Shoulder instability is a common pathology in young and athletic patients and can be expressed clinically in several ways: dislocation, subluxation or simple shoulder pain..
Anatomy and physiology
The shoulder joint is the most mobile joint in the body. It must compromise extreme mobility and stability. The compromise between thetwimperatives is fragile, which is why shoulder instability is common.
The lack of shoulder joint stability is mainly related to the shape of the articular bony surfaces: the head of the humerus is made up of a third of a sphere that articulates with the glenoid of the scapula which is almost flat. Unlike the hip, which is a much more "interlocked" joint, the shoulder draws its stability from the elements that surround it, namely the ligaments and muscles.
The both articular surfaces of the shoulder are therefore joined together thanks to all the ligaments located all around the shoulder. All of these ligaments make up what is called the capsule. The attachment of this capsule to the rim of the scapula is known as the glenoid labrum
In shoulder instability , the labrum detaches from the edge of the scapular rim.
In 95% of cases, shoulder instability is anterior (antero-medial dislocation), while in 5% of cases it is backwards (posterior dislocation).
Symptoms
Instability may be obvious in case of real dislocation or recognised subluxations identified from a standard previous radiograph in a dislocated position. In this situation simple shoulder x-rays would be sufficient and may show some wear of the anterior rim of the scapular or a glenoid fracture
Instability may be more difficult to establish in case of simple pain and in this situation a more accurate imaging is required such as an arthro MRI or arthro CT scan which shows the detachment of the glenoid labrum from the anterior rim of the scapula.
When patients dislocate over the age of 40 they require systematically an arthro CT or arthro MRI scan to detect the eventual presence of rotator cuff tendon tear associated.
Most often, there is a traumatic origin to this pathology such as a fall. On examination, the arm is perfectly mobile, and the strength is completely preserved. Pain and apprehension may appear when arming the arm.
In some young patients, we can note the existence of a possible hyperlaxity testifying of loose ligaments and consequently promote shoulder instability.
Treatment Principles
The first episode of instability or dislocation requires a standard shoulder x-ray. This will show if the articular surfaces are in place and then the upper limb should be immobilised in a sling for three weeks. This immobilisation period does not guarantee that there will be no recurrence which is the main complication as a result of a first dislocation.
The younger the patient is at the time of the first episode of dislocation the more chance there is of recurrence, as much as 80% of chance of a recurrent dislocation before the age of 20.
When several episodes of dislocation occur the immobilisation in a sling is useless. Some physiotherapy may be offered at that time which is essentially muscle strengthening.
Surgical treatment is required whenever the incidence of dislocations and discomfort with movement is no longer compatible with comfortable daily life, or sporting activity.
Different operating techniques
Bone block is the most commonly used technique to stabilise the shoulder. It can be performed through an open procedure resulting in a scar approximately 6cm in length at the front of the shoulder, or through keyhole surgery. The scapular fragment called coracoid is harvested. The coracobrachialis tendon is attached to it. This bone graft and its tendon will be fixed in place with one or 2 screws at the front of the articular surface of the glenoid. This graft will need to heal exactly as a fracture would be expected to heal.
"Bankart" procedure consists in suturing the ligaments (or labrum) back on the edge of the glenoid rim in order to "close the door to dislocation". This procedure is performed arthroscopically (endoscopy of the joint) through 3 key holes. This is a technically complex operation that must be carried out by a highly trained surgeon.
The choice between these 2 techniques is guided by the surgeon experience, but also by the age of the patient, his job and sporting activity:
Bone block is recommended for young and sporty patients that enjoy high risk sport such as tennis and basketball, or contact sport such as rugby.
Arthroscopic procedures are recommended for patients over 20 whose sporting activity is less at risk or less regular.
COMPLICATIONS
In the vast majority of cases the post-operative care of these procedures are simple but some complications may occur.
For bone block:
Infection ˂1%
Nerve palsy
Non healing of the bone block
Some limitation of mobility
Arthritis may occur over a longer period of time
For arthroscopy:
The most common complication is recurrence or failure to stabilise
In each case a rigorous surgical technique performed by a highly specialised surgeon will reduce the rate of complications.
Follow up and physiotherapy
Post-operatively to ease the healing of the ligaments or bone block a strict period of immobilisation for three weeks is mandatory. After this three week period physiotherapy will be organised in two major stages. The first lasts between one and two months, consists in recovering the mobility alone with a stick or in the water. The second stage when the mobility has returned and the shoulder is no longer painful, physio then concentrates on strengthening the rotator cuff muscles under the control of a physiotherapist.
Daily life activity maybe resumed after a month, post op. driving for example, After 2 moths patients may start gentle sporting activity , such as jogging or cycling.
Patients may progressively return to all sporting activity after the end of the fourth month post-operatively.
SUMMARY
Instability and recurrent dislocation of the shoulder is a very common pathology, particularly in young athletic patients and may significantly inhibit sporting activities. If necessary surgery can be performed, either as an open procedure, or preferably arthroscopically with a specialised technique performed by a highly trained surgery who can guarantee the best surgical result.
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