the Safety and Efficacy Evaluation of Chondron Compared With Mircrofracture of Knee

Inclusion Criteria: \- 1. Patients who underwent autologous chondrocyte implantation using CHONDRON (autologous cultured chondrocyte) or patients underwent microfracture more than 2 years ago. 2\. Patients who meet the above criteria 1, the patient or a guardian agreed to participate in the clinical trial, and signed a written agreement form Exclusion Criteria: \- 1. Patients with psychological disease or other patients who are determined to be unsuitable to this clinical trial by the investigators conducting the clinical trial. 2\. Patients who underwent autologous chondrocyte implantation applying CHONDRON (autologous cultured chondrocyte) or microfracture, and the lesion was treated with other procedures subsequently.