The shoulder joint...
Anecdotally, the more I speak to people, the more I realise how many of us have niggling shoulder complaints - me included! Whilst we all like to keep fit and active, as we get older we are more prone to overuse injuries. So why is the shoulder such a common joint to injure?
The anatomy of the shoulder
The shoulder joint (glenohumeral joint) is a ball and socket joint between the scapula and the humerus. It connects the upper limb to the torso and is one of the most mobile joints in the human body.
It is often the source of injury because we place a lot of load on it for everyday use. Think about the activities you do on a daily basis - housework, lifting, driving, typing, exercising - all using the upper limbs. Often we do things hastily and our poor old shoulder cops the brunt of it! Unlike the hip joint (another ball and socket joint which is deeper and more stable), the shoulder joint is quite shallow and has a smaller labrum. A common analogy is a golf ball sitting on a tee - a shallow articulating surface means the joint is more mobile and less stable. The following structures help to stabilise the shoulder joint:
- Rotator cuff muscles – The rotator cuff muscles have a very important role in stabilising the shoulder joint. They are often under heavy strain, and therefore injuries of these muscles are relatively common.
- Glenoid labrum – a fibrocartilaginous ridge surrounding the glenoid cavity. It deepens the cavity and creates a seal with the head of humerus, reducing the risk of dislocation.
- Ligaments – act to reinforce the joint and connect bones together to limit range of motion
- Biceps tendon – also helps the joint stability
One of the more common injuries associated with the shoulder is rotator cuff tendonitis. This refers to inflammation of the tendons of the rotator cuff muscles, usually occuring secondary to repetitive use of the shoulder joint. This condition usually occurs over time and can be the result of keeping your shoulder in one position for a while, sleeping on your shoulder every night, or participating in activities that require lifting your arm over your head.
Your rotator cuff is made up of muscles and tendons that keep the ball (head) of your (humerus) in your shoulder socket. It also helps you raise and rotate your arm. The muscles that make up the rotator cuff include:
- Supraspinatus. This holds your humerus in place and keeps your upper arm stable. It also helps lift your arm.
- Infraspinatus. This helps you rotate and extend you arm.
- Teres Minor. This is the smallest rotator cuff muscle and helps rotate the arm away from the body
- Subscapularis. This holds your upper arm to the shoulder blade and helps rotate your arm, hold it out straight and lower it
Symptoms of rotator cuff tendinitis include: (source https://www.healthline.com/health/rotator-cuff-tendinitis#symptoms)
- pain and swelling in the front of your shoulder and side of your arm
- pain triggered by raising or lowering your arm
- a clicking sound when raising your arm
- pain that causes you to wake from sleep
- pain when reaching behind your back
- a loss of mobility and strength in the affected arm
To help prevent these types of injury, we should be:
- using good posture while sitting
- avoiding lifting your arms repetitively over your head
- taking breaks from repetitive activities
- avoiding sleeping on the same side every night
- avoiding carrying a bag on only one shoulder
- carrying things close to your body
- stretching your shoulder throughout the day
If left untreated, these symptoms can become quite incapacitating and affect your everyday life. Following up with an allied health professional to get a proper diagnosis and treatment plan is paramount. Often the treatment is conservative with rest, avoiding overuse and taking anti-inflammatories when needed. Having a better understanding of the anatomy and the way your shoulder moves will assist you in being more biomechanically fluid in your movements. Most of us are very cognisant of correct lifting techniques to avoid a back injury, however we should apply proper mechanics to every joint in order to prevent injury. If this sounds like you, maybe its time for a check up? Movement is so good for you and we encourage you to do so for good physical health - you should not push through pain though. Listen to your body and the feedback it gives you and give yourselves time to heal when required. :)