© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any
current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating newcollective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in otherworks.

Evaluation of Forward Fall on the Outstretched Hand Using
MADYMO Human Body Model
Nader Rajaei, Member, IEEE, Saeed Abdolshah, Member, IEEE, Yasuhiro Akiyama, Member, IEEE, Yoji
Yamada Member, IEEE, Shogo Okamoto Member, IEEE,

Abstract—Falls and their related injuries pose a significant
risk to human health. One of the most common falls, theforward fall, frequently occurs among adults and the elderly. In
this study, we propose using a human body model, developed
using the MAthematical DYnamic MOdel (MADYMO)
software, in place of human subjects, to investigate forward
fall-related injuries. The MADYMO human body model iscapable of simulating items that cannot be assessed on humansubjects, such as human kinematics, human dynamics, and thepossibility of injuries. In order to achieve our goal, a set ofexperiments was conducted to measure the impact force during
a worst-case forward fall scenario (the outstretched hand
position) for two short fall heights. Similar to the experimental
design used on the human subjects, we generated a MADYMO
human model. After performing the simulations, the results ofthe experiment on the human subjects and the MADYMO
simulation model were compared. We demonstrated asignificant correlation between the MADYMO simulation andthe human subject experiments with respect to the magnitude
and timing of the impact forces. Consequently, we validated the
MADYMO human body model as a means to accurately assess
forward fall-related injuries. Additionally, we compared thepredicted results of a mathematical model with the MADYMO
human body model. The MADYMO model is reliable and candemonstrate an accurate impact time. Therefore, we conclude
that the MADYMO human model can be utilized as a reliable
model to investigate forward fall-related injuries from a typicalstanding position.
I.

INTRODUCTION

In most cases, falls pose a serious risk to human health,especially for senior individuals. According to the World
Health Organization report [1], falls are the second leading
cause of unintentional injury and death. An initial study
showed that approximately 11% of falls can cause a serious
injury for older adults [2]. In addition, falls can impose asignificant cost to the healthcare system. Recent
investigations regarding fall-related injuries in the UnitedStates show that the direct cost of medical care for fatal andnon-fatal fall injuries were approximately $616.5 million and$30.3 million in 2012, respectively. These costs increased to$637.5 million and $31.3 million in 2015 [3]. Hence, it is ofgreat interest in the field of biomechanics to introduce new
methods for preventing and/or reducing fall-related injuries[4]-[5].
One of the most common types of falls is the forward fall[6]. The forward fall mainly occurs due to an unexpected
perturbation of balance or a failure in recovery strategies [7]N. Rajaei, S. Abdolshah, Y. Akiyama, Y. Yamada and S. Okamoto arewith Department of Mechanical System Engineering, Nagoya University,
Nagoya, Japan (e-mail: nader.rajaei@mae.nagoya-u.ac.jp).

when tripping or slipping occurs during walking [6]-[8]. In
addition, the forward fall commonly occurs in the workplace,where there is the potential interaction between humans androbots.
Individual often uses the upper extremities for protecting
the head and trunk from impact when a forward fall occurs[6]-[9]. Hence, forward falls lead frequently to fractures of
the upper extremities, such as the Colles’ fracture (distal
radius fracture) [10]-[12]. A recent investigation has
indicated that approximately 40.5% of forward falls cause
moderate or severe injuries to individuals above 65 years ofage [13]. Thus, it is of critical importance to evaluate forward
falls and their related injuries and to develop strategies for
reducing these injuries.
Earlier studies have focused on measuring the magnitudeof the impact force that causes a distal radius fracture[14]-[17]. The researchers performed their experiments byexerting a force on a cadaveric hand. For instance, aninvestigation by Frykman (1967) showed an average impact
force of 2.26±0.01 kN for 48 cadaveric forearms (25 womenand 23 men of ages 65 and older) [14]. A similar protocol was
utilized by Myers (1991 and 1993) and Spadaro (1994); they
determined that wrist fractures occurred at impact forces of
3.39 ± 0.88 (Myers’s first study), 1.78 ± 0.65 (Myers’s
second study) [14]-[15], and 1.64 ± 0.98 kN (Spadaro’s
study) [17] .
Although the former studies indicated a range of impact
forces that produce a radial bone fracture, these in vitro
studies had limitations because the roles of the reactions fromthe upper extremity muscles were not considered.
Subsequent investigations on fall-related injuries wereconducted using human subjects [11], [18]-[22]. In one of thefirst studies, Chiu and Robinovitch (1998) [18] designed abiomechanical experiment involving the worst-case forward
fall (the outstretched hand position). They obtained theimpact force when there was a short distance between theparticipant’s hand and the ground. The results indicated thatthe impact forces consisted of an initial high magnitude peak(fmax1), occurring shortly after the hand contacts the ground,followed by a subsequent lower peak (fmax2). Then, theyexamined a strategy for reducing the impact force. They
compared the magnitude of the impact force when the handcontacted the ground having an infinite material stiffness withthat of the ground consisting of a compliant material (i.e. acompliant flooring). They found that decreasing the stiffnessof the ground leads to a reduced first peak magnitude (fmax1)
but did not show a large change in the magnitude of thesecond peak (fmax2) [19]. In addition, the magnitude of fmax1
was further reduced where a rigid layer is mounted on acompliant flooring [23].

