Evaluation of Psoas Muscle Atrophy and the Degree of Fat Infiltration After Unilateral Hip Arthroplasty

Objective: Atrophy of the muscles around the hip and thigh has been reported in patients with hip osteoarthritis (OA). Total hip arthroplasty (THA) reduces pain and improves quality of life and activity levels. Muscle strength of the hip and thigh also improves after THA. This study aimed to determine whether there is significant psoas muscle atrophy and to evaluate the degree of fat infiltration after unilateral hip arthroplasty. Subject and methods: Patients who underwent unilateral total hip arthroplasty for primary hip osteoarthritis and who had lumbar vertebra magnetic resonance imaging (MRI) for any reason in the one-year preoperative and postoperative period were evaluated retrospectively. The degree of fat infiltration was also graded visually based on a modified Goutallier rating system. Results: The study was conducted with a total of 58 patients aged between 38 and 75, including 15 males and 43 females. Compared to the preoperative psoas muscle area values on the operated sides of the patients participating in the study, the decrease in the postoperative psoas muscle area was found to be statistically significant (p:0.000; p<0.05). Furthermore, the decrease in psoas muscle area on the non-operated side of the patients was also statistically significant (p:0.000; p<0.05). There was also a positive correlation between preoperative and postoperative psoas muscle areas (p:0.000; p<0.05). Conclusion: Early identification of psoas muscle mass reduction may allow for a more proactive psoas strength improvement program to improve post-operative function and mobility.