Abstract
Introduction
We have carried out a 15 year survival analysis of a prospective, randomised trial comparing cemented with cementless fixation of press-fit condylar primary total knee replacements.
Methods
A consecutive series of 501 PFC knee replacements received either cemented (219 patients, 277 implants) or cementless (177 patients, 224 implants) fixation. No patients were lost to follow up. Revision was defined as further surgery, irrespective of indication, that involved replacement of any of the three originally inserted components (Femur, Tibia, Patella).
Results
Altogether 44 patients underwent revision surgery (24 cemented group Vs 20 cementless group). 11 cases were revised secondary to infection (7 cemented, 4 cementless, mean time to revision=5.1 years) and 26 were revised due to aseptic loosening (14 cemented, 12 cementless, mean time to revision=9.2 years). 7 cases were revised for other reasons (Instability, Anterior knee pain, polyethylene wear, patellar malallignment). For cemented knees 15-year survival=80.7% (95%CI, 71.5-87.4), 10-year survival=91.7 (95%CI, 87.1-94.8). For cemented knees 15-year survival=75.3% (95% CI, 63.5-84.3), 10-year survival=93.3% (95%CI, 88.4-96.2).
When comparing the covariates (operation, sex, age, diagnosis, side), there was no significant difference between operation type (Hazard ratio=0.83 (95%CI, 0.45-1.52) p=0.545), side of operation (HR=0.58 (95%CI, 0.32-1.05) p=0.072), age (HR=0.97 (95%CI, 0.93-1.01) p=0.097), diagnosis (OA vs non OA, (HR=1.25 (95%CI, 0.38-4.12) p=0.718). However, there was a significant gender difference (Males vs Females, HR=2.48 (95%CI, 1.34-4.61) p=0.004).
Conclusion
This single surgeon series, with no loss to follow up, provides reliable data of the revision rates of the most commonly used total knee replacement. The survival of the press-fit condylar total knee replacement remains good at 15 years irrespective of the method of fixation. This information is useful for strategic health authorities when establishing future requirements for revision knee surgery.
