Quadriceps Coxae-Sparing Modified Posterior Approach to the Hip Joint for Hemiarthroplasty

Abstract

Background:

Various approaches have been described for hip arthroplasty^1-3. The posterior approach to the hip remains a popular choice for hemiarthroplasty¹. In the classic description, it involves detachment of the short external rotators, which include the quadriceps coxae (QC) (i.e., piriformis, superior gemellus, obturator internus, and inferior gemellus) along with the obturator externus and quadratus femoris (as needed). Since the QC are important for joint stability, detachment during the approach is associated with higher rates of postoperative dislocations⁴, even following subsequent surgical repair of the QC. In the study by Stähelin et al.⁵, 15 of 20 repairs involving the QC had failed by 3 months postoperatively, primarily because the repair site could not withstand the forces of normal weight-bearing during the healing phase. Various muscle-sparing modifications of the conventional approach have been described to reduce the propensity for prosthetic dislocation^6-9. Hanly et al.⁹ described the SPAIRE (Sparing Piriformis and Internus, Repair Externus) technique. This minimally invasive modified posterior approach enables the preservation of the QC, possibly representing the greatest extent of muscle and tendon preservation. The advantages of this QC-sparing technique have been demonstrated in clinical studies of hemiarthroplasty^10,11 and total hip arthroplasty¹².

Description:

The patient is anesthetized and placed in a lateral decubitus position. Bolsters are utilized over the pubis and sacral areas to provide stable pelvic orientation. The contralateral limb is flexed at the hip (∼45°) and knee (90°), with adequate padding under the fibular head and lateral malleolus. Another padded bolster is placed between the legs to keep the topmost lower limb in neutral to slight abduction at the hip. The operative limb is flexed at the hip (∼30°), and a 10 to 15-cm straight skin incision is marked on the lateral aspect of hip, centered on the posterolateral tip of the greater trochanter. The deep fascia is opened distally to proximally, incised distally with scissors, and separated proximally with finger dissection. This step creates an intermuscular plane between the gluteus maximus posteriorly and tensor fasciae latae anteriorly. A Charnley hip retractor is applied. Internal rotation of the hip allows identification of the posterior border of the gluteus medius and short external rotators. The fat pad over the QC is swept medially with an abdominal sponge to identify the muscles. A plane is identified between the quadratus femoris and inferior gemellus. Next, a plane is developed between the QC and posterior hip capsule with use of a blunt hemostat from inferior to superior. Abduction of the hip just beyond neutral relaxes the QC and allows superior retraction. The quadratus femoris is detached from the trochanteric crest with use of a diathermy needle until the lesser trochanter is visualized. A capsulotomy is performed in a lazy L-shaped manner, with the first limb of the incision along the distal margin of the QC and the second along the base of the femoral neck. The second limb of the incision raises the musculocapsular flap consisting of the obturator externus along the osseous margin with use of a diathermy needle. This musculocapsular flap is tagged with sutures, which helps in its retraction posteriorly to protect the sciatic nerve and later aids in repair. Bipolar hemiarthroplasty is performed in a conventional manner. The musculocapsular flap is repaired transosseously, and the wound is closed in a layered fashion.

Alternatives:

Alternatives to this QC-sparing technique include the use of a conventional posterior approach, piriformis-preserving posterior approach, direct lateral approach, modified lateral approach, or direct anterior approach.

Rationale:

Preservation of the QC helps improve prosthetic hip stability in internal rotation, possibly because of the preserved proprioception. A minimally invasive approach reduces recovery time during rehabilitation. Preservation of the QC does not hinder visualization or result in component malposition¹².

Expected Outcomes:

Ball et al.¹⁰ compared the use of a modified muscle-sparing posterior approach versus a standard lateral approach. The authors reported comparable Oxford Hip Scores at 120 days (p = 0.25). Patient function and mobility were similar at 3 days and 120 days, regardless of the surgical approach. Length of hospital stay and return to pre-fracture place of residence were similar. Mortality rates and quality of life were also similar at 120 days postoperatively. Patients who underwent the modified muscle-sparing posterior approach experienced less pain during the early postoperative period. The mean score on the numeric pain rating scale was 4.4 (standard deviation, 2.8) among patients who underwent the modified muscle-sparing posterior approach versus 5.4 (standard deviation, 3.0) among patients who underwent the standard lateral approach (p = 0.04).

Important Tips:

• Place a padded bolster between the legs to keep the topmost lower limb in neutral to slight abduction at the hip.

• Develop a plane between the QC and posterior hip capsule with use of a blunt hemostat or a Cobb elevator from inferior to superior in order to help mobilize the QC and release their capsular attachments.

• Hip abduction just beyond neutral relaxes the QC and allows insertion of a Hohmann retractor deep to the QC in order to protect and lever them superiorly.

• A small Langenbeck retractor inserted deep to the QC protects them from shredding during broaching. Internal rotation at the hip beyond 90° (in 90° flexion and neutral adduction/abduction) further protects the QC from harm.

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