Introduction:
Flexion contracture in the knee joint before knee replacement surgery has been implicated as one of the factors that could affect the accuracy of digital templating.

Aim:
The aim of the study was to detect the accuracy of digital templating in predicting the size of knee implants and to detect the effect of preoperative flexion contracture in the knee joint on the accuracy of digital templating.

Material nad methods:
The flexion contracture of the knee joint was measured in every patient prior to knee replacement surgery and digital templating of the knee joint was made in mediolateral (ML), anteroposterior (AP) and AP long leg views. The sizes of prosthetic components predicted by templating were compared to the sizes of prosthetic components implanted during the surgery. The effect of flexion contracture on the accuracy of digital templating was analyzed using χ² test and Mann–Whitney U test.

Results and discussion:
The size of the prosthetic component predicted by templating matched the size of the implanted component in 45.2%–62.9% of the cases, in 91.9%–98.4% of the cases it was within the range of one size. Statistically significant effect of the flexion contracture in the knee joint on the accuracy of digital templating was observed in the femoral component, AP view if the flexion contracture exceeded 10°.

Conclusions:
Digital templating is very accurate method in predicting the size of knee implants. Flexion contracture in the knee joint that exceeds 10° diminishes the accuracy of digital templating of the femoral component in AP view.