Computer Assisted Mosaic Arthroplasty

Abstract

Mosaic Arthroplasty is a well-accepted surgical approach to treating focal cartilage defects of the knee. However, the task of creating the mosaic of osteochondral grafts that optimally restores the cartilage surface is technically demanding. Conventional techniques require the surgeon to reconstruct a complex, three-dimensional surface by eye and experience only. There is evidence that this type of procedure is sensitive to technique: grafts that are transplanted proud of the native cartilage surface tend to show evidence of cartilage fissuring and fibrillation prematurely. Two computer-assisted techniques (navigation by optical tracking and guidance by patient-specific templates) were investigated to determine whether they would have a beneficial effect on surgical execution, and whether any differences in execution had any correlation to surgical outcome. The experimental work can be broken into two parts: an in vitro study that compared the accuracy of execution of an optically navigated group versus a template guided group, and an in vivo animal trial that compared both computer assisted techniques to the conventional, non-assisted approach. The results of the pilot study indicated that, while there were higher errors in the individual measures of position, orientation, and plug depth in the optically navigated group, there was no significant difference in the overall fidelity of the geometric surface produced between the two groups. The results of the animal trial indicated that both computer assisted techniques produced morphological results that were superior to the conventional technique. The two computer-assisted techniques also showed a significantly better treatment effect as seen by their higher histological scoring. Furthermore, a significant linear correlation was found between morphological results and histological score. Overall, the experiments demonstrated that surgeons and patients could potentially benefit from the use of computer-assisted techniques in the short term. Further work is required to prove long-term beneficial effect.