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July 2023. Vol 24. Num 2
* Corresponding Author:
Khosro Khademi Kalantari, PhD.
Address:
Department of Physiotherapy, School of Rehabilitaon, Shahid Behesh University of Medical Sciences, Tehran, Iran.
Tel: +98 (21) 77561722
E-Mail: khosro_khademi@yahoo.co.uk
Research Paper
Ultrasonography of Knee Muscles During SLR With Dierent Posions of Hip
and Ankle in Patellofemoral Pain Syndrome
1. Department of Physiotherapy, School of Rehabilitaon, Shahid Behesh University of Medical Sciences, Tehran, Iran.
2. Department of Physiotherapy, Physiotherapy Research Center, School of Rehabilitaon, Shahid Behesh University of Medical Sciences, Tehran, Iran.
3. Department of Biostascs, Proteomics Research Center, School of Allied Medical Sciences, Shahid Behesh University of Medical Sciences, Tehran, Iran.
Saeed Mikaili
1
, *Khosro Khademi Kalantari
1
, Minoo KhalkhaliZavieh
1
, Aliyeh Daryabor
2
, Mehdi Banan Khojasteh
1
,
Alireza Akbarzadeh Baghban
3
Objecve Due to the substanal prevalence of patellofemoral pain syndrome and the importance of
quadriceps strengthening in knee rehabilitaon, determining the best way to acvate and strengthen
the patella stabilizing muscles is considered as one of important keys of treatment. The aim of this study
is to evaluate the eect of dierent hip rotaons associated with ankle dorsiexion during maximal
straight leg raising (SLR) maneuver in the sing posion on thickness and bers angle of vastus medialis
oblique (VMO) and vastus lateralis (VL) muscles using ultrasonography.
Materials & Methods This quasi-experimental study was performed on 40 individuals (healthy group: 20,
patellofemoral pain syndrome [PFPS] group: 20). VMO and VL thickness and ber angle were measured
using ultrasonography during maximal SLR in 6 posions: hip internal, hip external, and neutral rotaons
with and without ankle dorsiexion.
Results In between-group comparison, no signicant dierence was found for all variables with dierent
SLR maneuvers (P>0.05). In the within-group comparison, hip external rotaon compared to other hip
posions without ankle dorsiexion resulted in a signicant increase in VMO thickness and ber angle
in both groups (P<0.05). Also, adding ankle dorsiexion to dierent hip rotaons during SLR signicantly
increased the thickness and ber angle of VMO and VL.
Conclusion By changing hip rotaons with or without ankle dorsiexion during SLR, the trend of changes
in VMO and VL thickness and ber angle in the two groups followed the same paern. Moreover,
performing SLR in hip external rotaon with ankle dorsiexion can be recommendable for the
rehabilitaon of PFPS.
Keywords Vastus medialis oblique, Vastus lateralis, Ultrasonography, Hip rotaon, Ankle dorsiexion,
Patellofemoral syndrome
A B S T R A C T
Received: 17 Feb 2023
Accepted: 28 Jun 2023
Available Online: 01 Jul 2023
Citation
Mikaili S, Khademi Kalantari Kh, KhalkhaliZavieh M, Daryabor A, Banan Khojasteh M, Akbarzadeh Baghban A.
[Ultrasonography of Knee Muscles During SLR With Different Positions of Hip and Ankle in Patellofemoral Pain Syndrome
(Persian)]. Archives of Rehabilitation. 2023; 24(2):284-307. https://doi.org/10.32598/RJ.24.2.3670.1
:
https://doi.org/10.32598/RJ.24.2.3670.1
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Mikaili S, et al. Ultrasonography of Knee Muscles During SLR. RJ. 2023; 24(2):284-307
English Version
Introduction
atellofemoral pain syndrome (PFPS) is
often unreasoned knee anterior pain. Its
prevalence is 25% in the general population
and is more common in young and active
people [1]. Although patellar maltracking in
PFPS patients can be due to a variety of reasons, one of
the common signs associated with this disorder is the
lower activity of vastus medialis oblique (VMO) than
vastus lateralis muscle (VL) [2]. The VMO is located
at an angle of 45° to 50° to the longitudinal axis of the
femur on the medial side of the patella. The most im-
portant function of this muscle is as a dynamic stabilizer
of the patella to prevent excessive patellar lateralization
[3]. Dynamic stability of the patella is mainly performed
by the VMO and VL muscles, especially VMO [4].
Therefore, strengthening VMO can effectively improve
the function of people with PFPS.
