gms | German Medical Science

Objectives: Osteochondral transplantation is one of the known cartilage repair procedures for severe cartilage defects with an ICRS Grad III or IV. The matching of the surface contour is considered as key factor for its success. The alignment of the subchondral bone is considered more important and the question is now, whether its improvement could be achieved by guided transplantation. We state, that it is possible to match the surface of the recipient joint with the donor joint surface by using CT-data in a 3D software-analyzer. Based on this match, we state that customized milling guides for osteochondral transplantation can be manufactured using a 3D Printer.

Methods: We prepared 50 cadaver femoral pig bones for osteochondral transplantation from the posterior lateral condyle to the femoral head by using the Surgical Diamond Instrumentation (SDI, boneArtis). 25 procedures were performed by free hand. 25 pig bones received a CT scan. Data was imported into the 3 D software Inprint (Materialise). The subchondral bone plate of the femoral head and the posterior lateral femoral condyle were matched and customized milling templates were designed for harvesting and grafting by using a 3 D Printer (Formlabs). Two surgeons performed the operations randomly. Postoperatively all 50 bones were CT scanned and the alignment of the subchondral bone was measured at 4 points (0, 90, 180, 360°). Step up or down was documented. Results were analyzed by Chi-squared test, Variance and Correlation by using SPSS 26.

Results: The average step of the subchondral bone plate of the transplant and the recipient site was measured with 0.27 mm in the group with milling-guides and 0.73 mm in the group without guide. The Chi-squared test showed, that the guided transplants outperformed the transplants without guide at a 1% significance level (p<0.01). Furthermore, the milling guide displayed a 74% lower variance (Sigma² = 0.079) versus the transplants without a guide (Sigma² = 0.308). There was no correlation to the surgeons.

Conclusion: The use of 3 D printed milling-guides improved the alignment of the subchondral bone plate in autologous osteochondral transplantation significantly and made it more replicable throughout the series.