Direct anterior approach for total hip arthroplasty

Orthopaedic surgeons at Penn Medicine have introduced the minimally invasive direct anterior approach (DAA) to total hip arthroplasty (THA) as a complement to the traditional posterior and lateral approaches to THA surgery.

The DAA is unique in that surgeons operate in an intermuscular plane, between the sartorius and tensor fascia latae muscles superficially, and the rectus femoris and gluteus medius at the deeper level to access the hip joint. This approach allows the surgeon to minimize soft tissue trauma while executing a total hip arthroplasty.

The muscle-sparing nature and limited incision length of DAA have been cited as the source of several of the surgery’s reported benefits, including reduced pain, earlier functional recovery, shorter length of stay, greater hip stability and reduced risk of post-surgical dislocation.

The ideal DAA patient

DAA is indicted for the treatment of degenerative osteoarthritis of the hip, as well as femoral head and neck fractures, and avascular necrosis of the hip who have not benefited from non-operative or conservative treatment. Age, anatomy, and surgeon expertise are important factors in determining candidacy for DAA.

Generally, the ideal candidate for DAA is an individual whose bone density, acetabulum, and femur are amenable to standard surgical technique, and whose weight is within the healthy range. Typically, these individuals are active and wish a rapid return to full function. Among the advantages of DAA in this regard is the lack of formal post-surgical hip range of motion precautions.

Patients with relative contraindications to DAA include those with morbid obesity (BMI > 40), the presence of prior hardware, complex hip deformities, and previous surgeries, among others. These patients are generally better served by the posterior or lateral approaches to hip surgery.

Case report

Mrs. M, 66-years-old, was referred to orthopaedic surgeon Matthew J. Poorman, MD, at Penn Medicine Lancaster General Health (LGH) for an evaluation of right hip pain of one year’s standing. During this time, a series of right hip imaging studies found moderate to severe degenerative changes with joint space narrowing, subchondral sclerosis/cysts and osteophyte formation, confirming progressive degenerative disease at her hip.

After a comprehensive discussion of her options, which included both conservative measures and total hip replacement, with a focus upon the direct anterior approach, Mrs. M expressed her interest in an operative intervention, in line with her goal to return quickly to an active lifestyle, and was scheduled for surgery.

Following normal preoperative procedures, an oblique incision in line with the fibers of the tensor fascia lata muscle was made approximately two cm posterior and two cm distal to Mrs. M’s anterior superior iliac spine (ASIS). Dissection was performed down to the level of the tensor fascia lata muscle belly. The fascia was opened and the muscle retracted laterally. Retractors were placed to expose the hip capsule. A capsulotomy was performed and the capsular flaps were tagged with suture for later anatomic repair.

Based on preoperative templating, a femoral neck osteotomy was performed and the femoral head removed. Retractors were then placed to expose the acetabulum, and osteophytes and the hip labrum removed.

In accordance with the pre-operative plan, sequential reaming of the acetabulum was performed, using direct visualization and image intensification for additional guidance. After appropriate acetabular preparation, the final shell was impacted into its appropriate position using image intensification. The cup was found to have an excellent fit and was well seated.

Following supplemental screw fixation and cup irrigation, a neutral polyethylene liner was placed, which engaged the locking mechanism appropriately.

Attention then turned to preparation of the femur. Mrs. M’s leg was rotated to 90 degrees and retractors were placed. Additional capsule release was performed to expose the piriformis, conjoined, and obturator externus tendons. Adequate exposure was obtained without further soft tissue release (in difficult cases further release is performed only as needed, in a sequential manner). The leg was then extended, adducted and further externally rotated achieving excellent visualization of the proximal femur. The femoral canal was established.

Sequential broaching to the appropriate size was performed, with the broach found stable to axial and rotational stress. A calcar planar was applied, a trial neck and head placed, and the hip was reduced. Appropriate sizing and component positioning were confirmed on fluoroscopy. Limb lengths were approximately equivalent radiographically. Hip stability was assessed in extension and external rotation and found to be appropriate.

The hip was dislocated, and the trial head and neck removed before repositioning to expose the proximal femur. Retractors were placed, the broach was removed, and the wound copiously irrigated and suctioned. The final size stem was impacted into position and found to fit well and sit at the same level as the broach.

Thereafter, the final femoral head was placed onto a cleaned, dried trunnion, impacted, and found to engage well. The acetabulum was then copiously irrigated, and the hip reduced and confirmed to be concentric. Final radiographic assessment revealed a stem in good position and leg lengths equivalent radiographically. Stability was again assessed and determined to be appropriate.

Surgical site closure followed. This involved a dilute sterile betadine soak, joint irrigation, and after confirmation of excellent hemostasis, a multimodal periarticular injection. The capsular flaps were repaired. The deep space was again copiously irrigated. The fascia of the tensor fascia lata was repaired. The superficial space was closed in layers including buried subcuticular stitches. The skin was glued and a waterproof sterile silver dressing placed.

Mrs. M was ambulating without an assistive device and off of narcotic pain medications at her two-week follow-up appointment. At three-months, she reported no residual right hip pain, and the resumption of normal activities. Her incision was well healed, and her strength, hip flexion, and abduction were normal (5/5).

The orthopaedic surgeons at Penn Medicine specialize in advanced joint replacements. In addition to direct anterior approach total hip replacements, innovations include robotic-assisted surgery and tourniquet-less knee replacements. We are on the cutting edge of the latest advances in total joint replacement, including total knee and hip replacements, and joint replacement surgeries for the shoulders, elbows, and ankles.

Consultations and referrals

To refer a patient or receive consultation from Penn Orthopaedics, please call 877-937-7366, or submit a referral through our secure online referral form.

Performing Direct Anterior Approach Total Hip Replacement at Penn Medicine

• Matthew J. Poorman, MD
• Kimberly L. Stevenson, MD