Gobbi et al. determined the effectiveness of cartilage repair utilising bone marrow aspirate concentration and a collagen I/III matrix (Chondro-Gide, Geistlich, Wolhusen, Switzerland). They prospectively followed up, for 2 years, 15 patients (mean age, 48 years) who underwent surgery for grade IV cartilage lesions of the knee. Six of the patients had multiple chondral lesions; the average size of the lesions was 9.2 cm2. All patients underwent  a mini-arthrotomy and concomitant transplantation  with bone marrow aspirate concentrations covered with the collagen matrix. Patients showed significant improvement in all scores at the final follow-up. Patient presenting single lesions and patients with small lesions showed greater improvement. MRI showed coverage of the lesion with hyaline-like tissue in all patients, in accordance with the clinical results. Hyaline-like histological findings were also reported for all specimens analysed (Gobbi et al., 2011)