Kinematic Asymmetries in the Wrist and Elbow During Axillary Crutch Use
Keywords:upper extremity, crutch, asymmetry, kinematics
Axillary crutches are frequently prescribed in North America to enable patients to ambulate safely through the support of the upper extremities. However, crutch use may result in abnormal upper extremity forces and movement patterns, potentially resulting in discomfort or injury. This study evaluated three gait asymmetry measurement approaches to quantify asymmetries in joint angles during crutch-assisted swing-through gait (STG).
Fifteen healthy adult males (ages 23 – 34 years) performed 10 trials of STG (1.40±0.07ms-1), landing on the left leg. Joint kinematics were recorded using a 10-camera optical tracking system (Motion Analysis, USA; 240Hz). Bilateral joint angles of the elbow and wrist were computed using Visual3D (C-Motion, USA) and normalized to 100% of the gait cycle. Asymmetry was quantified using Matlab (MathWorks, USA) at each percentage of the gait cycle using the symmetry index (SI)1, the normalized symmetry index2, and the symmetry angle3.
Asymmetry varied throughout the gait cycle, and values varied between the different methods. The symmetry index showed areas of artificial inflation of the calculated value due to the required use of a reference value (Figure 1). The normalized symmetry index did not have the same artificial inflations but still required the use of a reference value. The symmetry angle required no reference value. When the indices for a particular joint doing a specific motion were graphed generally all indices resulted in similarly shaped graphs. Peak asymmetry for radial-ulnar deviation of the wrist occurred at ~85% of the gait cycle, and peak asymmetry for flexion-extension of the elbow occurring at ~60% of the gait cycle.
CONCLUSIONSAxillary crutch use results in asymmetries at the elbow and wrist. These asymmetries vary throughout the gait cycle. In clinical practice, more injuries are seen on the side of the landing leg and the side of hand dominance.
The authors would like to thank the Cumming School of Medicine & Alberta Health Services Clinical Research Fund Pre-Seed Grant (#18-1202) and Natural Science and Engineering Research Council of Canada Undergraduate Student Research Award for supporting this investigation.
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