Other studies also attempted to examine the humanreaction during a forward fall [24] and several different arrest
strategies for reducing the impact forces. One study
investigated the effect of elbow flexion movements after
contacting the ground [11]. The result showed that the actionof elbow flexion decreased the first impact force and caused adelay in the timing of the peak. In another study, DeGoede etal., [21] investigated the magnitude of the impact force forthree elbow angles, ranging from almost outstretched toalmost fully bent. They found similar impact force peaks,
including fmax1 and fmax2. In addition, they could specify thatthe magnitude of the impact forces were maximum when theelbow was extended to θElbow = 174º (the outstretched hand
position), whereas the forces decreased by approximately
40% at the reduced elbow angle.
Despite these efforts, the in vivo studies have also shown
some limitations due to safety considerations for the subjects
when falling from a standing position. To solve this issue,
Chiu and Robinovitch (1998) [18] proposed biodynamic
impact models. The proposed model was based on a simple
two-degree-of-freedom spring-mass-damper system that wascapable of explaining the nature of a forward fall at a largeheight and in the outstretched hand position.
This simple mathematical model predicted the applied
forces to the hand during the forward fall. However, themodel had some limitations due to the underprediction andoverprediction of the time of the impact force [18]. Therefore,
the model was not capable of demonstrating the precise handdisplacement and energy absorption. In this study, we
propose a human body model developed using theMathematical Dynamic Models (MADYMO) software[25]-[26] to predict the biomechanical factors related to a
forward fall. The MADYMO human model has been
generally utilized for occupant safety studies in theautomotive and transport industries. The software is mostly
validated for various loading conditions to the model’s head,shoulder, thorax, pelvis, and legs (details can be found in the
MADYMO Human Models Manual [25]). The MADYMO
human body model has an advanced numerical algorithm forsimulating human kinematics and human dynamics and canevaluate the possibility of injuries that cannot be assessed onhuman subjects. There has been no relevant evidence tosupport whether the MADYMO human model can be used forforward fall investigations, which means that the course of
forward fall event can be reconstructed using MADYMO
human model. To our knowledge, this is the first study using a
MADYMO human model for investigating forward falls.

II. MATERIAL AND METHOD
In this study, we first conducted a series of laboratory
experiments.
A. Subjects
Four young Japanese individuals (male) of ages 20-25
years (mean ± standard deviation = 23.75 ± 0.5 years),participated in this study. Their average height and body mass
were 174 ± 3 cm and 61 ± 5 kg, respectively. None of theparticipants reported any prior training, such as Jodo, martial
arts techniques, wrestling, or gymnastics. Moreover, they did

