What is it?
A common cause of shoulder pain is a condition known as shoulder impingement.
To explain exactly what shoulder impingement is, you first need to understand the anatomy of the shoulder. The main joint of the shoulder is the lenohumeral (GH) joint. This is the joint where the humerus (upper arm) attaches to the scapula (shoulder blade). The GH joint is a highly mobile joint, but due to this mobility, it lacks stability. To help compensate for the lack of stability, the shoulder is stabilised by a group of muscles called the Rotator Cuff. The Rotator Cuff is made up of 4 muscles - subscapularis, supraspinatus, infraspinatus and teres minor.
A second joint of the shoulder is the acromioclavicular (AC) joint. This is the where the end of the clavicle (collar bone) meets a lip of bone on the scapula called the acromion. The space just below this joint is called the subacromial space and it is in this space that the supraspinatus muscle and tendon lie, along with the subacromial bursa. A bursa is a fluid filled sac that sits between the tendon and bone, providing a cushioning between the two structures and helping to reduce friction.
Shoulder impingement occurs when either the supraspinatus tendon or the subacromial bursa (or both), become impinged or irritated on movement of the shoulder.
What causes it?
Unfortunately in some people, the structure of your shoulder makes you more susceptible to the condition. This includes those who are born with a smaller subacromial space or who develop bony spurs, both of which can contribute to impingement of the tendon or bursa. On occasion shoulder impingement can occur as a result of direct trauma to the shoulder.
However by far the most common cause of shoulder impingement is related to overuse and postural factors. Repetitive loads can cause wear and tear of the tendon over time, leading to scarring, micro-tears and inflammation of the tendon. Typical movement patterns that lead to shoulder impingement are those that involve lifting weight over shoulder height. An injured tendon doesn't work as effectively and so will change the dynamics of the shoulder's movement. Poor postural habits, including rounding of the shoulders are often a precursor to shoulder impingement. Weakness of the rotator cuff is a typical finding in those with shoulder impingement, as is joint stiffness in the shoulder and thoracic spine.
What are the common symptoms?
- Pain, usually with a catching sensation, on lifting the arm over shoulder height
- Pain lying on the affected side
- Pain that extends from the tip of the shoulder and down the outside aspect of the upper arm, occasionally down to the elbow
- Pain on reaching behind your back. For women, trying to unclasp or clasp your bra with the affected arm is often near impossible!
- General weakness in the affected arm
How does it relate to riders?
Shoulder impingement is certainly not restricted to riders, it can affect a wide range of people. However, there are some factors that make this a common condition in the equestrian. For starters, horse riding is about so much more than just riding. Caring for a horse involves a lot of heavy and repetitive work! Consider all the heavy lifting - saddles, hay bales, feed bags, rugs, often over shoulder height. Hours spent cleaning out stables and paddocks. For every hour spent in the saddle, there is usually triple that amount of time spent doing all the associated work of owning a horse.
Riders who have a tendency to ride with their shoulders rounded, elbows out and forearms rotated are more likely to develop shoulder impingement due to muscle imbalances and joint stiffness as a result of this poor posture. Poor postural habits combined with the heavy work associated with owning a horse makes some horse riders prime candidates for this condition.
How is it treated?
In the majority of cases, shoulder impingement can be managed conservatively with physiotherapy, including a specific exercise program. In some cases, patients may require a cortisone injection in conjunction with their therapy. In a very small number of patients, surgical treatment is required. Your physiotherapist can discuss your options with you upon assessment of your condition.
How long will it take to improve?
This will vary greatly from person to person and will depend on many different factors, including the severity of your condition and how long you've had it. Generally speaking the sooner you seek treatment, the easier it is to treat.