A Kinematic Comparison of Spring-Loaded and Traditional Crutches

in Journal of Sport Rehabilitation
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Context:

A novel spring-loaded-crutch design may provide patients additional forward velocity, relative to traditional axillary crutches; however, this idea has not yet been evaluated.

Objective:

To quantify elastic potential energy stored by spring-loaded crutches during crutch–ground contact and determine whether this energy increases forward velocity for patients during crutch ambulation. Because elastic potential energy is likely stored by the spring-loaded crutch during ambulation, the authors hypothesized that subjects would exhibit greater peak instantaneous forward velocity during crutch–ground contact and increased preferred ambulation speed during spring-loaded-crutch ambulation, relative to traditional-crutch ambulation.

Design:

Within-subject.

Setting:

Biomechanics laboratory.

Participants:

10 healthy men and 10 healthy women.

Interventions:

The independent variable was crutch type: Subjects used spring-loaded and traditional axillary crutches to ambulate at standardized and preferred speeds.

Main Outcome Measures:

The primary dependent variables were peak instantaneous forward velocity and preferred ambulation speed; these variables were quantified using high-speed videography and an optoelectronic timing device, respectively. Between-crutches differences for the dependent variables were evaluated using paired t tests (α = .05). Elastic potential energy stored by the spring-loaded crutches during crutch–ground contact was also quantified via videography.

Results:

Peak forward velocity during crutch–ground contact was 5% greater (P < .001) for spring-loaded-crutch ambulation than for traditional-crutch ambulation. Preferred ambulation speed, however, did not significantly differ (P = .538) between crutch types. The spring-loaded crutches stored an average of 2.50 ± 1.96 J of elastic potential energy during crutch–ground contact.

Conclusions:

The spring-loaded crutches appear to have provided subjects with additional peak instantaneous forward velocity. This increased velocity, however, was relatively small and did not increase preferred ambulation speed.

Seeley, Hunter, Bateman, Roggia, and Draper are with the Dept of Exercise Sciences, Brigham Young University, Provo, UT. Larson is with Alpine Orthopaedic Specialists, Logan, UT.