The term arthritis literally means inflammation of a joint but is generally used to describe any condition in which there is damage to the cartilage. Damage of the cartilage in the shoulder joint causes shoulder arthritis. Inflammation is the body's natural response to injury.
The acromioclavicular joint is part of the shoulder joint. It is formed by the union of the acromion, a bony process of the shoulder blade, and the outer end of the collar bone or clavicle. The joint is lined by cartilage that gradually wears with age as well as with repeated overhead or shoulder level activities such as basketball.
A rotator cuff is a group of tendons in the shoulder joint that provides support and enables a wide range of motion. A major injury to these tendons may result in rotator cuff tears. It is one of the most common causes of shoulder pain in middle-aged and older individuals.
Sports that involve overhead movements and repeated use of the shoulder at your workplace may lead to sliding of the upper arm bone from the glenoid. The dislocation might be a partial dislocation (subluxation) or a complete dislocation causing pain and shoulder joint instability. The shoulder joint often dislocates in the forward direction (anterior instability), and sometimes in the backward or downward direction.
A break in a bone that makes up the shoulder joint is called a shoulder fracture. The clavicle and end of the humerus closest to the shoulder are the bones that usually get fractured. The scapula, on the other hand, is not easily fractured because of its protective cover by the surrounding muscles and chest tissue.
The break or fracture of the clavicle (collarbone) is a common sports injury associated with contact sports such as football and martial arts, as well as impact sports such as motor racing. A direct blow over the shoulder that may occur during a fall on an outstretched arm or a motor vehicle accident may cause the clavicle bone to break.
The humerus is the bone that forms the upper arm. It articulates with the glenoid cavity of the scapula (shoulder blade) to form the shoulder joint and with the lower arm bones – the ulna and radius – to form the elbow joint. The proximal humerus is the upper end of the arm bone that forms the shoulder joint. The humerus is broadly divided into the head, neck and shaft region.
Shoulder tendonitis is a condition characterized by inflammation of the tendons which connect the muscles to the shoulder bones. Tendonitis of the rotator cuff tendons is known as rotator cuff tendonitis. If the biceps tendon is affected, the condition is known as bicipital tendonitis.
The biceps muscle is located in the front side of your upper arm and functions to help you bend and rotate your arm. The biceps tendon is a tough band of connective fibrous tissue that attaches your biceps muscle to the bones in your shoulder on one side and the elbow on the other side.
Osteoarthritis also called degenerative joint disease, is the most common form of arthritis. It occurs most often in older people. AC joint osteoarthritis affects the tissue covering the ends of bones (cartilage) in the AC joint of the shoulder. The cartilage becomes damaged and worn out causing pain, swelling, stiffness and restricted movement in the AC joint.
The shoulder consists of a ball-and-socket joint formed by the upper end of the humerus (upper arm bone) and a cavity in the shoulder blade called the glenoid. The glenoid cavity is surrounded by a rim of cartilage called the labrum. The labrum adds depth to the cavity making the joint more stable and positions the ball within the socket.
The biceps muscle is the muscle of the upper arm which is necessary for the movement of the shoulder and elbow. It is made of a ‘short head’ and a ‘long head’ which function together. These are connected to the shoulder joint by two tendons called the proximal biceps tendons and to the elbow joint by a single distal biceps tendon.
Throwing injuries of the shoulder are injuries sustained as a result of trauma by athletes during sports activities that involve repetitive overhand motions of the arm as in baseball, American football, volleyball, rugby, tennis, track and field events, etc. Throwing injuries are mostly seen in the shoulder and elbow and can occur due to improper techniques, training errors, muscle imbalance, and overuse of muscles.
A dislocation occurs when the ends of your bones are partially or completely moved out of their normal position in a joint. A partial dislocation is referred to as a subluxation, whereas a complete separation is referred to as a dislocation.
Calcification tendinitis is a problem with the shoulder’s tendons and muscles. This condition occurs due to the formation of calcium deposits in the tendons (tissue which attaches muscle to bone) of the rotator cuff (a group of muscles and tendons stabilizing the shoulder). This calcium build-up causes inflammation of the tissues surrounding it, and intense shoulder pain.
