Digital two-dimensional templating accurately predicts implant size without affecting surgical duration in total knee arthroplasty

PURPOSE: To evaluate the accuracy of two-dimensional (2D) digital templating in primary total knee arthroplasty (TKA) and to examine whether templating accuracy is associated with surgical duration. METHODS: All consecutive patients who underwent primary conventional cruciate-retaining (CR) TKA at a single academic center between October 2020 and March 2023 were retrospectively analyzed. Preoperative 2D digital templating was performed with TraumaCad (Brainlab AG) and compared with implanted femoral and tibial component sizes. Accuracy was assessed as exact matches and deviations of ±1, ±2, and ±3 sizes. Pearson correlation coefficients were calculated between planned and implanted sizes. The association between templating accuracy and surgical duration was assessed using correlation analysis and an independent-samples t-test, with patients stratified into predefined <2-size and ≥2-size deviation groups. RESULTS: A total of 360 patients (56% female) were included. The median planned component sizes were 6 (interquartile range [IQR], 5-8) for both femoral and tibial components; whereas the median implanted sizes were 6 (IQR, 5-7) and 6 (IQR, 5-7), respectively. Planned and implanted sizes were very strongly correlated for femoral (r = 0.865; p < 0.001) and tibial (r = 0.843; p < 0.001) components. Templating accuracy was high, with 92% of femoral and 89% of tibial components within ±1 size. Mean surgical duration was 76.8 ± 18.7 min and showed no statistically significant association with templating accuracy (r = 0.18; p = 0.629). Surgical duration did not differ statistically significantly between <2-size and ≥2-size deviation groups (p = 0.541). CONCLUSION: 2D digital templating demonstrated high accuracy for predicting implant sizes in primary CR TKA and was not associated with surgical duration. Although not invariably exact, it consistently defined a narrow range of suitable component sizes, underscoring its value in preoperative planning and inventory management. LEVEL OF EVIDENCE: Level III, diagnostic study.