Recently, minimally invasive hip surgery (MHS) has been developed as a mean of accelerating patient's time to full recovery. Previous analysis of early postoperative data showed that the time to reach complete functional independence (including walking 30 meters) wasn’t shortened with MHS compared to standard hip surgery (SHS). However there is only little evidence on the benefits of MHS on the quality of gait. Symmetrical distribution of load is a useful clinical tool related to it.

The aim of this secondary analysis was then to compare the quality of gait in patients with MHS or SHS.

Hundred and seventy patients were randomized into 2 groups, SHS and MHS. The major criterion was bilateral distribution of load assessed on a stabilometric platform 3 months after surgery. Other criteria were pain, lameness, need of a walking aid and difficulty in using stairs assessed by self-administered questionnaire at 3 and 12 months after surgery. Continuous and categorical variables of interest were compared using Student's t and Chi² tests.

Patients of the MHS group showed significantly more symmetrical distribution of load (48 vs. 52% in the MHS group and 45.2 vs. 54.8% in the SHS group, for operated and contralateral limb, respectively, P=0.020) and less functional impairment: decreased lameness (6.4 vs. 21% in MHS and SHS groups, respectively, P=0.021), need of walking aid (75.8 vs. 88.6% in MHS and SHS groups, respectively, P=0.027), difficulty in using stairs (14.5 vs. 34%, in MHS and SHS groups, respectively P=0.015) at 3 months after surgery. There were no more differences between groups 12 months after surgery and no difference in pain score.

MHS allows earlier recovery of symmetric load and physiological gait. Difference in pain can’t explain the differences in functional abilities that could be the result of the decreased muscle trauma and of the deterioration of proprioceptive sensors.