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