Crutch Gait Cycle
BIOM9541 Mechanics of the Human Body
Major Assignment
Ghoncheh Akhavan
Reweena Kaur
Elodie Manouvrier
Raniya Parappil
Abstract
Two point swing through crutch gait and Three point crutch gait are both methods of providing
individuals with lower limb ailments a means of mobility, whether it be for short term, long term
or variable periods of use. The benefits of utilising crutches for the purpose of locomotion
compared to other assistive devices such as wheelchairs is highly dependable on the technique of
the patient employed during gait. Subsequently the purpose of this study was to analyse the joint
kinematics of the lower extremities during both two point swing through and three point crutch
gaits of non-disabled test subjects compared to that of normal walking. Joint angles of the pelvis,
hip, knee and feet of the weight bearing leg were investigated. Utilising a motion capture system
comprising of four Viacom infrared cameras and placing retroreflective markers on both the
subject and crutches, joint angles in the sagittal, frontal and transverse planes during a complete
gait cycle were obtained. Results demonstrate that a marked increase in the pelvic tilt, decrease in
pelvic rotation, decrease in leg abduction and adduction, decrease in hip rotation and decrease in
knee flexion and extension arises through the use of crutches. Such data indicates that the use of
the aforementioned assistive device provides increased stability and restricts movement of the
body in the transverse and sagittal plane. Additionally it was observed that two point swing
through gait yielded more significant reductions in the joint angles than three point swing through
gait which is attributable to the grounding of both feet during the gait cycle imposing increased
rigidity on the lower extremities and possibly an increased load bearing capacity of the upper
limbs. Consequently the technique employed to achieve ambulation during crutch gait will affect
the resultant joint kinematics of the patient and as such will determine the method of gait
prescribed to rehabilitating individuals.
Introduction
Assistive devices such as wheelchairs, crutches and hearing aids are mechanical implements that
have been specifically designed to aid people with disabilities to accomplish what they need and
want to do. Walking aids are one of the common types of assistive devices, they are frequently
prescribed by physiotherapists to assist patients when normal ambulation is involved with pain,
impaired balance, weakness or musculoskeletal abnormality following trauma, surgery and
incapacitating pathology [1]. The use of walking aids can be categorized into three areas [2]:
•
For short term mechanical assistance (such as in lower-limb trauma).
•
Subject to variable use but especially for non-load-related tasks (such as for balance
in apprehensive elderly people).
•
For long term mechanical assistance to ambulation (such as in spinal cord injury).
Walking crutches have been widely used for 5000 years to assist people with minor legs,
amputees, paraplegics, people with torn ligaments and feet injuries to help balance and
ambulation. The materials of crutches have changed but the overall design of the crutches is
mostly the same [3]. Crutch walking offers some advantages that a person cannot gain by sitting
and using wheeled mobility. These advantages include improved growth of bone, improved
circulation of blood, reduced bladder infections and reduced pressure lesions [4]. They help
decrease the burden of the weight from the upper body and encourage the disable people to walk
more often. They have been designed to be light in weight and compact in size for convenient
usage, therefore people tend to choose walking crutches over wheelchairs to aid their ambulation.
There are two general types of crutches that most people use: axillary crutches and elbow crutches.
Axillary crutches are often used by temporary users and elbow crutches are often used by
permanent users. However it is said that ambulation with axillary crutches is less energy
consuming and needs less effort than ambulation with elbow crutches [5]. Needless to say, besides
many physiological and psychological benefits of crutches to individuals, they have many
drawbacks that sometimes deter individuals from using those including [3]:
 High-energy expenditure.
 Injuries due to repetitive loads on upper body.
 Problems due to not standing and walking.
 Specific disease and conditions such as crutch palsy, acne mechanical, formation of an
aneurysm and axillary artery thrombosis.
Therefore, it is necessary to ensure that crutches are optimally fitted to the patient and cause
minimum complication to crutch users. According to this fact, there have been a lot of
investigations to determine kinetics and kinematic characteristics of crutch gait walking and
comparing those results with normal walking. Stallard et al. (1978) monitored an increase of
24.5% bodyweight for single-foot landing and 35.1% for both feet landing in ground reaction
forces when compared with normal gait. However they did not report on horizontal reactions on
the lower limb, the ground reaction to crutches or on phase relationship. Sheng Li et al.
investigated biomechanical characteristics of a three-point crutch gait with 10%, 50% and 90%
weight bearing level and compared their kinetic and kinematic results with normal walking. They
observed large variations in ground reaction force from subject to subject, decrease in the speed
velocity due to decrease of cadence, constant loading pattern in un-affected side and shorter stance
phase and longer swing phase in affected side of the body. They also observed a decrease in hip
flexion and hip adduction in involved side, with a slight greater hip abduction and external rotation
in non-involved side which was due to the shift of the centre of gravity to the non-involved side. In
Wilson and Gilbert’s study (1982), it was found that the user’s hand, supports 1.1 to 3.4 times of
the body weight and the axilla support a horizontal force of 3 to 11% of their body weight [8].
