Poly(2-methacryloyloxyethyl phosphorylcholine)-grafted highly cross-linked polyethylene liner in primary total hip replacement: one-year results of a prospective cohort study

To control particle-induced osteolysis in total hip replacement (THR), we developed a new technique to graft poly(2-methacryloyloxyethyl phosphorylcholine) onto the surface of polyethylene liners. A prospective cohort study was conducted to investigate the clinical safety of this novel bearing surface. Between April 2007 and September 2008, we recruited a prospective consecutive series of 80 patients in five participating hospitals. These patients received a cementless THR; a 26-mm-diameter cobalt–chromium–molybdenum alloy ball and a poly(2-methacryloyloxyethyl phosphorylcholine)-grafted cross-linked polyethylene liner were used for the bearing couplings. These individuals were followed a year postoperatively. An evaluation of clinical performance was conducted through an assessment of hip joint function based on the evaluation chart authorized by the Japanese Orthopaedic Association. No patients were lost to follow-up. No adverse events were found to be correlated with the implanted liners. The average hip joint function score improved from 43.2 preoperatively to 91.7 postoperatively at 1 year. There was no implant migration nor periprosthetic osteolysis detected on radiographic analysis. On the basis of our results, we conclude that poly(2-methacryloyloxyethyl phosphorylcholine)-grafted cross-linked polyethylene liners are a safe implant option for hip replacement surgery for short-term clinical use.