The shoulder joint is a ball and socket joint. The ball-shaped head 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 labrum is a ring of fibrous cartilage that surrounds the glenoid to help in stabilising the shoulder joint. The biceps tendon attaches inside the shoulder joint at the superior labrum of the shoulder joint. The biceps tendon is a long cord-like structure that attaches the biceps muscle to the shoulder and helps to stabilise the joint. The term SLAP (superior-labrum anterior-posterior) lesion or SLAP tear refers to an injury of the superior labrum of the shoulder.
Shoulder Joint Arthritis
The term arthritis means inflammation of a joint, but is generally used to describe any condition in which there is damage to the cartilage. Damage to the cartilage in the shoulder joint causes shoulder arthritis.
The cartilage is a padding that absorbs stress. The proportion of cartilage damage and synovial inflammation varies with the type and stage of arthritis. Usually, the pain early on is due to inflammation. In the later stages, when the cartilage is worn away, most of the pain comes from the mechanical friction of raw bones rubbing on each other.
Frozen shoulder, also called adhesive capsulitis is a condition characterised by pain and loss of motion in the shoulder joint. It is more common in older adults aged between 40 and 60 years and is more common in women than men. Frozen shoulder is caused by the inflammation of the ligaments holding the shoulder bones together. The shoulder capsule becomes thick, tight and stiff bands of tissue called adhesions may develop. Individuals with a shoulder injury, shoulder surgeries, shoulder immobilised for a longer period of time, other disease conditions such as diabetes, hypothyroidism, hyperthyroidism, Parkinson’s disease and cardiac diseases are at risk of developing frozen shoulder.
Shoulder instability is a chronic condition that causes frequent dislocations of the shoulder joint. A dislocation occurs when the end of the humerus (the ball portion) partially or completely dislocates from the glenoid (the socket portion) of the shoulder. A partial dislocation is referred to as a subluxation, whereas a complete separation is referred to as a dislocation.
Shoulder Separation (AC Dislocation)
Acromioclavicular joint (AC joint) dislocation or shoulder separation is one of the most common injuries of the upper arm. It involves the separation of the AC joint and injury to the ligaments that support the joint. The AC joint forms where the clavicle (collarbone) meets the shoulder blade (acromion). It commonly occurs in young athletes and can result from a fall on the shoulder. A mild shoulder separation can occur when there is an AC ligament sprain that does not displace the collarbone. In more serious injuries, the AC ligament tears and the coracoclavicular (CC) ligament sprains or tears slightly causing misalignment in the collarbone. In the most severe shoulder separation injury, both the AC and CC ligaments get torn and the AC joint moves completely out of its position.
Shoulder Labral Tear
The shoulder joint is a “ball and socket” joint that enables the smooth gliding of the bones of the arm to enable movement of arms. However, it is inherently unstable because of the shallow socket. A soft rim of cartilage, the labrum lines the socket and deepens it so that it better accommodates the head of the upper arm bone. Traumatic injury to the shoulder or overuse of the shoulder (with repeated throwing or weightlifting) may cause a labral tear. In addition, ageing may weaken the labrum, leading to injury.
Playing more overhead sports activities and repeated use of the shoulder the t workplace may lead to sliding of the upper arm bone, the ball portion, from the glenoid, the socket portion of the shoulder. 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 may also dislocate in the backward or downward direction (posterior instability).Read More