Preoperative Knee Templating Accuracy Does Not Predict Radiographic or Clinical Outcome in Total Knee Arthroplasty.

Background and objective: The purpose of this study was to evaluate the accuracy of digital templating for primary total knee arthroplasty (TKA) and to evaluate whether accurate templating affects the clinical or radiographic outcome of TKA.

Materials and methods: We retrospectively reviewed 178 primary TKAs performed by a single surgeon with preoperative templating available and minimum 2-year clinical follow-up. Templated size was compared to the implanted size. Postoperative coronal alignment was measured on standing long-leg radiographs by two independent observers. UCLA Activity Scale and Knee Society scores (KSS) were evaluated after 2 years. Categorical variables are reported as number and percentage. Correlative data were analyzed using Spearman's correlation tests and reported as coefficients (r_s) with 95% CI. Significance was set at P<0.05.

Results: Preoperative templating accurately estimated the tibia within one size in 95% of cases (169 TKAs), while the femur was templated within one size in 99% of cases (176 TKAs). Templating accuracy did not correlate with postoperative coronal alignment within 3° of the mechanical axis (tibial accuracy: r_s=0.10, P=0.120; femoral accuracy: r_s= -0.07, P=0.338). Templating accuracy did not correlate with the postoperative UCLA Activity Scale score (tibia P=0.177; femur P=0.354), KSS function (tibia P=0.587; femur P=0.637), KSS expectation (tibia P=0.764; femur P=0.817), or KSS satisfaction (tibia P=0.760; femur P=0.811) at 2 years.

Conclusion: Preoperative digital templating for TKA reliably estimates the implanted femoral and tibial component sizes within one size; however, templating did not correlate with radiographic or clinical outcomes at 2 years.