Wheelchair Frame and Vibration
The choice of wheelchair frame and wheels play an important part in the management of spasticity and perceived comfort. The wheelchair frame can decrease the amount of whole-body vibration felt by the individual when traversing over rough surfaces such as bumps in sidewalks or, tile floors (Vorrink et al. 2008).
|Vorrink et al. 2008
|Population: Mean age: 46.2 yr; Gender: males=10, females=3; Level of injury: C=3, T=10; Severity of injury: complete=7, incomplete=2, unknown=4.
Intervention: Subjects were asked to perform an obstacle course in their own wheelchairs and were randomly assigned one of two types of wheels: spinergy or steel traditional spoke wheels.
Outcome Measures: Average speed, Peak acceleration, Root-mean-square, Visual Analog Scale (VAS).
|1. The two wheel types did not differ in their average speed, peak acceleration, and RMS or peak power.
2. Overall, the footplate compared to the axel had higher peak accelerations (p<0.001) and RMS values (p<0.001).
3. Spasticity and comfort measures on the VAS and the overall VAS did not differ significantly between the two wheel types.
4. Steel spoked wheels showed a trend towards being rated as higher in spasticity on 8/9 obstacles (p=0.06).
|Effect Sizes: Forest plot of standardized mean differences (SMD ± 95%C.I.) as calculated from pre- and post-intervention data.
|Garcia-Mendez et al. 2013
|Population: Mean age: 47.6 yr; Gender: males=32, females=5; Injury etiology: SCI=25, amputation=6, MS=3, other=3; Level of injury: paraplegia=20, tetraplegia=5; Mean duration of w/c use: 15.0 yr.
Intervention: Exposure to whole body vibration was measured over a 2 wk period using a vibration data logger (VDL) at the back support and the seat and a manual wheelchair data logger (MDL) which measures distance speed and continuous movement.
Outcome Measures: Shock-sensitive vibration evaluation method (VDV) of the seat surface and back support, duration of vibration exposure, frequency-weighted acceleration.
|1. Participants spent an average of 13.07 hr/day in their wheelchairs.
2. Nearly 31% of participants were exposed to vibration levels at the seat within the health caution zone, and the rest of the participants were exposed to levels above this zone.
3. Exposure to vibration measured at the back support was lower and tended to be localized within the health caution zone in comparison to the seat.
4. Suspension systems did not significantly decrease the vibration exposure at the wheelchair frame.
Whole body vibration levels measured at the seat surface and the back support were found to be higher than the health caution zone levels recommended by ISO 2631-1 (Garcia-Mendez et al. 2013). Vibration measured in the rigid frames and frames with suspension were noted to be lower than that measured on a folding frame wheelchair, but no comparison calculations were provided. The authors indicate that the use of suspension systems added to the frames did not significantly reduce vibration, but data or comparison calculations were not provided.
Vorrink et al. (2008) found no significant differences between wheel types in vibration forces, speed or meausres of spasiticty or comfort during propulsion.
There is level 2 evidence (from one randomized controlled trial: Vorrink et al. 2008) that the use of high-performance wheels verses standard steel-spoked wheels was no more effective in reducing spasticity or affecting comfort by absorbing vibration forces when wheeling.
There is level 4 evidence (from one post-test study: Garcia-Mendez e t al. 2013) to suggest that whole body vibration exposure for people who use manual wheelchairs are within or above the health caution zone established by ISO.