EARLY POLYETHYLENE FAILURE IN TOTAL KNEE REPLACEMENT

Abstract

A retrospective chart review of three hundred and eighty-seven PFC© and PFC Sigma© total knee replacements performed by a single surgeon over a seven-year period was completed. During that time, there were fourteen revisions for polyethylene failure. Survival analysis indicates a failure rate of 8%. Previous reports in the literature of the survivorship of the original PFC design demonstrated a five percent failure rate over a ten-year period. Gamma sterilization in air of the PFC polyethylene and the locking mechanism of the articular surface have been implicated in premature wear and failure of this prosthesis.

The purpose of this study was to determine the revision rate due to polyethylene failure for a cohort of PFC© and PFC Sigma© total knee prostheses implanted by a single surgeon.

The early to mid-term revision rate (8%) of the PFC© and PFC Sigma© polyethylene component appears to be abnormally high. The early failure of this tibial articulating component may be related to faulty polyethylene inserts and/or failure of the locking mechanism. Attention to preparation of the polyethylene and locking mechanism of the tibial insert may need to be addressed.

Three hundred and eighty-seven total knees were performed in a cohort of three hundred and twenty-two patients (64% female; mean age = 70 ± 9 years; mean BMI = 31 ± 6). Mean follow-up was forty-one months (± 23). The revision rate at seven years was 8%. At time of revision most prostheses were solidly fixed with no overt signs of loosening of the tibial component. However, there was movement of the polyethylene in the tibial tray in both the mediolateral and AP direction with obvious surface and backside wear. Marked synovitis with evidence of osteolysis, particularly on the femoral side, was also noted. Bone graft was required in almost all cases.

A retrospective chart review was conducted for PFC© and PFC Sigma© total knee systems implanted by a single surgeon between 1995 and 2002. Collected data included patient demographics, age, gender, body mass index, and reason for surgery. The amount of synovitis and osteolysis was documented during revision surgery.

During the routine follow-up of this cohort, patients were identified with marked synovitis and increasing pain in the knee even though there was no gross mal-alignment of the tibial or femoral component.