Treatment of osteochondral defects of the knee: results at 2 years using a cell-free biomimetic scaffold

Objectives: To successfully treat osteochondral defects is a real challenge for the orthopaedic surgeon, since only the formation of fibrocartilage and poor subchondral regeneration have yet been proved with the techniques currently available. Preclinical tests demonstrated that this new biomaterial (obtained by enucleating equine collagen type 1 fibrils with hydroxyapatite nanoparticles in 3 different layers with 3 different gradient ratios at physiological conditions) induced an ‘‘in situ’’ cartilage regeneration into the defect site, exploiting the self-regenerative potential due to the stem cells incoming from the bone marrow. The first pilot clinical study confirmed safety and manageability of the procedure, showing good and stable results over time on 30 patients. Methods: 99 patients (75 M, 24 F, mean age 32.9 yy) were treated for a total of 113 chondral/osteochondral lesions of the knee (36 medial femoral condyles, 25 lateral femoral condyles, 23 patellae, 23 femoral throcleas and 6 tibial plateaux). Mean size of the lesions was 3.4 ± 2.6 cm2. All patients and their clinical outcome were analyzed prospectively at 6, 12 and 24 months using the Cartilage standard Evaluation Form as proposed by ICRS. An high resolution MRI was performed and the MOCART scoring scale was used to analyze the repaired tissue. Results: A statistically significant improvement and function recovery comparing the pre-operative were recorded up to 24 months. IKDC subj score increased from 45.6 ± 16.2 to 69.9 ± 18.9 and 74 ± 18.6 at the 1 year and final evaluation respectively (p\0.05). Tegner score increased from 2.6 ± 2.0 to 4.2 ± 1.6 at 2 years’ follow-up (p\0.05). A tendency to a better clinical outcome was detected for OCD lesions. MRI evaluation confirmed the good results, showing a good filling in most of the lesions treated. Three patients failed, being re-operated for the same reason. Conclusions: The use of this biomimetic cell-free scaffold for osteochondral lesions of the knee allows to obtain function recovery and a good clinical outcome at short-time follow-up. Better results are recorded in case of OCDs. These promising results have to be proven at longer follow-up.