In a prospective series of 63 patients (64 hips) undergoing primary THA, two surgeons attempted to identify the TAL and, if it was found, to use it for acetabular component orientation. Patients in whom the TAL was identified served as the study group and the ligament was used for cup orientation in those patients; the remaining patients in whom the ligament could not be identified served as a control group and had free-hand cup positioning