Shoulder

Shoulder Injuries / Shoulder Pain

AC joint Separation

What is the Acromioclavicular Joint?

The acromioclavicular joint is formed by the outer end of the clavicle (collar bone) and the acromion process of the scapular (shoulder blade). The acromion is a bony process which protudes forwards from the upper part of the scapular. This joint forms the highest part of the shoulder.

The two bones are attached by the acromioclavicular ligament. There are several other ligaments which can be of importance in AC joint injuries, including the coracoclavicular (CC) ligament (divided into conoid and trapezoid sections) which joins the clavicle to the coracoid process, another forward protuding part of the scapula, slightly below and to the inside of the acromion.

A third ligament is the coracoacromial ligament which attaches the acromion process to the coracoid process, although it is rarely involved in this type of injury.The most common way of injuring the AC joint is by landing on the shoulder, elbow, or onto an outstretched hand

Symptoms include:

Pain at the end of the collar bone
Pain may feel widespread throughout the shoulder until the initial pain resolves, following this it is more likely to be a very specific site of pain over the joint itself
Swelling often occurs
Depending on the extent of the injury a step-deformity may be visible. This is an obvious lump where the joint has been disrupted and is visible on more severe injuries
Pain on moving the shoulder, especially when trying to raise the arms above shoulder height

AC joint injuries are graded from 1-6 using the Rockwood scale which classifies injuries in relation to the extent of ligament damage and the space between the acromion and clavicle. Grade 1 is a simple sprain to the AC joint, with damage increasing up to grade 6 which involves full rupture of both AC and coracoclavicular ligaments with the clavicle being displaced inferiorly. A step deformity may be apparent with grade 3, 4 & 5 injuries.

Shoulder Instability / Subluxation

What is shoulder instability?

No single structure is responsible for providing stability at the shoulder joint. Instead, the bony structure of the joint surfaces, the ligaments and muscles are all key components in maintaining a stable shoulder joint yet permitting a large range of movement in several directions.

Instability is often associated with subluxation (partial dislocation of the shoulder joint), which may be associated with pain and / or dead arm sensation. Indeed this is often what prompts the athlete to seek medical attention. In some people, this is not actually painful but can be quite annoying and prevent them from taking part in daily activities or sports.

Instability of the shoulder joint can be in one direction for example, anterior instability (out the front), posterior instability (out the back) or in more than one direction (known as multidirectional instability). The most common form of instability seems to be anterior and is probably because the joint capsule is at its weakest at the front of the joint.

Causes of shoulder instability:

There are many reasons why a shoulder may become unstable. If the joint surfaces are shaped slightly differently – for example if the glenoid fossa is slightly flatter than usual, or the head of humerus is more of an oval shape – the joint may not be as stable compared with other people who have “normal” joint anatomy.

Other structures support the bony anatomy to help provide stability to the shoulder. These include:

Glenoid Labrum – a ring of cartilage which deepens the glenoid fossa, making the “cup” of the socket deeper and hence improving stability
Joint Capsule – a membrane which encompasses the entire joint, providing stability but also maintaining the joint complex and holding the lubricating (synovial) fluid in the correct place
Ligaments – holding the bones together and providing stability by preventing them from moving when they shouldn’t be
Muscles – Work alongside the ligaments in preventing unwanted movement, but also initiate and create movement of the joint.

Instability may be caused by:

Trauma(traumatic instability)

Usually due to a particular accident or injury which damages the structures that provide stability
Sometimes due to an old injury – for example an injury which weakens the capsule may cause instability – known as “post traumatic instability”

Joint Laxity (atraumatic instability)

May be due to
- anatomical abnormalities
- generalized laxity (known as hypermobility)
- muscle weakness
- certain conditions, including pregnancy

“Acute on chronic” instability – a traumatic injury to an already lax joint

Rotator Cuff Injury

What are the rotator cuff muscles?

The rotator cuff is a group of muscles which work together to provide the Glenohumeral (shoulder) joint with dynamic stability, helping to control the joint during rotation (hence the name). The rotator cuff muscles include:

Supraspinatus
Infraspinatus
Teres Minor
Subscapularis

Due to the function of these muscles, sports which involve a lot of shoulder rotation – for example, bowling in cricket, pitching in baseball, swimming, kayaking – often put the rotator cuff muscles under a lot of stress.
Problems with the rotator cuff muscles can be classed into two categories – Tears of the tendons/muscles, and inflammation of structures in the joint.

Acute Tear

This tends to happen as a result of a sudden, powerful movement. This might include falling over onto an outstretched hand at speed, making a sudden thrust with the paddle in kayaking, or following a powerful pitch/throw.

