Patient-specific implants combined with 3D-printed drilling guides for corrective osteotomies of multiplanar tibial and femoral shaft malunions leads to more accurate corrections.

Abstract

Purpose: The aim of this study was to evaluate the feasibility of using patient-specific implants (PSI) for complex shaft corrective osteotomies in multiplanar deformities of long bones in the lower extremities. Additionally, it aimed to investigate the added value of these implants by quantifying surgical accuracy on postoperative CT, comparing their outcomes to two commonly used techniques: 3D virtual visualizations and 3D-printed surgical guides.

Methods: Six tibial and femoral shaft corrective osteotomies were planned and performed on three Thiel embalmed human specimen. Depending on the specimen a different respective technique was used; 1) '3D Visualization' using 3D virtual plan preoperatively and free-hand corrective osteotomy techniques with standard manually contoured plates; 2) '3D guided' utilizing 3D surgical guides and manually contouring of conventional implant; and 3)'3D PSI' utilizing a 3D surgical guide with a patient-specific implant. Accuracy of the corrections was assessed through measurements for varus/valgus angulation, ante/recurvation, rotation and osteotomy plane error as quantified on postoperative CT-scans.

Results: Twelve corrective osteotomies were performed. For, the median difference between the surgical plan and postoperative CT assessment was 3.4°, 4.6°, and 2.2° for the '3D visualization', '3D guided', and '3D PSI' methods respectively. Regarding ante/recurvation, the differences were 3.8°, 43.8°, and 1.2°, respectively. For rotation, the differences were 11.9°, 18.7°, and 3.5°, respectively. Discrepancies between planned and executed levels of osteotomy plane were 6.2 mm, 3.2 mm, and 1.4 mm, respectively.

Conclusion: PSIs with 3D-printed drilling guides for complex multiplanar corrective osteotomies of femoral and tibial shaft malunions is feasible and achieves accurate corrections. This technique enables precise determination of the osteotomy plane, guides correction in all three planes, and ensures satisfactory implant fitting; thus accurately translating the virtual surgical plan into clinical practice. The 3D PSI method is beneficial for complex cases with significant multiplanar deformities in bone anatomy, particularly with rotational malalignment.