[Long-term results in total knee arthroplasty. A meta-analysis of revision rates and functional outcome].

BACKGROUND: Total knee arthroplasty (TKA) is one of the most common procedures in orthopedic surgery and clinical success can be characterized by the revision rate and improvement of function. To quantify both characteristics two independent meta-analyses have been performed.

MATERIALS AND METHODS: A search in Medline provided a total of 96 studies on revision rates and 63 studies with functional results with a minimum follow-up of 5 years.

RESULTS: A total of 911 revisions among 20,873 TKAs were identified corresponding to a meta-revision rate of 4.4% after a mean follow-up of 10.7 years. Most common causes for revision were aseptic loosening (31%), infection (23%), polyethylene wear (16%) and patellar problems (14%). Revision rates were higher in younger patients (7.0% <60 years at time of operation, 5.0% between 60 to 70 years and 2.2% >70 years), after cementless TKA (8.3% cementless versus 3.6% cemented) and in studies with a higher rate of patients with rheumatoid arthritis. The second meta-analysis revealed a meta-improvement based on the Knee Society Knee Score of 51.3%, for the Knee Society Function Score of 30.6%, for the Hospital for Special Surgery Score of 36.1% and for the New Jersey Orthopedic Hospital Knee Evaluation System of 33.6%.

CONCLUSION: TKA is a successful treatment for osteoarthritis of the knee with an expectable revision rate of less than 5% within 10 years and a long-lasting functional improvement of more than 30% in any assessment score.