Quantitative cotyloid fossa thickness and proximity to obturator neurovascular bundle: implications for arthroscopic ligamentum teres reconstruction

The aim of the present study was to report the in vivo thickness of the cotyloid fossa at the acetabular ligamentum teres (LT) attachment and investigate the clearance of the obturator neurovascular bundle. Fifty-five consecutive patients undergoing a total hip arthroplasty for hip osteoarthritis were included. The thickness of the cotyloid fossa was measured at the acetabular LT attachment using a standard depth gauge. The minimal distance (clearance) of the obturator neurovascular bundle to the center of the acetabular LT attachment was measured in 7 patients (14 hips) who also underwent a computed tomography angiography. The average thickness of the cotyloid fossa at the acetabular LT attachment was 4.1 +/- 2.3 (range: 1-10) mm. The obturator vein was closest to the acetabular LT attachment, but the clearance was more than the defined safe zone of 15 mm in all cases. Based on the current findings, it can be assumed that bone anchors might not be suitable for fixation of the graft in LT reconstruction (LTR) and an alternative implant such as a cortical button should be considered. Acetabular fixation of the graft with a 12-mm cortical button is relatively safe concerning injury to obturator neurovascular structures. The results of the present study provide a better understanding of the cotyloid fossa anatomy and might be relevant for surgeons who perform arthroscopic LTR.