not have a history of major medical or neurological illnesses,
such as epilepsy, hand trauma, balance disorders, and falls.
The participants did not present bone disease or otherconditions that would increase the likelihood of a fracture
occurrence. All participants signed a written informed consent
prior to the experiments. The experimental protocol wasapproved by the Institutional Review Board of Nagoya
University, Japan. All experiments were conducted inaccordance with the approved guidelines.
B. Experimental Protocol
The objective of this experiment was to measure theapplied forces to each hand during a forward fall. To secure
the safety of the subjects and prevent injuries, the ground on
which the experiment was conducted was covered withcompliance flooring (i.e. a yoga mat).
The experiment was designed according to the protocol
utilized in most prior forward fall studies [18]-[20]. This
protocol was designed to be adapted in the in vitro study
design [13]. In this study, each participant wore tightsportswear clothing and an upper body harness (Fig.1). The
participants were instructed to place their knees on a soft
pillow fixed to the ground and flex their knees, allowing theparticipant to lean forward against the harness. In this position,
the thighs and the horizontal line parallel to the ground createdan angle of 30° (Fig.1).
A rope connected to the harness lifted the participants toan appropriate height from the ground. The participants were
instructed to maintain a position with their elbows fully
extended (the outstretched hand position). In this position, theFig.1. The experimental setup for the forward fall in the outstretchedhand position for fall heights of 5 cm and 8 cm.

angle between the participants’ arms and the vertical line wasestablished as 15°. Two force plates (M3D Force plate, Tec
Gihan Corp.) were fixed to the ground beneath theparticipants’ hands. The surface of the force plates wasconsidered to be a hard surface with infinite stiffness.
As previously mentioned, the participants’ safety was themain concern during this experiment. In order to prevent awrist fracture due to contact with the force plates, we designed
the experiments considering the amount of impact force
applied to each hand for two different fall heights (h = 5 cm
and 8 cm). The fall height was adjusted using the distance
between the palms and the upper surface of force plates. Every
participant completed six trials (two fall heights × three
repetitions = six trials).

In MADYMO, a multi-body system encompasses a
system of rigid and flexible bodies that connect withkinematic joints (e.g., translational, sphere, or revolutejoints). The model was designed based on 186 bodies,including 178 rigid and 8 flexible bodies. The chain bodyconnections in the upper and lower extremities consist of
several branches. Two separate branches of chain bodyconnections were developed for connecting the pelvis to thevertebra and head, as well as connecting the feet to the left
and right legs and shoes. The patella connects to the foot andtoes with two discrete branches of chain bodies for the left
and right foot. Similarly, two discrete branches wereconsidered for constructing the left and right connections
between the fingers and arms with the spine. Moreover, thesoft tissue (flesh and skin) in the human model ischaracterized by force-penetrations to the 64 deformableellipsoids chain bodies.
The model was verified by various loading tests,
including a volunteer test for low severity loading and postmodem human substitute tests for high severity loading [25].

D. Reconstruction of the Forward Fall Scenario in
MADYMO XMDgic Workspace
In order to reconstruct the fall in a manner consistent withthe experimental configuration (described in Section II.B),
we modified the position of the MADYMO human model andcreated a ground surface in the MADYMO Xmagic
workspace.

Fig. 2. The MADYMO Human model: (a) A mid-size male humanmodel representing the 50th percentile in the standing position. (b) The
MADYMO human model setup for simulating a forward fall. The fallheight was adjusted based on the distance between the surface planes
and the model’s hands to h = 5 cm and 8 cm

C. MADYMO Human Body Model Simulation Software
In this study, we used an effective and extensive humanmodel database, MADYMO, developed by TNO Automotive
Safety Solutions (TASS) BV, Netherlands [25]. The
MADYMO software consists of a solver, a database ofhuman body models, and the pre- and post- processers.
MADYMO has the capability to execute the numericalalgorithm for predicting dynamic and kinematic behavior,such as representing the reaction motion of the human body.
MADYMO is widely used in automotive occupant safety.
Moreover, this software has been utilized for otherapplications, such as the study of accident reconstruction,
injury biomechanics, and sports medicine [27]-[28].
MADYMO also supports several databases of multibody
human models. One of the released multibody human models
is the pedestrian human body model (or human body model)[25]. The pedestrian model has a height 1.76 m and weight75.3 kg and is released by default in a standing position. The
model is based on the 50th percentile male model population,and its geometry was designed based on a database from the
RAMSIS software package (RAMSIS 1997) [29].

