Acetabulum - Posterior Approach

Modern Study Review: Posterior Approach to the Acetabulum

High-Yield Summary

The posterior approach to the acetabulum is the gold standard for managing posterior wall and column fractures and remains essential in certain hip arthroplasty cases. It offers direct, extensile exposure of the posterior column and wall but lacks a true internervous plane, necessitating meticulous soft tissue handling. Despite the rise of minimally invasive and anterior approaches, this technique remains indispensable for complex posterior acetabular fractures due to its superior visualization and versatility.

Applied Anatomy & Intervals

Internervous Interval

None: This approach requires detachment of the short external rotators (innervated by the nerve to obturator internus) while sparing the gluteus maximus (innervated by the inferior gluteal nerve). No true internervous plane exists.

Anatomic Landmarks

Greater Trochanter (GT)
Posterior border of Gluteus Maximus (GMax)
Iliac crest (just superior to incision)
Sciatic nerve (posterior to short external rotators)

Patient Positioning & Setup

Table Type

Standard radiolucent orthopedic or fracture table

Patient Position

Lateral decubitus with the affected side up

Specialized Equipment

Limb positioner or assistant to internally rotate the hip (to tension short external rotators)
C-arm fluoroscopy positioned anteriorly or contralaterally for intraoperative imaging

Surgical Technique (The “Vital Steps”)

Incision & Superficial Dissection

Longitudinal incision centered over the GT, extending from just below the iliac crest to ~10 cm distal to the GT tip
Careful incision through subcutaneous fat
Fascia lata incised in line with the skin in the distal half, then extended superiorly along the anterior border of gluteus maximus

Deep Dissection & Exposure

Early identification and protection of the sciatic nerve
Retract split fascia edges to expose piriformis and short external rotators
Internally rotate the leg to place short external rotators on stretch
Detach short external rotators from femoral insertion
Elevate gluteus medius from outer ilium as needed
Consider trochanteric osteotomy for enhanced visualization if required
Incise posterior hip capsule to access acetabulum

The “Danger Zone”

Structure	Risk Description	Protection Strategy
Sciatic Nerve	At risk during short external rotator detachment; injury causes foot drop and sensory loss	Identify early; protect with retracted short external rotators; avoid excessive traction
Inferior Gluteal Artery (IGA)	Exits pelvis under piriformis; risk of bleeding during dissection	Gentle dissection around piriformis; avoid deep blind cuts
Short External Rotators	Detachment required; incomplete repair risks hip instability	Careful detachment and secure reattachment if possible

Post-Operative Pearl

Early mobilization with protected weight-bearing is encouraged to reduce hip stiffness. However, avoid active external rotation and resisted abduction for 6 weeks to protect the repaired short external rotators and posterior capsule.

Classic Clinical Notes