Abstract
Statement of purpose. Cement fixation of total knee replacement (TKR) is commonly cited as being the gold standard, with better long-term survival rates when compared to uncemented fixation so the authors set out to analyse the longterm survivorship without aseptic loosening in a series of 471 uncemented TKR.
Methods
A consecutive single surgeon series of patients undergoing routine follow up after a hydroxyapatite coated, uncemented and cruciate retaining TKR performed from 1992 to 1995 were analysed. All patients were invited for clinical review and radiological assessment. Revision of the TKR for aseptic loosening was the primary outcome. Secondary outcomes included Knee Society Score (0–200), range of movement, secondary surgical interventions and the presence of polyethylene wear or osteolysis on plain radiography.
Results
471 TKRs were performed in 356 patients (115 bilateral). 432 TKRs were accounted for through follow up. 39 TKRs in 31 pts were lost to follow-up representing 8% who had a mean KSS of 176 at 10 yr f/u. Mean f/u time period was 16.4 yrs (range 15.1–18.5 yrs). Average age at f/u was 81 yrs. 11 TKR had been revised for aseptic loosening. 19 TKRs in 19 patients had had revision of femoral/tibial components for any reason. A further 7 TKRs had undergone polyethylene insert exchange leaving an overall revision rate of 9% or 91% survival without revision. Survivorship without aseptic loosening was 96% (95%CI of 91.9–98.1%) at up to 18 years. A competing risks analysis was undertaken in order to avoid overestimation of survivorship adjusted for the competing risk of death within the study group. This analysis estimated a cumulative risk of revision for aseptic loosening at 18 years of 4.5%. Mean KSS was 176 (SD 21.5). Mean range of movement was 113 degrees of flexion.
Conclusion
Uncemented hydroxyapatite coated total knee replacement can achieve favourable long-term survivorship at least as good as that of cemented designs.
