Purpose: Hip dysplasia and femoroacetabular impingement may both lead to disability and hip osteoarthritis. The purpose of the current study was to compare the two entities in order to define differences in their clinical presentation.
Methods: The clinical presentation and WOMAC items, subscales and overall sum score were compared between 37 patients with femoroacetabular impingement and 37 patients with hip dysplasia.
Results: The average duration of symptoms was 33.3 ± 31.6 months in patients with femoroacetabular impingement and 34.5 ± 39.0 months in patients with dysplasia (p = 0.885). The anterosuperior impingement test was positive in all patients with femoroacetabular impingement and in 92% of hip dysplasia patients (p = 0.061). Mean internal rotation and abduction was significantly less in patients with femoroacetabular impingement (p = 0.001 and 0.007). The WOMAC subscales for pain, stiffness, and functionality as well as the overall sum score were not significantly different between patients with femoroacetabular impingement and patients with hip dysplasia. The qualitative analysis of WOMAC items revealed that symptoms related to sitting were significantly more often rated to be present in femoroacetabular impingement than in hip dysplasia patients. In the quantitative analysis, only the item 'getting in or out of a car' was rated significantly more severe in patients with femoroacetabular impingement.
Conclusion: In addition to obtaining a detailed history and examination, radiographic studies are needed for differentiation of the two entities and for the decision on treatment strategy.