Wheelchair Skills Training - Obstacles
Original Editor - Lee Kirby as part of the Wheelchair Service Provision Content Development Project
Getting Over Obstacles Or Gaps
Description and Rationale
The learner moves the wheelchair over an obstacle or a gap across the line of progression. Wheelchair users often encounter obstacles (e.g. door thresholds) of various sizes and shapes that they may not be able to simply roll over. Alternative strategies may be needed. For example, a wheelchair user might need to pop the casters over the obstacle. A gap in surface support is a commonly encountered barrier (e.g. due to a rut in the road, a water channel or a space between a subway platform and a subway train). Gaps that only affect one wheel at a time are not usually major obstacles. In this section, only gaps that are as wide as the wheelchair will be considered. Small-diameter wheels (such as casters) can drop into such gaps, causing a sudden deceleration that can tip the wheelchair over forward or lead to the wheelchair user falling out of the wheelchair. Even if no tip or fall occurs, it can be difficult to get the wheelchair out of the gap.
General Training Tips
- The best approach is to avoid obstacles or gaps, steering around them or straddling them.
- If the wheelchair gets hung up on an obstacle due to insufficient distance between the front and rear wheels (short wheelbase), the learner may be able to escape by backing up slightly; this will swings the casters from the rear-trailing position to the side- or forward-trailing one, where there is more space between the front and rear wheels.
- The most common approach to getting over a gap, although not necessarily the safest or most effective, is to approach the gap squarely.
- If the casters drop into the gap and they turn sideways (a common problem if the wheelchair is moved forward and backward repeatedly in an attempt to get the casters out of the gap), it can be very difficult or impossible to proceed without assistance.
Forward Approach, Stationary Method:
- The square-on forward approach is useful to include in training because the method used is part of a step-wise sequence leading toward the ascent of curbs.
- The wheelchair user should approach the obstacle and stop with the casters 5-10 cm before reaching the obstacle, to avoid striking the casters on the vertical section of the obstaclewhile popping them.
- This method is comprised of two steps: “pop” and “lean”. These cues can be verbalized as the steps are performed.
- The wheelchair user first briefly pops the casters from the floor, just high enough to clear the obstacle. To do so using the two-hand propulsion method, the wheelchair user applies forward forces of moderate intensity to the hand-rims (a “slap” vs. a “push”, as noted earlier). After the casters land beyond the obstacle and the rear wheels encounter resistance, the wheelchair user should lean forward to help power the rear wheels over the obstacleor gap and prevent rear tipping. Some rocking may be needed.
- Once the rear wheels are on top of a high obstacle, the wheelchair user should lean back to decrease the likelihood of a forward tip or fall out of the wheelchair.
- For a gap, the casters can be stopped at the edge of the gap. There is less need to pop the casters “high” than to pop them “long” to get across the gap. As for the “rolls on soft surface” skill, a long “step” can be achieved by ensuring that the hands remain on the hand-rims for as long as possible (i.e. 11:00-2:00 o’clock using the clock analogy).
Forward Approach, Momentum Method:
- This method is comprised of three phases: “approach”, “pop” and “lean”. As for the stationary method, the cues can be verbalized as they are performed.
- In preparing to pop the casters while the wheelchair user moves forward during the approach, the wheelchair user may briefly coast to allow correct placement of the hands when he/she is at the proper distance from the obstacle.
- The wheelchair user should initially approach at a slow speed, square to the obstacle or gap. It is simpler to pop the casters when moving slowly. Also, if the wheelchair user fails to pop the casters for long enough to clear the front edge of the obstacle or back edge of the gap, the sudden stop will be less jarring at a slow speed.
- The wheelchair user should not lean forward to look at the feet when he/she approaches the obstacle or gap, because that increases the weight on the casters. In timing the caster pop, the wheelchair user needs to understand where the casters are (often below the knees rather than under the feet). A mirror placed to the side of the obstacle or gap can be used to provide feedback.
- The correct position of the hands, at the beginning of the popping phase, is when they are ready to grasp the hand-rims, behind top dead center (11:00 o’clock on the right wheel, using the clock analogy). Then, the wheelchair user should accelerate the chair even faster than it is coasting, by using a stroke of moderate force that is powerful enough to pop the casters from the surface high enough and long enough.
- Once the casters have landed beyond the obstacleor gap and the rear wheels strike the obstacle or gap, the wheelchair user should lean forward and propel the rear wheels to bring the rear wheels over the obstacle or up out of the gap. If the obstacle is a high one, the wheelchair user should lean back once the rear wheels are on top of the obstacle.
- When moving forward over an obstacle or gap, some advanced wheelchair users prefer to allow the rear wheels to reach the surface beyond the obstaclebefore having the casters land on the surface. However, when initially learning the skill, it is preferable that the casters land beyond the obstacleor gap before the rear wheels strike the obstacle. This will be especially useful when learning to ascend curbs, to avoid “caster slap”.
- Although the techniques used for getting over gaps and obstacles are very similar and the gap technique is easier, the gap can be more intimidating for learners so we usually teach the learner how to get over an obstacle before progressing to the gap.
- The learner should start with a slow speed and progress to faster ones.
- The learner should start with low obstacles and progress to higher ones. Obstacles with a height of 10 cm or greater are negotiable in the right wheelchair. Before attempting to negotiate a high obstacle, the learner should be aware of how much clearance exists between the wheels and under the frame or chassis of the wheelchair, to avoid getting hung up on the obstacle.
- The learner should start with small shallow gaps and progress to more challenging ones.
- This is the first of a series of skills for which the ability to pop the casters in a specific location and to move forward are very helpful.
- To practice getting the timing correct without the fear of having the casters strike the obstacle or gap, the wheelchair user may practice propelling the wheelchair forward and transiently popping the casters at a predetermined point on the floor. This can be a line on the floor or a strip of bubble wrap. The horizontal distance over which the casters need to be off the floor can be gradually increased.
- The learner should start with the stationary approach then progress to the momentum method.
- For learners experiencing difficulties in coordinating the sequence of the three phases of the skill (approach, pop and lean), it may be useful to practice them in segments before putting the segments together.
- The wheelchair user may use the external environment if available (e.g. door frame) to pull the rear wheels over the obstacle or gap.
- As noted earlier for the “maneuvers sideways” skill, to get beyond a pair of obstacles (e.g. concrete parking bolsters) or gaps that are too close to wheel between, it may be possible to move one wheel (or pair of wheels) through the space at a time, transiently straddling the obstacles with one wheel (or pair of wheels) on either side of the obstacles or gaps and the wheelchair parallel with the obstacles or gaps.
- The wheelchair user may find it easier to back over a low obstacle or gap. The wheelchair user should approach the obstacle or gap slowly, because a sudden stop can cause a rear tip. As the wheelchair user approaches the obstacle or gap backward, he/she should lean forward to unload the rear wheels and further reduce the likelihood of a rear tip. The wheelchair user pulls the wheelchair straight backward by applying equal force to both wheels. Otherwise, the casters may turn and catch sideways on the obstacle or in the gap. Once the rear wheels are over the obstacle or gap, the wheelchair user should lean back enough to unload the casters as they reach the obstacle or gap, but not so much as to cause a rear tip.
- The oblique approach to a gap is often safer and more effective than the square-on approach. As long as three wheels are supported at any time, the wheelchair will usually remain upright. That being the case, an oblique approach to a gap (e.g. 30-45° from the line of progression so that only one wheel is unsupported at a time) is a useful strategy. The wheelchair user should keep his/her weight away from the unsupported wheel.
- See the wheelie variation later.