Effect of repeated intra-articular administration of collagen as a treatment for knee osteoarthritis: a case report

Intra-articular injections aimed at correcting underlying pathophysiological processes and providing pain relief are essential for managing knee osteoarthritis (KOA). Collagen, the primary component of articular cartilage, has a long half-life, making it a promising candidate for intra-articular injections with a low risk of serious side effects. The first of the two cases in this report involved a woman in her early 70s with a 6-year history of persistent left knee pain. The second case involved a woman in her mid-50 s with a >7-year history of right knee pain. Both patients received hyaluronic acid injections every 6 months, totaling 10 injections over 5 years. They were diagnosed with Kellgren-Lawrence grade 2 KOA. The patients received two 3-mL intra-articular injections of 6% collagen, administered at baseline and 6 months later. Improvements in clinical outcomes, including visual analog scale scores and Western Ontario and McMaster Universities Osteoarthritis Index scores, were observed and maintained in both patients, with no side effects reported. In summary, when collagen injections were administered to these two patients with KOA, clinical improvements lasted approximately 6 months, and repeated treatments demonstrated efficacy and safety similar to the initial course.