A method for quantifying the biodynamics of abnormal distal upper extremity function: Application to computer keyboard typing

Date of Completion

January 1999


Health Sciences, Rehabilitation and Therapy|Engineering, Biomedical




Clinical and laboratory methods for biodynamic applications of digital infrared motion capture (DMC) technology have typically been focused on the motions of large anatomic structures and/or structure groups such as the hip, knee, and/or ankle. The motions of these structures occur within a large spatial volume allowing for simple and straight-forward camera system configurations, while structure size allows for flexibility in marker placement. Biodynamic applications of DMC technology to the distal upper extremities (e.g. wrist, hand, and/or digits) have been limited due to the complex nature of the motions and anatomic structures involved. For this dissertation, a new method is developed for biodynamic applications of DMC technology to monitor distal upper extremity function. This method is used to record patterns of distal upper extremity function during computer keyboard typing. These recordings are used to identify movement abnormalities by quantifying joint displacement angles beyond established normal ranges. Development of marker placements, camera positioning, data analysis, display programs, and system validation are discussed in detail. A vector analysis approach was used to determine joint displacement angles for comparison with abnormal threshold values. In initial experiments, the clinically significant movement characteristics for the first digit, fifth digit, and wrist of both hands were assessed from a sampled subject population of twelve (six clinically symptomatic and six non-symptomatic) keyboard users. These subjects were asked to type two different sentences, each of which required use of every alphabetic key at least once. Results suggest that overall typing movements for each subject appear to be intrinsic and remain consistent regardless of the text that is typed. This is observed for movements within normal ranges and those exceeding normal ranges. In contrast, joint displacements are affected by the structure of the sentence. ^