title: Estimating severity of sideways fall using a generic multi linear regression model based on kinematic input variables.
abstract: Many research groups have studied fall impact mechanics to understand how fall severity can be reduced to prevent hip fractures. Yet, direct impact force measurements with force plates are restricted to a very limited repertoire of experimental falls. The purpose of this study was to develop a generic model for estimating hip impact forces (i.e. fall severity) in in vivo sideways falls without the use of force plates. Twelve experienced judokas performed sideways Martial Arts (MA) and Block ('natural') falls on a force plate, both with and without a mat on top. Data were analyzed to determine the hip impact force and to derive 11 selected (subject-specific and kinematic) variables. Falls from kneeling height were used to perform a stepwise regression procedure to assess the effects of these input variables and build the model. The final model includes four input variables, involving one subject-specific measure and three kinematic variables: maximum upper body deceleration, body mass, shoulder angle at the instant of 'maximum impact' and maximum hip deceleration. The results showed that estimated and measured hip impact forces were linearly related (explained variances ranging from 46 to 63%). Hip impact forces of MA falls onto the mat from a standing position (3650±916N) estimated by the final model were comparable with measured values (3698±689N), even though these data were not used for training the model. In conclusion, a generic linear regression model was developed that enables the assessment of fall severity through kinematic measures of sideways falls, without using force plates.
authors.affiliation: Sint Maartenskliniek Research, Nijmegen, The Netherlands; Radboud University Medical Center, Orthopaedic Research Laboratory, Nijmegen, The Netherlands. Electronic address: a.vanderzijden@gmail.com.
authors.forename: A M
authors.initials: AM
authors.lastname: van der Zijden
authors.affiliation: Sint Maartenskliniek Research, Nijmegen, The Netherlands. Electronic address: b.groen@maartenskliniek.nl.
authors.forename: B E
authors.initials: BE
authors.lastname: Groen
authors.affiliation: Radboud University Medical Center, Orthopaedic Research Laboratory, Nijmegen, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Tanck
authors.affiliation: Sint Maartenskliniek Research, Nijmegen, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: Nienhuis
authors.affiliation: Radboud University Medical Center, Orthopaedic Research Laboratory, Nijmegen, The Netherlands; Laboratory for Biomechanical Engineering, University of Twente, Enschede, The Netherlands.
authors.forename: N
authors.initials: N
authors.lastname: Verdonschot
authors.affiliation: Sint Maartenskliniek Research, Nijmegen, The Netherlands; Radboud University Medical Center, Department of Rehabilitation, Nijmegen, The Netherlands.
authors.forename: V
authors.initials: V
authors.lastname: Weerdesteyn
mesh_terms: D000058:Accidental Falls; D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D001860:Bone Plates; D003654:Deceleration; D005260:Female; D006620:Hip Fractures / Q000517:prevention & control; D006801:Humans; D016014:Linear Models; D008297:Male; D016139:Martial Arts / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D055815:Young Adult
keywords: Fall severity; Femoral fracture risk; Kinematic model; Linear regression model by stepwise regression; Sideways falls