ABSTRACT
A previous study by Koch and Nickel (1978) determined the changes in the distraction forces in the halo-vest during different activities. The present study determined the variations of forces in different directions between the halo and the vest also during different activities. Clip-on strain gauges were used to measure the strains in the bars, while an on-line computer system was used to compute the forces. Anterior-posterior forces were found to be comparable with vertical ones. These forces and the changes during a particular activity were caused by gravity forces of the head in activities involving a change in attitude; and vest distortion from changes in body shape, direct pushing from the lower abdomen, the arms and shoulders, or from supporting surfaces. Activities producing the highest force changes included bending forwards from a seated position and reaching over sideways while lying. Medial-lateral forces were small in comparison with vertical and anterior-posterior forces. Implications of the study were that pin-skull forces were multidirectional, and that certain improvements in design could be effected by accounting for the factors causing high forces and consequently cervical motion.
Subject(s)
Braces/standards , Spinal Injuries/therapy , Traction/instrumentation , Adolescent , Adult , Evaluation Studies as Topic , Humans , Male , Middle Aged , MovementABSTRACT
A simple design of elbow hinge distractor for the restoration of joint function in contractures, ankyloses, persistent dislocations, and nonunions is presented. Soft tissue releases and reshaping of joint surfaces is carried out surgically as required. Obtaining motion and stability is achieved with side plates attached to external fixation pins, one of which passes through the axis of rotation of the joint and about which flexion takes place. Distraction is obtained by a screw that separates the ulnar side plates from the humeral side plates. To aid in accurately placing the axis of rotation pin at surgery, a study was done to determine the best fit axis of rotation and how it relates to boney landmarks. One case of an ankylosed elbow is presented in detail, including the surgical technique. This and other previous cases have shown that good clinical results can be achieved in these otherwise poorly functioning elbows. Key index words: Elbow, Biomechanics.
