Evaluation of cartilage repair tissue after matrix-associated autologous chondrocyte transplantation using a hyaluronic-based or a collagen-based scaffold with morphological MOCART scoring and biochemical T2 mapping: preliminary results.

Background: In cartilage repair, bioregenerative approaches using tissue engineering techniques have tried to achieve a close resemblance to hyaline cartilage, which might be visualized using advanced magnetic resonance imaging.

Purpose: To compare cartilage repair tissue at the femoral condyle noninvasively after matrix-associated autologous chondrocyte transplantation using Hyalograft C, a hyaluronic-based scaffold, to cartilage repair tissue after transplantation using CaReS, a collagen-based scaffold, with magnetic resonance imaging using morphologic scoring and T2 mapping.

Study Design: Cohort study; Level of evidence, 3.

Methods: Twenty patients after matrix-associated autologous chondrocyte transplantation (Hyalograft C, n = 10; CaReS, n = 10) underwent 3-T magnetic resonance imaging 24 months after surgery. Groups were matched by age and defect size/localization. For clinical outcome, the Brittberg score was assessed. Morphologic analysis was applied using the magnetic resonance observation of cartilage repair tissue score, and global and zonal biochemical T2 mapping was performed to reflect biomechanical properties with regard to collagen matrix/content and hydration.

Results: The clinical outcome was comparable in each group. The magnetic resonance observation of cartilage repair tissue score showed slightly but not significantly (P= .210) better results in the CaReS group (76.5) compared to the Hyalograft C group (70.0), with significantly better (P= .004) constitution of the surface of the repair tissue in the CaReS group. Global T2 relaxation times (milliseconds) for healthy surrounding cartilage were comparable in both groups (Hyalograft C, 49.9; CaReS, 51.9; P= .398), whereas cartilage repair tissue showed significantly higher results in the CaReS group (Hyalograft C, 48.2; CaReS, 55.5; P= .011). Zonal evaluation showed no significant differences (P > or = .05).

Conclusion: Most morphologic parameters provided comparable results for both repair tissues. However, differences in the surface and higher T2 values for the cartilage repair tissue that was based on a collagen scaffold (CaReS), compared to the hyaluronic-based scaffold, indicated differences in the composition of the repair tissue even 2 years postimplantation.

Clinical Relevance: In the follow-up of cartilage repair procedures using matrix-associated autologous chondrocyte transplantation, differences due to scaffolds have to be taken into account.