It is thought that repetitive microtrauma, which leads to microfractures and sometimes an interruption of blood supply to the subchondral bone, may cause subsequent localized loss of blood supply or alteration of growth.Trauma, rather than avascular necrosis, is thought to cause osteochondritis dissecans in juveniles. In adults, trauma is thought to be the main or perhaps the sole cause, and may be endogenous, exogenous or both. The incidence of repetitive strain injury in young athletes is on the rise and accounts for a significant number of visits to primary care; this reinforces the theory that OCD may be associated with increased participation in sports and subsequent trauma. High-impact sports such as gymnastics, soccer, basketball, lacrosse, football, tennis, squash, baseball and weight lifting may put participants at a higher risk of OCD in stressed joints (knees, ankles and elbows).Recent case reports suggest that some people may be genetically predisposed to OCD. Families with OCD may have mutations in the aggrecan gene. Studies in horses have implicated specific genetic defects. Pathophysiology
Osteochondritis dissecans differs from "wear and tear" degenerative arthritis, which is primarily an articular surface problem. Instead, OCD is a problem of the bone underlying the cartilage, which may secondarily affect the articular cartilage. Left untreated, OCD can lead to the development of degenerative arthritis secondary to joint incongruity and abnormal wear patterns.OCD occurs when a loose piece of bone or cartilage partially (or fully) separates from the end of the bone, often because of a loss of blood supply (osteonecrosis) and decalcification of the trabecular bone matrix.
Pachydermodactyly is a superficial dermal fibromatosis that presents as a poorly circumscribed symmetric, infiltrative, asymptomatic soft-tissue hypertrophy of the proximal fingers, typically sparing the thumbs and fifth fingers and rarely extending proximally to the wrists or occurring distally. : 990

See also
Skin lesion

References
External links
A Case of Pachydermodactyly