Frozen shoulder injuries affect about 2 percent of the population, most of them between 40 and 60 years of age. The main symptoms of a frozen shoulder are stiffness, decrease in range of motion, and pain. There are no specific causes for frozen shoulder and no indication of when it may strike. People with diabetes, Parkinson's disease, hypothyroidism, or hyperthyroidism seem to be at a higher risk of developing problems. There are several frozen shoulder treatment options available to restore the range of motion, including medication, physical therapy, and surgery.