A Clinical Trial Examining the Accuracy of High Tibial Osteotomy When Performed by Experts Using a Novel Patient Specific Instrument (PSI)

Abstract

Purpose: Accuracy of angular correction is critical to the success of high tibial osteotomy surgery (HTO). This study set-out to determine whether a novel PSI design, which can used through a standard HTO skin incision, could deliver angular correction to within 3 of the preoperative plan in the coronal, sagittal, and axial planes. Methods: Eighteen HTOs were performed at three expert centres. PSI was designed using a CT scan, with angular correction determined using standard radiographs. Postoperative CT scans were used to determine the difference between planned and achieved angular corrections. Patient-reported outcome scores were collected preoperatively and at 3, 6, and 12 months postoperatively. Results: Mean difference between planned and achieved angular correction was not significantly different from 3.0 in the coronal plane (2.9, sd 2.8, p=0.907), and significantly less than 3.0 in the sagittal (1.5, sd 1.5, p=0.001) and axial planes (1.4, sd 1.7, p=0.001). A strong correlation existed between the size of the planned coronal angular correction and coronal plane error (r(16)=0.729, p=0.001), with a predicted 0.5 under-correction for each degree of intended correction. There was a significant increase in mean Oxford Knee Score (OKS) at 6 months (8 points, 95% CI 1-15, p=0.032) and 12 months (11 points, 95% CI 3-20, p=0.004) ). Conclusions: This study demonstrates that a novel PSI for HTO can deliver a mean angular correction within 3 of the 3D preoperative plan. However, larger coronal plane corrections were associated with increasing under-correction, which needs to be addressed before widespread adoption of this technique can be recommended.