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Soft tissue repair in posterior approach THA mitigates need for hip precautions
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The surgical approach for total hip arthroplasty continues to be a controversial topic among joint replacement surgeons. Traditional approaches, such as the posterior approach and the anterolateral approach, have been recently challenged by the direct anterior approach due to its intermuscular approach that allows for comparatively faster recovery rates. Although reports of decreased pain medicine requirements and shorter time to independent function with the direct anterior approach more easily associate this approach with the possibility of performing it at an ambulatory surgical center, direct anterior hip replacement also carries a steeper learning curve and several possible complications that are often related to femoral exposure and preparation, especially for the inexperienced surgeon. Thus, proponents of the anterolateral and posterior approaches seek to continue performing surgery via these approaches while improving function and narrowing the recovery gap for patients who undergo these approaches compared to those who undergo the direct anterior approach. It should be noted that the early pioneers of outpatient hip arthroplasty successfully used the posterior approach and may continue to do so.
The posterior approach to the hip is the most commonly performed total hip arthroplasty (THA) approach. It has a low implant-related complication rate and allows for extension of the approach proximally and/or distally to address potential intraoperative and/or future complications. However, early descriptions of the posterior approach to the hip included capsulectomy and release of the short external rotator muscles/tendons without posterior soft tissue repair, which resulted in a dislocation rate that was reported to be as high as 8%. In addition, this approach requires splitting the gluteus maximus muscle, which increases postoperative pain and soreness and ultimately leads to hip recovery rates that lag behind direct anterior approach (DAA) recovery rates based on patient pain, function and satisfaction metrics. However, the difference in function and patient satisfaction equalizes with time and is negligible when patients are re-examined 2 years after surgery.
Recent advances in polyethylene technology and manufacturing have decreased polyethylene volumetric wear rates. This allows for routine use of larger femoral heads without excessive implant wear/failure. These polyethylene improvements, coupled with increased attention to posterior soft tissue repair, have decreased posterior approach THA dislocation rates to a level comparable to that reported with DAA. In fact, the results have led many to abandon the previously strict “posterior hip precautions,” including limitations such as allowing hip flexion to a maximum of 90º, requiring elevated seats (including toilets) and using an abduction pillow between the legs during the first 6 weeks after surgery. Therefore, proponents of the posterior approach to THA have been able to continue performing surgery via this approach while narrowing the recovery gap as compared to patients undergoing DAA hip replacement.
Steps for posterior exposure
With the patient in a lateral decubitus position, a standard posterior approach to the hip is performed with a lateral incision that is centered about the greater trochanter. A self-retaining retractor is placed deep to the fascia after it is incised in line with the skin incision and the greater trochanteric bursa is retracted posteriorly to allow visualization of the abductor musculature, as well as the short external rotators. Lateral retraction of the gluteus medius muscle allows a view of the fascial communication between the gluteus minimus muscle and the piriformis tendon. This tissue layer is then penetrated and the gluteus minimus muscle is elevated and retracted laterally off the superior posterior hip capsule. Incising the capsule just proximal to and in line with the piriformis tendon allows creation of a full-thickness posterior flap. The path of the piriformis is then followed anteriorly toward the piriformis fossa while maintaining the posterior length of the soft tissue envelope for later repair.
Once the capsule is released anteriorly off of the femur, the capsular incision is extended distally off of the posterolateral femur to the level of the lesser trochanter. This is done while taking care to identify and control bleeding from the medial femoral circumflex artery as it travels within the quadratus femoris. At this point, the hip can be gently dislocated with flexion, adduction and internal rotation, and the surgeon may proceed with the THA procedure.
Repair soft tissue envelope
After the acetabular and femoral components are implanted and the anterior and posterior stability of the implants is ascertained, the repair of the posterior soft tissue envelope can proceed. It is done in a step-wise fashion in reverse order of exposure. Nonabsorbable sutures are placed in these locations: 1) inferior posterior capsule; 2) conjoint tendon; 3) superior posterior capsule; and 4) piriformis tendon. Sutures 1 and 2 are passed together through a 2-mm or 2.3-mm drill hole in the posterior aspect of the proximal femur at the level of the conjoint tendon and sutures 3 and 4 are passed together through a separate 2-mm or 2.3-mm drill hole at the level of the piriformis tendon.
Proximal sutures are then tied to the distal sutures either as a group or separately, and the capsular sutures are tied to each other and the external rotator stitches are also tied to each other. Through gentle internal rotation of the femur the surgeon can ensure the soft tissue envelope has been completely repaired if the sutures are not visible between the soft tissue and the bone posteriorly. The surgeon can confirm the tension of the repair is appropriate if no soft tissue or suture rupture occurs with this maneuver.
Suggestions for full tissue release
When releasing the superior capsule and piriformis off the proximal femur, achieving full anterior tissue release can be aided by gentle extension and internal rotation of the hip during release. Continued internal rotation of the hip during capsular release can further assist with full-thickness release of the tissue and can help with identifying any soft tissue that may cause difficulty during dislocation if left intact. If any difficulty with dislocation is encountered, an anterosuperior capsular release off the superior rim of the acetabulum may be required. The incision of the inferior capsule lateral to the transverse acetabular ligament during acetabular exposure may help mobilize the posterior capsule for later repair if the femoral neck offset and length are increased by the THA implants used. External rotation of the femur during posterior capsular repair may approximate the soft tissue to the femur, but internal rotation should be checked after sutures are tied to ensure the repair is maintained under maximum tension. If the capsular repair is obtained but piriformis length puts undue tension on the sciatic nerve, a side-to-side closure of the piriformis to the gluteus minimus investing fascia is a technique that may provide additional posterosuperior stability. Finally, a gluteus maximus tendon incision should be considered, especially if lengthening of the hip and/or posterior capsular repair result in a slight increase in sciatic nerve tension.
Middle-ground THA option
With the use of larger femoral heads and a robust posterior soft tissue repair, it may be possible to adjust rehabilitation regimens to allow for a more rapid return of hip function and daily activity without any associated increase in the rate of dislocation. Thus, this exposure and repair leads to a decrease in the disparity in patient-reported outcomes between DAA and posterior-approach THA. In practice, narrowing the recovery gap for patients who undergo THA allows surgeons who prefer the posterior approach to provide a middle-ground option to patients who might seek DAA due to its previously reported shorter, less restrictive period of recovery.
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- For more information:
- Daniel C. Smith, MD, can be reached at Mount Sinai Hospital/Mount Sinai West/Mount Sinai St. Luke’s Department of Orthopaedic Surgery, Division of Adult Reconstruction, 5 E. 98th St., 7th Floor, Box 1188, New York, NY 10029; email: daniel.smith@mountsinai.org.
- Daniel Charen, MD, can be reached at Mount Sinai West Hospital, Department of Orthopaedic Surgery, 1000 10th Ave., New York, NY 10019; email: daniel.charen@mountsinai.org.
Disclosures: Smith and Charen report no relevant financial disclosures.