Background: Manual evaluation is an important method for assessing ankle instability, but it is not quantitative. Capacitance-type sensors can be used to measure the distance on the basis of the capacitance value. We applied the sensor to the noninvasive device for measuring ankle instability and showed its utility. Methods: First, 5 ankles embalmed by Thiel’s method were used in an experiment using a cadaver. The capacitance-type sensor was fixed alongside the anterior talofibular ligament (ATFL) of a specially made brace, and the anterior drawer test was performed. The test had been performed for the intact ankle, with the ATFL transected and with both the ATFL and calcaneofibular ligament (CFL) transected. The anterior drawer distance was calculated by the sensor. Intra- and interinvestigator reliability were also analyzed. Next, as a clinical study, a brace with a sensor was fitted to 22 ankles of 20 patients with a history of ankle sprain. An anterior drawer test at a load of 150 N was conducted using a Telos stress device. The anterior drawer distances measured by the sensor and based on radiographic images were then compared. Results: The mean anterior drawer distances were 3.7 ± 1.0 mm for the intact cadavers, 6.1 ± 1.6 mm with the ATFL transected ( P < .001), and 7.9 ± 1.8 mm with the ATFL and CFL transected ( P < .001). The intrainvestigator intraclass correlation coefficients (ICCs) were 0.862 to 0.939, and the interinvestigator ICC was 0.815. In the experiments on patients, the mean anterior drawer distance measured by the sensor was 2.9 ± 0.9 mm, and it was 2.7 ± 0.9 mm for the radiographic images. The correlation coefficient between the sensor and the radiographic images was 0.843. Conclusion: We quantitatively evaluated anterior drawer laxity using a capacitance-type sensor and found it had high reproducibility and strongly correlated with stress radiography measurements in patients with ankle instability. Capacitance-type sensors can be used for the safe, simple, and accurate evaluation of ankle instability.
Background/Purpose To investigate the relationship between anatomical variation of the toe flexor muscles and the resulting variation of toe flexion angle from tendon excursion. Methods Six cadaveric lower extremities preserved by Thiel’s embalming method were evaluated. The toe flexor muscles were distracted individually and toe flexion angles measured. The anatomic variation were observed by gross anatomical dissection. Results The toes with tendinous slips of flexor hallucis longus (FHL) showed similar flexion angles between the FHL and flexor digitorum longus. However, there were differences observed regarding toe flexion and tendon excursion of the flexor digitorum muscle and quadratus plantae due to the anatomic variations. Conclusion The anatomical variation of the toe flexor muscles should be taken into account when evaluating toe function and applying exercise therapy for foot disorders.
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