Objective To analysis the influence of component design and related surgical technique on knee range of motion （ROM） after total knee replacement using Innex knee system. Methods Between September 2003 and December 2005, 88 patients with 98 knees had consecutively undergone posterior cruciate-sacrificing TKA with Innex systems. The posterior condylar offset, post-operative tibial slope and knee ROM were measured in 63 patients （70 knees）. The relationship of the change in posterior condylar offset and postoperative tibial slope with knee ROM was assessed using a scatterplot graph and Pearson＇s regression analysis. According to change of posterior condylar offset, which was measured by postoperative minus preoperative posterior condylar offset, patients were divided into 4 groups. The preoperative body mass index,flexion contracture, knee ROM, HSS score and the postoperative knee ROM of four groups were evaluated.Results The mean knee ROM had improved from 96.2°±11.9° preoperative to 109.8°±13.0° at final followup. The mean pre- and post-operative posterior condylar offset was （24.0±3.5） mm and （24.5±3.3） mm, respectively. The mean postoperative tibial slope was 5.5°±1.8°. There was statistical correlation between the difference in the posterior condylar offset and the change in knee ROM after TKA and no correlation between the postoperative tibial slope and knee ROM postoperatively. The preoperative body mass index, flexion contracture, knee ROM, HSS score did not show difference among four groups. There was a statistically difference in postoperative knee ROM among groups. Conclusion Restoration of posterior condylar offset is important to the maximum range of postoperative knee ROM when Orthopedic surgeons perform TKA with Innex systems.There was no correlation between the postoperative tibial slope and postoperative ROM.