Edinburgh Napier University

  Introduction
Revision knee arthroplasty surgery can range from patella resurfacing or polyethylene exchange, to staged revision and revision to a more constrained implant. Subsequently, the ability to elicit outcomes becomes difficult to obtain and hence information on functional outcome and survivorship for all modes of failure with a single revision system is valuable.

Methods
We retrospectively assessed 100 consecutive revision knee replacements that were converted from a primary knee replacement to a Triathlon total stabilizer (TS) knee system (Stryker Orthopaedics, Mahwah, NJ). Inclusion criteria included failure of a primary knee replacement of any cause converted to a Stryker TS knee system. Midterm outcome of at least 5 years was required. Implants survivorship, Oxford Knee Score (OKS), Forgotten Joint Score (FJS-12), Short Form (SF-) 12, reported patient satisfaction and radiographic analysis were recorded.

Results
The all-cause survival rate at 5 years was 89.0% [95% confidence interval (CI) 87.3 to 90.7]. The all-cause survival rate was generally static after the first 4 years. The mean OKS was 27 (SD 11.9, range 0 to 46), FJS was 32.3 (SD 30.4, range 0 to 100), SF-12 physical component summary was 40.6 (SD 17.6, range 23.9 to 67.1), and mental component summary was 48.3 (SD 15.5, range 23.9 to 69.1). Reported patient satisfaction in patients who were not re-revised was 82%.

Conclusion
The midterm survivorship of cemented Stryker Triathlon TS knee revision for all-cause mode of failure is good to excellent; however, future follow-up is required to ensure this survivorship is observed into the long term. Despite limited functional outcome, overall patient satisfaction rates are high.