However in a similar study performed by Goh, Toh and Bose (1986), almost different results were
collected. But when they tested the axillary forces by using the crutches correctly and incorrectly,
they realised that the axillary load was about 5 and 34% of body weight when the crutches were
used correctly and incorrectly, respectively [5]. Takehiro et al. (2008) investigated the kinematics
of the upper and lower body of non-disabled subjects during swing-through crutch gait using
axillary and elbow crutches. They did not find a big difference in energy consumption between the
two types of crutches, however in case of axillary crutches, elbow flexors used more energy in
order to enable shoulder abduction for high stability, and in the case of elbow crutches, elbow
extensors used more energy to keep the whole body weight on elbow joints. S.Vankoski et al.
(1997) performed gait analysis on children with high-sacral-level myelomeningocele, with and
without crutches. They found improvement in timing on stance phase, pelvic depression and hip
abduction, reduction in pelvic rotation and so significant difference in walking velocity.
It is evident that there is an obvious lack of information in analysing joint kinematics of different
crutch gait. It is important to have the knowledge of different types of crutch gait to prescribe the
most suitable one to the patients. The kinematic data of different crutch walking can be very
helpful to design more convenient crutches, which minimize the complications of current crutches.
In this study we tried to describe three-point and swing-through crutch gait using a motion capture
system and compared it to normal walking.
Method
To characterize biomechanically three point crutch gait and two point swing through crutch gait
and comparing to normal walking, a motion capture system was employed to obtain the kinematic
data, which was collected using a four camera Viacom system. The cameras were arranged at the
four corners of a marked walkway, approximately 4m x 1m in dimension to capture the subject’s
motion, a rough schematic of the experimental layout is shown in Figure 1 below.
Figure 1: Layout of experimental procedure [7]
Firstly the Viacom system was prepared for motion capture by calibrating the software system and
then setting the volume origin and axes using the calibration device, 5 marker wand and L-Frame.
Any interference from background radiation or those from the facing cameras were blocked out
prior to data collection. The subject was created in the Vicon Nexus program through inputting
measurements of body mass, height, leg length, knee width and ankle width. The 14mm diameter
retroreflective markers were attached to the subject in the following places, shown in Figure 2:
 Mid-way between the posterior superior iliac spines.
 Left and right anterior superior iliac spine.
 Left and right thigh (not in mirrored positions).
 Left and right knee.
 Left and right tibia (not in mirrored positions).
 Left and right ankle.
 Left and right heel.
 Left and right toe.
Additional markers were placed on both crutches (appropriately adjusted to the subjects height) at
the crutch pad, handgrip and crutch base as indicated by Figure 3.
Figure 2: Placement of markers on subject [13].
Figure 3: Placement of markers on crutch.
A static trail of the subject was captured to reconstruct markers, which were then manually
labeled, from which a Vicon Skeleton of the subject was created.
After everything was set up and the subject was prepared and notified of the motions required for
both two point swing through gait and three point crutch gait, motion data was captured for 3
consecutive trials for each of the gait cycles including normal walking. Care was taken to ensure
that each trial contained at least 2 complete gait cycles. After the data was captured the trial was
reconstructed and automatically labeled. Next, the captured data was reviewed and cropped to
include two complete gait cycles and the gaps were filled on Viacom system manually utilising the
spline fill and pattern fill tools provided by the Vicon program. Following this the events of foot
strike, the instant where the heel strikes the ground and foot off, the instant when the toe leaves the
ground.
All the captured data was exported to excel and then processed. Right pelvis, hip, knee and foot
progression angles were graphed against a normalised percentage of the gait cycle (foot strike to
foot strike) to obtain joint kinematic data for all three gait methods.
There were a few assumptions made in our experiment:
1. The left leg is impaired leg and the right leg is the normal functioning limb, which is the
weight bearing foot.
