Chondromalacia patella results from degeneration of cartilage due to poor alignment of the kneecap as it slides over the lower end of the thigh bone (femur) causes the sound...This process is, therefore, sometimes referred to as patellofemoral syndrome..Selective strengthening of the inner portion of the quadriceps muscle will help normalize the tracking of the patella...Consult nearest orthopedic surgeon they will do the needful.