Degenerative joint disease (DJD) starts with an inflamed joint, which results in mild pain, swelling, and disruption to the balanced 'wear and repair' cycle.
Inflamed synovial membrane allows unwanted cells to pass into the synovial (joint) fluid. These cells release destructive enzymes break down the lubricant and barrier function.
Destructive enzymes attack the synovial fluid and cartilage causing damage.
Eroded articular cartilage
Healthy cartilage is critical to the performance of the joint. Eroded cartilage loses its ability to evenly distribute the forces of movement into the subchondral bone, allowing injury to occur. It contains no sensory nerves or blood vessels, so it has a limited ability to repair itself.
Damaged subchondral bone
Subchondral bone does contain sensory nerves and blood vessels. When damage occurs, it can be an additional source of joint pain.