Comparison of outcomes between gap balancing and measured resection techniques for total knee arthroplasty: A prospective, randomized, controlled trial

OBJECTIVE: The aim of this study was to compare the effect of Gap Balancing (GB) versus Measured Resection (MR) techniques on the early clinical and radiological results of Total Knee Arthroplasty (TKA). METHODS: In this prospective study, 99 patients (99 knees) who underwent unilateral TKA between March 2018 and January 2019 were randomly allocated to one of two groups: The GP group, TKA with GB technique (19 male, 31 female; mean age = 55.9 ±16.5) and the MR group, TKA with MR technique (19 male, 30 female; mean age = 54.2 ± 18.7). Patients in both groups were comparable in terms of the demographic and clinical data. The angle of cutting block to PCA and Cutting Thickness of the Medial and Lateral Condyle (CTMC, CTLC) were intraoperatively measured. In radiographic analysis, Preoperative Mechanical Femorotibial Angle (Pre-mFTA), Postoperative Mechanical Femorotibial Angle (Post-mFTA), and joint line changes were examined. Femoral component Rotation Angle (FCRA) was also measured by computed tomography. In gait analysis, the spatiotemporal parameters (walking speed, step length, and single support time) and kinematics parameters (flexion angle, extension angle, and transversal rotation) were collected at 12 months postoperatively. Furthermore, Western Ontario and McMaster Universities Arthritis Index (WOMAC) were performed at 12 months after surgery. RESULTS: CTMC and CTLC were both significantly higher in GB group than in the MR group (9.8±2.0 mm vs 8.5 ± 1.2 mm; 7.9 ± 1.8mm vs 6.8 ± 1.4mm; P = 0.001, P = 0.002, respectively). Angle of cutting block to PCA was statistically lower in GB group than in the MR group (1.7 ± 1.5° vs 3.1 ± 0.5 °; P < 0.001). FCRA is greater in the GB group compared to the MR group, but the difference did not reach statistical significance (1.2 ± 2.8 ° vs 0.7 ± 2.0 °; P > 0.05). Although post-mFTA significantly improved compared with pre-mFTA in both groups, no significant difference was observed in the changes of post-mFTA between the two groups (0.9 ± 1.7° vs 0.3 ± 1.8°, P > 0.05). No significant differences were determined between the two groups in spatiotemporal gait parameters including walking speed, step length, and single support time. The sagittal max knee flexion range was significantly larger in the GB group than in the MR group (49.27 ± 5.24 ° vs 45.99 ± 8.21 °, P < 0.05). The flexion range did not reach the level of the control group. There was no significant difference between the two groups in WOMAC at 12 months follow-up (P > 0.05). CONCLUSION: Evidence from this study has revealed GB and MR techniques have both little effect on early clinical results of TKA. Nonetheless, GB technique can provide better knee flexion in the early postoperative gait status compared with MR technique. LEVEL OF EVIDENCE: Level I, Therapeutic Study