Minimally invasive total hip arthroplasty is purported to allow an improved and faster rehabilitation in the immediate postoperative period because of reduced soft-tissue damage compared with total hip arthroplasty performed with use of a standard approach. In the present study, a minimally invasive approach was compared with a traditional standard approach in terms of the effect on gait kinematics as demonstrated with gait analysis and electromyography.
Twenty randomized patients who underwent a primary total hip replacement with use of a minimally invasive modified Watson-Jones approach (minimally invasive group) were compared with a group of twenty patients who underwent a total hip arthroplasty with use of a standard transgluteal Hardinge approach (standard group). All patients received the same cementless implant, inserted with use of standard instruments, and all operations were performed by a single, experienced surgeon. The patients were evaluated with use of three-dimensional gait analysis and dynamic electromyograms at three time points: preoperatively, ten days postoperatively, and twelve weeks postoperatively. Temporospatial and joint-kinematic parameters were evaluated.
There were no significant differences between the two groups with regard to the temporospatial variables of velocity, cadence, step length, and stride length at any tested time point. With regard to the range of motion of the operatively treated hip, the minimally invasive group had a smaller decrease at the ten-day time point in comparison with the standard group. However, this finding was not significant. The reduction in the range of motion was mainly caused by reduced hip extension. A compensatory increase in the pelvic tilt was observed in both groups. One patient in the standard group showed a positive Trendelenburg gait ten days postoperatively; it had disappeared completely at the twelve-week time point.
With regard to gait kinematics in the early postoperative period (three months), the present study showed no significant benefit for patients who underwent a total hip arthroplasty through a minimally invasive Watson-Jones approach in comparison with those who were managed with a standard transgluteal approach.