Using the Exos Handmaster to measure digital range of motion: reliability and validity

Traditional assessment of digital range of motion via a standard goniometer is a weak correlate of hand function and task performance. Yet it remains one of the primary, quantitative methods of hand assessment used to determine an individual's ability to return to work or to assess his or her permanent functional impairment. Another technique more representative of functional performance would be immensely useful for clinicians, patients, employers and third-party payers. The objective of this research was to investigate the clinical feasibility of using the Exos Handmaster, a Hall-effect instrumented exoskeleton, to measure angular joint rotation of the metacarpophalangeal and interphalangeal joints. The work reported in this paper includes a description of modifications to the fixation technique and calibration procedures of the Handmaster and the results of an investigation of the unit's reliability and validity.