抄録
Objectives: We investigated the factors affecting polyethylene (PE) wear in cementless total hip arthroplasty (THA) patients followed up for more than 10 years after the operation.
Methods: Forty-one patients who underwent cementless THA (43 hips) were successfully followed up for more than 10 years postsurgery. The diagnoses were osteoarthritis (35 hips) and avascular necrosis of the femoral head (4 hips). The average age at surgery was 57.9 years, and the average follow-up period was 11.1 years. In all cases, the following Biomet prostheses were used: finned porous socket (Mallory/Head), Ringloc Type (ArCom) and Bi-Metric stem, with 28-mm head made of either CoCr (22 hips) or zirconium (21 hips). We studied the correlation between the PE wear on X-ray and the following factors: patient age, sex, weight, body mass index, PE thickness, setting angle and position (upper deviation ratio, outer deviation ratio) of the THA, lever-arm ratio, and osteolysis.
Results: There was a significant difference in average annual liner wear between the group with osteolysis (a.v. 0.09 mm) and the group without osteolysis (a.v. 0.06 mm). No significant difference was found for the other factors.
Conclusion: Our previous study on Hexloc conventional type PE liners established the factors affecting wear as follows: femoral head, age at operation, inclination angle, and liner thickness. In this study on the Ringloc acetabular liner (ArCom), however, we did not find any correlation of those factors to the wear, suggesting that better clinical outcomes can be expected by improving the locking mechanism and PE wear resistance. Considering the high wear rate in the group with osteolysis, we assumed that a long-term follow-up study on the correlation between osteolysis and PE wear would be useful.
