2025 ISAKOS Biennial Congress Paper
Better Forgotten Joint Score and Similar Clinical Outcome of Kinematic Alignment Vs. Mechanical Alignment: Preliminary Results of a Prospective Case Series
Edoardo Franceschetti, MD, Roma, Rome ITALY
Stefano Campi, MD, Rome ITALY
Giancarlo Giurazza, MD, rome ITALY
Pietro Gregori, MD, Roma, Lazio ITALY
Andrea Tanzilli, MD, Roma ITALY
Giovanni Perricone, MD, Rome, Rome ITALY
Rocco Papalia, MD, PhD, Prof., Rome ITALY
Fondazione Policlinico Campus Bio Medico , Roma, Italy, ITALY
FDA Status Not Applicable
Summary
Kinematic alignment had similar clinical results, but significantly higher FJS when compared to MA
Abstract
Rationale
The alignment strategy seems to influence the clinical results and implant perception after total knee arthroplasty.
The aim of this study is to compare the results of unrestricted kinematic alignment (KA) to mechanical alignment (MA) in a prospective case series from a single center.
Methods
A prospective, consecutive series of 50 knees who underwent TKA with unrestricted kinematic alignment using a calipered technique were compared with 50 mechanically aligned TKA performed during the same period. Preoperative HKA was measured on long-leg views. The arithmetic HKA was calculated, and patients were classified according to the CPAK classification. Due to the low number of valgus knees treated with KA, CPAK phenotypes 3, 6 and 9 were excluded from the study. The postoperative outcome was assessed using the KSS, OKS and FJS with a minimum follow-up of 1 year.
Results
The two groups had similar demographics. The mean preoperative HKA was similar in both groups (172.5°, SD = 4.7° in the KA group vs 172°, SD = 5.5° in the MA group; p = 0.67). The arithmetic HKA was 175.4°, SD = 4.6° in the KA group vs 174.9°, SD = 6.1° in the MA group, (p = 0.63). The two groups had similar distribution among the CPAK phenotypes.
The postoperative KSS functional and objective and OKS were similar. KA resulted in a superior FJS (88.6, SD = 18.9 vs 74.5, SD 27.1; p = 0.005).
Analyzing the results of the constitutional varus subgroups (CPAK 1, 4 and 7), KA resulted in similar KSS, but higher OKS (42.6, SD = 10.2 vs 38.1, SD = 7.2; p = 0.04) and FJS (87.5, SD = 20.1 vs 71.6, SD = 26.9; p = 0.01).
Conclusion
Kinematic alignment had similar clinical results, but significantly higher FJS when compared to MA. The constitutional varus subgroup resulted in higher OKS and FJS when treated with KA. These results need confirmation on a bigger cohort of patients with long-term follow-up to confirm the efficacy and safety of unrestricted KA.