Attenuated Patella Alta is an extremely rare condition affecting mobility and leg strength. It is characterized by an unusually small knee cap (patella) that developes out of and above the joint. Normally, as the knee cap sits in the joint, it is stimulated to growth by abrasion from the opposing bones. When not situated properly in the joint, the knee cap does not experience such stimulation and remains small and undeveloped.
A similar condition, patella alta, can occur as the result of a sports injury.
There has only been one documented case of the disorder arising from birth. In 1988, three year old Eric Rogstad of Minneapolis, Minnesota was discovered to suffer from the condition in both knees after several attempts by his parents and family physician to discover the cause of his abnormal difficulties with walking and running. After surgery and physical therapy, Eric gained the ability to walk and run without significant difficulty.
