Introduction: Skeletal muscles are essential for voluntary movement and functional physical performance. The iliopsas muscle plays a central role as the primary hip flexor and as a stabilizer of the trunk and pelvis. Pathologies such as snapping hip and iliopsoas impingement are often treated with tenotomy, a procedure that may affect strength, coordination, and functional capacity. Although the arthroscopic approach is considered minimally invasive and highly effective, the long-term effects ot this procedure on muscle function remain uncelar. Isokinetic dynamometry, regarded as the gold standard for assessing muscle strength and symmetry, enables objective evaluation ot these changes. Purpose: The aim ot this study was to determine the effect of iliopsoas tenotomy on the muscle performance of hip flexors and extensors. Methods: Adult participants (18-60 years) who had undergone iliopsoas tenotomy at least one year prior to the study were included. Individuals with recent injuries, significant hip pain, or hip endoprothesis were excluded. Before testing, participants completed the iHOT questionnaire, EQ-5D and the Tegner Activity Scale. Measurements were performed using a Humac Norm isokinetic dynamometer in the supine position. The testing protocol included four components: maximal isometric torque, concentric torque at 60°/s and 120°/s, eccentric torque at 60°/s, and isometric endurance of the hip flexors. Results for the operated and non-operated legs were compared using paired t-tests or the Wilcoxon signed-rank test, and the limb asymmetry index was calculated. Results: Eleven participants (1 male, 10 females) were included in the analysis. In concentric measurements of the hip flexors, the operated limb demonstrated lower performance across all parameters at the both 60°/s and 120°/s (p < 0,05). Statistically significant differences were also observed in the extensors. Eccentric measurements showed no significant differences, while the mean asymmetry index was low (3-5 %). Maximal isometric and flexor endurance did not differ significantly between limbs. Discussion and conclusion: Following iliopsoas tenotomy, distinct asymmetries in muscle performance were observed, particulary during concentric contrations and at higher angular velocities, where especially the extensors of the operated limb exhibited lower values. These differences exceeded the clinically relevant threshold of 10-15 %, potentially affecting hip function and increasing the risk of injury. Rehabilitation shpuld therefore targer both flexor and eccentric strengthening, as well as training at higher speeds. Despite certain limitations the findings highlight the importance of individualized rehabilitation and further research into the effects of iliopsoas tenotomy on hip muscle performance.
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