The shoulder is the most common site of pain reported by the wheelchair population. More than half of all people with weight bearing shoulder develop shoulder pain.
The length of weight bearing and wheelchair use correlates with the development of shoulder pain (that is, the longer you have been using a wheelchair the more likely you are to develop pain).
Weight bearing shoulders are more prone to injury as a result of:
- the repetitive nature of wheelchair propulsion
- the high-strength requirements placed on the shoulder muscles
- loading of the joints at extremes of motion
- muscular weakness or imbalance
- high internal joint forces and abnormal stresses applied to the subacromial area during weight bearing through the shoulder, wheelchair propulsion and transfers.
57-65% of manual wheelchair users have Rotator Cuff Tears as shown on MRI
Up to 75% of wheelchair users have radiographic changes in the shoulder joint
30-75% of wheelchair users develop upper extremity pain at some time
You can decrease your risk for injury by ensuring you reduce the amount of loading or resistance to the stroke for wheelchair propulsion. One simple way is to minimize the weight that has to be overcome with each stroke. With regard to the wheelchair, simply choose the lightest chair possible.
Other considerations in the weight of the wheelchair are the accessories and seating. There are many different considerations with regard to this. Keep in mind that the lightest option may not be the most appropriate due to other factors, such as capability and transportation issues.
Some easy ways to keep the weight of the mobility system down is to use spoked wheels rather than Mag wheels, and use a rigid frame rather than a folding frame. Rigid frames are lighter because they do not have the cross frame and hardware utilized by folding chairs. (The one consideration is transportation – how will you transport your chair in the car/van.) You may want to consider a power assist wheel or other power assistance device to reduce the amount of wear and tear on the shoulder joint.
DO use a cushion. Most wheelchair users may have a higher risk for skin breakdown due to lack of sensation or ineffective pressure relief if they are a higher level of injury without full use of the triceps. Choose the lightest cushion that provides the right level of skin protection for you.
The wheelchair setup will influence the propulsion technique and ultimately the amount of resistance or reactive force/stress that is translated back to the shoulder joint.
The more rearward the seat position is in relation to the wheel, the less rolling resistance and the more efficiency with propulsion the wheelchair will have. A more rearward seat positioning will promote a long and smooth stroke that limits high forces and the rate of loading on the pushrim that you will see with a short and abrupt “pumping”-style stroke. This is, of course, true only if the wheelchair user has adequate range of motion in his or her shoulder joint.
A rearward seat position basically has less drag because you are not loading the front casters as much, therefore not allowing a “ploughing” effect. The tradeoff is stability. The more rearward the seat position is, the less stable the wheelchair will be and the more likely it will tip backward.
For experienced users with a very low level of injury, this is not typically a problem; however, more inexperienced users or those with a higher level of injury may not have the seat set back as much or may need to use anti tippers.
Muscle imbalances. Most rotator cuff injuries are due to muscle imbalances of the shoulder. Shoulder strength and muscle length/range-of-motion imbalance can cause impingement of the soft-tissue structures of the acromiohumeral space.
Wheelchair users are even more susceptible to muscle imbalances. Nearly every motion and all repetitive motions are anterior, working such areas as the pecs, shoulder internal rotators, and anterior deltoid. These anterior muscles become tight and shortened, while the upper back muscles become weak and elongated. You can see these imbalances in the postures of chronic wheelchair users. A typical posture is rounded shoulders with mild thoracic kyphosis and forward head. This posture is even more accentuated by a non supportive wheelchair back that is stretched out, accommodating this poor posture.
It is important that we stretch the anterior musculature while strengthening the upper back, posterior shoulder, and scapular muscles. Check out http://www.thera-bandacademy.com/exercise/ for specific Rotator Cuff exercises.
Preventative maintenance with specific exercises is the key to longevity.
“Train before the Pain”