The VA-Cyberware lower limb prosthetics-orthotics optical laser digitizer

Characterization of the residual limbs and limb segments of patients for prosthesis and orthosis design has principally been a subjective process, highly dependent upon the skill, level of training, and experience of the prosthetist/orthotist involved. Even with the application of computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies in prosthetics and orthotics, residual limb/limb segment characterization has remained substantially subjective and dependent upon prosthetist/orthotist skill, training, and experience. To eliminate the variations and errors that frequently occur because of this dependence, and to further quantify the patient measurement process, rehabilitation engineering researchers at the New York Department of Veterans Affairs Medical Center developed an optical laser digitizer for quantitative characterization of patients' residual limbs'/limb segments' spatial geometry and surface topography. The optical digitizer developed is described, and results of laboratory and clinical tests with the digitizer are presented. Examples showing the capability of the digitizer to accurately, rapidly, repeatably, and consistently capture the contours over the entire surfaces of the residual limbs of patients with below-knee (BK) and above-knee (AK) amputation, the lower limbs of orthotics patients, and the feet and ankles of pedorthics patients, are given. In addition, results of a comparative clinical study of optical digitization and standard prosthetics CAD plaster wrap cast electromechanical digitization of the residual limbs of subjects with BK and AK amputation are presented. The enhanced accuracy, repeatability, and consistency afforded by optical digitization are shown. Finally, areas for refinement of the optical digitizer's design, identified in the project's laboratory and clinical tests, are discussed.