Synovial Pit of the femoral neck: a rare disease with rare presentations

Herniation pits are small benign oval lesions that were reported to be always lying within the super-lateral femoral neck, and were first described in 1982 by Michael J. Pitt. They are usually a unilateral incidental finding along with asymptomatic course. It was widely believed that herniation pits are a result of invagination of the overlying synovium into small cortical defects in the femoral neck. In our case; the mentioned lesions were found atypically bilaterally at the inferomedial aspect of the neck of femur of a 7-year old child. Radiological scans were efficient to obtain an adequate diagnosis whereas conservative management proved to be sufficient dealing with the lesions. Synovial pits may have atypical clinical and radiological course, and this can raise concerns especially with symptomatic hip that may encourage surgical interventions. However, due to benign course of these lesions, we do not recommend any surgical intervention for such lesions.

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.