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Title: The role of the vascular response to micromovement in the healing of experimental fractures
Author: Wallace, Andrew Lachlan
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1992
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The two most important elements in the clinical management of long bone fractures are generally considered to be the state of the vascular supply to the bone fragments and the requirement for mechanical stability. The contribution of each of these factors has been extensively studied independently, but their relative significance in the early phase of the healing process remains poorly defined. Recent evidence that intermittent micromovement at the fracture site may enhance the rate of union under experimental conditions has yet to be effectively demonstrated in clinical practice, particularly in high velocity injuries where bony comminution and soft tissue damage may be prominent. The objective of this thesis was to quantify the role of the vascular response to different mechanical environments, with and without suppression of musculoperiosteal collateral blood flow, after a transverse two-millimetre osteotomy of the ovine tibia which was held in an instrumented external fixation device. Three groups of skeletally mature three year old female Scottish blackface sheep were used for the study. In the well-vascularised groups the axial fixation stiffness was 460 N/mm and 240 N/mm respectively; in the devascularised group it was 240 n/mm and after subperiosteal exposure, a silicone rubber sleeve was interposed circumferentially between cortex and muscle. Outcome was assessed by in vivo measurement of fixator axial load and group reaction force, calculation of axial interfragmentary gap strain and external counting of dynamic uptake of Technetium-99m methylene diphosphonate at the osteotomy site. Regional blood flow was determined using the radioactive tracer microsphere technique at 14 and 42 days after osteotomy. Post-mortem, the isolated tibiae were mechanically tested in torsion and cross sections taken adjacent to the interfragmentary zone, from which area, perimeter, porosity and mineral apposition rate in cortex and callus were calculated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available