Abstract
Introduction: Although volumetric wear reduction has been demonstrated in knee simulator studies, there is no long-term in-vivo evidence supporting wear reduction and durability with uni-directional rotating platform PS design. This design was introduced to reduced spin-out and provide greater range of motion. This is the first long-term report of this implant, a prospective study investigating clinical and radiographic survivorship with 10 years follow-up.
Material and Methods: Between January 2000 to March 2001, 118 consecutive patients (141 knees) received cemented RP TKRs. All patients were followed prospectively using clinical and radiographic criteria as defined by the Knee Society. At minimum nine years follow-up 20 patients were deceased, 11 were lost to follow-up and two refused to participate in the study, leaving 85 patients (100 knees) for final analysis.
Results: Good to excellent results were achieved in 95% of patients. There were no cases of malalignment, spinout, aseptic loosening or osteolysis. The mean ROM improved from 111.2 ± 15.2 degrees to 119 ± 3.8 degrees. The mean WOMAC score was 30 ± 14, KSS scores improved from an average of 48 to 96. Sporting activities such as golf, tennis and walking was 29%, 12% and 32%, respectively.
Anterior knee pain was present in 15% of cases. The incidence of asymptomatic crepitation and painful crepitation requiring scar excision was 10% and 4% respectively. During this period we had one case of infection and one revision for fracture. Kaplan-Meier survivorship at 10 years for mechanical failure and failure for all failures was 100% and 95.7%, respectively.
Discussion and Conclusion: Ten-year follow-up of RP-PS design demonstrates excellent clinical and radiographic results with no failures for mechanical reasons. There were no spin-out and average ROM was 119 ± 3.8 degrees.
