Shoulder Dislocation, Instability and Labral Tears
Knowledge that empowers
What is it?
The glenohumeral joint is effectively a golf ball (humeral head-ball) sitting on a golf tee (glenoid-socket) that is sitting on a surf board (scapula).
The advantage of this configuration is that it allows a remarkable range of motion in all directions. The trade-off for having such large range of motion is that the shoulder is less stable than all other joints in the human body. It is however important to recognise that the shape or fit of the ball and socket does give the shoulder some stability. Normal shoulder function requires the muscles, tendons, ligaments and bone to work in a synchronous harmony.
At the outer edges of the socket is a cartilage rim known as the labrum. This structure further contributes to the stability of the ball and socket joint by effectively increasing the depth and size of the socket. The joint capsule, a soft tissue structure which surrounds the ball and socket joint, has several thickened areas known as ligaments. It is these ligaments that prevent the shoulder from moving beyond its normal range of motion and these again increase the stability of the shoulder joint.
Stability of the glenohumeral joint essentially refers to maintaining the humeral head (ball) in the centre of the glenoid (socket). Conversely, instability refers to an inability to keep the humeral head centred in its socket.
Traumatic injuries to the shoulder, causing dislocation or subluxation, can cause the shoulder to become unstable. When the humeral head becomes completely displaced from its socket, it is said to have dislocated. A dislocated shoulder normally requires relocation by a trained health professional. A subluxation refers to the humeral head becoming partially displaced from its socket, or slipping, before it relocates itself.
In a traumatic dislocation or subluxation of the shoulder, there is often significant injury to one or more of the stabilising structures of the shoulder including the humeral head and glenoid, the ligaments and/or the labrum. The dislocation or subluxation is often described by health professionals based on the direction that the ball becomes displaced from its socket:
Anterior – toward the front
Posterior – toward the back
Inferior – toward the bottom
Who is affected?
Shoulder dislocation is more common in 18-25 year olds who are involved in contact or collision sport (such as Rugby and Australian Football), and those who also have underlying ligamentous laxity (loose joints). Shoulder dislocations can also affect the older population after falls.
What are the symptoms?
In a traumatic dislocation or subluxation, the patient normally reports feeling the shoulder “go out” or “slip” out of place. A shoulder dislocation is normally a significantly painful and distressing injury. Immediately following relocation, it is common to continue to experience a sense of instability or loss of control of the shoulder and subsiding pain for some days.
How is the diagnosis made?
Shoulder dislocations and subluxations are usually diagnosed based on the patient’s history, reported symptoms and physical examination.
X-rays are be required to confirm the diagnosis and to identify any bony injuries. X-rays are normally repeated to confirm that the shoulder has been relocated within the socket after reduction. An MRI scan may be required to assess labrum, ligaments or tendons that support the shoulder for any associated injury. In some cases where an injury to the bone is suspected, a CT scan may be required.
What is the prognosis?
The rates of re-dislocation vary based on age, sporting involvement and injury to shoulder structures.
Younger people, those involved in collision/contact sports and those with significant structural injury to the shoulder (especially bone damage at the glenoid or humeral sides) can all increase the risk of recurrent dislocation. Those who have experienced a previous shoulder dislocation are at increased risk of a shoulder dislocating again.
Non surgical treatment
If your shoulder is still dislocated you will usually be seen at a specialist emergency clinic or hospital emergency department.
You may be given medication to allow the shoulder to relax prior to relocation, as muscle relaxation is the key to relocate the ball into the socket.
After relocation initially a sling is worn for comfort and your doctor may prescribe pain medication. A physiotherapist can guide you in restoring the movement of your shoulder. Exercises will help improve the strength and control of the muscles supporting the shoulder. Your physiotherapist can assist in guiding your return to work or recreation as your movement, strength and confidence return.
Surgical treatment
Surgery may be necessary where there is significant injury to the tissues that keep the shoulder joint stable.
The aim of surgery is to improve the stability of the ball within the socket and reduce the risk of recurrent dislocation. The type of surgery depends on the structure/s that have been injured and can involve repairing the labrum, bone and/or capsule.
Rehabilitation following surgery for shoulder instability normally involves:
- wearing a sling or brace for approximately 6 weeks after surgery
- exercises to restore range of motion to the shoulder
- a strengthening and return to work/sport program is commenced 3 months after surgery
Arthroscopic Shoulder Reconstruction
In this keyhole surgery, the torn labrum is anchored back to the glenoid (socket) with small bone anchors.
Tears of the ligament or capsule can be repaired with sutures, and in some cases the capsule is tightened to ensure stability of the shoulder. This procedure may be completed for anterior instability or posterior instability.
Revision of Failed Shoulder Reconstruction
In cases where patients have previously undergone surgical reconstruction for shoulder instability and this has failed, Associate Professor Raniga’s training and experience in the management of shoulder instability allow him to offer revision surgery to restore structural stability to the shoulder. Your clinical history, physical examination and imaging findings will assist greatly in planning for revision surgery.
Modified Open Latarjet Procedure
The Latarjet procedure is typically performed in patients who have labral and ligamentous injury with associated injury to the bone of the socket and/or the humeral head.
To access the shoulder joint, a small split incision is made in the subscapularis muscle at the front of the shoulder. In the Latarjet procedure the coracoid bone with the attached conjoint tendon is cut and transferred to the front of the socket to provide extra bony stability.
The conjoint tendon gives the shoulder a “sling” effect to prevent dislocation at the end-range of movement. Also, the injured labrum, ligaments and capsule are repaired to restore stability to the joint.
The Latarjet procedure has shown very good results through a long number of years in the scientific literature (around 95-98% success rate).
Associate Professor Raniga had the privilege of receiving intensive training in performing this procedure at the Bern University Hospital, (Switzerland), whilst on Fellowship. His technique is a more advanced modification of the original Latarjet Procedure.