Now that we’re seeing advanced prosthetic arms coming to market, rehab specialists need good metrics to evaluate the progress of individual patients that are adjusting to using the devices. A team of experts from a number of clinical institutions has come up with a set of tasks, like changing a shirt and using a spoon, and the criteria to rate how patients perform them.
The methodology is called Activities Measure for Upper Limb Amputees (AM-ULA) and involves 18 disparate tasks with objective standards by which to measure performance so that two therapists will have the same results. To validate their tool, a study involving 49 veterans using the new DEKA Luke arm at three hospitals was performed and led to some adjustments of the measure.
From Brown University:
Some existing measures are self-assessments where patients report how they are doing on a standardized scale, but Resnik said while those are essential, they don’t tell clinicians everything they need to know. For instance, an amputee might subconsciously use other body parts to compensate for an insufficiency with a prosthetic arm.
“This particular tool, because of the grading criteria that we use, considers aspects of movement quality that might not be picked up in a self report,” she said. “We look at the amount of body compensation used to perform a task – how much bending or use of other more proximal joints is involved in an activity. That’s important, because we know that upper limb amputees often develop problems in their neck and back.”
Resnik’s team built the new measure much like a prosthetics engineer builds an arm: they designed a prototype based on tasks from other measures, and refined it iteratively using feedback from content experts.
One of the key methods of refining the metric and ensuring its reliability was determining whether two independent raters, observing the same patient performance, arrived at the same ratings or strongly disagreed. The researchers also determined when raters differed with themselves when the test was administered twice within a short period of time. Originally the measure included 24 tasks, but ultimately six were dropped because the independent raters came to ratings that were too different, too often.
The researchers also validated the measure by making sure that the results made sense, based upon what was known clinically. For instance, scores of the AM-ULA were highest for people with amputation of the hand, lower for those with amputation above the elbow, and lowest for amputees with amputation at the shoulder.
More from Brown: New metric to track prosthetic arm progress
Article abstract in Archives of Physical Medicine and Rehabilitation: Development and Evaluation of the Activities Measure for Upper Limb Amputees