A QUANTITATIVE ASSESSMENT OF COMPRESSION PLATE FIXATION INVIVO - AN EXPERIMENTAL-STUDY USING THE SHEEP RADIUS

Commercial 6-hole dynamic compression plates (DCP's) and instrumented 4-hole DCP's were fixed to the tension (cranial) surface of intact and osteotomised radii in sheep. Strain gages were attached to the cranial and caudal surfaces of the intact radius on one side, and in similar locations underneath and opposite the plate on the contralateral side. Recordings were taken of the static strain changes imposed at the time of plate fixation, the decline in static strain in the plate over the experimental period, and the locomotor strains on bone and measuring plates. After plate removal at 21 weeks locomotor strain on the cranial cortex was 17% higher than normal, and within 14 days it had been restored to normal. All areas of the bones to which plates had been attached were more porotic than their contralateral pair.