The symptoms will usually include:

Sudden, tearing feeling in the shoulder, followed by severe pain through the arm
Limited movement of the shoulder due to pain or muscle spasm
Severe pain for a few days (due to bleeding and muscle spasm) which usually resolves quickly
Specific tenderness (“x marks the spot”) over the point of rupture/tear
If there is a severe tear, you will not be able to abduct your arm (raise it out to the side) without assistance

Chronic Tear

Usually found on the dominant side
More often an affliction of the 40+ age group
Pain is worse at night, and can affect sleeping
Gradual worsening of pain, eventually some weakness
Eventually unable to abduct arm (lift out to the side) without assistance or do any activities with the arm above the head
Some limitations of other movements depending on the tendon affected

Other common Shoulder problems

Glenoid Labrum Injury
Shoulder pain resulting from damage to the lining of the cavity the end of the upper arm bone sits in.

Inflammation of muscle attachments to the clavicle
Pain along the front of the collar bone.

Impingement syndrome
Impingement syndrome is when the rotator cuff tendons become trapped in the shoulder joint. Repeated impingement can lead to inflammation and thickening, which in turn will result in more impingement and trapping of the inflammed tendons.

Inflammation of the supraspinatus tendon
The supraspinatus muscle runs along the top of the shoulder blade and inserts via the tendon at the top of the arm (humerus bone). This muscle is used to lift the arm up sideways and is also important in throwing sports.

Inflammation of the subscapularis tendon

The subscapularis muscle originates from the underside of the shoulder blade and inserts at the front of the upper arm (humorous). It is mainly throwers that injure this muscle. A partial rupture of the muscle is more common than a complete rupture but the partial rupture will often heal with inflammation.

Pectoralis major muscle/ Tendon sprain
The pectoralis major muscle is a large powerful muscle at the front of the chest. It used to rotate the arm inwards, pull a horizontal arm across the body, pull the arm from above the head down and pull the arm from the side upwards. It is most likely to rupture at the point where it inserts into the arm (humerus).

Pectoralis major tendon inflammation
The tendon where it inserts into the arm (humerus) can become inflammed. It is common in racket players, rowers, swimmers, throwers and weight trainers.

Referred Shoulder Pain
Referred pain from cervicle spine and thoracic spine.

Rupture of the supraspinatus tendon
The supraspinatus muscle runs along the top of the shoulder blade and inserts at the top of the arm (humerus bone). This muscle is used to lift the arm up sideways and is also important in throwing sports as it is the muscle that holds the arm in the shoulder joint when you release what you are throwing.

Rupture of the long head of the biceps
The biceps muscle splits into two tendons at the shoulder. A long one and a short one. The long tendon runs over the top of the humerus bone (upper arm) and attaches to the top of the shoulder blade. A rupture of this tendon is rare in young athletes but more common in older ones.

Subacromial bursitis
Over the supraspinatus tendon is a bursa (small sack of fluid used to help lubricate the moving tendon). This bursa can become trapped in the shoulder causing pain and inflammation. The athlete is more prone to this injury if they overuse the shoulder particularly if the arm is at or above shoulder level. Or if the athlete has had a rupture of the supraspinatus tendon.

Less Common Shoulder Injuries

Deltoid muscle strain (front)
The deltoid muscle is the big muscle on the shoulder. It has three parts - the front (anterior), middle and back (posterior). The muscle lifts the arm up sideways. The front part helps to lift the arm up forwards (flexion) and the back part helps to lift the arm up backwards (extension).

Deltoid muscle strain (back)
The deltoid muscle is the big muscle on the shoulder. It has three parts - the front (anterior), middle and back (posterior). The muscle lifts the arm up sideways. The front part helps to lift the arm up forwards (flexion) and the back part helps to lift the arm up backwards (extension).

Dislocation of the sterno-clavicular joint
The clavicle (or collar bone) connects to the sternum (or breast bone) in the middle of the chest at the top. If the shoulder is subjected to a hard impact this joint can become damaged.

Fracture of the neck of the humerous
A fracture to the neck of the humerus is often caused by falling onto an outstretched hand or direct impact to the shoulder. It is seen more often in young adults, adolescents and the elderly.

Frozen Shoulder/ Adhesive capsulitis
A frozen shoulder (known also as adhesive capsulitis) is a condition that occasionally occurs in older athletes. It is this joint and the surrounding capsule that becomes inflammed and eventual there is a significant loss in mobility.

Inflammation of the long head of the biceps

Inflammation of this tendon is a fairly common complaint especially with swimmers, rowers, throwers, golfers and weight lifters.

Winged scapula

A winged scapula is a shoulder injury or condition in which the scapula or shoulder blade sticks out at the back, particular when pushing against something such as a wall.

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