The rates of osteolysis and loosening associated with a modular posterior stabilized knee replacement. Results at five to fourteen years.

BACKGROUND

Osteolysis and increased polyethylene wear have been reported in association with several designs of modular total knee prostheses. The purpose of the present study was to evaluate a modular posterior stabilized prosthesis to determine its clinical performance as well as the rates of component loosening and osteolysis.

METHODS

We performed a prospective, consecutive study of 193 knees in 131 patients who were managed with the modular Insall-Burstein II posterior stabilized total knee prosthesis by one surgeon. The mean age of the patients at the time of surgery was sixty-eight years, and the mean duration of follow-up was seven years (range, five to fourteen years). Clinical evaluation was performed with use of standard knee-scoring systems. Radiographs were evaluated for the presence of radiolucent lines, osteolysis, and loosening.

RESULTS

The overall result (as determined with the Hospital for Special Surgery scoring system) was rated as excellent for 112 knees, good for sixty, fair for fifteen, and poor for six. The mean postoperative flexion was 112 degrees. No clinical or radiographic loosening of the tibial component was noted. Eight knees had osteolytic lesions of the tibia. Thin, incomplete, nonprogressive radiolucent lines were noted around thirty tibial components (16%). There were three reoperations.

CONCLUSIONS

Despite previous reports of osteolysis, polyethylene wear, and loosening in association with some modular total knee implant designs, there was no loosening in this series of posterior stabilized total knee replacements and only eight knees had tibial osteolysis after a mean duration of follow-up of seven years. We believe that total knee arthroplasties that are performed with use of cemented modular posterior stabilized components can have a high rate of intermediate-term success.

LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.