Hip - Posterior Approach

Modern Study Review (AI-Generated)

High-Yield Summary

The Posterior Approach to the hip (Moore/Southern) remains a gold standard for total hip arthroplasty and complex revision surgeries due to its excellent exposure of the posterior capsule and short external rotators. Despite lacking a true internervous plane, it is favored for cases requiring extensive visualization and access. Minimally invasive and anterior approaches are increasingly popular for primary arthroplasty but have not supplanted the posterior approach in revision or trauma settings.

Applied Anatomy & Intervals

Internervous Interval

None: This approach splits muscle fibers rather than following a defined internervous plane.

Anatomic Landmarks

Posterior border of the Greater Trochanter (GT)
Posterior Superior Iliac Spine (PSIS) (for incision orientation)
Short external rotators: piriformis, superior gemellus, obturator internus, inferior gemellus
Sciatic nerve: critical neurovascular structure to identify and protect

Patient Positioning & Setup

Table Type: Standard orthopedic or radiolucent table (for fluoroscopy)
Patient Position: Lateral decubitus with operative side up
Specialized Equipment:
Limb positioner or assistant to maintain hip flexion and internal rotation
C-arm for intraoperative imaging if needed

Surgical Technique (The “Vital Steps”)

Incision & Superficial Dissection

Make a 15 cm curved incision centered over the posterior border of the GT
Curve incision proximally toward the PSIS or at a 30° angle from the GT
Incise fascia lata to expose vastus lateralis muscle

Deep Dissection & Exposure

Split gluteus maximus fibers longitudinally in line with muscle fibers
Retract split gluteus maximus fibers to expose short external rotators
Identify and protect the sciatic nerve lying deep and medial to short external rotators
Internally rotate the hip to place short external rotators on stretch and move the sciatic nerve away from the field
Place stay sutures in piriformis and obturator internus tendons
Detach short external rotators (piriformis, superior gemellus, obturator internus, inferior gemellus) from femur
Detach superior border of quadratus femoris if necessary
Reflect detached muscles posteriorly to protect the sciatic nerve
Incise posterior capsule and dislocate hip posteriorly

The “Danger Zone”

Structure	Risk Description	Protection Strategy
Sciatic Nerve	At risk during deep dissection and muscle detachment	Identify early; maintain hip internal rotation; gentle retraction
Inferior Gluteal Artery (IGA)	Runs beneath piriformis; branches supply deep gluteus maximus; may be cut during GMax splitting	Careful splitting of gluteus maximus; cauterize branches if needed
Cruciate Anastomosis	Near lower border of quadratus femoris; includes branches from femoral circumflex and inferior epigastric arteries	Avoid aggressive dissection near quadratus femoris border

Post-Operative Pearl

Limit hip flexion beyond 90°, adduction, and internal rotation for 6 weeks to reduce risk of posterior dislocation. Early mobilization with protected weight-bearing is encouraged under supervision.

Classic Clinical Notes