High-Density Autologous Chondrocyte Implantation as Treatment for Ankle Osteochondral Defects.

PURPOSE: Two-year follow-up to assess efficacy and safety of high-density autologous chondrocyte implantation (HD-ACI) in patients with cartilage lesions in the ankle. DESIGN: Twenty-four consecutive patients with International Cartilage repair Society (ICRS) grade 3-4 cartilage lesions of the ankle were included. Five million chondrocytes per cm2 of lesion were implanted using a type I/III collagen membrane as a carrier and treatment effectiveness was assessed by evaluating pain with the visual analogue scale (VAS) and American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score at baseline, 12-month, and 24-month follow-up, together with dorsal and plantar flexion. Magnetic resonance observation for cartilage repair tissue (MOCART) score was used to evaluate cartilage healing. Histological study was possible in 5 cases. RESULTS: Patients' median age was 31 years (range 18-55 years). Median VAS score was 8 (range 5-10) at baseline, 1.5 (range 0-8) at 12-month follow-up, and 2 (rang e0-5) at 24-month follow-up (P < 0.001). Median AOFAS score was 39.5 (range 29-48) at baseline, 90 (range 38-100) at 12-month follow-up, and 90 (range 40-100) at 24-month follow-up (P < 0.001). Complete dorsal flexion significantly increased at 12 months (16/24, 66.7%) and 24 months (17/24, 70.8%) with regard to baseline (13/24, 54.2%) (P = 0.002). MOCART at 12- and 24-month follow-ups were 73.71 ± 15.99 and 72.33 ± 16.21. Histological study confirmed that neosynthetized tissue was cartilage with hyaline extracellular matrix and numerous viable chondrocytes. CONCLUSION: HD-ACI is a safe and effective technique to treat osteochondral lesions in the talus, providing good clinical and histological results at short- and mid-term follow-ups.

Increasing the Dose of Autologous Chondrocytes Improves Articular Cartilage Repair: Histological and Molecular Study in the Sheep Animal Model.

BACKGROUND: We hypothesized that implanting cells in a chondral defect at a density more similar to that of the intact cartilage could induce them to synthesize matrix with the features more similar to that of the uninjured one. METHODS: We compared the implantation of different doses of chondrocytes: 1 million (n = 5), 5 million (n = 5), or 5 million mesenchymal cells (n = 5) in the femoral condyle of 15 sheep. Tissue generated by microfracture at the trochlea, and normal cartilage from a nearby region, processed as the tissues resulting from the implantation, were used as references. Histological and molecular (expression of type I and II collagens and aggrecan) studies were performed. RESULTS: The features of the cartilage generated by implantation of mesenchymal cells and elicited by microfractures were similar and typical of a poor repair of the articular cartilage (presence of fibrocartilage, high expression of type I collagen and a low mRNA levels of type II collagen and aggrecan). Nevertheless, in the samples obtained from tissues generated by implantation of chondrocytes, hyaline-like cartilage, cell organization, low expression rates of type I collagen and high levels of mRNA corresponding to type II collagen and aggrecan were observed. These histological features, show less variability and are more similar to those of the normal cartilage used as control in the case of 5 million cells implantation than when 1 million cells were used. CONCLUSIONS: The implantation of autologous chondrocytes in type I/III collagen membranes at high density could be a promising tool to repair articular cartilage.