Figures & data
Figure 1. Overview of the experimental groups.
Figure 2. Regions of interest for microCT analyses of drill holes and PMMA screws. 4 volumes of interest were defined. A) For the drill hole: a cylinder with a diameter of 1.1 mm and 2.5 mm in length. B and C) For the bone adjacent to the drill hole: a cylinder pipe with an outer diameter of 2.5 mm and inner diameter of 1.2 mm, extending from the cortex 2.5 mm into the marrow cavity. D and E) For measuring the bone formation surrounding the screw: a cylinder pipe with an outer diameter of 2.5 mm, inner diameter of 1.4 mm, extending from the cortex 1.0 mm into the marrow cavity. F) For measuring the tissue mineral density (TMD) surrounding the screw a longer cylinder, 1.8 mm in length, was defined including the cortical bone.”
Figure 3. MicroCT data from former drill hole in metaphyseal tibia. New bone was formed in the drill holes during the first week (panels A, B) and then gradually disappeared. The bone density surrounding the drill holes also increased during the first week before it decreased (C, D).
Figure 4. Pull-out force for metaphyseal screws. The force increased gradually during the first 2 weeks. From 2 to 4 weeks, there was no clear change.
Figure 5. MicroCT data from PMMA screws in metaphyseal tibia. Bone volume (BV/TV) and bone density (BMD) around the screws, cortex excluded, increased during the first week and then declined (panels A, B). Bone formation, including cortex, around the screws increased during the first week, and then declined (C, D). Tissue mineral density (TMD), cortex included, continued to increase up to 4 weeks (E).
Figure 6. Pull-out force for metaphyseal screws, 1 week (panel A) and 4 weeks (B) after insertion. Unskrewing of the screw had no important effect on the pull-out force compared to controls, either at 1 week or at 4 weeks. Removal of the cancellous bone reduced the pull-out force compared to leaving the cancellous bone intact after unscrewing.
