Undenatured type II collagen for knee osteoarthritis

Knee Osteoarthritis (OA) leads to significant pain and reduced function and affects patients’ overall quality of life (QoL). Conservative modalities are the first line of management, resorting to surgery only if they fail. However, these modalities have limitations, and do not address the underlying cause of knee OA. The use of nutraceuticals, including native/undenatured type II collagen (UC type 2), has evolved and shown promise in the conservative management of knee OA. This article highlights the mechanism of action, and qualitatively presents the pre-clinical, clinical and on-going scientific literature exploring the safety and efficacy of UC type 2 for the management of knee OA. A search was performed using multiple databases (PubMed, Web of Science, Embase and Scopus) employing terms for UC type 2 and Knee OA for articles published in English language, while adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. All pre-clinical and clinical studies utilizing UC type 2 for knee OA were included. Studies not using UC type 2 alone or not focusing on the management of knee OA were excluded. Twelve studies (3 pre-clinical studies, 8 clinical studies and 1 study with both pre-clinical and clinical component) met our pre-defined search and inclusion criteria, and were included in this review. UC type 2 acts <i>via</i> a specific immune mediated mechanism, known as oral tolerance, which can lead to reduced inflammation and enhanced cartilage repair in the knee joint. In addition, administration of UC type 2 (40 mg daily) is safe and efficacious in the short- and mid-term, reducing inflammation and pain, and improving function, range of motion (ROM) and overall QoL. Nonetheless, more adequately powered, prospective, multi-center, non-randomized and randomized controlled trials with longer follow-up are warranted to establish the long-term efficacy of UC type 2 in knee OA patients and justify its routine clinical use.