First, we modeled the ground using a plane surface withdimensions of 1.3 m × 1.0 m to be connected to the global
system (reference space). The characteristics of the groundreaction force (force-penetration response) were defined suchthat the plane induced the reaction of a hard surface with
infinite stiffness.
The released MADYMO human model defaults to a
standing position, as shown in the Fig.2 (a); however, it isrelatively simple to modify the dimensions and the posture.
Therefore, the orientation of the kinematic joints for the
ankles, knees, and hips were modified to generate a newhuman model position, as shown in the Fig.2 (b). In this new
position, the angle between the knees and the X-Y plane was
30°. Moreover, we rotated the angle of the wrist joints to avalue of 15° degrees between the wrists and X-Z plane.
In the MADYMO Xmagic workspace, we also designed
two separate surface planes below the hands. The
characteristics of force-penetration were considered, similar
to the ground model. The use of discrete planes allowed us toadjust the distance between the hands and planes to represent
the different fall heights. The fall height was adjusted to equal
the distances used in the experiment (h = 5 cm and 8 cm).
The fall simulations were executed, while a load of 9.81 N(gravitational force) was applied to the human model. Eachsimulation time was established as 0.6 s, including the preand post-impact phases. The human body model reached thetwo ground planes in approximately 0.1 s and 0.13 s for thefall heights of 5 cm and 8 cm, respectively.

III. RESULTS
The averages of the impact forces experienced by one
hand are shown in Fig.3. The plots include the results of thehuman experiment (black-dash lines) and MADYMO
simulation (blue-filled line) for the fall heights of 5 cm inFig.3 (a) and 8 cm in Fig.3 (b). In addition, Fig.3 also includes
the simulation results of a simple two-degree-of-freedom
mathematical model (red-asterisk lines) represented in theprevious study [18]. The model was designed to simulate aforward fall based on a spring-mass-damper system. In thismodel, the effective masses of the torso and upper extremities
were assumed to be two separate masses. Moreover, thestiffness and damping of the shoulder-torso and wrist-palm
were taken into consideration by including two separate
springs and dampers.

(a): 5cm
Fig.4. The MADYMO human model’s hand displacement during forward
fall from 5cm (magenta-filled line) and 8cm (cyan-filled line) fall heights.

(b) : 8cm

lower second peak. The plots show that the MADYMO
human model and mathematical model predict the magnitudeof the two peaks with an accuracy corresponding to theexperimental results. For the 5 cm fall, the first peakmagnitudes were measured as 389 N, 385 N, and 391 N for
the human experiment, MADYMO simulation, andmathematical model, respectively. The magnitudes of thesecond peaks demonstrated lower forces of approximately
286 N, 289 N, and 285 N for the human experiment,
MADYMO simulation, and mathematical model,
respectively. By increasing the fall height to 8 cm, we
obtained the first impact magnitudes of approximately 490 N,
495 N, and 494 N for the human experiment, MADYMO
simulation, and the mathematical model, respectively.
Subsequently, we measured lower impact forces for thesecond peaks at 316 N, 328 N, and 310 N for the humanexperiment, MADYMO simulation, and mathematical model,
respectively. The one-way analysis of variance (ANOVA),
using the SPSS software package (IBM Corp. Released 2016.
IBM SPSS Statistics for Windows, Version 23.0. Armonk,
NY: IBM Corp), indicated that increasing the fall heightsignificantly increases the magnitude of both peaks (p <0.0001). Additionally, increasing the fall height had a greater
effect on the first peak than the second peak.
The correlation coefficients for both fall heights were
calculated to assess the relationship between the impact force
for the human experiment and the MADYMO simulation.
The results show a positive correlation; r = 0.79 for 5 cm andr = 0.83 for 8 cm between impact forces for the humanexperiment and the MADYMO simulation.

Fig.3. The impact force profile during fall at (a) 5 cm and (b) 8 cm. The
figures consists of experimental (black dash line), MADYMO
simulation (blue filled-lien) and Mathematical model (red asterisk-line)
results