2. The stance phases of the diseased limb and crutches happen simultaneously (symmetry in
time).
3. The swing phases of crutches and the diseased limb are performed with pendular motion,
simultaneously (symmetry in time).
Results
Pelvic Tilt
40
35
Pos-Ant
30
25
20
Normal
15
3-Point
10
2-Point
5
0
0
20
40
60
Gait cycle (%)
80
100
Figure 4: Degree of pelvic tilt for one complete gait cycle of assisted and unassisted gait.
Pelvic Obliquity
30
25
Down-Up
20
15
Normal
10
3-Point
5
2-Point
0
-5
0
20
-10
40
60
80
100
Gait cycle (%)
Figure 5: Degree of pelvic obliquity for one complete gait cycle of assisted and unassisted gait.
Pelvic Rotation
30
25
Ext-Int
20
15
Normal
10
3-Point
5
2-Point
0
-5
-10
0
20
40
60
80
100
Gait cycle (%)
Figure 6: Degree of pelvic rotation for one complete gait cycle of assisted and unassisted gait.
It is evident from Figure 4 above that there exists a marked increase in the pelvic tilt through the
use of crutches. More so there exists some degree of overlap in the pelvic obliquity and pelvic
rotation joint angles between both unassisted and crutch assisted gait. Although the range in values
of angular displacement between normal gait and crutch gait is much larger than both two point
and three point crutch gait. Such a result is anticipated because the crutches provide stability and
restrict movement of the body in the transverse plan. Additionally there is no weight shifting from
one leg to another in crutch-assisted gait, which would ultimately minimise the magnitude of
pelvic obliquity.
Hip Flexion/Extension
70
60
50
Pos-Ant
40
30
Normal
20
3-Point
10
2-Point
0
-10 0
20
-20
40
60
80
100
Gait cycle (%)
Figure 7: Degree of hip flexion and extension for one complete gait cycle of assisted and unassisted gait.
Hip Abduction/Adduction
30
25
Ab-Ad
20
15
Normal
10
3-Point
5
2-Point
0
-5
-10
0
20
40
60
80
100
Gait cycle (%)
Figure 8: Degree of hip abduction and adduction for one complete gait cycle of assisted and unassisted gait.
Hip Rotation
50
40
Ext-Int
30
20
Normal
10
3-Point
0
-10
0
20
40
60
80
100
2-Point
-20
-30
Gait cycle (%)
Figure 9: Degree of hip rotation for one complete gait cycle of assisted and unassisted gait.
Through data analysis of the resulting hip angles in response to normal, two point swing through
and three point gait it is evident that hip movement in the sagittal plane is drastically reduced.
More specifically the subsequent degree of extension is nil with regards to crutch assisted gait i.e.
the supporting leg is always held in flexion. Considering the supporting leg, it is additionally
observed that during the gait cycle utilising crutches the extent of leg abduction and adduction is
minimised to less than 5o from its initial position. This value is smaller than that observed by
normal gait, which deviates up to 10o throughout the complete gait cycle. Such results lie in
agreement with the notion that through the use of crutches increased stability and rigidity is
experienced by the able bodied subject, derived from the pelvic angle data. Observing hip rotation
a noticeable decrease in both the magnitude and direction of this movement in the transverse plane
occurs. This is somewhat expected as during gait there is no second foot to provide a point of
anchorage during gait that would inevitably cause the body to rotate about its axis as a step is
taken. In conjunction the first noticeable difference between the two methods of crutch gait is
observed. Two point swing through gait rotation is less than that of three point gait. This is result
is anticipated as the grounding of two feet during swing through gait provides greater stability than
what would be experienced by one single planted foot on the ground. More hip movement and
angular displacement is facilitated about a single leg on the floor than two and hence such a result
is observed.
Knee Flexion/Extension
60
50
Ext-Flx
40
30
Normal
20
3-Point
10
2-Point
0
-10
0
20
-20
40
60
80
100
Gait cycle (%)
Figure 10: Degree of knee flexion and extension for one complete gait cycle of assisted and unassisted gait.
Knee Varus/Valgus
30
25
Val-Var
20
15
Normal
10
3-Point
5
2-Point
0
-5
-10
0
20
40
60
80
100
Gait cycle (%)
Figure 11: Degree of knee varus and valgus for one complete gait cycle of assisted and unassisted gait.
