Are cementless acetabular components the cause of excess wear and osteolysis in total hip arthroplasty?

The authors reviewed 175 primary cementless Biologic Ingrowth Anatomic System stem total hip arthroplasties with average followup of 7 years for wear and osteolysis. Group I (24 hips: fixed titanium heads, cemented polyethylene cups) had a wear rate of 0.10 mm per year, and lysis of 0%. Group II (62 hips: fixed titanium heads, cemented metal-backed cups) had a wear rate of 0.13 mm per year, and lysis of 31%. Group III (15 hips: fixed titanium heads, cementless cups) had a wear rate of 0.25 mm per year, and lysis of 87%. Group IV (74 hips: modular cobalt chromium heads, cementless cups) had a wear rate of 0.17 mm per year, and lysis of 24%. Wear rate was associated with younger age and male patients, but not polyethylene thickness. Age, gender, weight, and component stability had no effect on osteolysis rates. Group III had the statistically highest osteolysis rate. Group I had the statistically lowest osteolysis rate. Therefore, features of cementless acetabular cups, such as the screw holes, roughness of the metal shell, and locking mechanism, may cause increased wear and osteolysis.