A trial comparing two patient-specific instrumentations in Total Knee Arthroplasty

Abstract

Introduction: Surgeons may use patient-specific (PS) instrumentations / templates to achieve accurate bone cuts in total knee arthroplasty (TKA). We compared the tourniquet time, operation times, postoperative lower limb alignments, and individual components’ positioning in 2 different PS designs. Materials and Methods: A total of 60 knees in 55 patients (38 women, 17 men) were recruited. A total of 30 TKAs were performed using magnetic resonance imaging–based patient-specific instrument (PSI) system and 30 using computed tomography–based TruMatch (TMT) system. There was no difference in terms of the age, preoperative deformity, and diagnoses between the 2 groups, but there were more male patients in the PSI group (p = 0.01). Postoperative standing long films of the entire lower limbs were taken. Results: The mean (± standard deviation) tourniquet time was 49.1 ± 15.3 minutes for PSI and 42.9 ± 9.6 minutes for TMT groups (p = 0.07). The mean operation time was 73.7 ± 16.0 minutes for PSI group and 69.8 ± 17.9 minutes for TMT group (p = 0.38). The TMT group had significantly more outliers in tibial posterior slope (p = 0.025). There was no difference in the number of outliers in other parameters including femoral component varus, femoral component flexion, tibial component varus, and lower limb mechanical axis alignment between PSI and TMT groups. Discussion: The PSI is a new technique in TKA. The PSI and TMT systems had comparable results in the surgical times and component positioning. The PSI system may have advantages in providing more accurate tibial component posterior slope.