Anterior shoulder instability, also known as anterior glenohumeral instability, is a condition in which damage to the soft tissues or bone causes the head of the humerus (upper arm bone) to dislocate or sublux from the glenoid fossa, compromising the function of the shoulder. It is caused by trauma or injury to the glenohumeral joint in which the upper arm bone is dislodged from its usual position in the middle of the glenoid fossa, and there is no longer joint articulation.
Posterior shoulder instability, also known as posterior glenohumeral instability, is a condition in which the head of the humerus (upper arm bone) dislocates or subluxes posteriorly from the glenoid (socket portion of the shoulder) as a result of significant trauma. A partial dislocation is referred to as a subluxation whereas a complete separation is referred to as a dislocation.
An overhead athlete is at increased risk of injury due to the mechanism associated with rapid shoulder elevation, external rotation, and abduction. An overhead throwing motion is an intricate and skillful movement that presents a special challenge of needing the glenohumeral joint to surpass its physiologic limits during overhead sports activities.
Little league shoulder is an injury to the growth plate of the upper arm bone at the shoulder joint of children. It is an overuse injury caused by repeated pitching or throwing, especially in children between the ages of 10 to 15 years. This condition is mostly seen in baseball pitchers, but children in other sports who use improper throwing action are also at risk.
Shoulder injuries in baseball players are usually associated with pitching. While this overhand throwing activity can produce great speed and distance for the ball, when performed repeatedly, can place a lot of stress on the shoulder. While pitching, the arm is thrown outward and backward to generate speed. This action forces the head of the humerus forward, stressing the surrounding ligaments and tendons.
Proximal biceps tendinitis is the irritation and inflammation of the biceps tendon at the shoulder joint. The biceps muscle is the muscle of the upper arm which is necessary for the movement of the shoulder and elbow. It is made of a ‘short head’ and a ‘long head’ which function together. The long head of the biceps tendon is attached at the top of the shoulder joint. The short head is attached to your shoulder blade.
Rotator cuff repair is a surgery to repair an injured or torn rotator cuff. A re-tear may occur a few years after surgery due to multiple reasons including aging, a massive previous tear (more than 5cm), fatty degradation of the tendons, inflammatory arthritis, and inappropriate rehabilitation.
Rotator cuff calcification is the abnormal accumulation of calcium deposits in rotator cuff muscles and tendons. The rotator cuff is a group of 4 muscles and tendons in the shoulder joint that join the head of the humerus to the shoulder. It forms a sleeve around the humeral head and glenoid cavity, providing additional stability to the shoulder joint while enabling a wide range of mobility.
A tear in the rotator cuff can cause pain and disability. It can occur from degeneration of the rotator cuff due to overuse or from a sudden injury. Massive rotator cuff tears involve tears in two complete tendons of the rotator cuff. A tear of more than 5 cm is described as massive. A massive tear may be associated with degeneration and retraction of the tendon and can be difficult to repair if treatment is delayed.
Total shoulder replacement surgery is performed to relieve symptoms of severe shoulder pain and disability due to arthritis. In this surgery, the damaged articulating parts of the shoulder joint are removed and replaced with artificial prostheses. Replacement of both the humeral head and the socket is called a total shoulder replacement.
Conventional surgical methods such as total shoulder joint replacement are not very effective in the treatment of rotator cuff arthropathy. Reverse total shoulder replacement is an advanced surgical technique specifically designed for rotator cuff tear arthropathy, a condition where you suffer from both shoulder arthritis and a rotator cuff tear.
For a successful total shoulder replacement, accurate positioning of the implants is crucial to accomplish a good clinical outcome. Guided Personalized Surgery or GPS-guided shoulder replacement is an advanced technology developed to provide more accurate positioning of an implant.
Arthroscopy is a minimally invasive diagnostic and surgical procedure performed for joint problems. Shoulder arthroscopy is performed using a pencil-sized instrument called an arthroscope. The arthroscope consists of a light system and camera that projects images of the surgical site onto a computer screen for your surgeon to clearly view.
Rotator cuff repair is a surgery to repair an injured or torn rotator cuff. It is usually performed arthroscopically on an outpatient basis. An arthroscope, a small, fiber-optic instrument consisting of a lens, light source, and video camera. The camera projects images of the inside of the joint onto a large monitor, allowing your doctor to look for any damage, assess the type of injury and repair it.
