VALIDATION OF A 3D OPTOELECTRONIC MOTION ANALYSIS SYSTEM FOR THE WRIST JOINT

Objective. A study was undertaken to determine the experimental accura cy of a non-invasive optoelectonic 3-dimensional tracking system in as sessing wrist joint motion. Design. This was an in vivo experimental s tudy involving volunteer subjects performing prescribed wrist motions. Background. Current clinical practice does not include routine kinema tic analysis for evaluating arthritic disease state, although motion d isorders are common. Methods. Surface markers were applied to 24 subje cts assigned two hand postures in a test-retest factorial design for t he expected range of motion. The marker positions were measured optoel ectronically and using calibrated stereoradiography, to determine the positions of the surface markers and of key bone landmarks. Alignment and motion were compared for the three measurement techniques. Standar d kinematic analyses were performed to extract Euler angles and equiva lent screw displacement axes for paired postures. Results. The three m easurement techniques were highly correlated for wrist flexion-extensi on. Uncertainties were less than 6 degrees, similar to uncertainties f rom bone landmark identification errors when implanted markers cannot be used. Measures of motion exhibited higher correlations than those f or alignment. Equivalent screw displacement axis orientations had poor intraclass correlations, reflecting sensitivity to coordinate system definitions. Conclusions. For motion analysis in the wrist in vivo, a non-invasive optoelectronic measurement system is as accurate as stere oradiographic analysis of bone segments. Relevance A non-invasive opto electronic system is suitable as a clinical evaluation tool. Radiograp hic examination of the hand is not required for kinematic analysis, al though radiographs may provide other clinically useful information. Co pyright (C) 1996 Elsevier Science Ltd.