Normal Anatomy of the Shoulder Joint
The shoulder is the most flexible joint in the body making it the most susceptible to instability and injury. It is a ‘ball-and-socket’ joint. A ‘ball’ at the top of the upper arm bone, humerus, fits neatly into a ‘socket’, called the glenoid, which is part of the shoulder blade, scapula.
The shoulder joint is made up several bones and soft tissues. It has three bones, the collarbone (clavicle), scapula, and humerus. Humerus provides attachment to muscles of the upper arm. Scapula is the bone that connects the upper arm bone with the collarbone. It is a flat bone and roughly triangular in shape and provides attachment to the muscles of back and neck. The clavicle is an S-shaped short bone that connects the shoulder girdle to the body (trunk). It supports the shoulder in a functional position with the axial skeleton so that the arm has maximum range of movement. It also protects major underlying nerves and blood vessels as they pass from the neck to the axilla.
The coracoid process is the extension of the scapula around the shoulder joint at the front portion of the scapula. The acromial process is the extension of scapula around the shoulder joint at the back that forms a roof, acromion.
Glenoid is the smooth shallow depression at the end of scapula that forms the socket of shoulder joint.
The soft tissues of shoulder joint include:
Rotator cuff – A group of 4 tendons make rotator cuff and it holds the head of the humerus in the socket.
Biceps tendon – The biceps tendon is a long cord-like structure which attaches the biceps muscle to the shoulder and helps to stabilize the joint.
Caracoclavicular Ligament – This ligament connects the clavicle with the coracoid process of the scapula.
Acromioclavicular Ligament – It connects the clavicle with the acromion process.
Glenoid labrum – The Glenoid labrum is a ring of fibro cartilage surrounding the cavity of the scapula for stabilization of the shoulder joint.
Articular cartilage or the capsule – It is a capsule that surrounds the shoulder joint and helps to keep the ball and socket normally aligned.
Rotator Cuff Tear
Rotator cuff is the group of tendons in the shoulder joint providing support and enabling wider range of motion. Major injury to these tendons may result in tear of these tendons and the condition is called as rotator cuff tear. It is one of the most common causes of shoulder pain in middle aged adults and older individuals. It may occur with repeated use of arm for overhead activities, while playing sports or during motor accidents. Rotator cuff tear causes severe pain, weakness of the arm, and crackling sensation on moving shoulder in certain positions. There may be stiffness, swelling, loss of movements, and tenderness in the front of the shoulder.
Rotator cuff tear is best viewed on magnetic resonance imaging. Symptomatic relief may be obtained with conservative treatments – rest, shoulder sling, pain medications, steroidal injections and certain exercises. However surgery is required to fix the tendon back to the shoulder bone. Rotator cuff repair may be performed by open surgery or arthroscopic procedure. In arthroscopy procedure space for rotator cuff tendons will be increased and the cuff tear is repaired using suture anchors. These anchor sutures help in attaching the tendons to the shoulder bone. Following the surgery you may be advised to practice motion and strengthening exercises.