Kinematic Alignment Technique Outperforms Mechanical Alignment in Simultaneous Bilateral Total Knee Arthroplasty: A Randomized Controlled Trial.

BACKGROUND: The aim of this study was to compare the clinical results of kinematic alignment (KA) with those of mechanical alignment (MA) in single-stage bilateral total knee arthroplasty (TKA).

METHODS: In this double-blinded randomized controlled trial, 65 patients who had bilateral knee osteoarthritis underwent simultaneous bilateral TKA. One knee was randomly selected to be operated on with the calipered-KA technique and the other with MA. The participants were assessed via the Oxford Knee Score (OKS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire, and Visual Analogue Scale (VAS) before the surgery and the same plus the Forgotten Joint Score (FJS) at their last follow-up visit, two years postoperatively. Maximum knee flexion and the time reaching maximum knee flexion, named the recovery time, were also recorded. Hip-knee-ankle (HKA) angle, medial proximal tibial angle (MPTA), and lateral distal femoral angle (LDFA) were measured before and after the surgery using three-joint-view radiographs.

RESULTS: At two years, there were significant differences between the KA and MA techniques in terms of duration of surgery, recovery time, and final WOMAC, FJS, and maximum flexion range in favor of KA (P < 0.05), but no significant difference in VAS score or OKS. In patients who have a preferred knee, the KA knee was preferred over the MA knee by most patients. No prosthetic failure or revision was reported in either group.

CONCLUSION: The KA technique yields acceptable functional outcomes compared to the MA technique. The KA technique was associated with a shorter surgery time, a faster recovery time, and higher patient satisfaction in two-year follow-ups. Larger multi-center studies with longer follow-ups are warranted to confirm these findings.