A new quantitative evaluation system for distal radioulnar joint instability using a three-dimensional electromagnetic sensor

Abstract

Background The accurate assessment of distal radioulnar joint (DRUJ) instability is still challenging as there is no established objective evaluation method. This study aimed to develop a noninvasive measurement method using a three-dimensional electromagnetic sensor system (EMS) to quantitatively assess and characterize the normal DRUJ movement in healthy volunteers. Methods The DRUJ movement was mimicked using both a block model and saw bone. Movement of the models was measured by EMS, and the accuracy and reproducibility of the measurements were assessed. The movement was evaluated in 14 healthy volunteers (7 men and 7 women) by three hand surgeons. Measurement was done in a sitting position with the elbow flexed and the forearm pronated. One sensor each was attached to the distal radial shaft and the ulnar head. The examiners fixed the distal radius and moved the ulnar head from the dorsal to the volar side, measuring the dorsovolar ulnar head translation. The intraclass and interrater correlation coefficients (ICCs) were calculated using the average values of the measurements. The differences between the dominant and non-dominant sides and between men and women were also assessed. Results The accuracy and reproducibility assessment results of the EMS showed high accuracy and reproducibility. The ICC (1,5) for the intra-rater reliability was 0.856, and the ICC (2,5) for inter-rater reliability was 0.868. The mean ulnar head translation and difference between dominant and non-dominant sides were 6.00 ± 1.16 mm (Mean ± SD) and -0.12 ± 0.40 mm, respectively. There were no significant differences between any of the parameters.Conclusions A new measurement method using EMS could evaluate DRUJ movement with high accuracy, reproducibility, and intra- and inter-rater reliability. In healthy volunteers, the dorsovolar ulnar head translation was 6.00 mm. The difference between the dominant and non-dominant sides was < 1.0 mm with no significant difference. EMS provided an objective, non-invasive, real-time assessment of dynamic changes in the DRUJ. These findings could be useful in the treatment of patients with DRUJ instability.

Magnetically Levitated Flexible Vibration Sensors with Surficial Micropyramid Arrays for Magnetism Enhancement

“…Electromagnetic vibration sensors can directly convert mechanical vibration into current due to the Lenz effect, allowing a battery-less and self-sustainable operation to monitor the vibration of mechanical structures 1−4 and machines 5,6 as well as motions of the body 7−9 and joints. 10,11 Their core components are magnetically coupled to allow contactless operation and avoid mechanical abrasion, resulting in prolonged life spans and high durability that are preferable in harsh environments. Various electromagnetic vibration sensors have been developed with essential vibration elements physically connected with elastic springs, 12−14 diaphragms 15,16 and cantilevers 17−19 or levitated by a magnetic field.…”