The most common cause of shoulder pain and injury after a car accident, often caused by high impact or acute stress by stretching or tearing of tendons and ligaments in the shoulder joint. Symptoms include but not limited to sudden severe pain to the top or outer part of the shoulder, stiffness, swelling, limited range of motion, weakness, a popping or clicking sound while moving your arm, pain radiating down to the arm. Diagnosis is made via history taking, examination, MRI. Treatment is physical therapy, coticosteriod injections, arthroscopic or open surgical repair.