Your shoulder joint, also known as the glenohumeral joint, is the most flexible joint in your body. This joint and the surrounding structures (composing the shoulder girdle) are often injured during contact sports and sports that involve dynamic overhead movements. To understand common shoulder injuries in sports, it first helps to know about the anatomy of the shoulder.
Your shoulder girdle contains four joints:
In contact sports, the glenohumeral joint, AC joint and sternoclavicular joint can all be injured. In rugby, the AC joint tends to be the most frequently injured.
Glenohumeral joint injury
Your glenohumeral joint is a ball and socket joint with a very shallow socket to allow for a greater range of movement. Stability of the shoulder is achieved by the soft tissue bumper around the outside of the socket called the labrum (which deepens the socket), by the glenohumeral joint ligaments and by a group of small muscles/tendons called the rotator cuff.
It is the shallow nature of this socket that makes it more likely to dislocate upon impact of the arm, particularly at the extremes of range of motion. The most common way to dislocate is anteriorly, where the head of your humerus pops forward — this usually occurs when your arm is in an abduction external rotation position ie a high-five position. This is traumatic anterior shoulder instability and your subsequent risk of future dislocations is greater because of the damage sustained in this first traumatic dislocation.
Though less common, it is also possible to dislocate the shoulder posteriorly, when the upper arm is forced backwards with the arm in a more internally rotated position (ie across your body), such as when being tackled or falling heavily in rugby while carrying the ball.
AC and sternoclavicular joint injuries
Your AC joint is often injured during head-on contact eg during rugby when you're leading with your shoulder and sustain an impact on the point of the shoulder. This can dislocate or damage your AC joint.
Though less common, it is also easily possible to damage or dislocate your sternoclavicular joint. This is at the other end of the collarbone to the AC joint and whereas the AC joint tends to dislocate upwards, by the nature of this saddle joint, the sternoclavicular joint tends to dislocate forwards (anteriorly) or backwards (posteriorly). If a traumatic posterior dislocation is sustained, you may need emergency treatment due to the risk to underlying important structures.
In sports involving tackling, punching, blocking and overhead dynamic actions, such as rugby, boxing, basketball, tennis and badminton, as well as when loading above shoulder height in the gym, you can tear your labrum at the root of your biceps muscle (ie at the top of your socket). This may not cause significant problems in day-to-day activities but can cause pain and reduced function in more dynamic and sporting activities.
Rotator cuff tears
Another common sports shoulder injury in those over the age of 40 years old is a rotator cuff tear. These are the small muscles around the shoulder that help centre the ball of the joint on the shallow socket. Moving into the middle-age years, there is an age-based change in the rotator cuff, which is also influenced by your genetics. This means that relatively minor trauma that would have not caused the rotator cuff to tear when you were younger, can at this older age.
Sports that involve impact, falling or dynamic overhead arm movements, alongside accidents in sports such as cycling and motorcycling, put you at the greatest risk of shoulder injuries.
You are also more likely to sustain a shoulder injury after the age of 40 in any capacity. However, if you only play sports fairly infrequently, the so-called ‘weekend warrior’, then the risks of this are likely to be higher.
AC joint injuries
You may notice tenderness, pain and/or swelling above your AC joint ie at the top of your shoulder, alongside weakness and reduced mobility. An X-ray will help classify the extent of your AC joint injury eg if ligaments are sprained or torn, resulting in a dislocation of this joint. In more severe cases, this may need surgery.
Over the years, recurrent injuries to your AC joint can result in secondary arthritis of this joint. This can be successfully treated, in most cases, with an injection in the earlier stages and then surgery in the later stages to shave off the end of your clavicle.
Labral tears are an important part of the trauma of shoulder dislocations as well as recurrent shoulder instability if the tears occur at the front or back of the shoulder socket. This is often not a problem if the shoulder remains stable, but if the shoulder is not stable, then surgical repair of the tear with strong stitches and bone anchors is usually performed.
If the tear is at the top of the socket, under the attachment of the biceps tendon, the shoulder doesn’t dislocate, but the pain is felt generally on more dynamic, above-shoulder-height activities.
Depending on the type or severity of this tear, it may be possible to treat it without surgery, but in young patients, surgery is often required. Non-surgical treatment often involves rest, pain relief and physiotherapy.
If surgery is needed, there are two different procedures that are used: repair of your tear at the top of the socket with strong stitches and bone anchors as per other labral tears (a SLAP repair) or a biceps tenodesis, where the biceps tendon is cut inside the joint and fixed down to the humerus bone.
Sternoclavicular joint injuries
Sternoclavicular joint injuries are less common. These are usually anterior or posterior dislocations. You will feel pain over the joint where the collarbone meets the breast bone and a ‘bump’ or ‘lack of a bump’ compared with the other side.
Anterior dislocations, which cause more of a bump, are usually treated without surgery, unless the joint keeps popping in and out, in which case surgery can be performed to stabilise it.
Posterior dislocations, which cause a lack of a bump, can be more serious because they can compress vital structures, such as large blood vessels, your windpipe (trachea) and gullet (oesophagus). You may, therefore, need emergency treatment to pull this back into place, either with or without open surgery.
In a similar way to the AC joint, repeated trauma to the area can result in secondary arthritis in the joint. This is usually treated with painkillers, physiotherapy and injections, and rarely requires surgery.
Rotator cuff injuries
Rotator cuff injuries can range from small partial-thickness tears to large full-thickness tears, with varying disabilities. If you have a larger tear, you may struggle to lift your arm at all.
In milder cases, a steroid injection with physiotherapy may be enough to resolve the inflammation and pain. However, in more severe cases, where pain or weakness persists, surgery to repair the tear may be necessary, especially in more active individuals.
In those with very large tears, there can be a degree of urgency in the timing of surgery to prevent tears from becoming irreparable. If a large tear can’t be repaired, then this can result in long-term pain and poor function of the shoulder, and often progresses to a type of arthritis called rotator cuff arthropathy. This is considered to be such a problem that the British Elbow and Shoulder Society guidelines suggest that if you are aged over 40 years and have dislocated your shoulder, you should have an ultrasound scan or MRI scan of the shoulder to rule out a significant tear.
It is, therefore, important that if you sustain an injury to your shoulder, are over 40 years old, have pain and are struggling to move your arm, you should go to A&E where your shoulder can be examined, and if appropriate, sent for a scan to check for tears.
Mr Dylan Griffiths is a Consultant Orthopaedic Surgeon at Spire St Anthony's Hospital and Imperial College Healthcare NHS Trust, specialising in shoulder and elbow problems, rotator cuff problems, shoulder dislocations, sports injuries of the shoulder and elbow, and shoulder arthritis. He also has particular expertise in advanced arthroscopic (keyhole) techniques, complex arthroplasty (joint replacements) and trauma, and formerly played semi-professional rugby.
If you're concerned about symptoms you're experiencing or require further information on the subject, talk to a GP or see an expert consultant at your local Spire hospital.
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