I've suffered from chondromalacia patella in my right knee for about 4 years now, and surprisingly, skating is one of the few cardio activities that numerous orthopedic specialists and physical therapists have given me the green light. According to my doctors, skating is a relatively low impact exercise for the knee joint, and works to strengthen the majority of supporting musculature of the leg, strengthening the joint. Still can't play hockey though
However, CMP is not knee replacement surgery, so I'd check with your orthopedic surgeon or physical therapist before you get back on the ice.
