Two-Year Evaluation of Osteochondral Repair with a Novel Biphasic Graft Saturated in Bone Marrow in an Equine Model

Abstract

Objective To evaluate a biphasic cartilage repair device (CRD) for feasibility of arthroscopic implantation, safety, biocompatibility, and efficacy for long-term repair of large osteochondral defects. Methods The CRD was press-fit into defects (10 mm diameter, 10 mm deep) created in the femoral trochlea of 12 horses. In the contralateral limb, 10 mm diameter full-thickness chondral defects were treated with microfracture (MFX). Radiographs were obtained pre- and postoperatively, and at 4, 12, and 24 months. Repeat arthroscopy was performed at 4 and 12 months. Gross assessment, histology, mechanical testing, and magnetic resonance imaging (MRI) were performed at 24 months. Results The CRD was easily placed arthroscopically. There was no evidence of joint infection, inflammation, or degeneration. CRD-treated defects had significantly more sclerosis compared to MFX early ( P = 0.0006), but was not different at 24 months. CRD had better arthroscopic scores at 4 months compared to MFX ( P = 0.0069). At 24 months, there was no difference in repair tissue on histology or mechanical testing. Based on MRI, CRD repair tissue had less proteoglycan (deep P = 0.027, superficial P = 0.015) and less organized collagen (deep P = 0.028) compared to MFX. Cartilage surrounding MFX defects had more fissures compared to CRD. Conclusion The repair tissue formed after CRD treatment of a large osteochondral lesion is fibrocartilage similar to that formed in simple chondral defects treated with MFX. The CRD can be easily placed arthroscopically, is safe, and biocompatible for 24 months. The CRD results in improved early arthroscopic repair scores and may limit fissure formation in adjacent cartilage.