Introduction: Five patients presented to the emergency department of a tertiary referral teaching hospital with atraumatic fractures of their humerus sustained during a recreational dodgeball tournament.



Case Presentation: The patients were young healthy individuals that described the fracture occurring during the act of throwing.



Conclusions: The causes leading to fracture of the humerus during the act of a throw are discussed and the management strategies utilized

Gia An, V. V.

Sher, D.

Suzuki, A.

Trantalis, J.

kashan university of medical sciences

Arch Trauma Res. 2017 March; 6(1):e36051.
Published online 2016 July 27.
doi: 10.5812/atr.36051.
Case Report
Atraumatic Fractures of the Humerus Associated With Throwing
Whilst Playing Dodgeball: A Case Series and Review of the Literature
Vincent Vinh Gia An,1,* Arnold Suzuki,2 John Trantalis,2 and Doron Sher2
1Sydney Medical School, University of Sydney, Sydney, Australia
2Department of Orthopedic Surgery, Concord Repatriation General Hospital, Sydney, Australia
*Corresponding author: Vincent Vinh Gia An, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia. Tel: +61-405648186, E-mail:
vian2424@uni.sydney.edu.au
Received 2016 January 09; Revised 2016 March 29; Accepted 2016 April 23.
Abstract
Introduction: Five patients presented to the emergency department of a tertiary referral teaching hospital with atraumatic frac-
tures of their humerus sustained during a recreational dodgeball tournament.
Case Presentation: The patients were young healthy individuals that described the fracture occurring during the act of throwing.
Conclusions: The causes leading to fracture of the humerus during the act of a throw are discussed and the management strategies
utilized.
Keywords: Humerus, Atraumatic Fracture, Dodgeball, Thrower’s Fracture
1. Introduction
Fracture of a normal humerus, although rare, can oc-
cur during the act of throwing an object (1). Atraumatic
“ball-thrower’s” humeral shaft fractures have been associ-
ated with the act of throwing various objects including
stone, cricket ball, baseball, softball, snowball, handball,
shot put, javelins and hand grenades (1-12). The objective of
dodgeball is to throw a ball and hit the opponent to remove
them from the play area. There is no protective equipment
associated with the sport.
The game of dodgeball is most commonly played with
a 8.25 inch (21 cm) diameter rubber coated foam ball weigh-
ing 7.2 ounces (200 grams), but specifications across var-
ious leagues and tournaments worldwide range from a
foam or air filled 7 - 10 inches (17.8 - 25.4 cm) rubber or ma-
terial coated ball (13-15). In comparison, stringent regula-
tions govern the specifications of a major league baseball
which weighs 5 - 5.25 ounces (142 - 149 grams) and is 2.8 - 3
inches (7.3 - 7.6 cm) in diameter (16).
“Ball-thrower’s” fractures are typically found in pa-
tients who are unskilled, healthy adults. To our knowl-
edge, there is no case series in the literature describing
this injury pattern related to the sport of dodgeball. Given
recreational dodgeball is becoming an increasingly popu-
lar sport through many age groups, it is important to rec-
ognize this potential injury pattern.
This paper aims to present a series of five patients pre-
senting to a tertiary referring teaching hospital follow-
ing the same atraumatic mechanism of injury whilst play-
ing dodgeball, and summarise the literature regarding
this rare injury pattern. All patients described a full-effort
throw and audible crack was heard following the release of
the ball.
2. Case Presentation
The five patients presented to our institution with a
mean age of 27.6 years (range: 26 - 31). All were male. At the
point of injury all patients described the action of a “hard”
throw, a sudden audible “crack”, acute pain and deformity
of the arm at the point of release of the ball. All patients
denied any direct trauma to their arm. Three patients did
not report the technique they utilized for the throw. The
two that did recall described either a side arm or overhead
throw respectively.
On X-ray, all patients had closed, extra-articular spiral
distal-third fracture of the humerus with or without an as-
sociated medial butterfly fragment (Figure 1A and 2A). Two
patients had an associated butterfly fragment. All injuries
occurred with their dominant arm and there was no neu-
rovascular compromise of the affected limb related to the
fracture. No patient in this group had any relevant med-
ical or surgical comorbidity. Metabolic bone disease was
excluded in all patients as a predisposing factor through
routine investigations at outpatient follow-up.
All patients were acutely managed conservatively with
a hanging U slab. Following consultation with consul-