Observing knee flexion and extension angles from this experiment in Figure 10, it is evident that
there is a significant decrease in knee extension to the extent that it does not event occur in crutch
gait. Such results indicate that the lower extremities do not receive the complete forces of the body
during mid stance, implying that the use of crutches alleviates the loads experienced by the legs.
Additionally there is a slight decrease in the magnitude of flexion during crutch assisted gait
compared to normal gait. Further backing and expanding claims that the use of crutches restricts
movement in not only the transverse plane but additionally in the sagittal plane, i.e. imposes
rigidity in these directions. Upon closer examination it is evident that the degree of extension in
two point swing through gait is less than that in three point gait but the trends of angular
displacement still correlate with one another. This may be attributable to the decreased cadence
that resulted during two point swing through gait and the more subtle movements (with the
dominant leg) conducted by the subject in order to protect the ‘injured’ leg. Such a characteristic
gait cycle would inevitably impose smaller forces when both feet return to the ground and as such
less compensation of the body weight and its associated accelerations by the knees in the sagittal
plane is required. With regards to the frontal plane of the knee a shift from a movement more
valgus in nature to varus is nature is observed during both types of crutch gait. No noticeable
variation between the two types of gait is expected and subsequently this is what is observed.
Such a difference between normal walking and crutch assisted gait is hypothesized due to the
characteristics of normal gait. In this instance foot placement is not strictly parallel and veers in
towards a midline causing a degree of varus. Consequently eliminating the second foot and with
strongly directional gait through the provision of crutches, three point crutch alleviates any degree
of varus and instead imposes valgus on the knee joints.
Dorsiflexion/Plantarflexion
30
25
Pla-Dor
20
15
Normal
10
3-Point
5
2-Point
0
-5
0
20
-10
40
60
80
100
Gait cycle (%)
Figure 12: Degree of dorsiflexion and plantarflexion for one complete gait cycle of assisted and unassisted gait.
Foot progression
0
0
20
40
60
80
100
-20
Ext-Int
-40
Normal
-60
3-Point
-80
2-Point
-100
-120
Gait cycle (%)
Figure 13: Degree of foot progression for one complete gait cycle of assisted and unassisted gait.
It is evident from Figure 12 above that the normal gait, three point crutch gait and two point swing
through crutch gait follow the same trends in reference to foot angles. The degree of plantar
flexion is slightly higher during three point crutch gait to normal walking by a factor of
approximately 2o. This is expected as the total force of the body is imposed on one foot rather than
distributed through two and hence a larger angle is required to create a larger force that is exerted
onto the lower extremities to advance through the gait cycle. Closely observing two point swings
through gait the action of plantar flexion is virtually nonexistent and occurs much later in the
normalised gait cycle. Such an occurrence is in agreement with earlier claims indicating that
crutch assisted gait causes lower extremity rigidity in the sagittal plane.
Such decrease in joint displacement may possibly be attributable to an increased load bearing
capacity of the upper extremities causing a decreased necessity for lower limb movement to
instigate motion of the body. Such a hypothesis is in agreement with the results obtained for foot
progression, evident in Figure 13. Despite the magnitude of foot progression to exist at much
higher and unexpected/abnormal values, both the two point swing through and three point crutch
gait demonstrated decreased foot displacement compared to normal walking possibly as a result of
changes in load distribution throughout the body.
Discussion
Crutch gait may be defined as a form of overland cyclical limb locomotion characterized by the
fact that the supporting and propelling phases do not only occur during support with lower limbs
but also with upper limbs holding mobility aids. In spite of the fact that gait assisted with mobility
aids, especially with crutches, is not a natural physiological activity, it is the simplest and most
common form of external compensation of lower limb and balance disorders The main purpose of
this experiment is to identify and evaluate biomechanical kinematic and dynamic parameters of
three points, two point Swing Through crutch gait and normal walking with partial weight bearing
of one (diseased) lower limb [3]. In this experiment the subject was fitted with markers, which
were attached to a tape. They were placed on the body. The markers allowed identifying the body
segments and body orientation in three dimensional space. The subject is then made to walk and
the cameras record the movement, sending this data to the plugged in computer. The data is then
processed and relevant data is then converted in to a graph (as shown in the results section). In this
experiment, normal walking is compared to that of walking with a two point crutch and three point
crutches, with one leg being diseased. The subject was assumed to have a left leg diseased and
required support. The right leg is the normal leg, which is the weight bearing foot. The stance
phases of the diseased limb and crutches happen simultaneously. The swing phases of crutches and
the diseased limb are performed with pendular motion, simultaneously.
