SHOULDER DISLOCATION
What is it?
The shoulder joint is a ball and socket joint. Unlike the hip joint which is a deep ball and socket joint, the shoulder joint is very shallow. This is to allow a wide range of movement in the joint but this benefit comes with drawbacks. A large amount of movement means that the joint has a tendency to be too loose and if given the right force, it can dislocate or become unstable.
There are various structures which help to keep the joint in position and the most important ones are:
- Ligaments, which hold the bones together
- A rim of cartilage, which deepens the socket
- Muscles of the rotator cuff which keep the shoulder blade and ball in the correct position when moving or using the arm.
A shoulder dislocation usually only occurs during a specific injury or accident when the upper arm (humerus) is forced out of the shoulder joint. This may cause damage to the ligaments, nerves and muscles and tendons that surround the shoulder joint, as well as the bones themselves.
A
fracture to the ball or socket may occur with a dislocation.
What is instability?
Instability ranges from complete dissociation of the joint surfaces to subluxation (incomplete slipping from the joint).
A dislocation is more likely to damage the structure of the shoulder and in some cases can lead to a
frozen shoulder or
shoulder bursitis, particularly if you already have another underlying condition such as lupas or arthritis. It is very important to attend your nearest A&E to have your shoulder examined if you experience a shoulder dislocation and to have the dislocation reduced (put back in place) without damaging the structures around the joint.
When the top of the humerus (humeral head) is not moving normally within the socket you may feel as if the joint is slipping, catching or popping out of its socket. The medical term for this is subluxation. It is associated with pain and a sense of a ‘dead arm’ and understandably you would be apprehensive about moving your arm in certain positions.
The reason it feels dead is a combination of muscle weakness and nerve entrapment. The main nerves which supply the arm with motor control and sensation pass through the soft axilla (arm pit). If the humeral head is not able to support itself in the socket then the sheer weight of the arm will drag it down and press on those nerves.
Sometimes once the shoulder has dislocated once, you may experience a level of instability or subluxation afterwards, especially when swimming or throwing or reaching out to the side.
Types of instability - Traumatic
There are 2 types of instability: Traumatic and atraumatic
Traumatic instability
The main distinguishing feature of this is forceful, violent contact with a person (rugby) or the ground or hard object. This is known as traumatic instability. You can injure other structures around the shoulder when this happens, such as nerves and muscles, especially if you are older. This is called
shoulder impingement.
Usually the head of the humerus is forced forwards and downwards (anterior dislocation). Commonly the ligament in the front of your shoulder is over-stretched and can pull part of the rim of cartilage off the socket. If the cartilage is detached in this way it is called a ‘Bankhart lesion’.
This is sometimes detectable with an MRI (Magnetic Resonance Image) scan but may only be properly visible when the surgeon looks in your shoulder joint during surgery. Sometimes you can have a dent in the back of the humeral head known as a ‘Hill-Sachs lesion’.
Types of instability - Atraumatic
Atraumatic instability
For some people the shoulder is not involved in a specific accident/event but the joint gradually feels unstable. This may develop with specific, repetitive movements of the arm (e.g. conveyor belt workers in a factory or daily swimmers).
Sometimes people have ‘loose-joints’ and these can become a problem and start dislocating or slipping on everyday activities over time.
A few people can voluntarily make their shoulder sublux or dislocate as a party trick, but eventually the joint slips out when you don’t want it to. Do not do this movement! It trains the muscles incorrectly and reminds your brain of an incorrect movement.
Treatment
Traumatic instability
A dislocation will be slipped back into place (reduction) by an A&E Doctor and you will be required to wear a shoulder brace to immobilise it for a short while. You may gradually build up the muscles around your shoulder but if the joint continues to dislocate or sublux regularly, and this is stopping you doing what you want to do, the doctors may offer you an operation.
This is called an Anterior Stabilisation Operation.
Atraumatic instability
Surgery is not usually recommended unless an extended, appropriate course of therapy and exercise to strengthen the shoulder muscles has not worked. Surgery is not helpful for everyone and sometimes it can lead to other problems, so it is important that you work hard at controlled therapy to build muscle strength instead.
Treatment at Hand Kinetics
Our Hand Kinetics Hand therapists are an important part of your recovery from a shoulder dislocation.
Each traumatic shoulder dislocation is different and will require a thorough evaluation to determine the best treatment approach. Therapy will focus on protecting the shoulder, decreasing pain and improving motion through the use of activities, exercises and work- or sports-specific tasks.
Please talk to our principal therapist at Hand Kinetics to discuss your specific needs and shoulder problem before making an appointment and we will be happy to discuss treatment options with you.
Hand Kinetics Telephone: 0044 28 417 72301
www.handkinetics.com
contactus@handkinetics.com
