Shoulder instability

What is shoulder instability?

In shoulder instability the shoulder joint feels loose as though the ball is falling out of the socket.  In extreme cases the shoulder dislocates repeatedly and has to be reduced back into normal position.  It may occur following an injury such as a fall or commonly in contact sports such as rugby where the shoulder dislocates damaging the tissues.  It may also occur spontaneously due to generalised laxity of the joint.

The shoulder is the most mobile joint in the body. It is a ball and socket joint.  A number of structures are required to keep the shoulder joint stable.  These include:

  • The shape of the bones i.e. the head of the humerus which forms the ball and glenoid of the scapula bone that makes up the socket
  • The glenoid labrum which is made from fibrocartilage that deepens the socket
  • Ligaments and capsule surrounding the joint

Any disturbance to the normal anatomy of these structures of these structures may result in shoulder instability.

In a shoulder dislocation the glenoid labrum commonly detaches from the bone making the shoulder more susceptible to further dislocations.

A number of treatment options are available: 

  • Physiotherapy may help to strengthen the muscles surrounding the joint
  • If the glenoid labrum has been torn, then surgery may need to be performed to re-attach the torn glenoid labrum to the bone.  This restores normal anatomy and reduces the likelihood of further dislocations.  This can be done either by an open operation or through arthroscopic or keyhole surgery
  • If there is a large capsule this may be tightened, again by either open surgery, or through keyhole surgery using radiofrequency to shrink the tissues

This is a decision that should be made in consultation with your surgeon.  It depends on the lifestyle you lead, the number of dislocations you have had and the interference with normal daily living.

Studies have shown that if you are young (under 30 years of age), actively involved in sports and have had a shoulder dislocations, then there is a 50% chance of having a further dislocation in the future.

In certain circumstances, arthroscopic stabilisation of an unstable shoulder is not possible.  For example, when in addition to torn labrum, a piece of bone has detached from the socket (glenoid) of the shoulder. Arthroscopic intervention may also not be appropriate if there is a large divot of bone taken from the back of the ball (humeral head - Hill Sachs lesion) of the shoulder joint, when the shoulder dislocates.

In these cases, open surgery is necessary to compensate for the bone injuries.  The procedure involves the transfer of part of the coracoid bone to the front of the glenoid, thereby replacing missing bone or deepening the socket, such that there is increased contact between the ball and the socket.  In addition muscle attachments to the coracoid are transferred adding to the stability by acting like a sling in front of the shoulder.

In order to perform the surgery, the patient will usually have a nerve block to the arm and general anaesthetic.  Patients are usually discharge after a one night stay.

A wound is made over the front of the shoulder usually 8-10 cm in length.  The coracoid is divided and transferred to the front of the glenoid, where it is held with a screw.

In order for the bone to heal, the arm will be immobilised in a sling for approximately 4-6 weeks, before shoulder range of movement is re-established.  During the initial period many patients experience significant sleep disturbance and regular analgesia is likely to be required.  It is not possible to drive whilst the arm is in the sling.

A strengthening programme is subsequently employed usually light weights 6-8 weeks post surgery.  Non- contact sport is usually recommended three months following the surgery, with contact activity initiated between 3-4 months.  Rehabilitation may continue for nine months following the procedure.  Commitment to the physiotherapy programme is fundamental to the success of the surgery.

The aim of this procedure is to repair the torn labrum and ligaments in the shoulder following a dislocation. This returns tissues to the normal position and thereby tightens the shoulder preventing further dislocation. 

In order to perform the surgery, the patient will have a general anaesthetic.  The operation is generally performed as a day case or overnight stay if performed later in the day.

Usually three small wounds, approximately 0.5cm, are made around the shoulder in order to allow the passage of the arthroscope (camera) and the instruments into the shoulder.  Most commonly there is one wound at the back of the shoulder and two wounds at the front.

Bioabsorbable anchors are inserted into the socket (glenoid) of the shoulder joint, after small holes (2.8 mm) have been drilled.  Sutures attached to the anchors are then passed through the torn labrum, called the Bankart lesion and are then tied such that the labrum is repaired back to the bone.

In order for the labrum to heal, the arm will be immobilised in a sling for approximately six weeks, before shoulder range of movement is re-established.  During the initial period many patients experience significant sleep disturbance and regular analgesia is likely to be required.  It is not possible to drive for six weeks whilst the arm is in the sling.

A strengthening programme is subsequently employed usually allowing light weights 6-8 weeks post surgery with contact activity initiated between 3-5 months dependent on progress.  Rehabilitation may continue for six months following the procedure.  Commitment to the physiotherapy programme is fundamental to the success of the surgery.

Arthroscopic stabilisation surgery has a high success rate.

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