BackgroundAcetabular dysplasia (AD) is a well-known cause of osteoarthritis (OA) of the hip, with its prevalence previously determined on plain radiography. The prevalence of preexisting AD was reported as 7.3% in a patient-based Asian population. Although computed tomography (CT) could evaluate AD in multiple planes, its prevalence using multiplanar CT images has not been reported. We investigated its prevalence with CT on coronal, axial, and sagittal planes and then determined if adding the axial and sagittal planes enhanced the investigation.MethodsWe retrospectively examined 52 consecutive Japanese individuals (mean age 59.4 years) who had undergone CT for conditions unrelated to hip disorders. The inclusion criteria of CT images were (1) reconstructed axial slice thickness of ≤1 mm and (2) normal pelvic rotations and tilt. Exclusion criteria were (1) age <20 years, (2) neither hip center could be clearly detected, (3) evidence of hip OA. The parameters used to define AD on the coronal plane were the center–edge angle, Sharp angle, acetabular index, acetabular depth ratio, and acetabulum head index. The anterior and posterior acetabular sector angles were used as axial parameters and the vertical-center-anterior margin angle as the sagittal parameter. AD prevalence was calculated using multiplanar images and then compared with the previously reported Asian prevalence using 95% confidence intervals (CI). In this study, we defined “prevalence” as the proportion of subjects who had AD in at least one hip.ResultsThe mean prevalence of AD on coronal, axial, and sagittal planes was 16.9, 15.4, and 7.7%, respectively. The lowest prevalence found by combining the three planes was 25.0% (95% CI 15.2–38.2%). This prevalence was significantly higher than that in the previously reported Asian population (7.3%).ConclusionsAt the lowest estimate, the prevalence of AD evaluated in three planes was more than twice as high as the previously reported prevalence in Asians when we investigated its prevalence using multiplanar images. The prevalence of AD in the axial and sagittal planes was not negligible. We therefore suggest that it is important to add axial and sagittal planes’ data when investigating the prevalence of AD.

The coexistence of acetabular dysplasia (AD) and femoroacetabular impingement (FAI) has not been well discussed. This study was performed to elucidate the prevalence and morphological features of AD with coexisting FAI-related findings in a Japanese population. Computed tomography images were retrospectively evaluated. AD was classified as definite or borderline. The morphological findings that defined cam deformity were an α angle of ≥55°, head–neck offset ratio (HNOR) of <0.13, pistol grip deformity positivity and herniation pit positivity. The morphological findings that defined pincer deformity were acetabular index of ≤0° and a retroverted acetabulum. In total, 128 hips (male, 64; female, 64) were analyzed. The prevalence of coexistence of AD and FAI-related findings was detected in 23.4% of hips (definite AD and FAI, 7.8%; borderline AD and FAI, 15.6%). The percentages of hips with AD containing cam or pincer deformities among all were 54.3% and 4.3%, respectively. The percentage of AD with coexisting cam and that of AD with coexisting combined deformities was significantly higher in men, respectively. On the other hand, the most major morphological feature of FAI detected in hips with AD was a HNOR of <0.13. The coexistence of AD and FAI-related findings was common in a Japanese population, and 65.2% of hips with AD had some FAI-related findings. In discussing and managing AD, we recommend paying attention to the coexistence with FAI-related findings, especially in men and in borderline AD. In such hips, the most notable parameter as a morphological feature of FAI is a reduced HNOR.

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When performing surgery on a patient with mitochondrial myopathy, the merits of surgery must always surpass the possible grave risk of this condition.