This study was designed to evaluate the efficacy and safety of a modified microfracture using collagen, and to compare them with those of a simple microfracture to prove the non-inferiority of the modified microfracture using collagen in patients with cartilage defects in their knees.

This study was an open-trial study. One hundred subjects participated in it. The study was explained to the subjects and they voluntarily agreed to participate in it. Their eligibility to participate in the study was checked, and they were randomized either into the simple microfracture group or the modified microfracture group using collagen based on a centrally controlled randomization table. They were asked to follow the guidelines of the investigators during the study and to visit the hospital six times*, including for screening. At each visit, the subjects underwent an examination with doctors, a blood test, an X-ray procedure, an MRI, an observation with the naked eyes, and arthroscopy to evaluate the safety and efficacy of the procedure. (*If the screening date overlaps with the procedure date, the number of his or her visits would be five.)

Inclusion Criteria:

- 1. Patients with cartilage defects in their knee (Including Knee OA and Knee TA) 2. Knee osteoarthritis patients whose Kellgren-Lawrence Grading Scale score is lower than 3 (patients who received simultaneous or previous correction will be excluded).

3. Patients with misalignment of their tibia and femur, unstable ligament in their knee, or bony defects in the lesions of their knee, and/or who had been treated for alignment 4. Patients who were 15 years old or older 5. Patients or their representative (for adults), or patients and their parent/guardian (for minors), who agreed to participate in the study and signed the informed consent form

Exclusion Criteria:

• 1. If patients or their families suffer from or have ever suffered from an autoimmune disease.

  2. Patients who have ever suffered an anaphylactic reaction. 3. Patients who have ever suffered hypersensitivity to an implant. 4. Patients with a history of allergy to porcine or bovine protein. 5. Subjects with inflammatory arthritis, such as rheumatoid and gouty arthritis.

  6. Subjects with autoimmune disease related arthritis. 7. Subjects who are pregnant and/or breast-feeding and/or plan a pregnancy. 8. Subjects with tumors. 9. Subjects who have undergone radiotherapy or chemotherapy within the last 2 years (Exception: if the possibility of collagen treatment is confirmed with doctor's clinical decision).

  10. Subjects who are diabetic. (Exception: if the possibility of CartiFill™ treatment is confirmed with doctor's clinical decision, and/or patient's blood glucose level remains within the normal range and/or no other complications by diabetes mellitus.) 11. Subjects with infections, currently on treatment with antibiotics or antimicrobials (Exception: if the possibility of collagen treatment is confirmed with doctor's clinical decision).

  12. Subjects under adrenocorticoid therapy (Exception: if the possibility of collagen treatment is confirmed with doctor's clinical decision).

  13. Subjects with psychiatric disorders who are considered inappropriate to participate in this trial by the Principal Investigator.

  14. Patients who have ever suffered contraindications of the used Fibrin sealant. (The major contraindications are as follows: patients with hypersensitivity to aprotinin and those treatments for severe brisk arterial or venous bleeding.)