An anatomical artificial bone implant can improve three-dimensional correction accuracy in open-wedge high tibial osteotomy

Background: An anatomical artificial bone implant inserted into the osteotomy gap might be useful for accurate alignment correction during open-wedge high tibial osteotomy (OWHTO). The aims of this study were to evaluate morphological variation in the osteotomy surface, identify an anatomical implant's shape, and verify its usefulness for accurate three-dimensional (3D) correction.

Methods: Virtual OWHTO was performed with preoperative 3D computed tomography data from 100 knees. The tibial contour in the osteotomy plane was analyzed using principal component analysis to determine implant shape. An anatomical artificial bone implant with a 10° correction angle was made with a synthetic bone substitute. Coronal correction accuracy and changes in posterior tibial slope (PTS) and rotation were evaluated on eight cadaver knees that received the anatomical artificial bone implant and clinically on 85 in vivo knees that received conventional wedge-shaped spacers.

Results: The single-shape anatomical artificial bone implant was designed to occupy a posteromedial 30 × 25 mm region and had high contour congruency (mean mismatch, 0.73 mm; mean contact area coverage, 97.5%). Gap opening angle with the anatomical artificial bone implant was precise, avoiding excessive PTS change (mean, 0.6°) and rotational change (mean, 0.5°). In contrast, both PTS and rotational change with conventional spacers increased by a mean of 2.9°.

Conclusions: An anatomical artificial bone implant derived from the mean shape of 100 knees had high and consistent contour congruency. The anatomical artificial bone implant inserted with 3D surgical guidance provided accurate gap opening, reducing PTS change to less than 1° during OWHTO.