How long does it take chondromalacia patellae to heal completely?

Possibly never: Chondromalacia refers to a softening or wearing of the cartilage covering the bone of a joint. Symptoms may improve with rest, therapy, antiinflammatories, or injections, but the softening or wear typically does not improve or heal.

Months: It can take several months. Chondromalacia patella (runners knee) is due to overload of the patellofemoral joint (knee cap against the end of the thigh bone). Running causes high forces in this portion of the joint. So does arising from a chair, going up/down stairs. Treatment consists of activity modification, ice, anti-inflammatory meds and therapy aimed at flexibility and strengthening.