Radiographic analysis of subclinical appearances of the hip joint among patients with labral tears

Objective Labral tears can be complicated by hip diseases, including osteoarthritis or femoral acetabular impingement. To accurately plan hip arthroscopy or subsequent conversion to total hip arthroplasty, the presence of bony abnormalities in the hip joint must be evaluated. This study aimed to elucidate the utility of multiplanar reconstruction computed tomography (mCT) for the detection of subclinical coincidence of osteoarthritis or femoral acetabular impingement with a labrum tear. Materials and methods We retrospectively analysed 34 patients (36 hips) with labrum tears without apparent osteoarthritis or hip dysplasia from 2012 to 2015. The joint spaces were calculated using radiographs or mCT, and the detection rates of degenerative cyst and herniation pit were compared. Results Narrow joint spaces (< 2 mm) were more clearly detected in mCT (p < 0.05, chi-square analysis) than in radiographs. The detection rate of cysts in the acetabulum was 8.3% using radiographs and 36.1% using mCT (p < 0.001, chi-square analysis). Additionally, the detection of herniation pit was 8.3% and 25.0% using radiographs and mCT, respectively (p = 0.053, chi-square analysis). Conclusion We performed the radiographic analysis of patients with labral tears using radiographs and mCT. The mCT allowed for fine detection of narrow joint spaces and subtle subclinical appearances. The results of this study may provide surgeons with more appropriate strategies for the treatment of labral tears.

Radiographic Markers of Femoroacetabular Impingement: Correlation of Herniation Pit and Femoral Bump with a Positive Cross-Over Ratio

Introduction. The goal of this study was to research the association of femoral bumps and herniation pits with the overlap-ratio of the cross-over sign.Methods. Pelvic X-rays and CT-scans of 2925 patients with good assessment of the anterior and the posterior acetabular wall and absence of neutral pelvic tilt were enrolled in the investigation. Finally pelvic X-rays were assessed for the presence of a positive cross-over sign, and CT-scans for a femoral bump or a herniation pit. Additionally, if a positive cross-over sign was discovered, the overlap-ratio was calculated.Results. A femoral bump was found in 53.3% (n=1559), and a herniation pit in 27.2% (n=796) of all hips. The overlap-ratio correlated positively with the presence of a femoral bump, while a negative correlation between the overlap-ratio and the presence of a herniation pit was found. The latter was significantly more often combined with a femoral bump than without.Conclusions. We detected an increased prevalence of femoral bump with increasing overlap-ratios of the cross-over sign indicating a relation to biomechanical stress. The observed decreased prevalence of herniation pits with increasing overlap-ratios could be explained by reduced mechanical stress due to nontightened iliofemoral ligament in the presence of retroversion of the acetabulum.