In general, the short answer to your question is that you should not walk on the leg with osteochondritis dissecans (OCD) of the talus. If this applies to you, I recommend that you speak with your physician. More specifically, the talus is a bone that contributes to the ankle joint. OCD of the talus represents an injury
to the cartilage lining the weightbearing portion of the talus. Since cartilage is the smooth lining of a bone forming part of a joint, any fracture to the cartilage (as in OCD) disrupts smooth and otherwise "friction-less" movement of the joint (in this case, the ankle). Walking on (i.e. weightbearing) an OCD lesion results in worsening of that fracture and hence pain, much like repeated driving over a road with a small pothole can propagate that pothole. In many cases, OCD lesions often require surgery so that the cartilage injury does not propagate further damage, and ultimately result in arthritis
. In mild OCD lesions (i.e. incomplete cartilage fractures), these can be treated without surgery, but do require strict non-weightbearing and sometimes cast, splint or boot/brace until the lesion is healed. While there is no good evidence that these mild injuries have to be immobilized (i.e. cast/splint/boot), the general consensus is that mild injuries (and certainly more severe ones) should be protected from full weightbearing. Again, if these conditions should ever really apply to you or someone you know, please contact your physician or call 911 in cases of emergency.