Purpose: To compare the clinical outcomes and survival at long-term between hybrid and cemented primary total knee arthroplasty (TKA). A better clinical outcome and survival following a follow-up as long as 15 years with the use of hybrid fixation as compared with cemented fixation was hypothesized.
Methods: Case-control study of 126 patients with a mean age of 62.4 years who underwent hybrid TKA matched with 126 patients underwent cemented TKA. Clinical outcome was assessed by the Knee Society scores (KSS) and reduced Western Ontario and MacMaster Universities questionnaire (WOMAC). Radiological assessment was made by the Knee Society method.
Results: The mean follow-up was 15.7 (range 15-17) years. At the final follow-up, clinical scores were significantly better in the hybrid group, although the differences were not clinically relevant. Revisions for all reasons were performed in five knees in the hybrid group and 15 knees in the cemented group (p = 0.033). In the hybrid group, there was one aseptic femoral loosening and no aseptic tibial loosening. In the cemented group, the main reasons for aseptic revisions were polyethylene wear (six knees) and tibial loosening (four knees). Cemented fixation was a significant risk factor for aseptic revision (hazard ratio 2.3; 95% CI 1.3-3.7%; p = 0.004). Survival at 15 years for aseptic reasons was 96.5% (95% CI 93.4-98.7%) in hybrid groups and 90.3% (95% CI 88.7-93.9%) in cemented group (p = 0.020).
Conclusion: After a minimum follow-up of 15 years, hybrid fixation of primary TKA for osteoarthritis provide significantly higher clinical benefits compared with cemented fixation, but the differences were not clinically relevant. Hybrid fixation provides longer overall survival, although the femoral component survival was similar between groups.
Level of evidence: III.
Keywords: Cemented fixation; Hybrid fixation; Total knee arthroplasty; Total knee replacement.