Use of Collagen Scaffold and Autologous Bone Marrow Concentrate as a One-Step Cartilage Repair in the Knee: Histological Results of Second-Look Biopsies at 1 Year Follow-up

Chondral articular defects are a key concern in orthopaedic surgery. To overcome the disadvantages of autologous chondrocyte implantation (ACI) and to improve the outcomes of autologous matrix-induced chondrogenesis (AMIC), the latter technique is currently augmented with bone marrow concentrate injected under or seeded onto the scaffold. However, to date, only a little is known about histological outcomes of either the AMIC technique or AMIC associated with bone marrow concentrate. This study aimed to evaluate the quality of the repair tissue obtained from biopsies harvested during second-look arthroscopy after arthroscopic AMIC augmented with bone marrow concentrate. We analysed five second-look core biopsies harvested at 12 months follow-up. At the time of biopsy the surgeon reported the quality of the repair tissue using the standard ICRS Cartilage Repair Assessment (CRA). Every biopsy together with patient data was sent to our centre to undergo blind histological evaluation (ICRS II Visual Histological Assessment Scale) and data analysis. Five asymptomatic patients (mean age 43.4 years) had isolated lesions (mean size was 3.7 cm2) at the medial femoral condyle. All the implants appeared nearly normal (ICRS CRA) at arthroscopic evaluation and had a mean overall histological (ICRS II) of 59.8±14,5. Hyaline-like matrix was found in only one case, a mixture of hyaline/fibrocartilage was found in one case and fibrocartilage was found three cases. Our clinical and histological data suggest that this procedure achieved a nearly normal arthroscopic appearance and a satisfactory repair tissue, which was possibly still maturing at 12 months follow-up. Further studies are needed to understand the true potential of one-step procedures in the repair of focal chondral lesions in the knee.