Improved function and patient satisfaction with fewer residual symptoms following kinematically versus mechanically aligned total knee arthroplasty: A retrospective study from FP‐UCBM Knee Study Group
Stefano Campi, Giancarlo Giurazza, Edoardo Franceschetti, Michael T. Hirschmann, Andrea Tanzilli, Michele Paciotti, Biagio Zampogna, Matteo Pepe, Pietro Gregori, Umile Giuseppe Longo, Rocco PapaliaAbstract
Purpose
To compare residual symptoms, function and patient satisfaction following unrestricted kinematic alignment (KA) versus mechanical alignment (MA) in primary total knee arthroplasty (TKA). It was hypothesized that KA would reduce residual symptoms and improve function and satisfaction.
Methods
A retrospective cohort study was conducted on 622 patients undergoing primary TKA (315 KAs and 307 MAs) for end‐stage osteoarthritis between 2022 and 2024, with a minimum 1‐year follow‐up. All procedures used the same implant design and standardized perioperative protocols. Outcomes included patient satisfaction, functional performance, residual symptoms and joint perception, assessed using the Forgotten Joint Score (FJS) and Joint Awareness Score (JAS). Groups were compared using t tests and χ 2 tests ( p < 0.05).
Results
KA demonstrated significantly higher overall satisfaction compared with MA (94.0% vs. 81.1%; p < 0.001), as well as greater satisfaction with activities of daily living (92.7% vs. 83.1%; p < 0.001) and pain relief (90.2% vs. 82.1%; p = 0.005). Functional outcomes favoured KA, with fewer patients reporting difficulty getting in/out of a car (8.6% vs. 18.9%; p < 0.001) or chair (9.8% vs. 18.9%; p < 0.001), higher absence of limp (86.0% vs. 73.0%; p < 0.001) and greater return to activity (91.7% vs. 80.1%; p < 0.001). Residual symptoms were less frequent in the KA group, including pain (11.7% vs. 24.1%; p < 0.001) and popping (7.3% vs. 17.9%; p < 0.001), with a higher proportion of patients reporting a ‘normal’ knee (89.8% vs. 79.2%; p < 0.001). FJS (91.7 vs. 82.7; p < 0.001) and JAS (92.3 vs. 83.5; p < 0.001) were both significantly higher in the KA group. No statistically significant differences were observed in stair‐climbing ability, swelling or stiffness.
Conclusion
Unrestricted KA in TKA is associated with fewer residual symptoms, improved function and higher patient satisfaction compared with MA at 1 year. These findings support KA as a potential strategy to reduce the prevalence of the ‘unhappy knee’ after TKA.
Level of Evidence
Level III, retrospective comparative study.