Effect of hardware removal and second-look arthroscopy after open-wedge high tibial osteotomy.

Introduction: Open-wedge high tibial osteotomy (OWHTO) is the standard and safe procedure for medial compartment osteoarthritis. Although hardware removal (HWR) is performed after post-OWHTO bone union, the effects of HWR on OWHTO have been rarely reported. We hypothesised that HWR would improve range of motion (ROM) and implant-related complications. Thus, this study aimed to investigate the effects of HWR on postoperative ROM, the Japan Orthopaedic Association (JOA) score/visual analogue scale (VAS) score and hardware-related complications after OWHTO.

Methods: Patients who underwent OWHTO between January 2016 and June 2018 and HWR were retrospectively reviewed. To perform OWHTO, locking plates and prosthetic bone were used to achieve optimal stabilisation of biplanar osteotomy. HWR was performed after a second-look arthroscopy through the previous skin incision. For clinical evaluation, the JOA score, VAS score, and ROM were assessed before and 1 year after HWR using the Wilcoxon rank test. Logistic regression analysis was performed to identify the predictors of post-HWR improvement.

Results: Of 98 knees examined (91 patients), 80 (73 patients; 39 men and 34 women) were included. At the time of OWHTO, mean age was 64.0 ± 9.7 years and body mass index, 25.5 ± 3.1 kg/m; Kellgren-Lawrence (KL) grade 1 was seen in 20 cases, KL-2 in 46, and KL-3 in 14. Mean periods between OWHTO and HWR were 13.4 ± 2.0 months, and 11.9 ± 1.2 months between HWR and evaluation. The JOA score and flexion angle significantly improved after HWR (The JOA score: p = 0.026 flexion angle: p < 0.001); however, the VAS score and extension angle did not (VAS score: p = 0.162, extension angle: p = 0.934). Hardware irritation was observed in four cases (5%), which improved after HWR. Logistic regression analysis revealed that lower preoperative KL grade and flexion angle were predictors of improvement after HWR [KL grade: p = 0.008; odds ratio 3.244, 95% confidence interval (CI) 1.350-7.794; flexion angle: p < 0.001; odds ratio 1.150, 95% CI 1.062-1.245].

Conclusion: HWR improves flexion angle, clinical outcomes and hardware-related complications after OWHTO. Preoperative KL grade and flexion angle are predictors of improvement after HWR in patients who have undergone OWHTO.