A multicenter randomized controlled trial: matrix-augmented bone marrow stimulation with a polyglycolic acid membrane with hyaluronan vs. microfracture alone in local femoral cartilage defects of the femoral condyles

AIMS AND OBJECTIVES: Microfracture is the gold standard for the treatment of small localized chondral defects of the knee joint. There is evidence from animal studies that the augmentation of bone marrow stimulation by a matrix improves the quality of the repair tissue (matrix-augmented bone marrow stimulation = m-BMS). Aim of this randomized controlled trial was to examine the outcome of a matrix made of polyglycolic acid and hyaluronan in comparison to a conventional microfracture technique. MATERIALS AND METHODS: In a randomized controlled trail (RCT) patients between 18-60 years with an articular femoral cartilage defect of 1-4 cm2 in the weight bearing area of the femoral condyles with indication for MF were enrolled and randomized to MF or m-BMS using a polyglycolic acid membrane with hyaluronan. Defect filling in MRI assessment at 12 weeks postoperatively was defined as primary outcome measure. MRI scans and follow up examinations including patient reported clinical outcome scores (VAS pain, KOOS, IKDC and SF-36) were performed at 12, 54 and 108 weeks after surgery. RESULTS: There was no statistically significant difference between both groups in terms of defect filling assessed by MRI at 12, 54 and 108 weeks postoperatively. At 12 weeks there was a tendency towards higher degree of defect filling in the MF group when compared to the m-BMS group, whereas no difference was found after 54 and 108 weeks. The m-BMS group revealed superiority in terms of improvement over time in the KOOS subscales pain, knee-related symptoms, activity of daily living, sports and recreation and quality of life at 54 weeks and 108 weeks after treatment. CONCLUSION: This is the first RCT comparing m-BMS using a polyglycolic acid membrane with hyaluronan to any different treatment strategy in localized cartilage defects of any human joint. The use of the Chondrotissue® membrane in m-BMS of cartilage defects has proven to be a safe procedure with side effects comparable to those of MF. There seems to be an accelerated formation of cartilage repair tissue after MF when compared to m-BMS at 12 weeks postoperatively, whereas at one and two years after treatment there was no difference concerning the quantity of repair tissue. The improvement in clinical outcome scores over time after m-BMS might be due to the formation of cartilage repair tissue of higher quality. Long term follow up studies including histological assessment are desirable for further investigation.