Fig.3 demonstrates similar impact force characteristics
between the human experiment, MADYMO simulation, andmathematical model. The impact forces include two peaks;
the first one has a higher magnitude, which is followed by theFig.3 also shows that the first peak occurs approximately
0.025 s after the hand contacts the ground, while the second
peak occurs at 0.075–0.08 s. The mathematical model tends
to underpredict the time of the first peak and overpredict thetime of the second peak [18].
Fig.4 shows the hand displacement in the MADYMO
model during the fall for each of the two fall heights. During
the 5 cm fall, the displacements for the first and second peaks
were approximately 0.0046 m and 0.0036 m, respectively. By

increasing the fall height to 8 cm, the displacements wereapproximately 0.0058 m and 0.0043 m for the first andsecond peaks, respectively. These results indicate that
increasing fall height also has a significant impact on handdisplacement (p < 0.0001).
IV. DISCUSSION
In biomechanical studies, the potential fall-related injuries
on the upper extremity can be predicted using themathematical model where in vivo and in vitro show ethicalconstraints [30]. In occupant safety studies, the use of humanmodels is known as an alternative approach to investigate
impact-related injuries during an accident [31]. Hence, in thisstudy, we proposed to use one of the most advanced humanbody models to be developed by MADYMO software
package [25]. We utilized MADYMO mid-size male modeland investigated the applied force to the hand during aworst-case forward fall scenario (the outstretched hand
position).
In the first step, we measured the magnitude of the impact
force during the forward fall in the outstretched hand position
through laboratory experiments. Two short distances wereconsidered for the experimental fall heights (h = 5 cm and 8cm) due to avoiding the risk of participants’ radius bone
fracture. The results indicated that the impact force includes
two distinct peaks, an initial high peak followed by a second
lower peak. The results demonstrated that increasing the fallheight, even for a very short distance, leads to an increase in
the two peaks. Increasing the fall height has a significant
effect on the first peak, leading to an increase of
approximately 27%, while the second peak has an increase of
only 10%. Consequently, our results provide additional
evidence to support and confirm the previous findings
regarding the impact force during a forward fall [18]-[22].
A similar experimental setup was applied to the
MADYMO simulation. The position of the MADYMO
human model was established to reflect that of the humanexperiment. The simulation was performed for the two fallheights when the model came into contact with the stiff
surfaces. The simulation results for the impact forcesindicated a similar trend with distinct peaks. Even though
there is some discrepancy between the impact forces from theexperiment and the MADYMO simulation, the MADYMO
simulation results were acceptable and showed a positive
correlation with the human experiment. There is a slight
discrepancy between the magnitudes and times of the two
peaks in the MADYMO simulation and the experiment. We
speculate that this may be due to the algorithm used to solve
the wrist and shoulder displacements and force productions.
In a previous study, a simple mathematical model basedonaspring-mass-damper
systemwith
twodegrees-of-freedom was proposed [18]. This model canaccurately predict the magnitude of the impact forces (Fig.3),
similar to the MADYMO human model; however, the time
prediction of the first and second peaks was less accurate. The
mathematical model tended to underpredict the time of thefirst peak (i.e. the first peak always occurs at the 0 s in Fig.3)
and overpredict the time of the second impact force. This
discrepancy in the time prediction is most likely related to theassumptions considered for the model. In other words, themodel was designed with more attention given to predicting
the peak of the impact forces rather than the impact time. In
addition, the impact time prediction discrepancy suggests thatthe model is incapable of representing other factors, such as
displacement and energy absorption. According to the model,
the maximum hand displacements for the fall heights of 5 cm
and 8 cm were approximately 0.153 m and 0.164 m,
respectively. The maximum hand displacements in the
MADYMO human model were approximately 0.0046 m and0.0058 m during the 5 cm and 8 cm fall heights, respectively.
Hence, the relatively large hand displacements from themathematical model cannot accurately measure the amount ofenergy transferred to the hands during a fall from the standing
position. However, the MADYMO human model seems to becapable of measuring the actual amount of energy absorption.
From the biomechanical perspective, the effective factors
for determining the severity of the forward fall-related
injuries are the peak of impact force and moment of impact.
Hence, in this study, we demonstrate the MADYMO humanmodel as a superior model compared to the priormathematical model because it can accurately simulate themagnitude and time of the impact force, as well as the handdisplacement. This study should prompt us to perform
additional MADYMO simulations to investigate the injuries
produced by a fall from the standing position.
V. CONCLUSION
The main goal of this study was to evaluate the responseof the MADYMO human model during a worst-case forward
fall scenario (the outstretched hand position). Based on thisobjective, a set of human experiments was designed, and theimpact forces applied to the hands for two short fall heights
were measured. The short fall heights were considered due to
avoiding the risk of participants’ radius bone fracture. A
similar setup was designed in the MADYMO workspace, anda simulation was performed. Our results demonstrated astrong correlation between the human experiment and the
MADYMO human model, not only for measuring themagnitude of impact forces but also for providing accurate
impact times.
Next, a comparison was carried out between the results ofa mathematical model, which was designed based on a twodegree-of-freedom spring-mass-damper system, and the
MADYMO human model. Although both models accurately
predicted the impact forces during the forward fall, theMADYMO simulation was more reliable, as themathematical model indicated a discrepancy pertaining to thetiming of the impact forces. This lack of reliability does notallow the model to measure hand displacement and energy
absorption when the hands contact the ground. Because thehand displacement and energy absorption are critical factors
for fall-related wrist fractures, this study recommends using
the MADYMO human model for investigating a forward fallfrom a typical standing position.
ACKNOWLEDGMENT
This work was supported by JSPS KAKENHI Grant
Number 26750121, and METI “Strategic international
standardization
promotion
project:
International
standardization of human tolerance against fall injuries”.

