Hip Abduction Strength Assessment and its Effect on Functional Outcome Following Hip Arthroplasty - Original Article.

Aims and background: A subset of people has persistent functional impairment due to hip abductor muscle weakness post-hip arthroplasty. Hip abductor muscles collectively play a crucial role in maintaining pelvic stability, facilitating hip movements, and ensuring efficient gait mechanics. We aimed to prospectively evaluate the static abductor strength and lower extremity strength in patients undergoing hip arthroplasty and it's effect on functional outcome.

Materials and methods: Twenty patients who underwent total hip arthroplasty (THA) or bipolar hemiarthroplasty were included in our study. Their static and dynamic hip abductor strength was prospectively assessed at 4 weeks, 3 months, and 6 months. Static abductor strength was measured using dynamometer and manual muscle testing, while dynamic abductor strength using 6 min walk test, stand and sit test, and timed up go test and its effect on functional outcome by Harris Hip Score (HHS).

Results: Of 20 patients in our study, 16 underwent hemiarthroplasty and four underwent THA. Posterolateral approach was the most used approach. The median static abductor strength at 4 weeks was 0.37 kgf, 3 months was 0.59 kgf, and 6 months was 0.82 kgf (P < 0.001) which is statistically significant. Dynamic abductor strength was checked using 6- min walk test which showed improvement from 230 m at 4 weeks to 446 m at 6 months. Counts in sit and stand test increased from a median of 7 at 4 weeks to 14 at 6 months. Timed up and go test decreased from 32 s in 4 weeks to 15 s in 6 months. The functional outcome assessed by HHS showed 67. 50 at 4 weeks to 96 at 6 months.

Conclusion: My study confirms that there is significant improvement in hip static and dynamic abductor strength and functional outcome within 6 months following hip arthroplasty. The lateral approach for hip arthroplasty has better static hip abductor strength than the posterolateral approach. There is no statistically significant difference in hip abductor strength recovery between THA and bipolar hemiarthroplasty.