Efficacy of Intra-articular Collagen Injection in Patients With Knee Joint Pain Compared to Normal Saline Injection

Inclusion Criteria: 1. Adult patients aged 19 or older 2. Patients with knee joint pain due to chondromalacia, osteoarthritis (OA), or traumatic arthritis (TA) 3. Patients with 3 or lower score in the Kellgren-Lawrence grade 4. Patients with 40 mm or higher scores in the 100 mm VAS pain scale 5. Patients without significant pathological tests at their screening visit 6. Patients whose medication is confirmed within one week from their study enrolment and who agreed to maintain the medication dose during the study period if they need to keep taking it 7. When combination drugs are administered, considering the period of the drugs remaining in the body, patients who take the drugs stably for 2 weeks prior to participating in the trial (based on the screening, if it is confirmed that the patients took the drugs stably for 1 week prior to the screening, at the enrollment for injection, it should be assessed again, and the patients who are confirmed to have taken the drugs stably for 2 weeks prior to the trial could be registered). 8. Patients who, after taking drugs for anesthetic purposes (provided to the subject after the injection) within one week after the intra-articular injection, agreed to take anti-inflammatory agents for no more than 5 consecutive days and for no more than 10 days in a month, and could stop taking the drugs within 2 days after the next visit even if the pain in the observation site becomes severe and thus additional drugs are required. 9. Patients who agreed to use only the non-drug treatments (i.e., physiotherapy, osteopathy, and chiropractic therapy) allowed by the study investigators (Acupuncture is not allowed.) 10. Patients who agreed to receive the injection only in one knee when they feel pain on both knees (The other knee can be treated with prescribed drugs, but articular injections are not allowed.) 11. Patients or their representative (for adults) who agreed to participate in the study and signed the informed consent form Exclusion Criteria: 1. Patients or their family members with a history of or an ongoing autoimmune disease 2. Patients with a history of anaphylactic response 3. Patients with hypersensitivity to grafting materials 4. Patients with hypersensitivity to porcine protein 5. Patient with grade 4 in the Kellgren-Lawrence grade 6. Patients with severe effusion 7. Patients who were injured severely or received injection in their affected knee within six months, which would make evaluation of the knee difficult 8. Patients with inflammatory arthritis such as rheumatoid arthritis, rupus arthrosis, or psoriatic arthritis 9. Patients who have gout or calcium pyrophosphate (pseudogout) disease that started within six months from the screening visit 10. Patients with a history of radiation therapy or cancer treatment within two years 11. Patients with diabetes 12. Patients with an infection that required hospitalization for antibiotics or the administration of antiseptic agents 13. Patients who have been undergoing adrenocortical hormone therapy 14. Patients with liver, heart, or kidney disease 15. Patients who had been infected with a virus 16. Patients who have a serious health condition that may affect the study results 17. Patients who are pregnant, breastfeeding, or planning to become pregnant 18. Patients who are considered inappropriate for participation in this study due to their condition (e.g., a mental illness) based on the investigator's judgment * 8-15: The investigator can decide whether or not the patient will be administered the injection.