Osteochondritis dissecans (OCD) is a joint condition where a fragment of bone and its overlying cartilage begins to separate from the end of a bone within a joint. This separation can cause pain, swelling, instability, and sometimes pieces of bone or cartilage may break loose inside the joint, leading to locking or catching sensations.
The exact cause of osteochondritis dissecans is not fully understood, but it appears to be related primarily to repetitive trauma or stress on the joint. When joints undergo repeated impact or pressure—especially in young athletes involved in high-impact sports—small areas of bone beneath the cartilage can lose their blood supply. This lack of blood flow causes the affected bone tissue to weaken and eventually separate along with its covering cartilage. The process is aseptic, meaning it occurs without infection.
In some cases, OCD has a hereditary component known as familial osteochondritis dissecans. Here, genetic mutations affect proteins responsible for maintaining healthy cartilage structure and function. These mutations weaken the gel-like quality of cartilage so that it cannot properly adhere to underlying tissues. As a result, multiple joints may be affected early in life with symptoms appearing between childhood and adolescence.
Other factors that contribute include:
– **Mechanical stress:** Repetitive microtrauma from activities like running, jumping, or twisting motions places strain on certain parts of joints such as knees or ankles where OCD commonly develops.
– **Vascular insufficiency:** The subchondral bone (the layer just below cartilage) relies on small blood vessels for nourishment; disruption in this circulation leads to localized death (necrosis) weakening structural integrity.
– **Growth-related vulnerability:** Because OCD often affects children and adolescents whose bones are still growing at growth plates near joints (epiphyses), these areas are more susceptible due to ongoing development combined with physical stresses.
– **Joint anatomy variations:** Certain anatomical features might predispose individuals by concentrating forces unevenly across joint surfaces.
– **Endocrine influences:** Although less common than mechanical causes, hormonal imbalances affecting growth hormone levels can influence skeletal development and potentially contribute indirectly by altering tissue resilience around joints.
When an area affected by OCD loses stability completely—a fragment detaches—it may float freely inside the joint space causing more severe symptoms like intense pain during movement or weight-bearing activities along with swelling and episodes where the joint locks up temporarily.
Overall, osteochondritis dissecans results from an interplay between mechanical injury patterns disrupting normal blood supply within developing bones under articular surfaces combined sometimes with genetic predispositions affecting connective tissue strength. Understanding these causes helps guide treatment approaches aimed at preserving joint function before permanent damage occurs.
