Abstract:

Objectives: Although it is used as a landmark during various orthopedic procedures of the hip, few studies have focused on the anatomy of the zona orbicularis. Therefore, the purpose of the present research was to study its morphology to improve our understanding of its structure and potential variation. Methods: Ten adult cadavers (four males and six females) underwent dissection of the left and right hip joints to observe the morphology and location of the zona orbicularis. A digital caliper was used to measure the length and width of the zona orbicularis. Results: We found a zona orbicularis on all sides and that when present anteriorly, many of the inferior fibers of the zona orbicularis were confluent with the fibers of the iliofemoral ligament. The mean length for right sides was 35.95 mm and the mean length for left sides was 43.93 mm. The mean width for right sides was 3.74 mm and the mean width for left sides was 4.4 mm. There were no significant differences between the right and left sides for zona orbicularis length or width. There was no significant association between age and sex but a statistically significant correlation (r=0.959) between right and left zona orbicularis lengths (p=0.041). However, there was no significant correlation between the right and left zona orbicularis widths (p>0.05). The fibers of the zona orbicularis were found to be thicker and more visible along the posterior aspect of the femoral neck. Conclusion: Anatomically, the zona orbicularis is a consistent structure of the hip joint capsule. This structure can be seen on high resolution imaging such as MRI and magnetic resonance arthrography. The lengths of this structure may differ between sides, although based on our study, there were no differences between left and right side widths or between sexes or among ages.

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