Neo-osteogenesis of haversian trabeculae through a bone chamber implanted in a rabbit tibial cortex: A control model

Neo-osteogenesis of cortical bone trabeculae was observed as they regenerated into a bone chamber implant by appositional growth. Measures of change in bone area were obtained from 13 rabbits each week starting the third and ending the eighth week postimplantation. Observations were made using intravital microscopy and were analyzed using digital image processing. Images were computer-captured video frames equivalent to 78(6×13) separate observations. They were measured by tracing the trabecular outlines with a digitizing crosshair each week and comparing changes in area as a percent of the circular field-of-view (“slit-gap”) filled. Data supported the hypothesis that trabecular regeneration week 3 to week 8 followed the logistic growth curve regression: $$A\% = \frac{{100\% }}{{1 + 9.47e^{ - 0.7747(t - 3)} }}$$ where A% is the percent of slit-gap area covered by bone and t is time, at a very high significance level. Nevertheless, a highly significant linear regression fit the data. Statistical analysis showed that the regression line could be fit to bone area measurements from weeks 3 to 8 (W3-W8) postimplantation, giving a constant neo-osteogenesis rate of 7.42±0.67×10⁴ μm²/day and a decreasing linear neoosteogenesis rate from 73 μm/day at W4 to 21 μm/day at W8; the latter is based on a circlesegment approximation of trabeculum shape. This range approximated a bridge between ranges for cortical gap defect healing and porous ingrowth healing reported by other workers and supported the hypothesis that the BCI control model was a cross between gap healing and porous ingrowth.