VI. REFERENCES[1] World

Health Organization, “Falls Fact Sheet,” Internet:
http://www.who.int/mediacentre/factsheets/fs344/en, October 2012,
reviewed September 2016.
[2] Tinetti, M E., M. Speechley, and SF. Ginter. "Risk factors for falls
among elderly persons living in the community." New England journalof medicine vol. 319, no. 26, pp. 1701-1707,1988.
[3] E. R Burns, J.A. Stevens, and R. Lee. "The direct costs of fatal andnon-fatal falls among older adults-United States." Journal of safety
research vol.58, pp. 99-103, 2016.
[4] Nouredanesh, Mina, Andrew McCormick, Sunil L. Kukreja, and James
Tung. "Wearable vision detection of environmental fall risk using
Gabor Barcodes." In Biomedical Robotics and Biomechatronics(BioRob), 2016 6th IEEE International Conference on, pp. 956-956.
IEEE, 2016.
[5] Page, Solenne, Kyung-Ryoul Mun, Zhao Guo, Francisco Anaya Reyes,
Haoyong Yu, and Viviane Pasqui. "Unbalance detection to avoid falls
with the use of a smart walker." In Biomedical Robotics andBiomechatronics (BioRob), 2016 6th IEEE International Conferenceon, pp. 1000-1005. IEEE, 2016.
[6] O'neill, T. W., J. Varlow, A. J. Silman, J. Reeve, D. M. Reid, C. Todd,
and A. D. Woolf. "Age and sex influences on fallcharacteristics." Annals of the rheumatic diseases 53, no. 11, pp. 773,
1994.
[7] K. Mitsuoka, Y. Akiyama, Y. Yamada, and S. Okamoto, “Analysis of
Skip Motion as a Recovery Strategy after an Induced Trip,” in Systems,
Man, and Cybernetics (SMC), 2015 IEEE International Conference on,pp. 911-916.
[8] Nevitt, Michael C., and Steven R. Cummings. "Type of fall and risk of
hip and wrist fractures: the study of osteoporotic fractures." Journal of
the American Geriatrics Society 41, no. 11 (1993): 1226-1234.
[9] Hsiao, Elizabeth T., and Stephen N. Robinovitch. "Common protective
movements govern unexpected falls from standing height." Journal ofbiomechanics 31, no. pp.1-9, 1997.
[10] J. A. Baron et al., “Basic epidemiology of fractures of the upper andlower limb among Americans over 65 years of age.,” Epidemiology,
vol. 7, no. 6, pp. 612–8, 1996.
[11] P. H. Chou, Y. L. Chou, C. J. Lin, F. C. Su, S. Z. Lou, C. F. Lin, and G.
F. Huang, “Effect of elbow flexion on upper extremity impact forces
during a fall,” Clinical Biomechanics, vol. 16, pp. 888–894, 2001.
[12] L. M. Feehan and S. B. Sheps, “Incidence and Demographics of Hand
Fractures in British Columbia, Canada: A Population-Based Study,” J.
Hand Surg. Am., vol. 31, no. 7, pp. 1–9, 2006.
[13] J. a Stevens, J. E. Mahoney, and H. Ehrenreich, “Circumstances andoutcomes of falls among high-risk community-dwelling older adults,”
Inj. Epidemiol., vol. 1, no. 1, p. 5, 2014.
[14] G. Frykman, “Fracture of the distal radius including
sequelae--shoulder-hand-finger syndrome, disturbance in the distal
radio-ulnar joint and impairment of nerve function. A clinical andexperimental study.,” Acta Orthop. Scand., vol. 6470, no. April, p.
Suppl 108:38, 1967
[15] E. R. Myers et al., “Correlations between photon absorption properties
and failure load of the distal radius in vitro,” Calcif Tissue Int, vol. 49,
no. October 2016, pp. 292–297, 1991.
[16] E. R. Myers, A. T. Hecker, D. S. Rooks, J. A. Hipp, and W. C. Hayes,“Geometric variables from DXA of the radius predict forearm fractureload in vitro,” Calcif. Tissue Int., vol. 52, no. 3, pp. 199–204, 1993.
[17] J. A. Spadaro, F. W. Werner, R. A. Brenner, M. D. Fortino, L. A. Fay,
and W. T. Edwards, “Cortical and trabecular bone contribute strength
to the osteopenic distal radius,” J. Orthop. Res., vol. 12, no. 2, pp.
211–218, 1994.
[18] J. Chiu and S. N. Robinovitch, “Prediction of upper extremity impact
forces during falls on the outstretched hand,” Journal of biomechanics,
vol. 31, no. 12, pp. 1169–1176, 1998.
[19] S. N. Robinovitch and J. Chiu, “Surface stiffness affects impact force
during a fall on the outstretched hand,” Journal of Orthopaedic
Research, vol. 16, no. 3, pp. 309–313, 1998.
[20] C. E. Kawalilak, J. L. Lanovaz, J. D. Johnston and S. A. Kontulainen,“Linearity and sex-specificity of impact force prediction during a fall

