What do you Expect a Knee Brace to do?
What do you expect a knee brace to do? As a patient, this question has likely crossed your mind when you peruse through the many options available on the market today. As a therapist, this question is fundamental for prescription, and as an athlete or manual laborer have you not wondered whether bracing might in fact make your life easier?
Does this expectation depend on the brand? Vary with the cost? Depend on evidence of scientific rigor to support the intended mechanisms of action whether they are patellar tracking, knee stability, offloading or extension assist?
Recent years have seen the growth of knee bracing into a multi-million dollar industry. Today, many brace designs are available from single neoprene sleeve designs, offloader braces for the treatment of knee osteoarthritis to powered robotic exoskeletons for independently controlling lower extremity joint function. Difficulties can exist when attempting to sift through the promises, anecdotes, expert opinions and scientific evidence to support knowledgeable decision making when it comes to knee joint bracing.
Many knee braces are available that primarily offer support though structural design. Few however provide, in addition to this structural support, assistance for knee joint movement; a brace that responds to your inputs. This novel application has the potential to augment knee joint function making it easier to accomplish activities from those fundamental to daily living to alpine skiing and more. One particular category of this novel bracing phenotype is the knee extensor assist (KEA) design.
Knee bracing with augmented assistive device technology has recently attempted to address and enhance the role of the musculature to promote healthy knee function. Enhancing the muscles’ abilities also offers the possibility of reducing the wearer’s fatigue, which potentially may enhance performance in manual laborers, military foot soldiers, and athletes as well. KEA devices exemplify such assistive devices.
A number of KEA bracing options exist, from those that offer assistance through the use of elastics, springs or a combination of both. There are even those that are sport specific. The scientific literature to support the effectiveness of these knee braces is lagging behind design and innovation. In a single biomechanical analysis, a KEA device mounted to a knee-ankle-foot orthosis was shown to provide between 50 and 56% of the force required to stand up from sitting [1]. To my knowledge, this is the only rigorous scientific evaluation of this brace design. Despite the number of brace options, a dearth of scientific evidence exists to support their mechanisms of action. Are these braces functional? Are they strong enough to assist an athlete in improving performance? Can they be worn all day in individuals with knee OA? A fundamental question; do these braces contribute to measurable differences in joint function that have implications for enhancing capacity and knee joint performance?
Future testing of KEAs in new applications and settings has been proposed to determine the magnitude of benefit KEAs may provide. Improvements in current designs have also been suggested to increase the likelihood of KEA use among various populations. The potential exists for KEAs to benefit athletes, those managing knee osteoarthritis and individuals living with poor muscle control as a result of stroke or brain injury as a protective, performance and capacity enhancing device.
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