Prediction of Callus and Ulcer Development in Patients with Diabetic Peripheral Neuropathy by Isosceles Triangle-Forming Tuning Fork

Objectives: Tuning fork vibration sensation testing is widely used as a diagnostic test to detect diabetic neuropathy. However, evidence-based literature indicates that reliability between examiners is low. Attaching isosceles triangle diagrams on tuning forks lowers the discrepancy between examiners. This study aimed to analyze the relationship between vibration sensation measurement using an improved tuning fork and the presence of callus and wound development in patients with diabetic peripheral neuropathy. Methods: Participants included 56 general older adults and 52 patients with diabetic peripheral neuropathy. The methods included confirmation of the presence or absence of callus, range of motion of the ankle and the first metatarsophalangeal joint, vibratory sensitivity of the medial malleolus and the dorsal aspect of the first distal phalanx using an improved tuning fork, and touch-pressure sensitivity of the plantar aspect of the hallux. Patients with diabetic peripheral neuropathy were followed up for 3 years to check for the presence or absence of wounds. Results: When compared with the general older adults, the patients with diabetic peripheral neuropathy had significantly lower touch-pressure sensitivity ( p < 0.01), vibratory sensitivity at the distal phalanx ( p < 0.01) and medial malleolus ( p < 0.01), ankle dorsiflexion range of motion ( p < 0.01), and metatarsophalangeal joint extension range of motion ( p < 0.01). The area under the receiver operating characteristic curve with callus formation was 0.93 for the medial malleolus and 0.96 for the distal phalanx, indicating that the accuracy of the distal phalanx was higher ( p < 0.01) than the medial malleolus. According to the Cox proportional hazard analysis, the vibratory sensitivity of the distal phalanx was a significant risk factor for ulcer development ( p < 0.05). Conclusion: These findings suggest that the vibration sensation test, which we improved via the technique described in this study, is useful for predicting the occurrence of callus and ulcer.