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Abstract-It is hypothesized that the cane and forearm can be aligned to reduce muscular activity needed during ambulation. In this prospective study, 10 nonimpaired control subjects were tested both in stationary and dynamic weight-bearing states while using different cane prototypes and the platform cane (PC) as compared to the standard cane (SC). The outcome measures were: 1) root mean square (RMS) voltage (µV) of electromyographic (EMG) signal as a measure of muscle power and 2) distance of ambulation. Results of stationary cane use showed that Prototype 1 decreased RMS output by 19 percent (p=0.01), Prototype 2 with wrist splint decreased it by 23 percent (p=0.003), and the PC decreased it by 68 percent (p<0.0001) as compared to the SC (ANOVA, posthoc LSM). In conclusion, the two prototypes and the PC significantly decrease RMS voltage muscle output in the upper limb, compared to the SC.
Key words: biomechanics, cane, gait aid, upper limb.
INTRODUCTION
There has been an increase in the number of patients diagnosed with musculotendinous, neuropathic, or arthritic conditions of the arms as a result of repetitive trauma. Walking canes have also been implicated in worsening these conditions. Thus far, literature on use of the cane has focused on decreasing the muscle exertion in the leg but not the arm (1-5).
The upper limb has not been well studied as a weight-bearing limb. In evolutionary terms, clawed quadripeds bore weight through the shaft of the long bones that served as pylons. The hand or foot was used simply as a springboard and balance device. Similarly, as infants, we crawl on our hands with our wrists extended, but always bear weight predominantly through the wrist rather than the hand. Gorillas bear weight through their knuckles. This assists in maintaining a neutral wrist alignment and allows continued weight bearing through the long-- bone axis. In contrast, the human who uses a cane hyperextends his wrist when weight bearing, causing a malaligned vector of force through the hand at the level of the metacarpal bones. This creates torque about the wrist joint. Any person who has temporarily required the use of a cane or crutch knows the discomfort involved. It is well documented that chronic cane or crutch use leads to repetitive stress disorders such...