onto the outstretched hand using a single-damper-model,” J
Musculoskelet Neuronal Interact, vol. 14, no. 3, pp. 286-293, 2014.
[21] K. M. DeGoede and J. A. Ashton-Miller, “Fall arrest strategy affects
peak hand impact force in a forward fall,” J. Biomech., vol. 35, no. 6,
pp. 843–848, 2002.
[22] J. A. Ashton-Miller, “Biomechanical Factors Affecting the Peak Hand
Reaction Force During the Bimanual Arrest of a Moving Mass,” J.
Biomech. Eng., vol. 124, no. 1, p. 107, 2001.
[23] N.Rajaei, S. Abdolshah, Y. Akiyama, Y. Yamada and S. Okamoto,“Rigid Material on Top of a Compliant Flooring Effectively Reduces
the Impact Force In The Event of a Forward Fall” Availibe :https://arxiv.org/abs/1806.09747.
[24] S. Abdolshah, Y. Akiyama, K. Mitsuoka, Y. Yamada and S. Okamoto,“Analysis of Upper Extremity Motion during Trip-Induced Falls,” inRobot and Human Interactive Communication (RO-MAN), 26th IEEE
International Symposium on Robot and Human Interactive
Communication, pp. 1485-1490, 2017.
[25] MADYMO Human Models Manual Release 7.7. 2017. Available:
https://www.tassinternational.com/[26] https://tass.plm.automation.siemens.com/madymo[27] Doorly, Mary C., and Michael D. Gilchrist. "The use of accident
reconstruction for the analysis of traumatic brain injury due to head
impacts arising from falls." Computer methods in biomechanics andbiomedical engineering 9, no. 6, pp.371-377, 2006.
[28] Yang, King H., Jingwen Hu, Nicholas A. White, and Albert I. King.
"Development of numerical models for injury biomechanics research: areview of 50 years of publications in the Stapp Car Crash Conference."
Stapp car crash journal, 50 ,pp.429, 2006.
[29] Krüger, Wilhelm, Andreas Seidl, and Hartmut Speyer. "Mathematische
NachbildungdesMenschen-RAMSIS
3D
Softdummy."
FAT-Schriftenreihe 135 (1997).
[30] Kim, Kyu-Jung, and James A. Ashton-Miller. "Segmental dynamics offorward fall arrests: A system identification approach." Clinicalbiomechanics 24, no. 4, pp.348-354, 2009.
[31] King, Albert I. "Introduction." In The Biomechanics of Impact Injury,
pp. 1-33. Springer, Cham, 2018.