In the first section the hip flexion, abduction and rotation with normal walking, two point swing
through gait and three point gait is looked at. As shown in the result section, during hip
flexion/extension the changes observed in one gait cycle is relatively low and similar to one other.
However, the hip abduction/ adduction and rotation showed high differences in the data. This
could be due since while walking on the crutches, more pressure in used. Another reason for the
data being so, could be due to the assumption of one leg being diseased and therefore the weight is
on the right leg, having a significant effect on the results. This is then followed by the pelvis, knee
and then foot analysis. The data for the three variables are different because of many factors,
which are discussed below. The data varies quite a lot from the normal walking when compared to
Two Point Swing through Gait and three point gaits.
The hip shares a common segment (the femur) with the knee. During the loading response phase
of walking the hip flexes, adducts, and internally rotates. This motion is caused by the external
moments acting at the joint and is resisted by actions of the hip extensors, abductors, and external
rotators. The amount of hip flexion during loading response is minimal compared to the amount of
adduction and internal rotation motion. Excessive hip adduction and internal rotation during
weight bearing affects the kinematics. Excessive hip adduction and internal rotation can cause the
knee joint center to move medially relative to the foot. Because the foot is fixed to the ground, the
inward movement of the knee joint causes the tibia to abduct. The location of the body center of
mass can have an influence on the orientation of the resultant ground reaction force vector [7].
(Refer to results table)
In normal walking, the average stance phase of 61 percent and swing phase 39 percent are in
agreement (Murray et al, 1964). The speed of progression during the crutch gait was much slower
than that of normal walking. The palm experiences a peak force of the body weight; resulting in
both the hands, wrists and forearms virtually bear the whole body weight during the swing through
gait. [8]. Then, it was assumed that the legs, moving forward act like a rigid body with no flexion
at the knees and ankles when braced. The two crutches were regarded as rigid bodies with the
lower arms that do not undergo deformation during locomotion, which move forward thus
producing equal reaction forces on each side. As expected, cadence increased with normal, two
point swing gate and three point crutch gaits walking, but the values are significantly higher in the
crutch walking and associated with a shorter stride length showing the loss of motor function in
lower limbs.
It was observed that greater displacement and acceleration occur in the crutch group during the
crutch swing. Two point swing gate and three point crutch gaits walking subject adopted a walking
strategy with the elbow in a more flexed position during the crutch stance phase. These are
generated by concentric contractions of the hip flexors and extensors in normal walking [8].
Insufficiency in motor function of the lower limbs and their consequences are very visible in the
two point swing gate and three point crutch gaits walking subject during the crutch stance phase.
The hip muscles in the normal walking subject are strongly activated during this phase, permitting
a rapid displacement of the lower limbs after the body lift-off. The trunk and pelvis were
maintained in a position that resulted in a forward lean with the pelvis tilted forward. Although the
trunk and pelvis were relatively fixed in the sagittal plane, the pelvis has a normal movement in
the other planes. The use of crutches diminishes the lateral movement and rotation of the pelvis.
Compared with normal walking, crutch walking had diminished hip flexion and adduction, less
knee flexion, and decreased ankle plantar flexion at the toe-off. This indicated a shift of the center
of gravity from the involved side slightly toward the other side. This shift would help diminish
weight bearing. The average joint angle for pelvic obliquity and pelvic rotation is similar for all
the gate cycle types. It was noted in the results that the variation of pelvic angles is larger in
normal gait compared to crutch assisted gait due to the restricted movement provided by the
crutches. The decrease in pelvic rotation observed in this experiment, which was also observed in
this studies group mentioned in the Journal by (Vankoski. S et al 1998) [9]. For the subjects in the
two point swing gate and three point crutch gaits walking hip movement in the sagittal plane is
drastically reduced, which is shown clearly in the results recorded. The supporting leg during
crutch gait does not deviate more than 5o from its initial position during the gait cycle. This lies in
agreement with the notion that crutches provide increased stability and rigidity during gait. The
rotation provided by the 2-Point hip rotation is less than 3-Point rotation. There is a significant
decrease in knee extension using crutches compared to normal gait, with the 2 point gait providing
more extension than the 3 point gait [9].
