Download Anterior Hip Muscle Forces during an Ice Hockey Sprint Start

Anterior Hip Muscle Forces during an Ice Hockey Sprint Start
+1Shelburne, KB; 1Torry, MR; 1Krong, J, 1Decker, MJ; 1Philippon, MJ
1
Steadman♦Hawkins Research Foundation, Vail, CO
[email protected]
INTRODUCTION:
Anterior hip pain is common in athletes such as runners, soccer
and hockey players, who perform repetitive and highly load hip flexion
motions [1]. Recently, the increased diagnosis of hip labral pathology
has focused attention on the causes of hip labral injury [1]. It has been
suggested that one etiology of anterior hip pain and labral injury may be
impingement of the iliopsoas on the anterior acetabular labrum [2]. The
high incidence of anterior labral pathology in hockey players prompted
this investigation of the load borne by this muscle during a hockey start.
Identifying the cause of anterior hip pathology may lead to strategies to
prevent the injury through modified training and early detection. In
addition, the high repetitive muscle forces may be a cause of
abnormality in bony morphology that gives rise to femoroacetabular
impingement (FAI). Unfortunately, direct measurement of hip muscle
forces in vivo is unworkable. Studies utilizing instrumented hip
prostheses have contributed to our knowledge of hip joint loads.
However, these data cannot easily be used to infer muscle force, or
applied to the normal or injured joint, or a specific sport that exhibits
unique performance characteristics.
The purpose of this study was to calculate the muscle forces in the
hip during a hockey skated sprint start. We hypothesized that the force
in the muscles spanning hip would be dramatically larger than found
during common physical activity.
of the joint, a static optimization problem was solved that minimized the
square of muscle stress.
METHODS:
Hip muscle forces were calculated using a musculoskeletal model
of the body that contained a detailed representation of the muscles
spanning the hip. The body was represented as a 10-segment, 23 degreeof-freedom articulated linkage, actuated by 54 muscles. The model was
built in OpenSim [3] and based on the anthropometry and muscle
parameters reported by Delp [4], Anderson and Pandy [5], and
Shelburne et al. [6]. In this model, the hip was represented as a three
degree-of-freedom ball and socket joint. The musculoskeletal model
required as input the force exerted on the ice by the skate and joint
angles recorded for a hockey start. These inputs were obtained from
measurements of one professional (NHL) hockey player (age 26 yr,
height 177 cm, and mass 70.1 kg) who performed a series of skated
hockey sprint starts on artificial ice over two force plates embedded
under the ice. Fifty-three retro-reflective, spherical markers were
attached to select anatomical landmarks. A ten-camera motion analysis
system (Motion Analysis, Santa Rosa, CA, USA) was used to capture
three-dimensional hip motions at a frequency of 120 Hz. Ice reaction
forces (IRF) were recorded at 1200 Hz. For this report, only the right
skate (push off limb) was analyzed.
Figure 2: Predicted force in the muscles in the two positions of the
hockey start shown in Figure 1.
RESULTS:
Muscle forces in the first position were dominated by the hip
extensors (Figure 2, red bars). In the second position, muscle force
increased dramatically in the hip flexors and adductors. Prior to
opposite skate strike, force in the iliopsoas muscle was 90% of its
maximum capacity in the musculoskeletal model. The extensor and
adductor muscles produced force concentrically as the start progressed
from the first to second position (Figure 3). Conversely, the iliacus and
psoas lengthened, thus producing force eccentrically.
2000
Iliopsoas
FIRST POSITION
Gluteus
Maximus
Muscle Force (N)
1500
SECOND POSITION
Semimem
1000
Gluteus
Medius
500
Adductor
Brevis
Adductor
Magnus
0
Figure 1: Musculoskeletal model of the hip during peak push off (left)
and just prior to opposite skate strike (right).
Static optimization theory was used to calculate the values of the
unknown muscle forces during the hockey sprint start. A static
optimization problem was solved at two time instants. The first
calculation was made during push off at the time of maximum IRF. The
second was made just prior to ice contact of the opposite skate. Since the
number of muscles spanning the hip far exceeds the degrees of freedom
600
FIRST POSITION
Muscle Length (mm)
500
Semimem
SECOND POSITION
400
200
Adductor
Magnus
Gluteus
Maximus
300
Gluteus
Medius
Adductor
Brevis
Psoas
Iliacus
100
0
Figure 3: Predicted muscle lengths in the two positions of the hockey
start: the first position is shown in red, second position is shown in blue.
DISCUSSION:
A 3D model of the body including a detailed model of the hip
musculature was used to calculate muscle forces during a hockey start.
Force in the iliopsoas muscle rose dramatically from the early part of the
hockey start to just before opposite skate strike. High repetitive force in
the iliopsoas may be one reason for the high prevalence of anterior hip
pain and anterior labral injury in professional hockey players. In
addition, high iliopsoas force occurred as the muscle lengthens thus
promoting potentially high muscle forces that can be elicited by
eccentric contraction.
High iliopsoas force occurred because a high flexion torque is
required at the hip to maintain force between the skate and the ice. The
torque is high particularly because the right leg extends the right skate
far from the hip joint center thus creating a large moment arm between
the reaction force on the ice at the skate and the hip joint center.
REFERENCES:
1. Philippon MJ, Schenker ML. Op Tech Orthop 15:261–6, 2005.
2. Alpert JM, et al. Am J Sports Med 37:1594-1598, 2009.
3. Delp SL, et al. IEEE Trans Biomed Eng. 54:1940-1950, 2007.
4. Delp SL, Zajac FE. Clin Orthop Relat Res 284:247-259, 1992.
5. Anderson and Pandy J Biomech Eng. 123:381-390, 2001.
6. Shelburne et al. J Biomech. 37:797-805, 2004.
ACKNOWLEDGEMENTS:
Supported by the Steadman♦Hawkins Research Foundation and Smith
& Nephew.
Poster No. 2018 • 56th Annual Meeting of the Orthopaedic Research Society