Cartilage extra-cellular matrix biomembrane for the enhancement of microfractured defects.

PURPOSE

The purpose of the study was to evaluate whether the biomembrane made of cartilage extracellular matrix, designed to provide cartilage-like favourable environments as well as to prevent against washout of blood clot after microfracture, would enhance cartilage repair compared with the conventional microfracture technique.

METHODS

A prospective trial was designed to compare the biomembrane cover after microfracture with conventional microfracture among patients with grade III-IV symptomatic cartilage defect in the knee joint. Patients aged 18-60 years were assigned to either the microfracture/biomembrane (n = 45) or microfracture groups (n = 19). Among them, 24 knees in the microfracture/biomembrane and 12 knees in the microfracture were followed up for 2 years. Cartilage repair was assessed with magnetic resonance imagings taken 6 months, 1 year, and 2 years postoperatively, and the clinical outcomes were also recorded.

RESULTS

Compared with conventional microfracture, microfracture/biomembrane resulted in greater degree of cartilage repair (p = 0.043). In the intra-group analysis, while microfracture showed moderate to good degree of cartilage repair in nearly 50 % of the patients (47 % at 6 months to 50% at 2 years; n.s.), microfracture/biomembrane maintained an equivalent degree of repair up to 2 years (88% at 6 months to 75% at 2 years; n.s.). The clinical outcome at 2 years also showed improved knee score and satisfaction and decreased pain in each group, but the difference between the two groups was not statistically significant.

CONCLUSIONS

Compared with conventional microfracture, biomembrane cover after microfracture yielded superior outcome in terms of the degree of cartilage repair during 2 years of follow-up. This implies that initial protection of blood clot and immature repair tissue at the microfractured defect is important for the promotion of enhanced cartilage repair, which may be obtained by the application of a biomembrane.

LEVEL OF EVIDENCE

Prospective comparative study, Level II.