Are Pelvic Anatomical Structures in Danger During Arthroscopic Acetabular Labral Repair? Definition of Safe Bone Depth

Purpose: The purpose of this study was to evaluate safe depth for suture anchor insertion during acetabular labral repair and to determine the neighbouring structures at risk during drilling and anchor insertion.

Methods: Ten human cadaveric hips (six males and four females) were obtained. Acetabular labral surface was prepared and marked for right hips as 12, 1 and 3 o'clock positions, for left hips 12, 11 and 9 o'clock positions. Those were defined as anterior, anterior-superior and superior zones, respectively. These labral positions were drilled at defined zones. After measurements, depth of the bone at 10° and 20° drill angles on zones was compared statistically.

Results: Acetabular bone widths at investigated labral insertion points did not statistically differ. A total of 14 injuries in 60 penetrations occurred (23.3 %) with free drill penetrations, and no injuries occurred with stopped drill penetrations. The bone depth was gradually decreasing from 10° to 20° drill angles and from anterior to superior inserting zones without significant importance. The risk of perforation to the pelvic cavity started with 20 mm drill depth, and the mean depth for all insertions was calculated as 31.7 mm (SD 2.6).

Conclusions: It is anatomically possible that some pelvic structures sustain iatrogenic injury during acetabular drilling for anchor placement. Being aware of mean pelvic vault is important in which drilling after excessive pincer rim trimming could easily decrease the depth of acetabular bone without a standard. Careful drilling by using stopped drill bit is crucial to prevent iatrogenic injury.