ADVANTAGES OF COMPUTER-NAVIGATED KNEE REPLACEMENT: IMPLICATIONS FOR BIOMECHANICS, PAIN MANAGEMENT, AND RECOVERY

The knee joint, through its anatomy, biomechanics, and function, represents a highly complex mechanism. In recent years, the implantation of knee prostheses has markedly increased worldwide, driven by the need to reduce pain and improve mobility. Although total knee arthroplasty currently remains the most common treatment for advanced-stage gonarthrosis, achieving optimal surgical outcomes, restoring full functional mobility, and accurately predicting postoperative results continue to pose significant challenges.

The aim of our study was to determine the advantages of surgical treatment of gonarthrosis using a computer-assisted navigation system and to assess how these advantages influence the biomechanical characteristics of the knee joint and postoperative pain.

A total of 100 patients who underwent primary total knee replacement between 2020 and 2024 (using only a sliding implant with patellar resurfacing) were evaluated on Randomized bases. Patients were allocated to the two study groups using a stratified randomization approach with a 1:1 allocation ratio. Stratification was performed by sex to ensure an equal distribution of male and female patients between the navigation-assisted total knee arthroplasty group and the standard surgery group. This approach was chosen to minimize potential confounding related to sex-specific differences in postoperative pain perception and functional recovery. All eligible patients meeting the inclusion criteria were assigned to one of the two groups according to the predefined randomization scheme prior to surgery. All patients received a prosthesis with a tibially fixed polyethylene insert and preservation of the posterior cruciate ligament (Fa. Aesculap). The patients were divided into two main groups: the N-group, who underwent computer-assisted navigation-guided total knee arthroplasty with patellar resurfacing (OrthoPilot®, Fa. B. Braun, Aesculap), and the S-group, who underwent standard total knee arthroplasty with patellar resurfacing. Pre- and postoperative pain assessment was performed using the 0-10 Numerical Rating Scale (NRS), while the knee joint range of motion was evaluated using the neutral-zero method. The postoperative follow-up period was 6 months.

No significant differences were observed between the groups with respect to age or sex. In the preoperative period, 22.0% of patients in the navigation-assisted group reported moderate pain, whereas 78.0% reported severe pain. In the standard surgery group, moderate pain was observed in 26.0% of patients, and severe pain in 74.0%. According to postoperative day 4-5 data, 38% of patients in the N group and 26% in the S group reported mild pain. Moderate pain was present in 48% of the N group and 52% of the S group. Severe pain was noted in 14% of the N group and 22% of the S group. Importantly, pain distribution between the N and S groups during postoperative days 4-5 did not differ significantly (P>.05). At the 6-week postoperative evaluation, 46.0% of patients in the navigation group (N) reported no pain, 40.0% reported mild pain, 12.0% reported moderate pain, and only 2.0% reported severe pain. In the standard group (S), 30.0% were pain-free, 40.0% reported mild pain, 28.0% moderate pain, and 2.0% severe pain. At the 6-month postoperative follow-up, 68% of patients in the N group were pain-free, 28% had mild pain, and 4% had moderate pain. In the S group, 60% were pain-free, 34% reported mild pain, and 6% reported moderate pain. Based on proportional distribution between groups, no statistically significant differences were identified (P>.05). Frequency analysis showed that the mean preoperative knee flexion amplitude in the navigation-assisted group (N) was M=109.70°, SD=10.32, while in the standard group (S) it was M=104.40°, SD=10.48. By postoperative day 5, a marked reduction in flexion amplitude was observed in both groups (N: M=58.70°, SD=15.28; S: M=46.00°, SD=11.07). During subsequent rehabilitation, a clear recovery trend was noted. At 6 weeks postoperatively, the mean flexion amplitude increased to M=119.40°, SD=6.97 in the N group and M=110.00°, SD=9.04 in the S group. At the 6-month follow-up, both groups reached their maximal recovery levels; however, the navigation-assisted group continued to demonstrate superior knee flexion amplitude (N: M=121.00°, SD=7.00; S: M=113.40°, SD=8.48).

Comparative analysis between the groups demonstrated that, overall, patients who underwent navigation-assisted surgery exhibited significantly greater knee flexion amplitudes across the four time points assessed (F=31.343, p<.001). Notably, the between-group differences did not emerge immediately but became pronounced at later stages-specifically from the 6-week to the 6-month postoperative period. A statistically significant interaction between time and group was identified (Amplitudes×Group: F(3,96)=3.458, p=.019), indicating that the rate of improvement in knee flexion amplitude differed between groups. Patients treated with computer-assisted navigation recovered motion amplitude more rapidly and more completely than those who underwent the standard procedure. The results further show that by postoperative week 6, 16% more patients in the navigation-assisted group had achieved a pain-free status compared with the standard surgery group. Conversely, moderate pain was observed 16% more frequently in the standard technique group than in the navigation group at the same postoperative interval.