PAPER 020: MIS TOTAL HIP ARTHROPLASTY: A PROSPECTIVE TRIAL COMPARING THE EARLY RESULTS AND COMPLICATIONS OF THE MINI-POSTERIOR AND G3 APPROACHES

Abstract

Purpose: To compare the early results and complications associated with two different minimally invasive surgical techniques, the mini-posterior and G3 approaches.

Method: The senior author prospectively allocated successive patients into either posterior or G3 groups for all primary total hip replacements from April 2005 to July 2006.

Results: Of 173 hips, 116 hips were introduced via a mini-posterior approach, 57 via a G3. There were no significant differences in composition of the two groups in average age, gender, length of hospital stay, or early functional outcome. The posterior group patients were generally heavier, but OR time was significantly less than in the G3 group, as were blood transfusion rates. Technical issues were noted in 25% of cases, including calcar and periprosthetic fracture (9), malposition of the acetabular and femoral components (6), and leg length discrepancies (28). There was one death and one infection. There were 3 dislocations, from both groups, deemed to be more a function of improper component implantation, rather than of the surgical approach. Of 4 with neurologic symptoms, one patient from each group experienced anterior thigh numbness with activity; in the G3 group there was a lateral femoral cutaneous nerve deficit, and a severe sciatic nerve deficit. There were 7 (4%) patients who required additional surgery, 5 for periprosthetic fracture or implant malposition. Two re-operations were attributed to being likely specific to the surgical approach and its limited visualization, both G3s with femoral component malposition. Technically it was appreciated that there was a fine line between a too tight femoral component (heightened fracture risk) and one too loose (heightened subsidence risk). The strengths of this study are that it reflects the experience of one career arthroplasty surgeon performing a consecutive, nearly randomized to two MIS approaches, consecutive case series of primary total hip arthroplasties, using the same fiber-metal acetabulum and tapered fiber-metal HA coated femur prostheses in all cases.

Conclusion: The G3 approach is technically difficult, with a long “learning curve”. This difficulty was acutely accentuated in larger patients. The mini-posterior incision was relatively easy, even in the larger patient, and became the preferred approach for the more challenging case.