Spring-Assist Technology
There's a spring built into the shaft of every in-Motion crutch. When you press down, it gives a little, so the force of each step reaches your hands and wrists more gradually. Researchers have been measuring that effect since 1989. This is what they found.
How it works
A standard crutch is a rigid pole. When your weight lands on it, the force spikes almost instantly and runs straight up into your wrists and shoulders. Do that a few thousand times a week, month after month, and the wear adds up.
The spring changes the timing. It stretches the impact across a longer moment, so the force builds gradually instead of arriving all at once. In a 2007 study at Penn State, that alone cut the rate of force build-up by a third and lowered the total impact per step by up to a quarter.
The peak force ends up about the same. The difference is how you get there.
Illustrative, based on Segura & Piazza (2007) and Liu et al. (2011)
A standard crutch loads in a sharp early spike, then again at push-off. Researchers found the spring turns that into a single, gradual rise — the force builds slowly instead of slamming in.
Why it matters
Because the spring slows how fast the force builds, less of the jolt travels up your arms with each step. In testing, the rate of force build-up dropped by a third and the total impact per step fell by 13 to 26 percent.
Segura & Piazza, Arch Phys Med Rehabil, 2007 · see study
An early study of spring-loaded axillary crutches measured the peak load on the hand and wrist dropping by roughly a quarter compared with a standard crutch. Those are the joints that take the brunt of crutch use, day after day.
Parziale & Daniels, Am J Phys Med Rehabil, 1989 · see study
A standard crutch hits the ground in two force peaks per step. Researchers found an optimized spring smooths that into a single peak, and the energy the spring stores gets returned into your stride instead of being lost into the pavement.
Liu et al., Int J Adv Robotic Syst, 2011 · see study
Because the spring gives some of that stored energy back as you push off, your body doesn't have to supply all of it. In a gait study, calf muscle activity was measurably lower on spring-loaded crutches than on standard ones.
Kang et al., J Phys Ther Sci, 2016 · see study
rate of force build-up vs. a standard crutch (p < .001)
less total impact per step through the crutch
lower peak load on the hand and wrist
Figures come from the peer-reviewed studies cited below. They describe the spring-loaded crutch designs tested in each study.
The research
Spring-loaded crutches have been studied in university labs for more than thirty years. Here are the studies behind the claims on this page. Every one is linked so you can read it yourself.
Spring-loaded crutches cut the rate of force build-up by 33% and reduced the total impact per step by 13–26% (both p < .001). Peak force was slightly higher, but the authors concluded the change in mechanics is “likely to reduce overuse injury in crutch users.”
Read on PubMedOne of the earliest lab tests of spring-loaded axillary crutches. It found the initial peak load reduced by about a quarter and the impact force by about a fifth versus a standard crutch.
Read on PubMedForce through an optimized spring-loaded crutch came out as a single peak, versus the two peaks of a standard crutch. The stored elastic energy made a significant contribution to the work of walking — energy returned rather than lost.
Read full text (open access)Calf (gastrocnemius) muscle activity was significantly lower with spring-loaded crutches than with standard axillary crutches (42.4% vs. 49.9% of maximum, p = 0.020), while the spring lifted the body higher per step. The authors concluded spring-loaded crutches allow efficient gait with less muscle effort and may help protect the upper limbs.
Read full text (free)The rest of the crutch
The forearm handle is set at 13 degrees to keep your wrist closer to a neutral position, instead of bent back the way a flat grip forces it.
The spring inside the shaft absorbs the impact of each step. It's the piece every study on this page is about.
Its own insurance code: E0117, “crutch, underarm, articulating, spring assisted.”
The tip pivots to stay flat on the ground as the crutch angle changes, so you keep full contact on stairs, slopes, and uneven ground.
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Forearm and underarm models, in short and tall. Backed by a real warranty and real people who answer the phone.
The in-Motion crutch is a Class I medical device (forearm HCPCS E0110, underarm HCPCS E0117). The studies cited here tested spring-loaded crutch designs in general and are shared to explain the principle behind our technology, not as medical advice or a promise of results. Individual experiences vary. Talk with your clinician about what's right for you.