Long-term followup of cementless versus hybrid fixation for total knee arthroplasty

In a prospective trial, 99 patients (100 knees) with osteoarthritis were randomized to either cementless or hybrid fixation of cruciate-retaining Miller-Galante-I total knee arthroplasties between January 1987 and December 1988. Thirty-one patients died during the study period and two additional patients were lost to followup, leaving 67 total knee arthroplasties for analysis. Thirty-nine patients underwent revision surgery at an average of 6.9 years postoperatively. The main reason for revision surgery was failure of metal-backed patellas with 25 knees revised at an average of 7.4 years, and the second most common reason was tibial polyethylene failure. Survival curves showed 60% survival at 14 years for all knees, and 85% survival at 14 years when failures for metal-backed patellas and infection were excluded, with no significant difference between the two groups. Failure of metal-backed patellas was significantly higher in the cementless group. Tibial polyethylene failure occurred in five of the hybrid group and none of the cementless group, but this was not a significant difference. Surviving prostheses were assessed at an average of 12.8 years (range, 11.5-13.5 years). Average clinical scores were 94.8 points preoperatively, and 143 points at the latest followup, with significantly higher scores in the hybrid group. Differences in outcome between the two groups were not sufficiently significant to recommend one method of fixation over another. With elimination of poor design features related to the patellofemoral articulation and thin tibial polyethylene, cruciate-retaining total knee arthroplasties can yield good durable results, whether cementless or hybrid fixation is used.