Difference in Muscle Strength and Functional Outcome in Direct Lateral Approach versus Posterior Approach in Total Hip Arthroplasty: A Prospective Cohort Study.

Background and Purpose: The choice between posterior approach (PA) and direct lateral approach (DLA) for total hip arthroplasty (THA) remains a contentious issue regarding clinical outcome optimization and restoring patient function. Previous studies have evaluated the postsurgical outcomes mostly in the form of Harris hip score (HHS), and the data to objectively measure the postoperative muscle power is scarce. We intend to objectively compare the hip abduction and extension strengths and other functional outcomes with a very simple tool in PA and DLA in the Indian population as most patients do not undergo as intensive rehabilitation in the postoperative period as in the western world. Materials and Methods: A total of 158 patients underwent THA during the study period, of which 48 met inclusion criteria and only 42 completed 6 months follow-up. Patients were evaluated preoperatively, postoperatively at 2 weeks, 6 weeks, 3 months, and 6 months follow-up. At each visit, muscle strength was tested using a customized sling device mounted on a pulling apparatus fitted on the wall, as well as a pain score (VAS), Harris hip score (HHS), and Short Form Survey (SF-36). Results: The study showed statistically significant better hip muscle strength at 2 weeks postoperative for leg press test and 2 weeks as well as 6 weeks postoperative for hip abduction strength in the PA. However, no differences were noted during the 3 or 6 months follow-up period among the DLA and PA. The surgical approach used has no effect on VAS, HHS, or SF-36 scorings. Conclusion: The weak abductor mechanism at 2 and 6 weeks and extension mechanism at 2 weeks in a cohort of DLA in contrast to the PA are seen in the early postoperative period and hence are short-lived muscle weakness. However, there is no effect on VAS, HSS, and SF-36 scores. Therefore, the surgical approach is to be chosen according to the surgeon's expertise.