Does the gap balance technique really elevate the joint line in total knee arthroplasty? A single-center, randomized study

Abstract

Objectives: This study aims to compare patients undergoing total knee arthroplasty (TKA) with gap balancing (GB) versus measured resection (MR) techniques in terms of joint line (JL) using radiographic measurements from both femoral and tibial sides. Patients and methods: Between August 2019 and May 2021, a total of 107 patients who underwent TKA were included in this randomized study. The patients were divided into two groups as the GB group (n=54; 9 males, 45 females; mean age: 66.6±7.4 years; range, 51 to 81 years) and the MR group (n=53; 10 males, 43 females; mean age: 64.0±6.8 years; range, 50 to 80 years). The adductor tubercle joint line (ATJL) and the tibial tubercle joint line (TTJL) were evaluated for JL measurement. Clinical and functional evaluation was made using the range of motion of the joint, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Knee Society Score (KSS)-Knee and Functional scores. Results: The mean follow-up was 34.2±3.5 months in the GB group and 34.4±3.3 months in the MR group (p=0.80). The mean operation time was 119.1±14.9 min in the GB group and 118.6±17.5 min in the MR group (p=0.89). A total of 31 (57.4%) patients in the GB group had a degree of release of 3-4, while 21 (39.6%) patients in the MR group had a degree of release of 3-4 (p=0.26). The ATJL measurement was similar in the GB and MR groups, while the TTJL measurement was significantly different between the two groups (p=0.01). There was no significant correlation between the ATJL measurement and the degree of release, while there was a significant correlation between the TTJL and the degree of release (r=0.731, p<0.001). Conclusion: While ATJL measurements in TKA showed similar results with GB and MR techniques, the amount of release may have caused the significantly higher JL elevation in the GB group in TTJL measurements. Based on these findings, we suggest that radiographic JL measurements on both the tibial and femoral sides in TKA may provide a more accurate assessment and we recommend to measure JL from the femoral side.