Instability and Labral Tear
The shoulder is the most mobile joint in the human body. Its mobility is almost unique in the animal kingdom. It is a ball-and-socket joint like the hip joint. The difference is that in the shoulder joint the boney socket is very shallow to allow for greater movement.
This therefore compromises its stability. Relying more heavily on the cartilage and ligaments than bone for stability, the shoulder joint is at much greater risk of injury which results in loss of stability
What is instability?
If ball dose not remain well centered in in its socket, we call that “instability”.
When the ball is in the joint we call it located, or enlocated.
If it comes out of its socket completely, even for a second, we call that a dislocation.
What cases instability
To answer this we have to appreciate what keeps the ball in the socket. The ball is relatively large with respect to the socket. The analogy is like a golf ball sitting on a tee. The bony socket is extremely shallow and is deepened by cartilage called the labrum. The ligaments which includes the capsule attach the ball to the socket via the labrum.
When a first time dislocation occurs, the labrum gets torn off, called a Bankart lesion, and the ligaments may get stretched.
Once this has occurred, when the should is reduced to its normal postion, the labrum rarely relocates completely. A persistent Bankart lesion occurs. Recurrence is more likely if the cartilage around the shoulder joint has been torn (Bankart Lesion) or the ligaments have been stretched or torn.
The injury usually occurs when the arm is forced out of postion (dislocates), for example, following a fall. These injuries can also occur as a result
of repetitive trauma, such as in the throwing athlete or swimmers where possible subluxations or repeated stretching of the capsule occurs.
The torn labrum usually occurs at the front (anterior) of the socket, but can occur at the back (posterior) or the top (superior) of the socket (or all three).
How is Shoulder Instability Diagnosed?
The diagnosis of this condition is largely based on the history provided.
X-rays taken at the time of a dislocation make a definite diagnosis.
The degree of shoulder looseness or laxity of the shoulder joint can also be assessed by specific tests during the examination. However the shoulder may be normal at clinical evaluation as the muscles play an important role in the stability of the shoulder and it is sometimes difficult to test the ligaments alone if you are awake and reflexly tightening these muscles.
Repeat X-rays performed some time after the initial dislocation are sometimes done to see if any damage to the bones of the joint have occurred, such as a bony bankart or a Hill-Sacks lesion. Bony injuries are best shown up on a CT scan. Occasionally done to further evaluate the bones. An MRI (magnetic resonance imaging scan) with or without a dye(arthrogram) image the torn cartilage.
How is Shoulder Instability Initially Treated?
After a shoulder has dislocated, an exercise program is done in conjunction with a physiotherapist as soon as the shoulder is comfortable enough. The goal of therapy is to restore shoulder motion and increase the strength of the muscles around shoulder. Strong muscles, especially those of the rotator cuff, may help to protect and prevent the shoulder from re-dislocating or subluxing. Once full function of the shoulder has returned, you may gradually return to your pre-injury activities.
The risk of ongoing instability can be very high and largely depends on:
Your age. if you are under the age of 20 at initial dislocation the chance of recurrent dislocation is extremely high, especially in people who go back to high risk sports. By the age of 40 years old the chances are quite small. However as you grow older the chance of associated injures such as rotator cuff tendon tears or fracture increase.
How traumatic the dislocation was. A fracture or a large tear to the cartilage or ligaments occurred, recurrent instability is more common.
Activates you return to. If you play a high risk sport you are more likely to re-dislocate.
When would I need an Operation?
Despite a course of physiotherapy in which full shoulder motion and strength are restored, the shoulder may still feel loose or unstable. Treatment options then consist of activity modification and surgery.
Activity modification is primarily an option for people who experience instability only with certain activities such as playing basketball, contact or overhead racquet sports. In these people, avoidance of the activity may reduce their episodes of subluxation or dislocation.
Surgical treatment is considered in people
- not willing to give up the activities or sports which provoke their episodes,
- in people in whom instability occurs during routine daily activities (dressing, sleeping, etc) or work.
- after an initial dislocation in “high risk” individuals not willing to take the risk of suffering another dislocation.
Technique of Reconstruction
It is usually, but not always possible to stabilize the shoulder by arthroscopic techniques.
The surgery includes examination of the shoulder under anaesthesia to fully assess the extent and direction of the instability while the muscles surrounding the shoulder are completely relaxed.
An arthroscope is used to inspect the inside of the shoulder joint in order to evaluate the joint and its cartilage. The arthroscope allows direct assessment of the condition of the labrum and rotator cuff tendons.
The operation tightens the ligaments that are loose and repair the torn cartilage (labrum). In this type of operation the ligaments and labrum are fixed back into their original position. The ligaments are reattached by reshening up the edge of the bony socket and using sutures through the labrum and ligaments to hold them in the appropriate place for healing. The sutures are often anchored to bone with a special anchors.
Most, not all, of these anchors are now made of plastics such as PEEK. Metal anchors may also be used. These anchors are inserted into the bone and hold the sutures that are used to reattach or tighten the ligaments. these anchors stay in the bone permanently
To correct severe instability, especially when the episodes of dislocations have caused significant damage to the bones of the joint as well as cartilage and ligaments (Large bony Bankart lesion), open surgery is sometimes necessary.
In this situation an incision is made over the shoulder and the tendon of subscapularis is divided to gain access to the joint. The capsule, ligaments and labrum are repaired., A bone graft is often required to replace the damaged bones. Some local bone can be removed and fixed (grafted) to the glenoid called the Latarjet or Bristow procedures.
Rehabilitation after Surgery