The shoulder joint is a ball and socket joint. A ball at the top of the upper arm bone (the humerus) fits neatly into a socket, called the glenoid, which is part of the shoulder blade (scapula). The labrum is a ring of fibrous cartilage surrounding the glenoid, which helps in stabilizing the shoulder joint.
The shoulder joint provides a wide range of movement to the upper extremity, but overuse or trauma can cause instability to the joint. The Latarjet procedure is a surgical procedure performed to treat shoulder instability by relocating a piece of bone with an attached tendon to the shoulder joint.
Acromioclavicular (AC) joint stabilization is a surgical procedure employed to treat severe cases of AC joint dislocation. AC joint dislocation is the separation of the collar bone or clavicle from the acromion (the top portion of the shoulder blade or scapula at the outer edge of the shoulder) due to severe trauma.
The labrum can sometimes tear during a shoulder injury. A specific type of labral tear that occurs when the shoulder dislocates is called a Bankart tear. This is a tear to a part of the labrum called the inferior glenohumeral ligament and is common in the young who sustain a dislocation of the shoulder. A Bankart tear makes the shoulder prone to repeat dislocation in patients under 30 years of age.
A tear in the pectoralis major muscle occurs when the tendon attaching the muscle to the upper arm bone is damaged as a result of trauma or injury. In the case of a rupture, operative treatment is employed for repairing the torn muscle in active and young patients irrespective of the chronicity of the injury. The most commonly used techniques to repair a pectoralis major tear are suture anchors and bone tunnel procedures.
The shoulder is the most flexible joint in the body. Injury and trauma can tear or stretch the labrum and/or ligaments, causing loosening and instability of the shoulder joint which can lead to partial or complete dislocation of the joint. Bony instability, also known as shoulder instability or glenohumeral instability, refers to the inability to retain the head of the humerus in the glenoid socket due to serious trauma sustained by the soft tissues, and glenoid and humeral bones of the shoulder joint.
A clavicle fracture refers to a broken collarbone and is a common injury associated with contact sports such as football and martial arts, as well as impact sports such as motor racing. A direct blow over the shoulder, a fall on an outstretched arm, or a motor vehicle accident may also cause the clavicle bone to break. Most clavicle fractures occur in the shaft or middle portion of the bone.
Superior Capsular Reconstruction is a surgical procedure to repair massive, irreparable rotator cuff tears. The surgery involves reconstruction of the superior capsule of the shoulder joint using an autograft (tissue from the same person) or an allograft (tissue from a donor).
Subacromial decompression is a surgical procedure performed for the treatment of a condition called shoulder impingement. In shoulder impingement, the degree of space between the rotator cuff tendon and shoulder blade is decreased due to irritation and swelling of the bursa or due to development of bone spurs.
Acromioplasty is the surgical removal of a small part of the surface of the acromion (bony process on your shoulder blade). The shoulder joint is made up of a ball and socket joint, where the head of the humerus (upper arm bone) articulates with the socket of the scapula (shoulder blade), which is called the glenoid.
Failed shoulder surgery is a surgery that did not meet expectations and resulted in recurring pain or other unwanted symptoms. All surgeries are associated with risks, some have a higher risk than others. The most commonly reported failed shoulder surgeries include rotator cuff repairs and shoulder stabilization for shoulder instability.
Latissimus dorsi tendon transfer is a surgical procedure performed to reconstruct the irreparable rotator cuff tears in your shoulder. The procedure typically involves detaching the latissimus dorsi tendon from its original location and transferring it to the shoulder to repair the rotator cuff.
The acromioclavicular (AC) joint is one of the joints present within your shoulder. It is formed between a bony projection at the top of the shoulder blade (acromion) and the outer end of the clavicle (collarbone). The joint is enclosed by a capsule and supported by ligaments.
The shoulder is the most flexible joint in the body that enables a wide range of movements including forward flexion, abduction, adduction, external rotation, internal rotation, and 360-degree circumduction. Thus, the shoulder joint is considered the most insecure joint of the body, but the support of ligaments, muscles, and tendons function to provide the required stability.
