1, 12, 35Īlthough the knee scooter remains a popular ambulatory aid, there is the potential for negative secondary effects of its use and it has the requirement of being piloted by 3 of 4 limbs. 27 Decreased muscle activity presents further risks as this decrease can reduce blood flow in the extremity and can reduce the force applied to venous walls, resulting in stagnation or reduced flow that can result in deep vein thrombosis.
27 This diminished EMG activity may help explain muscle atrophy that occurs during nonweightbearing. 27 However, the gastrocnemius of the immobilized limb was shown to have significantly lower activity during the use of every device, with the lowest activity occurring while using the knee scooter. 27 Some muscles involved in stabilizing the lower extremity while using assistive devices demonstrated higher levels of activity than normal walking. 27 It found that use of these devices resulted in different levels of muscle activity compared with normal walking gait. 1, 12, 23, 27, 35 A study by Sanders et al examined the relationship between electromyographic (EMG) activity in lower extremity muscles while using different ambulatory assistive devices, including a knee scooter, standard axillary crutches, and a novel prosthetic device. The type of ambulatory assistive device prescribed can affect the extent to which muscle atrophy is experienced because of the variability in limb positioning, muscle activation, and blood flow to the extremity. 2, 8, 27, 32 This loss of strength and muscle mass can lead to increased impairment and prolong the time to return to normal activity. 8, 17, 19, 32 Further, limb immobilization causes muscle atrophy, with the most rapid decreases to muscle size and strength occurring early on during nonwieghtbearing. 8, 17, 28, 34 Although the prolonged periods of nonweightbearing are necessary for healing, prolonged immobilization of the lower extremity can cause other unwanted effects such as increased swelling or stiffness. The amount of time a patient must use these devices is related to injury severity and the presence of other comorbidities. 8, 14, 17, 28 The ability to ambulate while maintaining nonweightbearing status is achieved through the use of assistive devices such as standard axillary crutches, knee scooters, or wheelchairs. 13, 17 Although injury type and severity are variable, injuries of the foot and ankle often require patients to undergo a period of nonweightbearing to facilitate healing.
Foot and ankle injuries are a common cause of disability.
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