Shoulder pain is one of the most common reasons people see a doctor, according to the American Academy of Orthopaedic Surgeons. Most pains located in and around the shoulder involve the tendons, ligaments or muscles. Orthopedic surgeons group these types of shoulder problems into two broad categories, instability and impingement injuries. Less frequently, pain can arise from broken bones or underlying disease.
Pain in the front left shoulder can arise from several diseases unrelated to the shoulder, according to the American Academy of Family Physicians. Pneumonia, a peptic ulcer, cancer and restricted blood flow, or ischemia, in an artery serving the heart can present as pain in the left shoulder. Diseases related to the shoulder that can cause pain include arthritis and bursitis, according to MedlinePlus.
Bone fractures in the left arm or shoulder can cause pain. These bones include the collarbone, or clavicle; the shoulder blade, or scapula; the glenoid and coracoid process, which form parts of the shoulder socket; and the upper arm bone, or humerus.
Instability of the shoulder joint can cause pain, and is most often a result of an injury that forces the joint out of its normal position. The American Academy of Orthopaedic Surgeons says people with shoulder instability experience pain when raising the arm or trying to use arm through a normal range of motion, such as buttoning a shirt or pulling on a zipper. The rotator cuff is a tendon linking four muscles that hold the ball of the shoulder in the socket and allow for circular motion. Injuries to these muscles and the tendons attaching them to the shoulder bones are common causes of pain. Likewise, injuries to ligaments connecting the bones to each other also cause shoulder pain. Another common injury is a tear of the soft fibrous tissue, or labrum, surrounding the head of the upper arm bone.
Impingement pain occurs when shoulder tissues rub against each other or against bones. This can be caused by repetitive motion such as swimming, throwing or overhead lifting, leading to pressure on the rotator cuff from the upper part of the shoulder blade or scapula. The repeated rubbing of these tissues can cause inflammation and swelling that in turn cause greater irritation and pain with each motion. This inflammation can occur in the sac of fluid covering the rotator cuff call the bursa. This is called bursitis. Inflammation that stems from rubbing of the tendons is called tendonitis.