Biometric Assessment of Superior Gluteal Neurovascular Bundle to Acetabulum of Hip Joint

Abstract

Introduction: The superior gluteal nerve (SGN) is a branch of sacral plexus with root value of L4, L5 and S1. It leaves pelvic cavity through greater sciatic foramen along with superior gluteal artery above piriformis. This neurovascular bundle lies in close proximity to superior acetabular rim. Iatrogenic damage to SGN is common during hip arthroplasties and may be primarily attributed to inappropriate placement of retractors. Alarmingly high percentage of affected individuals are stuck with persistent irreversible damage to SGN. Vascular injuries are not as common but pose a challenging scenario to surgeons. Hence in both situations prevention is of supreme importance. Precise knowledge of course and relation of superior gluteal neurovascular bundle (SGNVB) to clinically useful landmarks such as the superior rim of acetabulum is desired. With an aim to provide baseline data for the Indian population we conducted this study. Material and methods: 200 dry adult Indian hip bones {Left side -109(male:66, female:43); Right side-91(male:66, female:43)} were photographed in anatomical position. Two lines- line A and line B were drawn. Line A corresponded to a horizontal passing through the anterior inferior iliac spine (AIIS) and roof of GSN while line B passed tangentially through the highest point on the acetabular rim parallel to line A. The vertical distance (white line) between the 2 lines was measured (Fig.2) was measured using Image J software. Results: The mean distance calculated was 0.62 ± 0.16 cm (0.68 ± 0.38 cm in right hip bones and 0.60 ± 0.30 cm in left side hip bones). The difference between the two sides and the two genders were compared and found to be statistically non- significant. Conclusion: A safe zone of 0.5 to 0.7 cm beyond the superior acetabular rim should be considered during surgeries around hip joint. The safe zone can be easily measured by the surgeons intraoperatively and be used as a guide to careful positioning of the retractors while performing surgeries around the hip joint. Better localization of SGNVB using the anatomic landmark defined in this study may be used to decrease surgical morbidity. KEY WORDS: Superior Gluteal, Acetabulum, Hip Joint, Total hip arthroplasty, Safe Zone.