The Radiographic Prevalence of Cam Morphology in Thai Patients Undergoing Total Hip Replacement: A 15-Year Review

Abstract Background : Total hip replacement (THR ) is a common procedure that can relieve the pain and improve the functions of patients with advanced osteoarthritis (OA ) of the hip . Femoroacetabular impingement (FAI ), with either a cam or pincer morphology, produces chondral or labral damage that can develop into hip OA . This condition, which is commonly unrecognized, can be identified in some patients undergoing a THR . Objectives : The present study aimed to determine the radiographic prevalence of cam morphology and the causes of THR during a 15 -year period . Materials and methods : The authors retrospectively reviewed the medical records of all THR cases at a tertiary hospital in Thailand between 2002 and 2017 to identify the causes of the THRs . For patients with primary hip OA, preoperative radiographs were reviewed by two orthopedic surgeons to detect cam and pincer morphologies . The patients were subsequently classified into three groups : “abnormal morphology ”, “no abnormal morphology ”, and “indeterminate morphology ”. The descriptive statistics for this study were summarized . Results : Of the 1,250 patients (providing 1,475 hips that underwent THR ) in the study, 856 (68 %) were female . The mean age of the study cohort was 54 .4 + 15 .1 years . Idiopathic avascular necrosis (AVN ) was the most common etiology (390 cases; 27 %). The most common disease among the very young age patients (≤ 30 years ) was AVN due to drugs (40 cases; 35 %). Of the 167 patients with primary hip OA, 37 hips (22 %) had abnormal morphology (34 hips with cam morphology, 4 hips with pincer morphology, and one patient with both morphologies ). Conclusions : Idiopathic AVN was the most common cause of the THRs . Cam morphology was found in at least one -fifth of the cases with advanced primary hip OA . Keywords : cam morphology, femoroacetabular impingement, total hip replacement, radiographic prevalence, osteoarthritis