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Shoulder posterior stabilization: arthroscopic

Pre-Operation

ANATOMY OF POSTERIOR SHOULDER INSTABILITY

This is much less common than anterior shoulder instability. In this type of shoulder instability, the shoulder dislocates “out the back” rather than the more common “out the front”. The diagnosis is often delayed, as it often presents with vague symptoms. Classically, it presents with posterior shoulder pain and decreased athletic performance in high risk sports activities (football, throwing, racket sports, swimming, weight lifting). It usually develops due to repetitive micro-trauma (overuse), but can occur following more acute trauma, or as a result of a seizure or electrocution injury.

The capsuloligamentous structures that usually prevent posterior instability of the shoulder are weaker than their anterior counterparts. The muscles around the shoulder joint (cuff muscles) play an important role in stabilizing the shoulder, by pulling the head of the humerus into the socket of the shoulder joint (“concavity-compression”), and the subscapularis muscle is especially important in the prevention of posterior dislocation or instability.

Some patients will have an anatomic predisposition to this problem, especially an abnormality of the orientation of the shoulder socket (retroversion) or abnormal bone development (posterior dysplasia). Others may have torn the ligaments and/or labrum (step) at the back of the shoulder joint that normally prevent posterior instability.

 
Again small puncture holes (portals) are made through the skin and into the shoulder joint, through with instruments are passed. Using a combination of suture anchors (fastened to bone) and sutures, it is possible to repair any damage to the posterior labrum, and/or the adjacent capsule and ligaments, all of which may be damaged and stretched.

TREATMENT

NON-OPERATIVE TREATMENT

This treatment will succeed in up to 70% of cases, if there has been no acute traumatic injury to the shoulder joint, but only 15% success rate if there has been an acute injury which caused the instability.

The treatment involves strengthening and proprioceptive training, as well as improved scapular control, and is best supervised by a sports physiotherapist.

OPERATIVE TREATMENT

In a similar fashion to the evolution of surgical treatment for anterior shoulder instability, posterior shoulder instability can be treated arthroscopically (“key hole surgery”), with success rates similar to those of the open procedure (See “shoulder arthroscopy” on the “shoulder surgery” page for more details about shoulder arthroscopy)

ARTHROSCOPIC SHOULDER STABILIZATION

The set up is similar to that for anterior shoulder stabilization. The patient is under a general anesthetic. The procedure is performed in an operating theatre with the patient lying on their side, and the arm to be operated on in traction.

Operation

The series of photos above demonstrates the posterior labral tear on MRA, and the arthroscopic repair performed. 

The photographs above show the posterior capsule being tightened (“imbricated”)

Potential
complications

Despite our best attempts, potential complications are a risk with any injury or surgical procedure. You need to be aware of these rare potential complications.

The more common ones are listed here, but please ask the surgeon if there are any you are particularly concerned about.

1. Infection

If this only involves the skin, this will respond to antibiotics (sometimes intravenous and requiring admission to hospital). If the infection is deeper and involves the joint, then the joint may have to be washed out in the operating theatre to cure the infection. The risk of infection is less than 1%.

2. Wound healing

Sometimes this is delayed, and/ or may produce and thickened scar. The latter is more likely if you have a history of “keloid” formation following other skin lesions or surgery.

3. Post-operative pain

Pain after surgery

4. Post-operative stiffness/ frozen shoulder

This can take 18 months to resolve, is poorly understood, can occur after any shoulder injury and fortunately is rare following arthroscopic shoulder stabilization.

5. Recurrence of the injury

Although the repair is very solid, it is possible to redo the injury if sufficient force was to be exerted on the repair, especially during the first 6 weeks following surgery. Return to the sport which caused the injury obviously can result in recurrence of the original injury.

6. Vascular injury

Vascular injury and bleeding

7. Nerve injury

On rare occasions one of the nerves close to the shoulder joint can be damaged by accidental contact with a sharp instrument or suture. The axillary nerve is most at risk. Damage to the nerve may be permanent, with permanent weakness, and is a serious complication. Fortunately it is very rare.

