Evaluation of the flexion gap with a distal femoral trial component in posterior-stabilized total knee arthroplasty

Purpose A distal femoral trial component was manufactured, and flexion gap size and inclination were evaluated with or without the distal femoral trial component in total knee arthroplasty (TKA). This study aimed to evaluate the effect of the distal femoral trial component on flexion gap size and joint inclination in posterior-stabilized (PS)-TKA. Materials and methods A total of 84 patients with medial osteoarthritis who underwent mobile-bearing PS-TKA using modified gap techniques were included in this retrospective study. The flexion gap size and inclination before and after setting the distal femoral trial component were evaluated and compared with the final gap size and inclination. Results The joint gap size and inclination were significantly lower in those with than in those without the distal femoral trial component (P = 0.005, P < 0.001). The final gap size and inclination were similar to the gap size and inclination with the distal trial component (P = 0.468, P = 0.158). Conclusions The joint gap size and medial tension in PS-TKA were significantly reduced after setting the distal femoral trial component. The flexion gap measured using the distal femoral trial component was similar to that when the final trial component was set. To more accurately perform the gap technique TKA, the flexion gap should be measured using the distal femoral trial component.