Revision total knee arthroplasty using a fully cemented single-radius condylar constrained prosthesis has excellent ten-year survival and improvements in outcome measures : a cohort study of 358 implants.

Aims The aim of this study was to describe the long-term outcomes following revision total knee arthroplasty (RTKA) using a fully cemented condylar constrained knee (CCK) arthroplasty. Methods This retrospective study included a consecutive series of patients who underwent RTKA using CCK components (Triathlon Total Stabilizer) in a non-designer centre, between 1 January 2008 and 31 December 2019. There were 344 patients, who underwent 358 revision procedures (330 unilateral and 14 staged bilateral). Their median age was 70.5 years (IQR 63 to 77) and 197 (55.0%) were female. The SPECIFIC criteria were used to define the mode of failure. The median follow-up was 9.8 years (IQR 6.7 to 13.4). Patient-reported outcome measures (PROMs) were collected prospectively (preoperatively, at one year, and at final follow-up (mean 9 years (4 to 16)), using the Oxford Knee Score (OKS) and the EuroQol five-dimension three-level questionnaire (EQ-5D-3L). Results The indications for RTKA were loosening (n = 131, 36.6%), instability (n = 124, 34.6%), or infection (n = 54, 15.1%). At final follow-up, 102 patients (28.5%) had died, and 30 patients (30 RTKAs; 8.4%) had undergone at least one re-revision, which consisted of secondary patellar resurfacing and/or polyethylene exchange in ten patients (33.3%). The overall ten-year survival was 91.7% (95% CI 88.6 to 94.9); however, this differed significantly (p = 0.029) according to the indication for revision: aseptic loosening, 96.0% (95% CI 92.6 to 99.5); infection, 86.6% (95% CI 77.8 to 96.4); and instability, 85.3% (95% CI 77.4 to 93.9). There were significant (p < 0.001) improvements in PROMs at one year (OKS mean change (MC), 12 (95% CI 11 to 14); and EQ-5D-3L MC, 0.214 (95% CI 0.11 to 0.31)), which were sustained at the final follow-up (OKS MC, 9 (95% CI 7 to 11); and EQ-5D-3L MC, 0.172 (95% CI 0.09 to 0.23)). The patients who underwent revision for aseptic loosening had significantly better OKSs compared with those who underwent revision for infection or instability at both one year (p = 0.008) and at the final follow-up (p = 0.024). Conclusion RTKA using a cemented CCK arthroplasty had excellent ten-year survival and clinically meaningful improvements in PROMs. However, revision for instability or infection was associated with significantly worse survival and PROMs.