A paper published in the Journal of American Academy of Orthopaedic Surgeons says that patients with a painful stiff shoulder are frequently diagnosed with frozen shoulder. This is a vague diagnosis because there are many factors that contribute to motion loss in the shoulder say researchers from George Washington University Medical Center in Washington. According to them frozen shoulder is not necessarily the result of an injury. The condition can start out as some soreness in the shoulder before the patient begins to notice some progressive restriction of movement. Researchers say that the best way to help restore the patient's