The purpose of this clinical trial is to evaluate the safety and efficacy of CartiFill implanted at the site of knee joint cartilage defect in a 6-year, long-term, follow-up investigation.

Inclusion Criteria:

1. Patients who have undergone microfracture surgery or microfracture surgery using collagen 6 years (±1 year) ago as part of the previously conducted post-marketing clinical trial (Protocol No. 03CAR).
2. Males or females aged 19 to 70 years.
3. Patients or patients whose legal representatives have agreed to participate in the clinical trial and signed the written consent.

Exclusion Criteria:

1. Patients who have undergone microfracture surgery or microfracture surgery using collagen as part of previously conducted post-marketing clinical trial (Protocol No. 03CAR) but have since then received cartilage surgery, such as high tibial osteotomy (HTO), partial/full implant arthroplasty, etc., at the same site. (Does not include biopsy for diagnosis, a simple arthroscopic examination, or HTO plate removal procedure, etc.)

   ※ Does not include non-invasive treatment or medication such as exercise therapy, physical therapy, manual therapy, extracorporeal shock wave, joint cavity injection, etc.

2. Patients who are deemed by the clinical trial manager to be unfit to participate due to psychiatric conditions, etc.

The study population consisted of subjects with cartilage defects of the knee joint who had previously participated in a post-marketing clinical trial (Protocol No. 03CAR) and had undergone microfracture surgery with or without collagen implantation. Subjects were enrolled approximately 6 years (±1 year) after surgery and voluntarily agreed to participate in this long-term follow-up study.