Editorial Commentary: Decreased Hip Ligament Thickness in Patients With Dysplasia May Contribute to Hip Instability, Above and Beyond Associated Acetabular Under‐coverage

Hip dysplasia is a pathomorphologic deformity that leads to decreased acetabular coverage and hip instability. Many different radiographic measurements have been explored to characterize hip dysplasia, including the lateral center-edge angle, femoral-epiphyseal acetabular roof index, and Tönnis angle. Magnetic resonance imaging offers 3-dimensional characterization of the hip pathomorphology that may be more detailed than 2-dimensional radiographs, as well as a modality that is free of radiation. Recent research has shown that dysplastic hips are associated with significantly thinner ligament thickness compared with non-dysplastic hips. The iliofemoral ligament is the most important hip capsular structure and helps to stabilize the hip joint, particularly in hip extension and external rotation. Differences in iliofemoral ligament thickness may help to explain why patients with dysplasia are more prone to hip instability, above and beyond their acetabular under-coverage. This reiterates the need for routine capsular closure and/or plication in patients with femoroacetabular impingement syndrome to prevent further instability.