Muscle-tendon-related abnormalities detected by ultrasonography are common in symptomatic hip dysplasia.

INTRODUCTION: Hip dysplasia is characterized by reduced acetabular coverage of the femoral head leading to an increased mechanical load on the hip joint and the acting hip muscles. Potentially, the muscles and tendons functioning close to the hip joint may present with overuse-related ultrasonography findings. The primary aim was to report the prevalence of muscle-tendon-related abnormalities detected by ultrasonography in 100 patients with symptomatic hip dysplasia. The secondary aim was to investigate correlations between muscle-tendon-related abnormalities detected by ultrasonography and clinically identified pain related to muscles and tendons.

MATERIALS AND METHODS: One hundred patients (17 men) with a mean age of 29 ± 9 years were included. Muscle-tendon-related abnormalities were detected with a standardized ultrasound examination. Correlations between muscle-tendon-related abnormalities detected by ultrasonography and clinically identified pain related to muscles and tendons were tested with Spearman's rank correlation coefficient.

RESULTS: The most prevalent ultrasonography findings were identified in the iliopsoas tendon [50% (95% CI 40; 60)], the adductor longus tendon [31% (95% 22; 40)] and the gluteus medius/minimus tendons [27% (18; 36)]. Significant correlations between ultrasonography findings and pain related to muscles and tendons were only found for the iliopsoas tendon (ρ = 0.24 and p = 0.02) and the gluteus medius/minimus tendons (ρ = 0.35 and p < 0.001).

CONCLUSIONS: Muscle-tendon-related abnormalities detected by ultrasonography in the hip and groin region are common in patients with symptomatic hip dysplasia, and the ultrasonography findings of the iliopsoas and gluteus medius/minimus tendons are weakly to moderately correlated to pain related to muscles and tendons in these structures. Both the iliopsoas and the gluteus medius/minimus have a pronounced stabilizing role in the dysplastic hip joint, and the common muscle-tendon-related abnormalities in these patients may be caused by injuries related to excessive use or degenerative changes in the muscle-tendon tissue.