Correlation between Component Size and Functional Knee Score in Patients Undergoing Bilateral Simultaneous Total Knee Arthroplasty: A Cross-Sectional Study

Simultaneous bilateral total knee arthroplasty (simBTKA) has been a favored surgical solution to reduce costs and patient suffering. We aimed to evaluate the rate of asymmetry of component size in patients undergoing simBTKA and its impact on knee function as we believe that implant asymmetry may affect the functional outcomes in those patients. A cross-sectional study design was done on on 60 patients (120 knees) with simBTKA using patient-specific templating (PST). Patients were included if they had Kellgren–Lawrence Grade III-IV osteoarthritis. Revision surgeries, staged BTKA, or patients with bone defects, valgus deformity, severe varus deformity (defined as above 20°), and extra-articular deformities were excluded from the study. The outcome measures were interlimb component asymmetry, Knee Society Score (KSS), and range of motion (ROM). The comparison between pre- and postoperative findings was done using a dependent t-test. A total of 29 (48.34%) patients had symmetrical femoral and tibial components, whereas the rest had asymmetry, of them, 11.7% had both femoral and tibial component size asymmetry. There were no statistically significant differences between the changes in KSS and ROM in the smaller implant and larger implant groups (P = 0.5 and P = 0.4, respectively). The total number of complications was eight and as follows: superficial infection, aseptic loosening, rupture of the patellar tendon after a bathroom fall, anemia requiring blood transfusion, residual varus deformity, deep venous thrombosis, periprosthetic fracture, and malalignment. There is no correlation between the interlimb component asymmetry and the knee function. However, there was statistically significant improvement from preoperative to postoperative KSS and ROM in small and large implants.