Abstract
Patient selection has always been considered an important criterion in determining the success or failure of a TKA. In the early days of TKA, orthopaedic surgeons and patients were both uncertain as to the long-term outcomes and most TKAs were performed in patients >65 years of age. Since that time, a number of peer-reviewed studies have provided Level III evidence indicating that TKA was a reliable procedure with 91% to 99% survivorship during the first decade and 85% to 97% during the second decade of follow-up. These encouraging TKA results have prompted a growth in TKA utilisation, particularly in younger patients and a move away from procedures such as osteotomy and UKA which have been associated with higher re-operation rates. As a result, over the past decade, the fastest growing TKA patient cohorts have been in the 45–54 (337% increase for females, 271% for males) and 55–64 (260% increase for females and 213% for males) year old patient groups!
The Swedish Knee Arthroplasty Register has followed Swedish TKA patients since 1975 and has provided useful insights with regards the use of knee arthroplasties in younger patients (i.e. an encouraging TKA revision risk reduction from 1976 to 2009, a higher revision rate for UKAs and higher revision rates for both TKAs and UKAs in younger patients). The Australian National Joint Replacement Registry has also found that age adversely affects knee arthroplasty revision rates, noting higher cumulative, ten-year revision rates for both UKA and TKA patients <55 years of age (UKA 25%, TKA 13%) and 55–64 years of age (UKA 17%, TKA 8%) and a 6X greater revision rate for TKA patients <55 compared to those >75 years of age! In addition, although mobile-bearing TKAs have often been promoted for use in younger patients, higher cumulative revision rates were noted for mobile-bearing TKAs (7%) as compared to fixed-bearing TKAs (5%) at 10 years.
In summary, although TKA outcomes have improved with time, the lack of long-term supporting data should prompt surgeons to be cautious in offering TKA to patients with 20 to 40 more years of life expectancy. New TKA bearing couple technologies (ie. cross-linked polyethylenes and improved femoral counterfaces) should be encouraged, but their introduction should not be based on laboratory tests alone, but also supported by safety and efficacy studies in patients and long-term post-market surveillance data.
