Abstract: BACKGROUND: In recent years, computer-assisted navigation has gradually attracted attention in the medical field. Some scholars have reported that the clinical effects of computer navigation in total knee arthroplasty vary. To explore the clinical effect of the new generation of Brainlab Knee 3 navigation system, this study is conducted.
OBJECTIVE: To analyze the application effect of computer navigation system (Brainlab Knee 3) combined with gap balance technology in total knee arthroplasty. 
METHODS: A total of 71 patients received total knee arthroplasty at the Department of Joint Surgery of Dalian Second People’s Hospital from November 2020 to May 2021. In the navigation group, 35 patients underwent total knee arthroplasty by computer navigation combined with gap balance. In the traditional group, 36 patients underwent osteotomy with traditional surgical instruments. The difference between medial and lateral joint spaces, knee range of motion, hospital for special surgery knee score, hip-knee-ankle angle, deviation values of coronal femoral component angle, coronal tibial component angle, and sagittal tibial component angle were compared between the two groups.  
RESULTS AND CONCLUSION: (1) In the navigation group, the differences of intraoperative medial and lateral joint gap at knee extension 0, 1, and 2 mm were found in 19, 14, and 2 cases, respectively. The gap difference was 0 mm in 18 cases, 1 mm in 15 cases and 2 mm in 2 cases at 90° degree knee flexion. In the traditional group, the gap difference at knee extention was 0 mm in 10 cases, 1 mm in 20 cases, and 2 mm in 6 cases. The gap difference at 90 degree knee flexion was 0 mm in 10 cases, 1 mm in 15 cases and 2 mm in 8 cases. (2) The operation time in the navigation group was longer than that in the traditional group (P < 0.05), and two patients in the navigation group developed lower limb intermuscular vein thrombosis after surgery, and none of the patients in the traditional group had complications. (3) The range of motion between the two groups increased significantly at 6 and 12 months after surgery, and the range of motion in the navigation group was higher than that in the traditional group (P < 0.05). (4) At 12 months after surgery, the hospital for special surgery knee scores of both groups increased significantly, and the hospital for special surgery knee score in the navigation group was higher than that in the traditional group (P < 0.05). (5) At 6 months after surgery, the deviation values of hip-knee-ankle angle, coronal femoral component angle, coronal tibial component angle, and sagittal tibial component angle of navigation group were significantly lower than those in the traditional group (P < 0.05). (6) The results showed that computer navigation technique combined with gap balance in total knee arthroplasty had advantages in postoperative range of motion, lower limb alignment and the accuracy of tibial prosthesis component position, and joint function recovered well. 

Key words: total knee arthroplasty, computer navigation system, Brainlab Knee 3, lower limb alignment, joint motion range, hip-knee-ankle angle