Clinical Information
Sagittal Plane Motion Chart
Introduction
Through numerous clinical studies, the Wijit DBS has been shown to provide many advantages over the use of standard manual wheelchair push rims, particularly in the areas of injury prevention and the promotion of a healthier lifestyle. These clinical studies include (click on each link to jump to that section):
- Case Studies (studies involving the effects on individual disabled persons)
- Clinical Papers (funded research projects done using scientific guidelines)
- Clinical Articles (studies that are source material from published articles)
Areas of Interest
The upper extremities are highly sensitive to overload due to their anatomical structure and the characteristics of the load placed on the structure by everyday life. It is widely understood that manual wheelchair users are much more prone to repetitive stress injuries of the hand, wrist, elbow and shoulder compared to the general population. These injuries include:
- Hand and wrist injuries such as arthritis, carpal tunnel syndrome, and tendonitis
- Shoulder injuries including rotator cuff injury
- Fractures, strains, and dislocations
These injuries are caused by the act of pushing the wheels 2,000 to 5,000 times per day, as well as by the magnitude and direction of the loads imposed on the joints in the process of self-propelling the chair. Wheelchair users are also prone to hand injuries such as friction burns, while braking or injuries caused by the fingers becoming entangled in the spokes.
The Wijit DBS protects the hands from injuries caused by direct interaction with the pushrim and spokes. It reduces the number of “pushes” per day by a factor of 2 to 3 times, which reduces the possibility of repetitive stress injury.
The Wijit is significantly easier to self-propel than a push-rim wheelchair, which helps the user maintain a more active lifestyle. This should reduce the incidence of cardiovascular complications and obesity. In many cases, the Wijit has enabled the user to transition from a power wheelchair to a manual wheelchair with resulting benefits to their cardiovascular condition and weight.
Case Studies
We are pleased to provide the following case studies on individual users:
Teenage male with C5-C6 SCI and TBI
Clinical Papers
The Wijit was studied as part of a NIDRR funded research project at the Rancho Los Amigos National Rehabilitation Center. The following papers summarize the results of this research:
Shoulder Joint Load During Lever Wheelchair Propulsion by Philip Requejo, Sharon Lee, Lisa Jaubert MPT, Ernest Bontrager, and Sara Mulroy
Wheelchair propulsion places an added burden on the upper extremities. The highly repetitive and weight-bearing nature of wheelchair propulsion often has been associated with development of upper limb pain in persons with SCI. Using a lever-propelled wheelchair has been suggested to be more efficient and less physically demanding than a pushrim-propelled wheelchair. Propelling with a lever mechanism also is thought to provide a more effective transfer of power by increasing mechanical advantage and placing the arms in a more natural segmental position and orientation.
Upper Extremity Kinetics During Wheelchair Lever Propulsion by Philip Requejo, Ernest Bontrager, and Sara Mulroy
Lever-propelled wheelchairs have been described as more efficient and less physically demanding than pushrim-propelled wheelchairs. Propelling with a lever mechanism is thought to provide a more effective transfer of power by placing the arms in a more natural segmental position and orientation. The objective of this work was to determine the joint forces and moments during lever propulsion using a kinematic and kinetic model and an instrumented lever.
Preservation of Upper Limb Function and the Wijit, by the Consortium for Spinal Cord Medicine
The Consortium for Spinal Cord Medicine published a report titled Preservation of Upper Limb Function Following Spinal Cord Injury: A Clinical Practice Guideline for Health-Care Professionals in 2005. This study outlined 35 recommendations that are generally applicable to all wheelchair users, not just SCI patients. This document summarizes these recommendations and how the Wijit relates to the recommendations.
Shoulder Muscular Demand During Lever-Activated vs. Pushrim Wheelchair Propulsion in Persons with Spinal Cord Injury, by Philip Requejo, Sharon Lee, Sara Mulroy, et al
The high demand on the upper limbs during manual wheelchair use contributes to a high prevalence of shoulder pathology in people with spinal cord injury. Lever-activated wheelchairs have been presented as a less demanding alternative mode of manual wheelchair propulsion. The objective of this study was to evaluate the shoulder muscle electromyographic activity and propulsion characteristics in manual wheelchair users with spinal cord injury propelling a standard pushrim and lever wheelchair design.
Clinical Articles
The following articles provide background information on upper extremity injury among wheelchair users.
Heavy Handed. Repetitive Strain Injury Among Manual Wheelchair Users, By Rory A. Cooper, Ph.D., Michael L. Boninger, M.D., and Rick N. Robertson, Ph.D
Prolonged manual wheelchair use can lead to pain and repetitive strain injury (RSI) of the upper extremities. The number of manual wheelchair users experiencing pain tends to increase with the time spent using a wheelchair. Although manual wheelchairs have improved tremendously over the past 15 years, many people continue to develop arm pain and injury due to cumulative trauma.
The Influence of Altering Push Force Effectiveness on Upper Extremity Demand During Wheelchair Propulsion, by Jeffery W. Rankin, Andrew M. Kwarciak, W. Mark Richter, and Richard R. Neptune
Manual wheelchair propulsion has been linked to a high incidence of overuse injury and pain in the upper extremity, which may be caused by the high load requirements and low mechanical efficiency of the task. Previous studies have suggested that poor mechanical efficiency may be due to a low effective hand-rim force (i.e. applied force that is not directed tangential to the hand-rim). As a result, studies attempting to reduce upper extremity demand have used various measures of force effectiveness (e.g., fraction effective force, FEF) as a guide for modifying propulsion technique, developing rehabilitation programs and configuring wheelchairs. However, the relationship between FEF and upper extremity demand is not well understood. The purpose of this study was to use forward dynamics simulations of wheelchair propulsion to determine the influence of FEF on upper extremity demand by quantifying individual muscle stress, work and handrim force contributions at different values of FEF.