Aim of the study: To compare the outcomes of three knee arthroplasty design philosophies and surface tribology.• A zirconium-surfaced, bicruciate-stabilised implant designed to mimic kinematic movement and improve flexion and outcomes;• A cobalt-chrome surfaced, multi-radius design with built-in femoral external rotation to aid balancing and patella tracking through a deeper trochlea groove;• A zirconium-surfaced, single-radius implant designed on surface conformity, particularly within the patello-femoral joint.
Methods: 313 knee replacements - 103 Journey II, 103 Genesis II and 107 Profix - were statistically assessed at a minimum of 2 years using WOMAC, Oxford and SF-12 scores, and range of movement.
Results: There was no difference between the actual or unit change in WOMAC scores (p = 0.140 and p = 0.287), SF-12 physical (p = 0.088) or mental scores (p = 0.975) between the three implants; or between the actual or unit change in Oxford score (p = 0.912 and p = 0.874) for the Journey II or Genesis II. The Journey II produced more flexion and range of movement than the Genesis II (p < 0.001 and p = 0.018) and Profix (p < 0.001 and <0.001) with no difference between the latter two (p = 0.402 and 0.568); with no difference in extension between the three implants (p = 0.086). There was no difference between those with or without a resurfaced patella.
Conclusion: The three design philosophies and surfaces yielded no difference in outcome scores at 2 years post-operatively. The Journey II demonstrated better post-operative flexion. Resurfacing the patella did not alter the outcome scores or flexion.
Keywords: Arthroplasty; design philosophy; outcome scores; zirconium.