| Popis: |
This thesis examines, in three phases, the biological and mechanical properties of impacted morcellised bone graft and the use of synthetic additives. Phase I. The mechanical strengths of different mixtures of bone graft were found to follow sound Engineering principles. The distribution of particle sizes from different bone mills determines the mechanical strength of graft from that mill. Theoretical increases in strength by improving particle size distribution were confirmed by mechanical tests Washing the graft or the addition of synthetic additives (Controlled Release Glass - Corglaes(r) (Giltech Ltd. Ayr, Scotland) & Tricalcium Phosphate/Hydroxyapatite - TCP/HA (Stryker Howmedica Osteonics, Berkshire, England)) also improved strength. Phase II. An in-vivo ovine defect model allowed biological assessment of impacted pellets, made of mixtures found in Phase I to be mechanically strong. Bone densitometry and histological analysis were used. Phase III. An ideal mixture of bone graft and an additive was compared with allograft bone alone, in an ovine femoral revision hip replacement model. The subsistence over time and 3D micromotions under load of the implant were similar between the two groups. Histological analysis showed increased biological activity around the proximal femur in contrast to the relative isolation of the distal graft. These experiments highlight potential mechanisms with which to improve impacted bone graft strength and support further analysis of Corglaes(r) and TCP/HA as bulking agents and/or bone graft enhancers. |
