title: The relation between mechanical impact parameters and most frequent bicycle related head injuries.
abstract: The most frequent head injuries resulting from bicycle accidents include skull fracture acute subdural hematoma (ASDH), cerebral contusions, and diffuse axonal injury (DAI). This review includes epidemiological studies, cadaver experiments, in vivo imaging, image processing techniques, and computer reconstructions of cycling accidents used to estimate the mechanical parameters leading to specific head injuries. The results of the head impact tests suggest the existence of an energy failure level for the skull fracture, specific for different impact regions (22-24J for the frontal site and 5-15J for temporal site). Typical linear patterns were described for frontal, parietal and occipital skull fracture. Temporal skull fracture described considerably higher variability. In term of contusion mechanogenesis, the experiments proved that relative brain-skull motion will not be prevented if the maximum frequency of the impact frequency spectrum stays below 150Hz or below the frequency corresponding to the impedance peak of the head under investigation. The brain shift patterns in humans, both in dynamic and quasistatic situations were shown to be very complex, with maximum amplitudes localized at the level of the inferolateral aspects of the frontal and temporal lobes. The resulting brain maximum amplitudes differed when the head was subjected to a sagittal or lateral motion. Finally, the presented data support the existence of a critical elongation/stretch criterion for the occurrence of ASDH due to BV rupture, located around 5mm elongation or 25% stretch limit. In addition, a tolerance level lying around 10,000rad/s(2) for pulse durations below 10ms was established for BV rupture, which seems to decrease with increasing pulse duration. The described research indicates that injury specific tolerance criteria can provide a more accurate prediction for head injuries than the currently used HIC. Internal brain lesions are strongly related to rotational effects which are not appropriately accounted by the commonly accepted head injury criterion (HIC). The research summarized in this paper adds significantly to the creation of a fundamental knowledge for the improvement of bicycle helmets as well as other head protective measures. The described investigations and experimental results are of crucial importance also for forensic research.
authors: Biomechanics Section, Katholieke Universiteit Leuven, Belgium; Department of Experimental Neurosurgery and Neuroanatomy, KU Leuven, Belgium. Electronic address: moneaaida@yahoo.com.
authors: Aida Georgeta
authors: AG
authors: Monea
authors: Biomechanics Section, Katholieke Universiteit Leuven, Belgium.
authors: Georges
authors: G
authors: Van der Perre
authors: Biomechanics Section, Katholieke Universiteit Leuven, Belgium.
authors: Katrien
authors: K
authors: Baeck
authors: Department of Experimental Neurosurgery and Neuroanatomy, KU Leuven, Belgium.
authors: Hans
authors: H
authors: Delye
authors: Biomechanics Section, Katholieke Universiteit Leuven, Belgium.
authors: Peter
authors: P
authors: Verschueren
authors: Biomechanics Section, Katholieke Universiteit Leuven, Belgium.
authors: Esmeralda
authors: E
authors: Forausebergher
authors: Biomechanics Section, Katholieke Universiteit Leuven, Belgium.
authors: Carl
authors: C
authors: Van Lierde
authors: Department of Metallurgy and Materials Engineering, KU Leuven, Belgium.
authors: Ignace
authors: I
authors: Verpoest
authors: Biomechanics Section, Katholieke Universiteit Leuven, Belgium.
authors: Jos
authors: J
authors: Vander Sloten
authors: Department of Experimental Neurosurgery and Neuroanatomy, KU Leuven, Belgium.
authors: Jan
authors: J
authors: Goffin
authors: Department of Experimental Neurosurgery and Neuroanatomy, KU Leuven, Belgium.
authors: Bart
authors: B
authors: Depreitere
mesh_terms: D001642:Bicycling / Q000293:injuries*; D001696:Biomechanical Phenomena; D003288:Contusions / Q000150:complications; D006259:Craniocerebral Trauma / Q000150:complications; D005260:Female; D020199:Hematoma, Subdural, Acute / Q000150:complications; D006801:Humans; D008297:Male; D055595:Mechanical Phenomena; D012887:Skull Fractures / Q000150:complications
keywords: Acute subdural hematoma; Bicycle accidents; Cerebral contusion; Head injury; Injury biomechanics; Injury criteria; Mechanopathogenesis; Skull fracture