I have a shoulder dislocation, what now? – Part A

Shoulder dislocations are quite common among sports participants. Today’s blog will address anterior shoulder dislocations, which is when the arm (Humeral head) is shifted forward out of its socket (Glenoid Fossa).  See picture below for anatomical reference (picture 1).

Picture 1

Brief Biomechanics Review

It is important to first understand the anatomical relationship and mechanics of the shoulder, in order to understand the injury and its management options. Starting from the fact that the glenoid fossa contact area (see above) corresponds on average to only ⅓ of the contact area of the humeral head. Such particularity gives the shoulder great freedom of movement; in turn allowing one’s hand to travel in various directions for functional reasons. The shoulder is the only joint in the body with this unique characteristic.

Nevertheless, such ‘natural’ mobility comes at a cost. Shoulders, from a structural point of view,  are prone to instability by default. As a result, it is a joint that heavily relies on its ligament system and muscle support. Going into great detail here is not needed; so your attention should be drawn to the key message now, a structure called Labrum. The name originates in the Latin language and it means ‘lip’. In the shoulder, it has the important function of deepening the glenoid fossa by increasing its contact surface with the humeral head. It also seals the joint, promoting greater stability and an anchor point for some surrounding structures (picture 2).

Picture 2

Definition, Incidence and Risk Factors

Apart from the direction in which the dislocation occurs, shoulder dislocations can be further subdivided into two categories depending on how it happened or what caused it to ‘pop out’ in the first place. Clinicians will refer to this event as ‘mechanism of injury’. So, someone can have a traumatic or a non-traumatic dislocation. The last meaning no external force was applied to the joint and the joint has dislocated on its own. In that case, most scenarios are of subluxation, which means partial dislocation. These are mostly related to sports where there is a need to move the arm in extreme angles repetitively; for instance, Volleyball and Swimming. Other scenarios include congenital increased joint laxity or residual instability from a previous traumatic episode, a very common cause that comes out of ineffective rehabilitation.

Traumatic dislocations can be of greater consequence and; therefore, are a bigger concern. These can happen when external forces are applied to one’s shoulder such as during a rugby tackle, a fall from a mountain bike or a surfing wipe out. If you are into surfing you would’ve probably heard of Mark Mathews shoulder dislocation at a heavy Jaws surfing session, you will find the footage on youtube.

The worst of a traumatic anterior shoulder dislocation, apart from concomitant injuries that may stem from it, is to have residual instability that can lead to further episodes of joint dislocation, where less force is involved.

Not surprisingly, the literature reports young males as the group with greatest incidence. Testosterone-filled individuals are just more prone to take risks and generally more competitive within their chosen sports.

Data from a recent systematic review reported recurrence rates among nonoperatively treated initial anterior dislocations of 46% at 2 years and 58% at longer-term follow-up.

Treatment Overview

Treatment after an anterior shoulder dislocation will vary according to the pathway used to restore the normal joint alignment. There are two main possibilities where the first is called ‘closed reduction’. The term means putting the shoulder back in place without the need of surgery. The second is a surgical repair, which is an approach selected on an individual basis, depending on the patient requirements, the surgeon and any associated injuries that may arise with the initial dislocation. The two common ones are Hill-Sachs and Bankart injuries, the first is a type of fracture of the head of the humerus and the latter represents a labrum tear leading joint instability. I will refrain from going over these now and expand on it in another blog.

There is some debate in the literature regarding best practice after closed reduction. Some surgeons advise clients to be put in a sling with the shoulder in internal rotation (forearm towards the body) whilst others advocate immobilisation in sling with the shoulder in external rotation (forearm away from the body). The reason for the second and less orthodox approach is mainly an attempt to avoid a stiff shoulder. The literature reports a slightly higher incidence of re-dislocations with the shoulder immobilised in external rotation.

For those involved with highly demanding physical activities, surgical stabilisation following traumatic anterior shoulder dislocations lead to a lesser chance of re-dislocating or partially dislocating their shoulders in future.

As far as physiotherapy is concerned, there will be some variation depending on client, surgeon and associated injuries. Surgical cases tend to progress slowly given that healing times of any repairs need to be respected in other to achieve a stable joint. On closed reduction cases, respecting healing time is just as important. Allowing outer ranges of motion too soon is likely to lead to further instability. Strengthening of scapular stabiliser muscle groups and the rotator cuff group is the main objective. Also important to ascertain normal shoulder mechanics and strength ratios have been restored. Remember, the shoulder heavily relies on its muscles not only to move your arm through space but also to stabilise it in its socket as it moves.

Take Home Message

I was once taught as an undergraduate student the ‘3 dislocations rule’ which basically states one dislocation episode is fine, two are still manageable and three or more are surgical. Over the years I have observed enough to challenge that rule quite frequently. My new rule is anterior shoulder dislocations are unique and must be assessed on an individual basis. Don’t take it for granted, listen to your health professional and challenge anyone who dismisses its seriousness too quick. A qualified professional will perform a thorough evaluation of your case.

Bruno Rebello (APAM)

Physiotherapist

References

Handoll HHG, Al-Maiyah MA. Surgical versus non-surgical treatment for acute anterior shoulder dislocation. Cochrane Database of Systematic Reviews 2004, Issue 1. Art. No.: CD004325. DOI: 10.1002/14651858.CD004325.pub2.

Hanchard NCA, Goodchild LM, Kottam L. Conservative management following closed reduction of traumatic anterior dislocation of the shoulder. Cochrane Database of Systematic Reviews 2014, Issue 4. Art. No.: CD004962. DOI: 10.1002/14651858.CD004962.pub3.

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