8. Regional pain syndrome

This rare complication is poorly understood and difficult to treat. It manifests as disproportionate pain following the surgery, and slow recovery. There may be symptoms of swelling, color changes and stiffness also.

9. Complications related to the anesthetic

In a young healthy patient these are also rare, but in the presence of poor health and other medical conditions they may be significant. Your anaesthetist will review you prior to surgery and will only proceed with surgery if it is reasonably safe to do so. Usually your surgeon will have ordered some preliminary tests if he has any concerns and will liaise with the anaesthetist prior to surgery.

Post-Operation

POST-OPERATIVE GUIDELINES

Immediately post-operation

  • You will wake up in the recovery ward with a nurse looking after you. Your arm will be in a sling with a pillow, and there will be dressings on your shoulder. The wounds will be closed with stitches.
  • You will be kept in the recovery ward until you have recovered from the anaesthetic, and have managed to have something to eat and drink.
  • Your surgeon will review you before discharge to explain to you what was found during surgery and the details of the operation performed, as well as the expected outcome

Discharge to first post-operative review

  • You will be asked to phone your surgeon’s rooms to make an appointment for your first post-operative review, usually 7-14 days following surgery.
  • Between discharge and first review, you will be instructed to perform some simple exercises for the elbow, wrist and hand to prevent them from become stiff. Simply take the arm out of the sling, and while keeping the elbow resting on the pillow, move the elbow, wrist and hand in all directions for 2 minutes. Repeat this at last 4 times each day. When not performing your exercises, keep the arm in the sling.
  • You are only allowed to lift the elbow away from your side far enough for cleaning your arm-pit and applying de-odorant.
  • Take the medication as prescribed by your anaesthetist for pain.
  • Leave the dressings intact and keep the wounds dry until your first review.

First post-operative review (7-14 days post surgery)

  • At this review your surgeon will check the wound and remove the stitches.
  • He will go over the operative findings and procedure performed.
  • He will also refer you for physiotherapy to supervise your rehabilitation.
  • A second review appointment will be made for 6 weeks post surgery

First post-operative review to second post-operative review

  • You will be able to externally rotate your shoulder to neutral (ie the position required for using a key board or eating at a meal) as long as the elbow is kept in contact with the pillow
  • You will also be able to lift your elbow slightly away from your side.
  • An appointment with a sports physiotherapist should be organised for within a week of your surgery. They will instruct you in passive exercises (pendulum exercises, passive abduction to 120dg, and passive flexion to 90dg, as well as active ER, but no IR beyond neutral, as well as scapular control work)

Second post-operative review

  • At this review the surgeon will assess your progress and re-examine the shoulder.
  • Following this review, your physiotherapist will introduce rotator cuff strengthening, with avoidance of IR, horizontal adduction and flexion until control is sufficient.

General guidelines

  • Strengthening work – can be gently introduced when 6 weeks post-surgery. This will commence with isometric exercises and will be supervised by the physiotherapist. The range of motion for resisted exercises will only be progressed as your scapular control improves.
  • Convention weight training – should be possible around 4 months post surgery, but avoiding positions of flexion and internal rotation (that is bench press type movements)
  • Return to full contact sport – is usually possible around 5 months, with the patient making a graded return to contact work and when strength has been 100% restored.

Final review

Your surgeon will review you at the completion of your rehabilitation and prior to your return to full sports activities

Results

Although results for posterior stabilization, are not as successful as those for anterior stabilization, successful return to all activities is possible in 80-90% of patients, according to the literature.

Complications

If at any stage you experience significant pain that is not relieved by resting the arm in the sling and taking the analgesics, shortness of breath, fever, chills, loss of power or sensation in the arm, significant swelling or colour changes in the arm, contact your surgeon by phoning the rooms or private hospital. If you are unable to contact your surgeon, see your local GP or the local A&E department.