Second-Generation Metal-on-Metal Total Hip Arthroplasty

Lim, Seung Jae; Moon, Young Wan; Son, Jeong Gyeong; Park, Youn Soo

Abstract

PURPOSE
To report the short-term results of second-generation metal-on-metal total hip arthroplasty (THA). MATERIALS AND METHODS: One hundred and sixty-five patients (169 hips) were followed for more than 2 years after primary THA using a modern metal-on-metal bearing conducted between April 2000 and March 2002. All patients were examined clinically and radiographically. RESULTS: The average Harris hip score improved from 53.9 points preoperatively to 94.2 points at the time of the last follow-up. All prostheses demonstrated radiographic evidence of bone ingrowth. Nine patients (10 hips) had an osteolytic lesion localized at the greater trochanter. Patients with osteolysis had a significantly higher rate of positive skin-patch tests for cobalt than controls (p=0.031). Of these, two hips underwent revision operation due to recurrent dislocation and imminent fracture through the greater trochanter, respectively. There was no evidence of metal wear on the retrieved bearing surfaces, but microscopic analysis of periprosthetic tissues revealed abnormal histological findings consistent with delayed-type hypersensitivity. CONCLUSION: Early results of THA using the current metal-on-metal bearing design were encouraging in most of the patients. However, this implant bearing should be avoided in patients with a history of allergic reaction to metals.