tant orthopedic surgeons (JT, DS), four patients received
open reduction and internal fixation. All surgical cases
were fixed using plate-screw osteosynthesis, specifically
Copyright © 2016, Kashan University of Medical Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial
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Gia An VV et al.
with the use of lag screw fixation and locking or dynamic
compression plating (Figure 1B and C). There were no post-
operative complications and all patients were discharged
the day following their surgery.
The last patient received conservative management,
with conversion from the hanging U Slab to the Sarmiento
brace (Figure 2B). All fractures proceeded to union, and
all patients regained full function of their arms at latest
follow-up.
One patient presented on post-operative day 42 com-
plaining of a “funny feeling”, although on examination
and radiologic investigation there were no abnormalities
or hardware failure. This patient was managed conserva-
tively with simple analgesia. At 1 year post-operatively, this
patient presented again with a four-day history of right
arm (the fractured and repaired arm) pain. Clinical and
radiologic examination was again normal, and the patient
was again managed with simple analgesia.
Another patient presented four months post-
operatively complaining of pain and a “pop” making
a pass with his fractured arm playing football. X-ray
revealed an acute, oblique, mildly displaced fracture
proximal to the cortical plate. This patient was managed
conservatively with his arm placed in a sling and analgesia.
3. Discussion
This study presented a series of five atraumatic frac-
tures of the humeral shaft occurring during a maximal-
effort throwing action whilst playing dodgeball. Four of
the patients were managed surgically, whilst the other was
managed conservatively. All fractures proceeded to union.
To our knowledge, this is the first study to present a series
of fractures secondary to throwing whilst playing dodge-
ball.
Atraumatic fractures of the humerus secondary to
throwing are a rare incidence, with only case reports and
series detailing this particular mechanism of injury. “Ball-
thrower’s” fractures typically occur in recreational base-
ball players attempting a hard throw, although these frac-
tures have been identified in various other sports and ac-
tivities (1-12). Concomitant radial nerve injury resulting in
wrist drop occurs in up to 3 - 16% of patients (3-9), although
all patients in our series were neurovascularly intact.
The overhand throwing kinetics in dodgeball have
been likened to the kinetics in baseball pitchers (17). The
act of throwing is a complex motion involving 6 main
phases: wind-up, stride, arm-cocking, acceleration, follow-
through and release (18). The action of opposing rotational
forces from the proximal and distal ends of the humerus
arm-cocking and acceleration phases of throwing result in
torsional forces causing fracture (11).
A professional baseball pitcher has an average angular
velocity of shoulder internal rotation of 6000 deg/sec, and
the elbow has an average angular velocity of 4600 deg/sec
(11, 19-21). During the arm-cocking phase of the throw-
ing action when the arm is in maximal external rotation
the muscular forces at the proximal end of the humerus
including subscapularis, pectoralis major, and latissimus
dorsi muscles apply an internal rotational force to initiate
the throw (11, 22, 23). Prior to commencing the acceleration
phase, the forearm, hand and object to be thrown create an
external rotation inertial force upon the distal end of the
humerus (11, 24). Therefore, there are opposing rotational
forces applied to the humerus, namely internal rotational
proximally and external rotation distally.
During the acceleration phase prior to ball release, an-
tagonist muscle groups and the overall kinetic energy of
the arm results in fracture (9). Some controversy in the lit-
erature exists regarding the precise muscle groups respon-
sible at the time of humeral failure.
The location of the humerus fracture with our series
of five patients was the consistent with previous reports in
baseball pitchers who fractured at the junction of middle
and distal thirds of the humerus (9, 11). The mean torque
required to cause bony failure in cadaveric humeri is re-
ported as 53+/-17 Nm (25).
Between 92+/-16 Nm and 90+/-20 Nm of torque is pro-
duced during a full force throw by pitchers (11, 20). This
was nearly double the torque required for bone failure (25).
The maximum stressed part of the humerus during the
throw was the distal third, which explains why the major-
ity of thrower’s injuries occur within the distal third of the
humerus (3, 9).
