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Saturday, March 13, 2004

Minimally invasive THA both promising,challenging

By Mary Ann Porucznik

Minimally invasive surgery has the potential for minimizing surgical trauma and pain as well as reducing recovery times. However, when applied to total hip arthroplasty (THA), this technique is extremely challenging and very different from a standard THA, said the author of Scientific Paper 207 yesterday.

The presentation included a description of the technique and a report on one surgeon's results. The report was presented in two parts, examining the initial complications of the first 100 patients and the results of the first 30 minimally invasive THA with more than a two-year follow-up. All were performed by a single surgeon using a two-incision technique (one for the acetabular component and the other for the femoral component). Specially designed instruments and flouroscopy were used to ensure the proper starting points for the incisions and accurate component position and alignment.

The minimally invasive two-incision THA technique avoids transecting any muscle or tendon. One incision is for acetabular preparation and component placement; the other is for femoral preparation and component placement. Standard implants with well-established designs were used to maintain the present expectation for implant durability. Fluoroscopy was used for component preparation and placement.

The first 100 procedures were performed on 75 men and 25 women. The average age of these patients was 55 years old (range: 30 to 76 years). Most patients (87 percent) had a diagnosis of osteoarthritis; eight patients had developmental dysplasia of the hip and five were diagnosed with avascular necrosis. The average weight was 171 lb (range 102 to 255 lb).

Operating time for the first few cases was considerable, but with refinements, was reduced to between 80 and 120 minutes (average 101 minutes). There was one complication of a proximal femoral fracture that occurred during preparation. Using a stem with distal fixation, the surgeon was able to complete the THA without extending or altering the incisions. Since the surgery, the fracture has healed and ingrowth has occurred.

Among the 30 cases with more than two-year follow-up, 18 procedures were performed on males and 12 on females. The average age of patients was 54 years (range: 29 to 68 years old). The average follow-up was 25 months (range: 24 to 30 months). No patient was lost to follow-up.

There were no other complications, no dislocations, no failure of ingrowth and no re-operations. Because fluoroscopy was used during insertion, 91 percent of the femoral stems showed neutral alignment on radiographs (range: neutral to 3 valgus). The abduction angle for acetabular components averaged 45 (range: 36 to 54).

After the first 12 cases, an outpatient protocol was initiated. In the subsequent 88 patients, 75 patients (85 percent) chose to go home the day of surgery, and the remaining 13 patients chose to go home the day after surgery. All patients were discharged to home, not to other care facilities.

Postoperative recovery was tracked carefully. Patients spent an average of 5 days on crutches and used a cane for an average of 8 days. Patients were off all narcotics in an average of 6 days, and returned to work an average of 8 days after surgery. All components have shown ingrowth without migration.

According to presenter Richard A. Berger, MD, of Chicago, "There are conditions that are not yet amenable to the minimally invasive two-incision procedure. This procedure is very challenging in very obese patients, and patients with marked abnormal hip joint anatomy, prior surgery or complete hip dislocation are better candidates for an alternate total hip arthroplasty approach.

"When performed by a trained surgeon, the minimally invasive two-incision procedure achieves excellent success. Nevertheless, it employs novel approaches that can disorient even experienced surgeons. Optimizing patient outcomes using this approach requires meticulous surgical technique, specialized instrumentation and special instruction. As such, attendance and active participation in pre-training exercises, anatomy labs, cadaver training and proctoring programs are essential to minimize complications and ensure success."

  Prep and drape for two-incision minimaally invasive total hip; a small bolster under the ischuim on the affected side elevates the pelvis.
  Picture showing lit Hohman retractor placement and superior view of acetabulum.
  Illustration of retus femoris retracted medially, exposing the capsule.

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Last modified 20/February/2004