Prevalence of Focal (Superior) and Global (Central) Acetabular Retroversion in 538 Patients with Symptomatic Femoroacetabular Impingement and Hip Dysplasia

Purpose: Variations in both acetabular version (AV) and femoral torsion (FT) are becoming increasingly recognized as contributing factors to the development of hip pain in patients with femoroacetabular impingement (FAI) and hip dysplasia. The true prevalence of acetabular retroversion is still unknown in this patient population. Our purpose was to determine (1) the prevalence of AV abnormalities in symptomatic hips with FAI and dysplasia; (2) the prevalence of combined abnormalities of AV and FT and the prevalence of McKibbin’s index abnormalities in these patients; and (3) what subtypes of FAI and dysplasia are associated with abnormalities of AV and acetabular retroversion.

Methods and Materials: A total of 462 symptomatic patients (538 hips) presented with hip pain due to FAI or hip dysplasia at a tertiary referral center for hip preservation surgery between 2011 and 2015. We retrospectively compared measurements based on computed tomography/magnetic resonance imaging of central and cranial AV, FT, and McKibbin’s instability index.

AV was considered normal between 10 and 25 degrees. The allocation to each subgroup was based on morphological reference values for femoral head coverage, lateral center edge angle, α angle, and the neck-shaft angle calculated on plain radiographs. These patients were also compared with a control group of 48 hips of asymptomatic patients.

Results: Of the 538 hips included, 30% were found to have abnormal central AV; severe abnormalities were found in 6%. Severe acetabular retroversion (< 5 degrees) was found in 2%, moderate acetabular retroversion (< 10 degrees) was present in 12%, moderate increased central AV (> 25 degrees) was present in 18%, and severe increased central AV (> 30 degrees) was found in 4%.

Furthermore, 68% of the hips presented with some combination of abnormal central AV and FT. The most frequent abnormal combination was an increased FT combined with a normal central AV (22%).

We found significantly (p < 0.001) higher mean central AV for the dysplasia (22 degrees) and the control group (20 degrees) as compared with the retroversion group (13 degrees). Interestingly, the mean superior (17 degrees) and central (19 degrees) AV of the study group was normal. The mean McKibbin’s index of the study group was 38 degrees. Finally, increased central AV was most often present in hip dysplasia (37%), and acetabular retroversion was most often present in mixed-type FAI (21%).

Conclusion: Abnormalities in central AV are prevalent in 30% of patients with hip pain eligible for hip preservation surgery, and severe abnormalities are prevalent in 6%. Furthermore, various morphological changes about the hip have been found to be associated with specific abnormalities in central AV. Based on these results, the evaluation of young patients with hip pain should always include an assessment of AV and FT to best decide what treatment approach should be undertaken to optimize outcomes.

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Publication History

Article published online:
17 December 2020