Bones of the Shoulder
The shoulder joint is a ball and socket joint made up of three bones, namely the humerus, scapula, and clavicle.
The end of the humerus or upper arm bone forms the ball of the shoulder joint. An irregular shallow cavity in the scapula called the glenoid cavity forms the socket for the head of the humerus to fit in. The two bones together form the glenohumeral joint, which is the main joint of the shoulder.
Scapula and Clavicle
The scapula is a flat triangular-shaped bone that forms the shoulder blade. It serves as the site of attachment for most of the muscles that provide movement and stability to the joint. The scapula has four bony processes - acromion, spine, coracoid and glenoid cavity. The acromion and coracoid process serve as places for attachment of the ligaments and tendons.
The clavicle bone or collarbone is an S-shaped bone that connects the scapula to the sternum or breastbone. It forms two joints: the acromioclavicular joint, where it articulates with the acromion process of the scapula and the sternoclavicular joint where it articulates with the sternum or breast bone. The clavicle also forms a protective covering for important nerves and blood vessels that pass under it from the spine to the arms.
Soft Tissues of the Shoulder
The ends of all articulating bones are covered by smooth tissue called articular cartilage, which allows the bones to slide over each other without friction, enabling smooth movement. Articular cartilage reduces pressure and acts as a shock absorber during movement of the shoulder bones. Extra stability to the glenohumeral joint is provided by the glenoid labrum, a ring of fibrous cartilage that surrounds the glenoid cavity. The glenoid labrum increases the depth and surface area of the glenoid cavity to provide a more secure fit for the half-spherical head of the humerus.
Ligaments of the Shoulder
Ligaments are thick strands of fibers that connect one bone to another. The ligaments of the shoulder joint include:
- Coracoclavicular ligaments: These ligaments connect the collarbone to the shoulder blade at the coracoid process.
- Acromioclavicular ligament: This connects the collarbone to the shoulder blade at the acromion process.
- Coracoacromial ligament: It connects the acromion process to the coracoid process.
- Glenohumeral ligaments: A group of 3 ligaments that form a capsule around the shoulder joint and connect the head of the arm bone to the glenoid cavity of the shoulder blade. The capsule forms a watertight sac around the joint. Glenohumeral ligaments play a very important role in providing stability to the otherwise unstable shoulder joint by preventing dislocation.
Muscles of the Shoulder
The rotator cuff is the main group of muscles in the shoulder joint and is comprised of 4 muscles. The rotator cuff forms a sleeve around the humeral head and glenoid cavity, providing additional stability to the shoulder joint while enabling a wide range of mobility. The deltoid muscle forms the outer layer of the rotator cuff and is the largest and strongest muscle of the shoulder joint.
Tendons of the Shoulder
Tendons are strong tissues that join muscle to bone allowing the muscle to control the movement of the bone or joint. Two important groups of tendons in the shoulder joint are the biceps tendons and rotator cuff tendons.
Bicep tendons are the two tendons that join the bicep muscle of the upper arm to the shoulder. They are referred to as the long head and short head of the bicep.
Rotator cuff tendons are a group of four tendons that join the head of the humerus to the deeper muscles of the rotator cuff. These tendons provide more stability and mobility to the shoulder joint.
Nerves of the Shoulder
Nerves carry messages from the brain to muscles to direct movement (motor nerves) and send information about different sensations such as touch, temperature, and pain from the muscles back to the brain (sensory nerves). The nerves of the arm pass through the shoulder joint from the neck. These nerves form a bundle at the region of the shoulder called the brachial plexus. The main nerves of the brachial plexus are the musculocutaneous, axillary, radial, ulnar and median nerves.
Blood vessels of the Shoulder
Blood vessels travel along with the nerves to supply blood to the arms. Oxygenated blood is supplied to the shoulder region by the subclavian artery that runs below the collarbone. As it enters the region of the armpit, it is called the axillary artery and further down the arm, it is called the brachial artery.
The main veins carrying de-oxygenated blood back to the heart for purification include:
- Axillary vein: This vein drains into the subclavian vein.
- Cephalic vein: This vein is found in the upper arm and branches at the elbow into the forearm region. It drains into the axillary vein.
- Basilic vein: This vein runs opposite the cephalic vein, near the triceps muscle. It drains into the axillary vein.