Osteochondritis dissecans is a condition which typically affects the knees of boys more than girls between the ages of 10 & 15. We do not know why it occurs, but there are a number of theories including genetic and overuse elements (some feel that it is like a stress fracture). Some think that there is an area of the bone which has a relatively tenuous blood supply which can be compromised especially at a critical stage of development.
Part of the bone supporting the surface of the knee starts to crumble and this leads to a vague discomfort and often swelling which is exercise-related. Sometimes an area of bone wil break off completely and form a “loose body” within the joint and this can get caught between the surfaces leading to true locking of the knee.
We can often get the area to resolve simply with rest, especially in the younger child before growth has ended, but sometimes this can be accelerated by keyhole surgery to encourage healing. If the fragment is loose, then it will sometimes need to be removed in which case a procedure to reconstitute the surface (see Knee Articular) will be necessary, but if possible, I try to secure fragments back while they heal using small dissolving pins or screws, and am involved in the development and analysis of a new osteoinductive implant..