Pre-operative gluteus medius tendon degeneration and its impact on strength and functional ability one year after total hip replacement

ObjectiveHip osteoarthritis is a common cause of disability and surgery is often unavoidable. Patient satisfaction is high and functional ability improves after surgery. However, residual impairment and pain are common. Degenerative changes in tendons and muscles are probable causes. The aim of this study is to investigate gluteus medius (GMED) tendon degeneration in relation to muscle strength, physical function and walking distance before and one year after total hip replacement.Material and methodsIn total, 18 patients were examined pre- and post-operatively, of whom 15 were available in the final analysis. Muscle strength, physical function and walking distance were assessed. Tendon biopsies were assessed microscopically, and the total degeneration score (TDS) was calculated.ResultsA correlation between the TDS and muscle strength was found for the hamstrings, GMED and quadriceps pre- or post-operatively. No correlations were found between the TDS and functional ability. Functional ability and muscle strength improved significantly after surgery.ConclusionOur results indicate a correlation between tendon degeneration and the muscle strength of the hip and knee in patients with hip OA and one year after THR. To minimise post-operative residual discomfort, rehabilitation programs should probably be modified over time to match the pre- and post-operative needs. Further studies are needed.This study was registered at https://www.researchweb.org/is/vgr/project/279039 (in Swedish).ConclusionOur results indicate a correlation between tendon degeneration and the muscle strength of the hip and knee in patients with hip OA and one year after THR. To minimise post-operative residual discomfort, rehabilitation programs should probably be modified over time to match the pre- and post-operative needs. Further studies are needed.This study was registered at https://www.researchweb.org/is/vgr/project/279039 (in Swedish). There are negative correlations, which suggest patterns between degeneration in the GMED tendon and muscle strength in the muscles acting around the hip in patients with hip OA, before and after THR.The strength training of muscles acting around the hip joint may need to be adjusted before and after THR.