Pushrim biomechanics and injury prevention in spinal cord injury: Recommendations based on CULP-SCI investigations

Abstract

Over 50 percent of manual wheelchair users with spinal cord injury (SCI) are likely to develop upper-limb pain and injury. The majority of studies related to pain have implicated wheelchair propulsion as a cause. This paper draws from a large multisite trial and a long-standing research program to make specific recommendations related to wheelchair propulsion that may decrease the risk of upper-limb injury. The studies include over 60 subjects over 1 yr after a traumatic SCI below the second thoracic level. Specific aspects of the propulsive stroke that may relate to injury include cadence, magnitude of force, and the pattern of the hand during the nonpropulsive part of the stroke. Lower peak forces, slower cadence, and a circular propulsive stroke in which the hand falls below the pushrim during recovery may help prevent injury. In addition, wheelchair users should use the lightest weight adjustable wheelchair possible. Future work should include interventional trials and larger studies that allow for more complex statistical models that can further detail the relationship between wheelchair propulsion, user characteristics, and upper-limb injuries.

Manual wheelchair stroke characteristics during an extended period of propulsion

“…Furthermore, rapid loading of the arms during propulsion has been associated with a variety of overuse injuries including carpal tunnel syndrome. 7 Given the many injuries associated with propulsion, recent wheelchair research combined with ergonomic principles have lead to the creation of specific recommendations clarifying optimal propulsion technique. These recommendations appear as part of a clinical practice guideline developed by the Consortium for Spinal Cord Injury.…”

“…1 These guidelines indicate that wheelchair users should take long smooth strokes that minimize peak handrim and rate of rise forces, maximizing the time spent in propulsion and using the lowest possible cadence. 7 The purpose of this study was to administer a prolonged propulsion task that was challenging yet sustainable to discover how individuals' biomechanics would change to maintain a target velocity All dynamometer parameters were held constant to ensure that any biomechanical changes seen were not because of changes in the system. We hypothesized that as wheelchair users were challenged over time, their propulsion biomechanics would deteriorate.…”

A theoretical analysis of the influence of wheelchair seat position on upper extremity demand

“…Upper extremity pain and injuries that frequently occur in wheelchair users (e.g., Boninger et al, 2005;Mercer et al, 2006) can be very debilitating and lead to a decrease in independence and quality of life (e.g., Pentland and Twomey, 1994;Gutierrez et al, 2007;Requejo et al, 2008a;Riggins et al, 2011). The high incidence of pain and injury is correlated with the high physical demand placed on the upper extremity during wheelchair propulsion (e.g., Boninger et al, 2005;Requejo et al, 2008a). In addition to generating the mechanical power required to propel the wheelchair, the upper extremity muscles must also help maintain joint stability (e.g., Requejo et al, 2008a;Requejo et al, 2008b).…”

“…Seat position is an easily adjustable parameter that directly influences propulsion biomechanics (e.g., Boninger et al, 2000;Richter, 2001;Kotajarvi et al, 2004;Gorce and Louis, 2012) and upper extremity demand (e.g., Boninger et al, 2005;Mulroy et al, 2005;Requejo et al, 2008a). Thus, identifying the optimal seat position that minimizes upper extremity demand holds great promise for reducing the risk of pain and injury.…”

“…A number of studies have examined the influence of seat position on propulsion mechanics and found relationships with specific biomechanical measures such as cadence (e.g., Masse et al, 1992;Boninger et al, 2000;Richter, 2001;Kotajarvi et al, 2004;Gorce and Louis, 2012), handrim forces (e.g., Boninger et al, 2000;van der Woude et al, 2009), joint ranges of motion (e.g., Hughes et al, 1992;Wei et al, 2003;Gorce and Louis, 2012) and electromyography (EMG) activity (e.g., Masse et al, 1992;Gutierrez et al, 2005;Louis and Gorce, 2010). High levels of these measures have been identified as risk factors for upper extremity pain and injury (e.g., Boninger et al, 2005;Gutierrez et al, 2005;Gorce and Louis, 2012).…”