A novel, minimally-invasive technique of cartilage repair in the human knee using arthroscopic microfracture and injections of mesenchymal stem cells and hyaluronic acid--a prospective comparative study on safety and short-term efficacy.

INTRODUCTION Most current cell-based cartilage repair techniques require some form of scaffolds and 2 separate surgical procedures. We propose a novel, scaffold-less technique of cartilage repair in the human knee that combines arthroscopic microfracture and outpatient intra-articular injections of autologous bone marrow-derived mesenchymal stem cells (MSCs) and hyaluronic acid (HA). MATERIALS AND METHODS Seventy matched (age, sex, lesion size) knees with symptomatic cartilage defects underwent cartilage repair with the proposed technique (n = 35) or an open technique (n = 35) in which the MSCs were implanted beneath a sutured periosteal patch over the defect. Prospective evaluation of both groups were performed using the International Cartilage Repair Society (ICRS) Cartilage Injury Evaluation Package, which included questions from the Short-Form (SF-36) Health Survey, International Knee Documentation Committee (IKDC) subjective knee evaluation form, Lysholm knee scale, and Tegner activity level scale. Postoperative magnetic resonance imaging (MRI) evaluation was also performed at 1 year for most patients. RESULTS There were no clinically significant adverse events reported through the course of our study. At the fi nal follow-up (mean = 24.5 months), there was significant improvement in mean IKDC, Lysholm, SF-36 physical component score and visual analogue pain scores in both treatment groups. CONCLUSION In the short term, the results of this novel technique are comparable to the open procedure with the added advantages of being minimally invasive and requiring only a single operation under general anaesthesia. Its safety has been validated and its efficacy is currently being evaluated in an ongoing randomised controlled trial.