Millions of people worldwide are affected by osteoarthritis (OA), occurring due to the wear down of protective cartilage that cushions the end of bones. Cartilage is a firm, slippery tissue that enables nearly frictionless joint motion. Although osteoarthritis can damage any joint, the disorder most commonly affects joints in your hands, knees, hips and spine. Unfortunately, there exists yet no cure for the damage in the joint, although the symptoms can be managed. Hence, the EU Horizon funded RESTORE project aims to enhance two novel approaches to repair osteoarthritic knee cartilage repair: via implantable nanoenabled COPLA® scaffolds and bioprinted human cartilage microtissues.

But besides the breakdown of cartilage, osteoarthritis affects the entire joint. It causes changes in the bone and deterioration of the connective tissues that hold the joint together and attach muscle to bone. However, it is still unknown what are the actual dependencies between knee OA and meniscal degeneration, i.e. which is the cause and which is the consequence.

The exact understanding of the interplay between different tissues in the knee in relation to the degenerative process has recently been explored by a RESTORE project partner, Institute of Orthopedic Research and Biomechanics at Ulm University Medical Center, by spatial biomechanical mapping of the articulating knee joint surfaces of mildly and severely degenerated human knee joints, including their menisci and tibial and femoral articular cartilage, using a multiaxial mechanical testing machine.

Figure 1. Representative biomechanical mappings of the instantaneous modulus (IM) measurements of mildly and severely degenerated menisci, with all values given in megapascals.

The results of their study indicate that degeneration-related (bio-)mechanical changes are likely to be first detectable in the menisci before the articular knee joint cartilage is affected. If these findings are further reinforced by structural and imaging analyses, the treatment and diagnostic paradigms of OA might could be modified, focusing on the early detection of meniscal degeneration and its respective treatment, with the final aim to delay osteoarthritis onset.

The original research article titled Osteoarthritis-Related Degeneration Alters the Biomechanical Properties of Human Menisci Before the Articular Cartilage was published in Frontiers in Bioengineering and Biotechnology in May 2021.