and mark the iliac crest (from the posterior superior iliac spine forward to the ASIS), the anterior superior iliac spine (ASIS) as the hinge point of the incision, the pubic symphysis and pubic tubercle for orientation of the medial extent of the anterior column, and the greater trochanter and femoral shaft axis for the distal limb. The skin incision is the classic inverted-J or hockey-stick, beginning along the iliac crest to the ASIS then turning distally - its precise dimensions are the first step of the exposure below.

The strategy is to peel muscular attachments off the ilium subperiosteally so the bone of the anterior column is laid bare without dividing any major muscle belly on its nerve supply. The two moves are to strip iliacus off the inner table to expose the iliac fossa and pelvic brim, and to strip the abductors (gluteus medius and minimus) and TFL off the outer table to expose the gluteal surface and superior acetabulum. The whole safety of the approach rests on dissecting between muscles supplied by different nerves, so neither muscle is stripped of its innervation and function is preserved. Straying medial denervates sartorius or rectus femoris (femoral nerve) or injures the femoral neurovascular bundle; straying lateral or posterior toward the greater sciatic notch threatens the superior gluteal neurovascular bundle and the abductors.

Structures are best remembered layer by layer, because each is endangered at a distinct point of the dissection.

Extensions. Carry the crest limb further posteriorly along the iliac crest toward the posterior superior iliac spine to expose the entire inner table back to the sacroiliac joint and the entire outer table back to the greater sciatic notch, delivering the whole anterior column and iliac wing on a single exposure. Prolong the distal limb down the anterolateral thigh to expose the AIIS, the anterior femoral neck and capsule, and to continue into the anterolateral approach to the femoral shaft when simultaneous femoral exposure is needed. For both-column fractures, convert to the extended iliofemoral by adding a trochanteric osteotomy and reflecting the abductors proximally and posteriorly, connecting anteriorly with a Kocher-Langenbeck-type posterior exposure - this gives simultaneous access to both columns but at the cost of higher abductor morbidity and a high rate of heterotopic ossification, so reserve it for complex and delayed reconstructions. Closure. Because muscle has been stripped off bone rather than divided, closure is about re-attaching muscle to the iliac crest and restoring the interval. Use drill holes through the iliac crest (or heavy sutures passed around the crest) to re-attach the abdominal wall musculature and the iliacus to the inner lip and the abductors and TFL to the outer lip with strong non-absorbable sutures. Repair the rectus femoris if its heads were divided, and re-approximate the sartorius over TFL interval loosely. In children, carefully close the iliac apophysis (the cartilaginous growth centre) over the crest, having split it at the start, to restore growth. Place one or two deep drains - the subperiosteal iliac surfaces ooze and the dead space is large - and close the fascia, subcutaneous tissue and skin in layers. Post-operative care. - Neurovascular observation of the limb, with specific attention to femoral nerve function (quadriceps contraction) and LFCN territory sensation (anterolateral thigh)

• Thromboprophylaxis (mechanical and chemoprophylaxis) given the pelvic surgery and limited early mobility
• Heterotopic ossification prophylaxis is recommended for the extensile and extended variants (indomethacin or local radiotherapy), as the abductors have been stripped
• Mobilisation depends on the procedure: protected weight bearing after fracture ORIF; the osteotomy or arthroplasty protocol dictates loading after reconstructive work
• Physiotherapy for hip and knee range of movement and quadriceps reactivation

• Acetabular fracture ORIF of anterior column and anterior wall fractures - buttress or neutralisation plating along the pelvic brim
• Both-column fractures (the anterior component, or both columns via the extended variant)
• Pelvic reorientation osteotomies: Salter innominate, Bernese periacetabular (Ganz), triple innominate (Tonnis), Chiari - see the pelvic osteotomies overview
• Paediatric acetabular dysplasia: Pemberton and Dega osteotomies, open reduction of the dislocated hip
• Anterior capsulotomy of the hip for open intra-articular work
• Tumour resection and reconstruction of the ilium and acetabulum, iliac biopsy and curettage
• Irrigation and debridement of selected anterior septic arthritis of the hip

Guidelines, registries and global practice Acetabular surgery is practised to the same anatomic and biomechanical principles across all major examination systems (advanced orthopaedic practice and advanced orthopaedic practice, DNB and MS, MRCS, SICOT). The Letournel and Judet classification and the concept of column-specific approach selection are universal, and CT with three-dimensional reconstruction is the standard for operative planning worldwide. Side-by-side principles (where guidance converges): | Body | Position on acetabular approach selection |

|------|-------------------------------------------| | AO Foundation | CT mandatory for all operatively considered acetabular fractures; the approach is chosen to expose the displaced column directly; anterior column fractures are addressed anteriorly, posterior fractures posteriorly; delay definitive fixation until the soft-tissue envelope recovers | | BOA and BOAST (open and soft-tissue) | Early soft-tissue assessment, photographic documentation, joint orthoplastic care for open injuries, and definitive fixation only once the soft tissues permit | | AAOS and OTA | Anatomic reduction of the weight-bearing dome and restoration of congruence as the primary goals; approach selection individualised to the fracture pattern on CT | Global practice variation: in high-resource settings, pre-contoured pelvic plating systems, patient-specific guides and intra-operative 3D imaging are increasingly used to assist reduction through these approaches. In resource-limited settings, the same anterior exposure is used with small-fragment reconstruction plates contoured freehand along the pelvic brim, and external fixation has a larger role in temporisation. The anatomy of the approach, its internervous planes and its danger structures do not vary. Consent (globally applicable): discuss lateral femoral cutaneous nerve injury with anterolateral thigh numbness (the commonest morbidity), the small but serious risk of superior gluteal bundle injury and abductor weakness, femoral nerve palsy, infection and haematoma from the large iliac dead space, heterotopic ossification (especially with the extended variant, where prophylaxis is advised), and thromboembolic disease.