 Decalcification bone scaffold is a tissue engineering scaffold with the closest biomechanics and structure of normal cartilage. The objective of the study is to evaluate the clinical efficacy of arthroscopic decalcification bone scaffold combined with microfracture in the repairment of articular cartilage defects by randomized controlled trial. Sixty patients with clinically diagnosed knee cartilage injury according to 1: 1 were divided into experimental group and control group. The experimental group will be treated with decalcification bone scaffold combined with microfracture .The control group will be treated with microfracture . The patients will be treated by the same surgeon in this study group. MRI evaluation, Lysholm score, IKDC score, Tegner score, VAS score are selected as the measures of outcome, while the blood routine, blood biochemistry, urine, CRP, ECG and other laboratory tests will be recorded inclduing the incidence of adverse events. 