Posterior approach to the hip.

The posterior approach to the hip joint, also known as the Southern Moore approach, is the most common and practical technique used in total hip replacement surgery. First popularized by Moore, it is often referred to as the southern approach.

The posterior approach to the hip joint is used for:

1. Total hip replacement, including revision procedures.
2. Hemiarthroplasty of the hip.
3. Open reduction and internal fixation of posterior acetabular fractures.
4. Open reduction of posterior hip dislocations.
5. Removal of loose bodies.
6. Dependent drainage of a septic hip.
7. Pedicle bone grafting.

All posterior approaches provide easy, safe, and rapid access to the joint and can be performed with just one assistant. Because they do not compromise the hip’s abduction mechanism, they prevent the loss of abductor strength in the immediate postoperative period. This approach also offers excellent visualization of the femoral shaft, making it a common choice for revision joint replacement when the femoral component needs to be replaced.

Patient Positioning

• Place the patient in the proper lateral decubitus position, with the affected limb facing upward.
• It is essential to protect the bony prominences of the legs and pelvis by padding under the lateral malleolus and knee of the lower leg, as well as by placing a pillow between the knees.

Landmarks and Incision

Landmarks:

• Greater trochanter.
• The posterior border of the trochanter is more superficial than the anterior and lateral parts, making it easier to palpate.

Incision:

Make a curved incision, 10 to 15 cm long, one inch behind the posterior edge of the greater trochanter (GT):

• Begin 7 cm above and behind the greater trochanter.
• Curve the incision behind the greater trochanter and continue it along the femoral shaft.

The mini-incision approach shows no long-term benefits for hip function.

Internervous Plane

• There is no true internervous plane for the posterior approach to the hip joint.
• Intermuscular plane: Gluteus maximus, which is innervated by the inferior gluteal nerve.

Superficial Dissection

• Incise the fascia lata to expose the vastus lateralis distally.
• Extend the fascial incision to match the skin incision.
• Split the fibers of the gluteus maximus at the proximal end of the incision; cauterize vessels during the split to avoid excessive blood loss.

Deep Dissection

• Internally rotate the hip to place the short external rotators on stretch.
• Place a stay suture in the piriformis and obturator internus tendons (short external rotators). Evidence suggests that repairing the short external rotators during closure reduces the dislocation rate.
• Release the piriformis and obturator internus muscles near their femoral attachments. Reflect them posteriorly to protect the sciatic nerve.
• Incise the capsule using a longitudinal or T-shaped incision.
• Dislocate the hip by internally rotating it after the capsulotomy.

Approach Extension

Proximal Extension:

The posterior approach to the hip can be extended proximally toward the iliac crest to expose the ilium.

Distal Extension:

The posterior approach can be extended distally along the femoral line down to the level of the knee. The vastus lateralis can be either split or elevated from the lateral intermuscular septum.

Dangers

Structures at risk during the posterior approach to the hip include:

1. Sciatic nerve: It can be damaged by compression from the posterior blade of a self-retaining retractor used to split the gluteus maximus. Extend the hip and flex the knee to help prevent sciatic nerve injury.
2. Inferior gluteal artery.
3. First perforating branch of the profunda femoris artery.
4. Femoral vessels.
5. Superior gluteal artery and nerve.

Related Anatomy

Gluteus Maximus:

• Origin: From the posterior gluteal line of the ilium and the bone immediately above and behind it; from the posterior surface of the lower part of the sacrum and the side of the coccyx; and from the fascia covering the gluteus medius.
• Insertion: Into the iliotibial band of the fascia lata and the gluteal tuberosity.
• Action: Extends and laterally rotates the thigh.
• Nerve supply: Inferior gluteal nerve.

Greater Trochanter

Five muscles are attached to it:

1. The gluteus medius is attached to its lateral side by a broad insertion. Below this attachment, the bone is covered by the origin of the iliotibial tract.
2. The gluteus minimus is attached to the anterior side of the trochanter, where its tendon is cut in the anterolateral approach.
3. The piriformis inserts via a tendon into the middle of the upper border of the greater trochanter. Its insertion serves as a surgical landmark for the introduction of certain types of intramedullary rods into the femur.
4. The tendon of the obturator externus: Immediately below the insertion of the piriformis lies the trochanteric fossa, a deep pit that marks the insertion of the obturator externus tendon.
5. The obturator internus tendon, along with the two gemelli, inserts onto the upper border of the trochanter, behind the insertion of the piriformis.

References

• Book: “Surgical Exposures in Orthopaedics” – 4th Edition.
• Onyemaechi N, Anyanwu E, Obikili E, Ekezie J. Anatomical Basis for Surgical Approaches to the Hip. Ann Med Health Sci Res. 2014 Jul;4(4):487-94. doi: 10.4103/2141-9248.139278. PMID: 25221692; PMCID: PMC4160668.