MORPHOLOGICAL ANOMALIES OF THE HIP IN PATIENTS WITH LABRUM LESIONS: CONTRIBUTION OF ON PLAIN X-RAYS

Abstract

Purpose of the study: Labrum lesions can be an important source of hip pain. Besides the classical causes, certain morophological anomalies can be associated with labrum lesions. The purpose of this work was to study the contribution of plain x-rays to the search for morphological anomalies of the hip in patients with labrum lesions.

Materials and methods: Twenty-six patients with labrum lesions were included in this study. The plain x-rays protocol included an anteroposterior view of the pelvis in the standing position, a Lequesne oblique view and a lateral view of the neck in the hip flexion position. Patients with severe hip dysplasia (VCA or VCI < 15° or THE > 15°) were excluded. Measurements were made after digitalization using a dedicated software. Measures were: neck-shaft angle, acetabular cover, lateral alpha (neck axis, center of the head, most lateral point of the head sphere), lateral offset, acetabular version. Femoral data in flexion were compared with 20 controls.

Results: Acetabular cover was considered moderately insufficient in five patients (VCA and/or VCE 15–25°). These patients had the same alpha angle as the control population (56°), i.e. no anomaly of the neck-head junction. The 21 patients with non-dysplastic hips exhibited a significantly greater alpha angle (64±9° versus 54.6±8°, p< 0.01) than the controls. All controls presented an alpha angle ≤ 69°. Among the 21 non-dysplastic patients, five presented coxa vara (< 125°), five acetabular retroversion, nine an alpha angle > 69°. In all, 77% of patients presented morphological anomalies of the hip. Among the six «normal» hips using these measures, three presented a pistol-grip aspect which could not be quantified with these measures.

Discussion: This analysis confirms the association between morphological anomalies detectable on plain x-rays and labrum lesions in patients who do no present severely insufficient acetabular coverage. We were unable to detect any difference in femoral offset compared with the control population.

Conclusion: A standard x-ray protocol can, in the majority of cases, detect morphological anomalies of the hip, an important etiological diagnostic element for understanding pathogenic mechanisms.