Figure 4 | Scientific Reports

Figure 4

From: Smart bone plates can monitor fracture healing

Figure 4

Impedance data distinguished femur fractures completely healed from those with varied healing in a bone plate model. Histology sections are stained and false-colored like in Fig. 2. (A) Representative histology section of a well-healed mouse at day 26; a large bony callus completely bridges the fracture ends. Black box outlines position of the high-magnification image in (B). (B) High-magnification image of (A) with black arrow pointing to the electrode fully-integrated in new trabecular bone. (C) X-ray radiograph of sample in (A). (D) Surface rendered, three-dimensional µCT image of sample in (A). (E) Representative histology section of a mouse with mixed healing at day 26; the fracture callus includes cartilage, fibrous tissue, and trabecular bone. Black box outlines position of the high-magnification image in (F). (F) High-magnification image of (E) with black arrow pointing to the electrode fully-embedded in the callus, surrounded by a mixture of new trabecular bone and fibrous tissue. (G) X-ray radiograph of sample in (E). (H) Surface rendered, three-dimensional µCT image of sample in (E). (I) R (normalized as a ratio to day 2) at 15 kHz plotted over days post-fracture. Data markers and lines are colored according to degree of healing – shades of red for mice sacrificed at day 12 (F1, F2, F3), shades of blue for mice sacrificed at day 26 that healed well (F4, F5, F6), shades of purple for mice sacrificed at day 26 that healed poorly (F7, F8), and shades of brown for control mice sacrificed at day 26 (C1, C2). Normalized R clearly rises at a faster rate in two mice with complete bony calli, F4 and F5. (J) X (normalized as a ratio to day 2) at 100 kHz plotted over days post-fracture. Normalized X clearly rises at a faster rate in two mice with complete bony calli, F4 and F5. (K) Impedance data at all measured frequencies is fit to an equivalent circuit model (inset), and the R2t parameter is extracted, normalized as a ratio to day 2, and plotted over days post-fracture. This analysis is able to clearly distinguish the samples that are classified as union by orthopaedic surgeons (F4, F5, and F6 in Table 1).

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