There are many causes of left shoulder pain in or around a person's shoulder joint. MedlinePlus states that shoulder pain can be caused by general wear and tear with aging, repetitive shoulder use and traumatic injury. Many shoulder injuries respond well to conservative care, although medical intervention may be necessary in some cases.
Torn Rotator Cuff
Torn rotator cuff muscles can cause left shoulder pain. According to the American Academy of Orthopaedic Surgeons, tears of the rotator cuff--a group of four muscles and several tendons that stabilize and act upon the humerus or upper arm bone--is one of the most common causes of pain and disability in adults.
The four muscles that compose the rotator cuff include the supraspinatus, infraspinatus, teres minor and subscapularis. The AAOS notes that most rotator cuff tears occur in the supraspinatus muscle, although any part of the rotator cuff can be involved. Rotator cuff tears can be caused by traumatic injury, although the most common cause is excessive use of the muscles and tendons over a period of years. Athletes who perform overhead arm motions, such as baseball players, tennis players and weight lifters, are particularly susceptible to torn rotator cuff muscles.
Shoulder Separation
A shoulder separation can cause left shoulder pain. The Sports Injury Clinic website states that a shoulder separation, also known as an acromioclavicular or AC separation, occurs when the ligaments that bind the shoulder blade and the collar bone are damaged. The three principle ligaments that stabilize the AC joint are the acromioclavicular ligament, coracoclavicular ligament and coracoacromial ligament.
Common symptoms associated with a shoulder separation include pain at the end of the collar bone, diffuse shoulder pain transitioning to focal pain over the injury site, swelling around the affected area, the presence of a step deformity or noticeable depression in the shoulder and pain with shoulder active range of motion. According to the Sports Injury Clinic, shoulder separations or AC joint injuries are graded from one to six on the Rockwood scale, which considers the extent of ligament damage and the space between the shoulder blade's acromion and collar bone. Grades of four to six on the Rockwood scale often require surgical intervention to repair the shoulder.
Bursitis
Bursitis can cause left shoulder pain. According to the Canadian Centre for Occupational Health and Safety, bursitis is the inflammation of a bursa. A bursa is a small fluid-filled sac that lies between tendons and bones and helps reduce friction between the two during movement. Although bursae are found throughout the body, two of the most common areas for bursa-related problems are the knee and the shoulder.
The CCOHS notes that if tendons around the shoulder become thickened and rough due to overuse, the surrounding bursae are subjected to increased friction and can become irritated. Common signs and symptoms associated with shoulder bursitis include shoulder pain, shoulder stiffness and reduced shoulder active range of motion. Certain individuals have a greater risk for shoulder bursitis, including people who work with their arms above shoulder level.
