The shoulder is the most common source of pain for stroke survivors. Proper shoulder support is key to prevention and treatment.
But first, what is shoulder subluxation and what causes it? Simply put, it’s a partial dislocation of the shoulder joint. For stroke survivors, it’s usually caused by weak rotator cuff muscles, which connect the upper arm bone to the shoulder blade. These muscles are responsible for maintaining shoulder joint alignment during arm movement. When the rotator cuff is weak, gravity pulls the arm down and away from the shoulder blade, causing shoulder subluxation. Slumped posture caused by weak back muscles can increase shoulder subluxation. Occasionally, muscle stiffness causes subluxation by placing uneven stresses on the shoulder joint, pulling the joint out of alignment. In these cases, usually the arm bone has pulled forward and away from the shoulder blade.
As many as 84 percent of stroke survivors develop shoulder pain associated with shoulder subluxation and motor weakness. A physical therapist or physician can diagnose the condition by feeling the space between the arm bone and the shoulder blade. The space should be less than one-finger width. A separation of one-finger width is considered a mild subluxation. The more finger widths of separation, the more severe.
Here are some prevention and management strategies to improve arm function and strength:
- Constraint-induced movement therapy (forcing the use of the affected arm by restraining the unaffected arm with a sling)
- Mental practice with motor imagery (rehearsing a physical activity by memory without body movement)
- Task-specific training (relearning a given task by training specifically for that task).
With improved function and strength, the risk for shoulder subluxation decreases. But make sure the shoulder joint is protected during all exercise and training activities.
Slings and Other Support Devices
There are many types of shoulder slings that can help reduce subluxation. Slings that support the weight of the arm while allowing the elbow to straighten are the best option for reducing subluxation while promoting use of the arm, which is vital to recovery.
Slings that hold the elbow bent and the forearm close to the body (such as the triangular sling) promote stiffness that can lead to shoulder pain and shouldn’t be used for long periods of time. An incorrectly fitted sling can do more harm than good. Work with a physical therapist to choose the most appropriate style and to learn how to wear it correctly. Other positioning devices may be used to support the shoulder while in a wheelchair or bed. Wheelchair devices such as lap trays and arm troughs may be effective for reducing shoulder subluxation. It’s important to position the device and the arm correctly to prevent over-correction. Pillows can help with proper positioning in bed. For lying on the back, pillows should be placed under the forearm. This allows the upper arm to rest on the mattress. Ask a physical therapist to teach you proper positioning for each lying position.
When caring for someone with stroke, follow careful patient handling procedures. It’s important to protect the survivor’s weak arm during the transfer from bed to a chair, for example. Never pull on the affected arm when helping the person move, get dressed or bathe. When putting on a shirt, always put the affected arm into its sleeve first. Range of motion exercises must also be done properly to prevent shoulder subluxation and pain. Overhead exercises without appropriate instruction and support of the shoulder blade have been shown to substantially increase the risk of shoulder pain after stroke. Other conditions such as stiffness (hypertonicity) and decreased range of motion, particularly in turning the arm away from the body (external rotation), can also contribute to shoulder pain.
Help is available. Find a physical therapist in your area at moveforwardpt.com.