Osteoarthritis (OA) is the type of arthritis usually associated with age or wear and tear. OA begins with the breakdown of articular cartilage. Cartilage is the substance that caps the ends of our long bones at our joints, imparting an irreplaceable shock-absorbing function, and articular cartilage is the cartilage that makes up integral parts of our joints.
The numerous and interwoven arms of the complex molecules of proteoglycans and collagen that make up this cartilage are essential to its elasticity and compressibility. If these structures break down due to genetic defects, chemicals, or trauma (whether repetitive or isolated) the essential functions are diminished, leading to transmission of normal everyday wear and tear stresses to the stiff, non-compressible bone.
Cartilage is not capable of healing itself so the process goes on until it is recognized and treated. An example would be a fracture through the mortise (true ankle joint) which involves the articular cartilage surface. This permanent irregularity causes constant unsustainable forces to be transmitted to the tibia, which tries to grow and heal, but ends up forming osteophytes (bone spurs), which together with the irregular, abraded, and now rapidly wearing cartilage, leads to end-stage osteoarthritis.
The difficult part of any personal injury case in which arthritis is claimed to be the outcome of injury depends on the documentation of the development of symptoms and signs, which do not pre-date the event. The expert witness should describe the symptoms and signs of OA and relate them specifically to the patient under discussion. The jury must be taught the basics of the disease and the applicability to the patient using both patient reports and medical evidence. These principles must be described and taught in a way that can be easily understood by a lay jury using audio-visual aids and references in the medical literature to support the chain of events.