Shoulder instability
The shoulder is one of the most commonly dislocated joints. Instability means that the shoulder can dislocate (be pulled out of joint) or experience subluxation (move more than it should). The shoulder joint is a ball and socket joint like the hip, but this instbility is more common because the shoulder joint is much more shallow than the hip which allows it to be a very mobile/flexible functional joint. Both dislocation and subluxation happen for a variety of reasons.
The three main causes of shoulder instability are:
- Traumatic dislocation – where the shoulder undergoes an injury with sufficient force to pull the shoulder out of joint such as a violent tackle in rugby, or a fall onto an outstretched hand
- Non-traumatic dislocation –caused by repeated shoulder movements gradually stretching out the soft tissue cover around the joint causing the rotator cuff muscles to become weak, regularly working with your hands above your head may contribute to this
- Positional non-traumatic – the ability to dislocate your shoulder without any form of trauma. This may start off as a party trick, but if repeated, it can happen during everyday activities. If you are able to do this it is strongly recommended that you don’t
What causes instability?
- Shoulder dislocations are common in athletes—especially among those participating in repetitive, overhead sports, including baseball and volleyball. There are three common reasons that your shoulder can dislocate:
- Repeated, overhead movement. You can dislocate your shoulder if you’re an athlete participating in an overhead sport, like Walsh Jennings, or have a career involving repetitive, overhead movements. The repetition causes the muscles in the shoulder joint to weaken over time, and the connective tissue around the shoulder joint to expand.
- Trauma in daily life or contact sports. High-impact activities can cause your shoulder to dislocate, too. For example, an epileptic seizure or electrocution may cause this injury, as can contact sports like football or skiing.
- It’s in your genes. You may have been born with loose joints (laxity) throughout the body, which is also referred to as being double-jointed. Because of this, you may be able to willingly dislocate your shoulder.