Several extrinsic factors (terrain, footwear, and clothing) along with Physical factors (weight,
height, physique) of the subject can play a major role in affecting the magnitude of the results
obtained. The subjected psychology (in this case, the subject was a non injured person using a
crutch) can have varying effect on the cadence, step length, speed, foot ankle. Another issue that
was a major concern was marker dropout. Several markers weren’t detected due the light from
other objects being reflected and the camera not being able to capture the sensors. These results in
parts of the gait cycle being missing and therefore affected the accuracy of the data collected. In
the experiment, the test was conducted on one individual, therefore not showing a good variation
for a fair test.
This conceptual study presents an experiment, which aims at analyzing biomechanically and
kinesiologically three point crutch gait, Two Point Swing through Gait and normal walking.
Furthermore, the experiment can be expanded by changing several factors. Many recent studies
have showed the usage of pressure sensors on paraplegic subjects to study their gait cycle. The
subject can be made walk up and down the stairs to obtain the force and velocity, by using sensors
or force plates. By studying more parameters over a wider range of subject range of all age group,
can be lead to a better understanding of the gait cycle.
Conclusion
Both two point swing through gait and three point gait permit an individual to ambulate safely
over a designated path, but with significant variations in terms of joint kinematics compared to
normal walking. Walking with crutches enhanced both stability and increased rigidity of the lower
extremities in the transverse and sagittal planes, whilst the use of two point swing through gait
yielded more significant decreases in the joint angles of the pelvis, hip, knee and foot compared to
that of three point crutch gait. This is attributable to both an increase of imposed loads on the
upper extremities and the added restriction in movement provided by the additional leg that comes
into contact with the ground. Hence it is evident that the complexity of the series of movements
required for such an activity to occur indicate that further analysis of forces, moments and angles
of both the upper and lower limbs are essential prior to advising the appropriate technique of
crutch gait for an individual.
References:
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
Ricky Mullis, MSc, Rebecca M. Dent, BSc ,2000 “Crutch Length: Effect on Energy Cost and Activity Intensity in Non-Weight-Bearing
Ambulation “ Arch Phys Med Rehabil ;8 1569-72.
Jack Crosbie, Edward Armstrong, Jennifer Kempson 1992 “ Is walking aid height critical? “ Australian physiotherapy , vol.38 no.4
Dorota Shortell et.al 2001, “ The design of a compliant composite crutch “ Journal of Rehabilitation Research and Development ,
Vol.38 No.1 PP: 23-32
Maurice A. et.al. 1993 “A quantitative comparison of four experimental axillary crutches” Journal of prosthetics and orthotics, Vol 5, no.
1
Adriana Segura, McNair Scholar, Penn State “ Biomechanical Evaluation of Crutch Design Variations “Departments of Kinesiology,
Mechanical Engineering, Bioengineering Orthopaedics and Rehabilitation Penn State
STALLARD, L, SANKARANKUTTY, M. ROSE, G. K. (1978). Lower limb vertical ground reaction forces during crutch walking. J.
Med. Eng. Tech. 2, 201-202.
Sheng Li, MD, Charles W. Armstrong, PhD, Daniel Cipriani, MEd, PT 2001 “Three-Point Gait Crutch Walking: Variability in Ground
Reaction Force During Weight Bearing” Arch Phys Med Rehabil Vol 82
Luc Noreau, Carol L. Richards, FranCois Comeau and Daniel Tardif, BIOMECHANICAL ANALYSIS OF SWING-THROUGH GAIT
IN PARAPLEGIC AND NON-DISABLED INDIVIDUALS, J. Biomechani~s, Vat. 28. No. 6, pp. 689 700, 1995
Stephern Vankoski, Carolyn Moore, Kimberly D statler, John FSarwalk, The Influence of Forearm crutches on the pelvic and hip
kinematics in children with myelomeningocele: don’t throw away, 1998.
Dworak. L, Rzepnicka. A, Murawa.M, 2010. “Swing-through gait from the perspective of biomechanics and kinesiology. Critical
analysis of the current state of knowledge and the idea behind the research”. Chir Narzadow Ruchu Ortop Pol. Vol 76 (6). Pp 392-8.
Goh, JC, Toh SL, Bose K.1986. “Biomechanical study on axillary crutches during single-leg swing-through gait.”Prosthet Ortho Int. Vol
10(2). Pp 89-95.
Christopher Kirtley, 2006. “ Clinical gait analysis: Theory and practice” Elsevier Health Sciences
Lauren Kark, 2011, Step-by-step guide to motion capture, lecture notes distributed in BIOM9541 Mechanics of the Human Body.
University of New South Wales, Sydney.