Patient-Specific Instrumentation in Medial Proximal Tibial Angle-Based Medial Open Wedge High Tibial Osteotomy: Improved Correction, Accuracy, and Cartilage Regeneration at Second-Look Arthroscopy.

Abstract

To assess the precision of patient-specific instrumentation (PSI) in medial open wedge high tibial osteotomy (MOWHTO) based on medial proximal tibial angle (MPTA) and evaluate cartilage regeneration and clinical outcomes. From August 2018 to December 2022, patients undergoing PSI-guided MPTA-based MOWHTO were included, with a minimum follow-up period of 2 years. Exclusion criteria included MOWHTO without PSI, surgical planning not based on MPTA, bilateral knee surgery, procedure changes during surgery, and loss of follow-up. Accuracy was classified into 3 categories: high, acceptable, and low accuracy based on the correction error (≤1°, 1°-2°, and >2°, respectively). Paired-sample t-tests compared preoperative and postoperative alignment and clinical scores, while rank sum and Fisher's exact tests assessed arthroscopic findings. Radiological and clinical assessments were conducted on 39 patients. Cartilage regeneration was assessed by arthroscopy in 30 knees during implant removal. The error between preoperative planning and postoperative MPTA was at 0.1° ± 1.7° (95% CI: -0.5 to 0.6). The number of knees having the high, acceptable, and low accuracy was 21 (54%), 9 (23%), and 9 (23%) (p-value = .03) respectively. No significant changes were observed in posterior tibial slope. The KOOS showed a significant improvement after surgery compared to the preoperative score, from 47 ± 18 to 74 ± 14 with 100% patients exceeding the threshold for minimal clinically important difference. The mean weight-bearing line percentage significantly improved 19.5% ± 10.1% to 59.0% ± 7.3%, and the mean MPTA was corrected from 84.7° ± 1.8° preoperatively to 92.6° ± 2.1° postoperatively. A second-look arthroscopy revealed significant cartilage regeneration on the medial femoral condyle surfaces. The use of PSI in MPTA-based MOWHTO resulted in highly and acceptably accurate correction in the majority of cases, preservation of the PTS, and improved clinical outcomes in all patients. Furthermore, MOWHTO promotes cartilage regeneration at MFC following a 2-year follow-up. Level IV, retrospective study.