Hyodo Y1, Wachi M1, Jiroumaru T2
1Kanazawa Orthopaedic ＆ Sports Medicine Clinic, Shiga, Japan, 2Shiga School of Medical Technology, Shiga, Japan
Background: The longitudinal and transverse arches of the foot play important roles in load absorption. The support ligaments for the medial longitudinal arch are substantially affected by plantar aponeurosis. Furthermore, a study evaluating navicular height change as an indicator of medial longitudinal arch height showed that tibial nerve block reduced the activity of the abductor halluces by 27%, and increased the decline of the navicular bone during the loading phase. Thus, many studies have evaluated plantar aponeurosis and the abductor hallucis as sources of support for the medial longitudinal arch; however, the role of the abductor digits minimi(ADM) is still unclear. The ADM maintains the lateral longitudinal arch in combination with the fibularis longus and brevis. Electromyography (EMG) of the ADM usually involves the use of fine-wire electrodes. Although fine-wire electrodes can measure the deep muscle activity that surface electrodes cannot, they are invasive and painful, which restricts the subjects and affects the accuracy of data related to walking or running. In contrast, surface EMG is not invasive, is easy to use, and can be used to measure dynamic movement.
Purpose: To identify whether the ADM has an adequate area to enable surface EMG measurement, and to determine whether it is possible to collect data regarding the activity of this muscle.
Methods: The subjects were 20 healthy males (age 28.5±4.6 years). The thickness and width of the ADM were measured using a digital ultrasonic diagnostic apparatus with a B-mode, linear probe. The ankle joint was fixed in the intermediate position while the patient lay in the supine position on a bed. The muscle width (from the plantar part to dorsal part) and muscle thickness (from the subcutaneous to the deep layer) were measured at three positions: 10 mm, 20 mm, and 30 mm from the calcaneus to the fifth metatarsal. The surface area available for the surface electrode was calculated. The measurement conditions of the toes were: maximum flexion, maximum extension, and the intermediate position. SPSS software was used to compare the muscle widths and thicknesses at each position via one-way ANOVA. If there were significant differences between positions, each value was compared with the post hoc Dunnet test. The average and standard deviation of foot length were calculated.
Results: The surface area of the ADM was 234±19 mm2. The widths of the ADM were 11.7±1.0 mm at 10 mm, 11.7±1.1 mm at 20 mm, and 11.8±1.2 mm at 30 mm, with no significant differences between positions. The muscle thicknesses were 11.4±1.3 mm at 10 mm, 11.3±1.3 mm at 20 mm, and 11.2±1.3 mm at 30 mm, with no significant differences between positions.
Conclusion(s): The ADM has sufficient area on which to place surface electrodes and enable the conduction of EMG in an experimental study.
Implications: If the activity of the ADM can be clearly measured using surface EMG, the functional role of the muscle can be clarified. Furthermore, evidence of the contribution of the ADM during walking may lead to the prevention of disability due to dysfunction of the ADM.
Keywords: abductor digiti minimi, digital ultrasonic diagnostic apparatus, place surface electrodes
Funding acknowledgements: None
Purpose: To identify whether the ADM has an adequate area to enable surface EMG measurement, and to determine whether it is possible to collect data regarding the activity of this muscle.
Methods: The subjects were 20 healthy males (age 28.5±4.6 years). The thickness and width of the ADM were measured using a digital ultrasonic diagnostic apparatus with a B-mode, linear probe. The ankle joint was fixed in the intermediate position while the patient lay in the supine position on a bed. The muscle width (from the plantar part to dorsal part) and muscle thickness (from the subcutaneous to the deep layer) were measured at three positions: 10 mm, 20 mm, and 30 mm from the calcaneus to the fifth metatarsal. The surface area available for the surface electrode was calculated. The measurement conditions of the toes were: maximum flexion, maximum extension, and the intermediate position. SPSS software was used to compare the muscle widths and thicknesses at each position via one-way ANOVA. If there were significant differences between positions, each value was compared with the post hoc Dunnet test. The average and standard deviation of foot length were calculated.
Results: The surface area of the ADM was 234±19 mm2. The widths of the ADM were 11.7±1.0 mm at 10 mm, 11.7±1.1 mm at 20 mm, and 11.8±1.2 mm at 30 mm, with no significant differences between positions. The muscle thicknesses were 11.4±1.3 mm at 10 mm, 11.3±1.3 mm at 20 mm, and 11.2±1.3 mm at 30 mm, with no significant differences between positions.
Conclusion(s): The ADM has sufficient area on which to place surface electrodes and enable the conduction of EMG in an experimental study.
Implications: If the activity of the ADM can be clearly measured using surface EMG, the functional role of the muscle can be clarified. Furthermore, evidence of the contribution of the ADM during walking may lead to the prevention of disability due to dysfunction of the ADM.
Keywords: abductor digiti minimi, digital ultrasonic diagnostic apparatus, place surface electrodes
Funding acknowledgements: None
Topic: Outcome measurement; Musculoskeletal: lower limb; Musculoskeletal
Ethics approval required: Yes
Institution: Ethics Review Board of Kanazawa Orthopaedic & Sports Medicine Clinic
Ethics committee: Kanazawa-OSMC
Ethics number: 2018-001
All authors, affiliations and abstracts have been published as submitted.
