Tips to decrease shoulder strain in manual  wheelchair patients.

Shoulder injuries are all too common in the manual wheelchair user. Some studies estimate that up to 75% of manual wheelchair users will develop shoulder pain during their lifetime. It makes sense when you think about the fact that the shoulder was not designed for weight-bearing and locomotion. The impact of a shoulder injury can be devastating for the wheelchair user, impacting both their functional mobility and independence.

As clinicians, we can play a direct role in prevention via providing proper wheelchair prescription and setup, as well as providing education to our clients on muscular balance.

Etiology

Before we focus on prevention, it is necessary to briefly review the etiology of shoulder injuries. Rotator cuff tears, degenerative changes, and other pathologies about the coracroacromial arch are commonly found in wheelchair users with symptomatic shoulder pain. These degenerative changes occur from repeated microtraumas when the joint space between the humeral head (upper arm) and the acromioclavicular (A/C) shelf decreases to the point where repeated contact occurs on the same area on the supraspinatus tendon. The position and the repetitive loading of the shoulder joint for propulsion and transfers most likely contribute to these changes.

Preventive Strategies

As clinicians, we have three opportunities to help prevent shoulder-related injuries in our manual wheelchair clients. The opportunities are during the prescription phase for a new or replacement wheelchair, the adjustment/fitting of a wheelchair, and the assessment and treatment for muscular imbalances.

Wheelchair Prescription. Since we are nearly certain that repetitive stress or loading is the underlying cause of injury, it would make sense that we attempt to 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 prescribe the lightest chair possible. When dealing with Medicare and other third-party payors, you cannot expect to have coverage for lightweight or ultralight-weight wheelchairs without some resistance or requirement of strong medical necessity for this in your documentation. For active wheelchair users, those that are most appropriate are more expensive and fall under the K0005 code due to weight and adjustability. Fortunately, during the last few years, Medicare has allowed for an “advance determination process” for wheelchairs that fall under this code; so you, as a clinician, have an opportunity to medically justify the need for the lighter, more adjustable wheelchair.

Other considerations in the weight of the wheelchair are the components and seating devices. There are many different considerations with regard to the components. Keep in mind that the lightest option may not be the most appropriate due to other factors, such as capability and transportation issues. Having said this, the following are three more strategies to reduce the overall weight of the wheelchair: 

• Use spoke wheels rather than Mag wheels.

• 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 possibly transportation.)

• Use seat cushions. Most active users may not need a high-end pressure-relief cushion. However, 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 with out full use of the triceps. The point here is that you want to prescribe the lightest cushion that provides adequate skin protection.

Lastly, here’s one more issue worth mentioning with regard to prescription. About 10–15 years ago, the school of thought of many of the physicians and therapists was that if a client had the capability to propel a manual wheelchair, then a manual wheelchair should be prescribed over a power wheelchair. With regard to paraplegics and lower quadriplegics, this may be so. However, for higher quadriplegics—in particular, C5–C6 quadriplegics who do not have full function of their triceps—there should be greater consideration for power mobility. These clients are operating with a very limited muscle mass; and they are not only more likely to be susceptible to shoulder injury, but they are also are at great risk for bicep tendonitis and wrist injuries, which could eventually lead to loss of independence with transfers and self-care. Manual mobility in the community for many of these clients is extremely difficult and puts additional stresses on the joints of the upper extremities. Power mobility would spare the repeated stresses and microtrauma, sparing the available upper-extremity musculature for transfers and other functional tasks more likely for maintaining greater independence over time.

Centers for Medicare and Medicaid Services is reevaluating and revising the requirements for wheelchair coverage, and is now considering community mobility versus the rigid restriction within the home only with regard to qualification for mobility devices.

Wheelchair adjustments and pushing techniques. 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 “plowing” 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 antitippers.

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 nonsupportive wheelchair back that is stretched out, accommodating this poor posture. It is important that we teach wheelchair users stretches to the anterior musculature while strengthening the upper back, posterior shoulder, and scapular muscles. This is best achieved by having these clients perform exercises in prone or at least modified prone by flexing forward in their wheelchairs so that they can work the upper/lower trapezius, posterior deltoids, and rhomboids. A focus should also be on the external rotators of the shoulder. By restoring muscle balance, the acromiohumeral space can be preserved, minimizing the pressure on the rotator cuff.

The consequences of shoulder injury to the wheelchair user can be devastating. Preventive measures such as proper wheelchair prescription/fit and restoration of muscule balance can greatly assist in minimizing overuse injuries to the shoulder, maintaining independence.

Kevin Lockette is the president and owner of Ohana Pacific Rehab Services, LLC, with clinics in Honolulu and Kailua, Hawaii.