Osteoarthritis: Is It Simply a Disease of Worn Cartilage?

Osteoarthritis is commonly understood as a condition that develops as cartilage wears down with age. While cartilage damage is an important feature, current research recognizes osteoarthritis as a disease involving interactions among cartilage, bone, synovium, ligaments, menisci, surrounding muscles, and adipose tissue.[1][2]

Joint pain and functional decline may not be attributable to changes in a single tissue. Inflammatory responses within the joint, structural changes in bone, the condition of the muscles and ligaments, and nervous system responses involved in pain processing should also be considered.

Cartilage Damage Is One Aspect of Joint Changes

Articular cartilage is the smooth tissue covering the ends of bones. It reduces friction during joint movement and helps absorb external impact.

As osteoarthritis progresses, the balance between chondrocytes and the extracellular matrix may be disrupted, contributing to the weakening and deterioration of cartilage. Aging, repetitive mechanical stress, inflammatory responses, oxidative stress, and metabolic changes can all contribute to this process and alter the joint environment.[1]

Age is a major risk factor. However, body weight, muscle mass, previous joint injury, repetitive joint use, exercise habits, genetic factors, and metabolic status may also influence the onset and progression of the disease.[1][2]

Changes in the Subchondral Bone and Synovium Occur Together

Directly beneath the cartilage lies the subchondral bone. As osteoarthritis progresses, the density and structure of subchondral bone may change, and abnormal bone remodeling may occur.[1]

Cartilage and subchondral bone do not function in isolation; they exchange mechanical forces and cellular signals. This is why osteoarthritis research examines subchondral bone and synovium alongside cartilage.

The synovium is the tissue that surrounds the joint. When inflammation develops in the synovium, inflammatory mediators may be released and may affect chondrocytes and surrounding tissues.

Unlike rheumatoid arthritis, osteoarthritis is not a disease primarily driven by pronounced systemic inflammation. However, low-grade chronic inflammatory responses may occur within the joint, and synovitis is being studied in relation to pain and disease progression in some patients.[1]

Pain Does Not Always Correspond to the Degree of Cartilage Damage

Even when imaging studies reveal a similar extent of joint damage, pain intensity can vary from person to person. Cartilage contains very few nerves, whereas nerves are present in the synovium, subchondral bone, ligaments, and surrounding tissues.

Changes in tissues other than cartilage and inflammatory responses may also contribute to pain. When pain persists over a prolonged period, changes may occur in how the peripheral nerves and central nervous system process pain. Recent research therefore examines both joint structure and nervous system responses.

Research Has Expanded to Include Aging and the Cellular Environment

Cellular senescence has recently gained attention in osteoarthritis research. One area of study is whether cells whose function changes with aging may release inflammatory signals that affect surrounding tissues.

For this reason, research has expanded beyond cartilage damage alone to include aging, immune responses, and the metabolic environment. Therapeutic research likewise explores approaches that regulate inflammatory responses, slow the progression of changes in cartilage and subchondral bone, and support recovery within the affected joint.[1][3]

Current treatment and management approaches include exercise, weight management, medication, and injection therapy to help reduce pain and maintain joint function. The most appropriate approach may vary depending on the symptoms and condition of the joint.

Regenerative medicine research using stem cells and cell-derived substances is also ongoing. This field investigates not only the formation of new chondrocytes but also the regulation of inflammation within the joint, intercellular signaling, and the tissue environment. However, the efficacy and appropriate scope of use of regenerative therapies still require clinical validation, and investigational technologies should be clearly distinguished from approved treatments.

Osteoarthritis Requires a Whole-Joint Perspective

Osteoarthritis is a complex joint disease involving changes in cartilage, bone, synovium, and muscles, as well as inflammatory responses and aging-related processes. A whole-joint perspective provides an important framework for understanding pain and functional decline, as well as for evaluating developments in treatment research.

Health information cannot replace an individual diagnosis or treatment plan. If pain or limited mobility persists, evaluation by a healthcare professional is advisable.

About EHL BIO

EHL BIO is a biotechnology company focused on advancing human health through stem cell-based regenerative medicine. By investigating the self-repair capacity of cells, EHL BIO is developing new approaches to aging and disease. By combining premium healthcare with advanced biotechnology, EHL BIO provides solutions aimed at supporting healthier, more vital lives.