Comparison of MMIC lumped and quasi-lumped quadrature coupler performance

Minimally invasive (MI) total hip replacement (THR) supposedly provides improved ambulation in the immediate post-operative period. This study used a prospective blinded design to analyse early post-operative walking ability using gait analysis. Seventeen patients were available for full analysis with nine having had the MI technique and eight having the standard incision (SI) technique. Patients were blinded as to the incision used, as were all physiotherapists and assessors. Differences in temporal–spatial variables and joint kinematics measured 1 day pre-operatively, 2 days post-operatively and 42 days (6 weeks) post-operatively were compared between groups. There was no significant difference in velocity, step length of the affected or unaffected leg, stride length or stance phase duration between the MI and SI groups between any of the timepoints tested. There was no significant improvement in the gait kinematics of the MI group compared to the SI group either 2 days post-operatively or 6 weeks post-operatively. Contrary to previous studies, there was no improvement in early post-operative gait for those patients who received THR using the minimally invasive technique.