We suggest short range stiffness (SRS) at the elbow joint as an alternative diagnostic for EMG to assess cocontraction.Elbow SRS is compared between obstetric brachial plexus lesion (OBPL) patients and healthy subjects (cross-sectional study design). Seven controls (median 28. years) and five patients (median 31. years) isometrically flexed and extended the elbow at rest and three additional torques [2.1,. 4.3,. 6.4. N. m] while a fast stretch stimulus was applied. SRS was estimated in silico using a neuromechanical elbow model simulating the torque response from the imposed elbow angle.SRS was higher in patients (250. ±. 36. N. m/rad) than in controls (150. ±. 21. N. m/rad, p = 0.014), except for the rest condition. Higher elbow SRS suggested greater cocontraction in patients compared to controls. SRS is a promising mechanical alternative to assess cocontraction, which is a frequently encountered clinical problem in OBPL due to axonal misrouting.

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PLEXUS is an expert system which has been designed to advise physicians on the complex subject of brachial plexus injuries. Patient history information and results of neurological, neurophysiological and neuroradiological examinations are entered into the computer by the physician. Computer output consists of the localization of the injury, indication of the severity of the injury, and a treatment plan. PLEXUS was validated in cooperation with four international experts and was tested clinically in four hospitals. The independent validation showed that PLEXUS has a good performance. Features which must be improved include the extension of the functionality of the system to facilitate a more direct communication, and enhancement of the system's ability to assist in data gathering and entry. This study highlights the importance of thorough validation for the development of these kinds of systems.@en