“Ball thrower’s” fractures seldom occur in players at
the competitive or professional level (11, 26-28). Normal
bone will remodel in response to the stresses as demon-
strated by baseball pitchers humeri that have thicker and
denser cortices (11, 29). Computed tomography analysis
has found that lower thickness of the cortices was highly
correlated with the likelihood of fracture. Therefore, thin-
ner the cortex the less torsional stress it can withstand
(30). Recreational players who have not had the opportu-
nity for compensatory bony remodeling or skeletally im-
mature patients may be more likely to sustain a spiral dis-
tal humerus fracture.
The history of prodromal symptoms prior to the onset
of injury may indicate the development of a stress fracture
in the humerus. This would allow the action of a throw in
a recreational player to exceed the tolerances of torsion of
the normal humerus and result in a complete fracture (11,
31). Three (50%) of our cases reported an aching sensation
associated with throwing prior to their injury, which may
have been indicative of pre-existing stress fractures. Other
2 Arch Trauma Res. 2017; 6(1):e36051.
Gia An VV et al.
Figure 1. Representative X-Rays of Patients Managed Surgically
A, at presentation prior to treatment; B and C, 6 weeks following open reduction and internal fixation using 2 compression screws and a 5 + 6 locking compression plate.
Figure 2. Representative X-Rays of Patients Managed Conservatively
A, at presentation prior to treatment and B, after application of hanging U-Slab.
previously reported mechanisms contributing to fracture
include muscle fatigue and poor throwing techniques (9,
32). Therefore, patients reporting these prodromal symp-
toms could be considered at-risk of developing “throwers’
fractures, and should be counselled appropriately.
The optimal management strategy for “throwers’ frac-
Arch Trauma Res. 2017; 6(1):e36051. 3
Gia An VV et al.
tures remains unclear. Several papers have cited non-
surgical management with a hanging cast with conver-
sion to a functional brace as the gold standard of treat-
ment, although it should be noted that these recommen-
dations are made based on low-quality evidence (3, 9,
33). Surgical management via open reduction and inter-
nal fixation of the fracture demonstrates similar outcomes
when compared to conservatively managed cases (9). A
recent study by Kim et. al demonstrated favourable out-
comes when using a locking plate system via an anterior
humeral approach for distal thrower’s spiral fractures of
the humerus, demonstrating a slightly accelerated union
time compared to previously reported times associated
with bracing (17.3 weeks vs. 5 months) (9, 34). Future stud-
ies should investigate and compare conservative and sur-
gical management strategies in the setting on “throwers’
fractures prospectively. Irrespective of management, all
patients in our case series proceeded to union.
Overall, the reliability and validity of conclusions and
statements made regarding “thrower’s” fractures are lim-
ited by the low-quality of evidence, and the rarity of the
injury pattern. Future cross-sectional studies using ortho-
pedic registries could provide more reliable data in order
to formulate a consistent, evidence-based approach to the
prevention, management and rehabilitation of thrower’s
humeral fractures.
3.1. Conclusion
The popularity of dodgeball as a recreational sport is
increasing and it is important to recognize that this is an
injury that will likely present more frequently for orthope-
dic management. The management of the humerus frac-
ture can be either non-operative through casting and func-
tional bracing, or operative achieving similarly good re-
sults. Patient expectations need to be addressed through
discussions of operative and non-operative management
strategies. The exact mechanisms underpinning the tor-
sional moment on the humerus resulting in bony fail-
ure remain unclear and require further biomechanical
and prospective cross-sectional studies. A submission has
been made to the Australian Dodgeball Federation outlin-
ing recommendations to screen potential “at risk” players
with arm pain and advise them to avoid throwing activi-
ties and to seek medical clearance prior to participating in
dodgeball.
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Arch Trauma Res. 2017; 6(1):e36051. 5


Atraumatic Fractures of the Humerus Associated With Throwing Whilst Playing Dodgeball: A Case Series and Review of the Literature

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Atraumatic Fractures of the Humerus Associated With Throwing Whilst Playing Dodgeball: A Case Series and Review of the Literature

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