Slip and tilt: modeling falls over railings
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ORIGINAL ARTICLE
Slip and tilt: modeling falls over railings H. Muggenthaler 1
&
M. Hubig 1 & A. Meierhofer 2 & G. Mall 1
Received: 24 April 2020 / Accepted: 30 September 2020 # The Author(s) 2020
Abstract Falls over railings are frequent case scenarios forensic experts are confronted with. An important issue is the differentiation of accidental and non-accidental falling scenarios. From a biomechanical point of view, this is a challenging task and should be addressed in a multifactorial approach. This work presents a simplified mechanical model in terms of a cranked rod that can be used in cases without relevant dynamic components in terms of pushing or jumping. If the anti-slip and the anti-tilt condition are violated, the possibility for a person to get over a railing should be assumed and investigated in more detail. Because our approach also involves uncertainties, the formulae should be understood to be part of a multifactorial approach. Numerical simulation, experimental reconstruction, injury pattern, and trace analysis can yield additional substantial connecting facts. Keywords Fall analysis . Moment equilibrium . Force equilibrium . Anti-slip condition . Anti-tilt condition
Introduction Falls over railings are frequent case scenarios forensic experts are confronted with. Issues like injury severity [1, 2], which depends on falling height and landing substrate, as well as the differentiation of accidental and non-accidental causes of falls [3, 4] have to be addressed. When a victim is being pushed against a railing or when a person actively jumps over or from a balustrade, the landing point can show some horizontal distance from the balustrade [5]. A distinct horizontal distance between the railing and the landing point can be an important indicator for non-accidental falls. Especially in cases where a victim got over a railing without relevant initial horizontal velocity, it is of utmost interest whether, for example, leaning against a railing can result in accidental overcoming the safeguard or not. The methods presented in the following were motivated by a real case with a runty woman (1.58 m, 65 kg) that fell over a balcony railing. The case circumstances led to the H. Muggenthaler and M. Hubig contributed equally to this work. * H. Muggenthaler [email protected] 1
Institute of Legal Medicine, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
2
Institute of Legal Medicine, Medical University of Graz, Graz, Austria
assumption of a non-accidental scenario. However, the woman deposed that while she would have hung out the laundry on the balcony, a tablecloth would have slipped over the handrail of the balcony. As she would have tried to catch the slipping tablecloth, she would have lost balance and would have fallen from the third floor’s balcony. The falling height was about 8 m. She sustained fractures of the right metacarpus (ossa metacarpalia 3, 4, and 5), of the first and fourth lumbar spinal body and of the os sacrum. The railing height was 0.92
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