The impact of posterior tibial slope on knee flexion in PCl sacrificing total knee arthroplasty

Introduction Range of motion (ROM) is one of the critical factors in determination of the total knee arthroplasty effectiveness. Increased motion is associated with improved function and increased patient satisfaction. Posterior tibial slope has been theorized as advantageous to ROM. The purpose of this study is to evaluate and quantify the effect of the tibial slope on the postoperative maximal knee flexion.Patients and methods A total of 60 patients who had undergone total knee arthroplasty with the posterior stabilized prostheses were divided into two groups; each group included 30 patients. The only difference between groups was the use of a 0° (group A) or 7° (group B) posterior sloped tibial cutting block. Preoperative ROM and Hospital for Special Surgery knee scores were prospectively obtained from each patient. Similar data were obtained for all patients at 3 months after surgery and at each patient’s follow-up examination. Preoperative and postoperative radiographs of each surgical knee were obtained and measured to determine the tibial slope angle.Results Use of the 0° cutting block in group 1 resulted in a mean postoperative proximal tibial slope of 1.3°±2.96° (range: −3° to 7°), whereas using the 7° cutting block in group 2 resulted in a mean postoperative proximal tibial slope of 7.27°±2.66° (range: 1°–11°). The difference between the groups was statistically significant (P=0.001). The mean values of the postoperative maximal flexion angles were 115.2°±12.59° (range: 91°–130°) and 122.5°±11.96° (range: 94°–136°) in groups 1 and 2, respectively. There was a significant difference in the maximal flexion between the two groups (P=0.0125).Conclusion An increase in the posterior tibial slope can significantly increase the postoperative maximal knee flexion.