Background Short-term studies on the function of a total knee system can be an important tool for the orthopedic surgeon provided they give relevant data. The vast majority of studies on outcomes of total knee systems are not published for ten or more years after the release date. During that period the implant company, primarily to satisfy the FDA for distribution purposes, provides most of the information about the performance of a knee system. Though these studies do prove a basic level of safety, it is thought by many that much of the rest of the data is inflated for sales purposes. The objective of this study is to compare the performance of four total knee systems during a one-year follow up.
Methods A retrospective chart review where patients will be selected from three orthopedic practices in the Portland Oregon area. Those subjects that meet inclusion criteria. and do not fit any exclusion criteria will be placed into the study group. Main Outcome Measure- Range of motion.
Results A total of 249 knees from 190 patients were included in the study. Average range of motion at one year was as follows: Zimmer CR 112, Zimmer PS 114, Osteonics CR 120, and Osteonics PS 114. There was no significant difference (P=.441). There was significant differences in ROM between the Zimmer CR and the Osteonics CR at three months (P=.016). There was significant differences in ROM between the Zimmer CR and the Osteonics CR at six months (P=.008). There was significant differences in ROM between the Zimmer PS and the Osteonics CR at six months (P=.026).
Conclusions The results showed that by one year there was no statistical difference in ROM between the four total knee replacement systems. The patients who received the Osteonics CR or PS gained motion faster initially than the Zimmer CR or PS.
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