Osteonal Microcracking Pattern: A Potential Vitality Marker in Human Bone Trauma

Abstract

In forensic anthropology, the differential diagnosis between peri- and postmortem bone fractures is mainly based on macroscopic criteria. In contrast, studies focusing on bone histology are very scarce. In a recent publication, we showed that (perimortem) fractures in fresh human bones exhibit a different osteonal microcracking pattern than (postmortem) damage in dry bones. In the current work, we explored whether this osteonal microcracking pattern is distinctive of the vitality of (perimortem) fresh bone fractures. To this end, we compared the number, length and structural distribution of microcracks in vital humeral fractures from forensic autopsy cases with experimentally reproduced, three point-bending fractures in fresh and dry human humeri. Half of the fresh experimental bones were fractured whilst applying axial compression, i.e., attempting to simulate intra vitam conditions more accurately. The results showed a similar osteonal microcracking pattern between vital fractures and experimental fractures of fresh humeri subjected to axial compression. Interestingly, this pattern was significantly different from the one observed in the experimental fractures of fresh humeri without axial compression and dry humeri. This supports our hypothesis that the osteonal microcracking pattern can potentially be used as a marker for vital perimortem trauma, providing a histomorphometric tool for fracture timing.

Osteonal Damage Patterns from Ballistic and Blunt Force Trauma in Human Long Bones

“…It has been well documented that approximately 80 to 90% of MCKs are located in the broad and brittle interstitial area of the cortical bone as it is easier for them to initiate there due to the presence of large hydroxyapatite crystals, reduced osteocyte density, and limited bone remodelling [15,16,27,28]. Nevertheless, Ebacher et al [12], Winter-Buchwalder et al [15], and Schwab et al's [16] studies have all noted the presence of microcracking patterns related with bone trauma and highlighted the importance of focusing on osteonal MCKs in fresh fracture histological analysis [15]. The results of our study on osteonal microcrack damage, when comparing GST and BFT traumatic death cases, showed that total osteonal damage is greater in GST despite the difference not being significant.…”

“…As highlighted in previous papers, there is a need for further investigation into osteonal microcracking patterns since osteonal MCKs specifically have been associated with fresh fractures [12,15,16]. So far, there has not been a focus on osteonal microcracking patterns in relation to trauma type but only literature on BFT cases and trauma timing [14][15][16]. These studies have demonstrated that in fresh BFT cases, a higher proportion of osteonal MCKs can be observed when compared to dry bone which has greater interstitial MCKs [15,16].…”

“…Despite microcracks (MCKs) diminishing stiffness, they represent a form of defence against crack formation and bone failure through a phenomenon known as microcrack toughening [13]. The mechanics surrounding MCKs are still yet to be fully understood and have mainly been investigated in terms trauma timing in BFT cases [14][15][16]. MCKs, however, are also impacted by trauma circumstances and thus are of forensic relevance [12,13].…”

“…As highlighted in previous papers, there is a need for further investigation into osteonal microcracking patterns since osteonal MCKs specifically have been associated with fresh fractures [12,15,16]. So far, there has not been a focus on osteonal microcracking patterns in relation to trauma type but only literature on BFT cases and trauma timing [14][15][16].…”

“…So far, there has not been a focus on osteonal microcracking patterns in relation to trauma type but only literature on BFT cases and trauma timing [14][15][16]. These studies have demonstrated that in fresh BFT cases, a higher proportion of osteonal MCKs can be observed when compared to dry bone which has greater interstitial MCKs [15,16]. Hence, it is important to further investigate the osteonal microcracking pattern in BFT cases and define the osteonal microcracking pattern in a different trauma type such as GST.…”