Development of novel biomechanical outcomes using motion capture to characterize hand function in multiple sclerosis

BACKGROUND: Nine-Hole Peg Test (9HPT) is limited to a single outcome and can be insensitive to impairment in people with MS (PwMS). OBJECTIVES: To develop novel biomechanical outcomes that better characterize upper extremity function in PwMS. METHODS: 16 PwMS and 16 healthy controls (HC) completed the manual dexterity test (MDT, an iPad adaptation of 9HPT). A Kinect® device was used to capture bilateral 3-dimensional, multi-joint hand motion and an advanced mathematical model was constructed to yield novel outcomes. Cross-sectional associations between the MDT outcomes and clinical characteristics (arm spasticity, dysmetria, upper extremity weakness) were evaluated and effect size calculated. RESULTS: 16 PwMS (mean age 55.91 years, disease duration 13.90 years) and 16 HC (mean age 40.45 years) completed the study. The novel measure of Time to Grab had a large effect size for dominant hand (η²p 0.23) and non-dominant hand (η²p 0.17). Several other novel measures (Actual Distance-xy (Insertion to Removal), Time to Grab, Time to Lift, Movement Delay (PiH), Movement Time (PiH), Movement Time (EH), and Abnormal Records of Local Maxima (Insertion to Removal)) and the traditional outcome of MDT total time had a large effect size for the non-dominant hand (η²p 0.25, 0.17, 0.17, 0.32, 0.23, 0.17, 0.20, 0.15, respectively). CONCLUSIONS: MDT Total Time showed an ability to discriminate PwMs from HCs supporting the continued use as a conventional measure. Several novel measures were also identified that demonstrated potential to discriminate PwMS from HCs and correlated with various clinical measures that the traditional measure did not.