Preliminary experience with the patient-specific templating total knee arthroplasty: 40 cases compared with a matched control group

BACKGROUND AND PURPOSE: Patient-specific templating total knee arthroplasty (TKA) is a new method for alignment of a total knee arthroplasty that uses disposable guides. We present the results of the first 40 consecutive patients who were operated on using this technique. METHODS: In this case-control study, we compared blood loss, operation time, and alignment of 40 TKAs performed using a patient-specific templating alignment technique with values from a matched control group of patients who were operated on by conventional intramedullary alignment technique. Alignment of the mechanical axis of the leg and flexion/extension and varus/valgus of the individual prosthesis components were measured on standing, long-leg, and standard lateral digital radiographs. The fraction of outliers (> 3˚) was determined. RESULTS: Mean mechanical axis of templating TKAs was 181° with a fraction of outliers of 0.3, and mean mechanical axis of conventional TKAs was 179˚ (outlier fraction 0.5). Fraction of outliers in the frontal plane for femoral components was 0.05 in the templating TKAs and 0.4 in the conventional TKAs, and for tibial components the corresponding values were 0.2 and 0.2. In the templating TKAs and conventional TKAs, fraction of outliers in the sagittal plane was 0.4 and 0.9, respectively, for femoral components and 0.4 and 0.6 for tibial components. Mean operation time was 10 min shorter and blood loss was 60 mL less for templating TKA than for intramedullary-aligned TKAs. INTERPRETATION: Patient-specific templating TKA showed improved accuracy of alignment and a small reduction in blood loss and operating time compared to intramedullary-aligned TKA, but the fraction of outliers was relatively high. Larger RCTs are needed for further evaluation of the technique and to define the future role of patient-specific template alignment techniques for TKA.