Regarding therapeutic management, most researchers
agree that non-surgical and non-pharmacological inter-
ventions are first-line treatments for PFPS. An effective
and non-invasive method for these individuals is physio-
therapy, including general strengthening of the quadriceps,
muscular stretching, patellar taping, and specific VMO
strengthening [5]. The muscular imbalance between VMO
and VL may lead to patellar lateralization, causing PFPS.
Therefore, attention to specific VMO strengthening is cru-
cial [6]. In previous studies, different exercises have been
introduced to specifically strengthen VMO, including open
and closed kinetic chain exercises [7], changes in the tibia
[8] and hip rotations [9], adding ankle dorsiflexion during
SLR exercise [10] and hip adduction [11]. One of the exer-
cises suggested for VMO activation is the SLR maneuver
with different angles of hip rotation. Sykes et al. (2003)
showed that SLR with external hip rotation could increase
VMO electrical activity relative to VL [9]. Although other
studies have demonstrated that SLR with external hip rota-
tion cannot be used as a specific exercise to activate VMO,
there is still controversy [12]. On the other hand, another
study mentioned that adding contraction of ankle dorsi-
flexor muscles during SLR exercise can effectively activate
VMO and VL [10,13].
While performing the SLR maneuver in the supine
position, the activity of the rectus femoris muscle is
dominant over the VMO muscle due to hip flexion [14].
To our knowledge, no study has been performed on
VMO muscles to create more activity while perform-
ing the SLR maneuver sitting. Therefore, because the
rectus femoris suffers from active insufficiency in the
sitting position [15], it can be expected that by creating
this change, the activity of other parts of the quadriceps
muscle will be more dominant than the rectus femoris.
In recent years, ultrasonography has been widely used to
measure morphological changes in skeletal muscle, such as
thickness and fiber angle [16]. Compared to existing imag-
ing methods, ultrasonography is a method with high valid-
ity and reliability to examine the relationship between the
strength and size of muscles [17]. Therefore, in this study,
ultrasonography was used to record changes in the thick-
ness and fiber angle of the knee muscles.
Regarding the importance of VMO strengthening in
patients with PFPS and disagreement about exercises
that specifically activate VMO, this study measured the
thickness and fiber angle of VMO and VL muscles dur-
ing SLR exercise in different positions of this maneuver
in individuals with and without PFPS. These positions
included performing SLR exercises with maximum
muscle contraction in a sitting position by combining
different hip rotations with and without maximal con-
traction of the ankle dorsiflexor muscles.
Materials and Methods
Study participants
This quasi-experimental study was performed on 40
volunteers in two groups. One group included 20 healthy
individuals (13 males and 7 females) with a mean age of
23±2.1 years, a height of 170±6 cm, and a weight of
64.65±3.61 kg. The inclusion criteria for healthy indi-
viduals were as follows: no history of knee pain in the
last three months before the study, no record of specific
pathology in the lower limbs, and no pain in performing
more than two activities of running, jumping, sitting for
a long time, and going up and down the stairs. Another
group consisted of 20 individuals with PFPS (13 males
and 7 females) with a mean age of 22.75±3.43 years, a
height of 169±8 cm, a weight of 64.1±4.63 kg, and no
history of knee and hip trauma. The inclusion criteria in
the PFPS group included pain in the front of the knee
and around the patella during at least two activities pre-
viously mentioned, knee pain for at least the past three
months felt for most days, pain in the medial and lateral
facet of the patella [18,19]. The exclusion criteria were a
history of lower limbs surgery in the past 12 months be-
fore the study, previous musculoskeletal injuries of the
hip, knee, or ankle, inflammatory and swelling condi-
tions in the knee, and a history of dislocation or sublux-
ation of the patella [18].
P
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July 2023. Vol 24. Num 2
PFPS individuals were selected by simple non-random
sampling from patients referred to the physiotherapy
clinic of Shahid Beheshti University of Medical Scienc-
es and healthy individuals from healthy students of that
university. To determine the sample size, a pilot study
was performed on 10 cases in each group with α=0.05
and a power of 80%. Finally, 20 subjects in each group
were calculated. In this project, all participants signed
written informed consent. Individuals also completed a
demographic information questionnaire.
Visual analog scale (VAS) was used to assess pain in
people with PFPS, and they were asked to show their
pain intensity on the pain ruler from 0 to 10. Due to the
evaluation of maximal isometric contraction in the pres-
ent study, individuals with moderate pain intensity (VAS
between 3 and 6) were included.
Study procedure
To evaluate the interrater reliability of sonographic
measurements, including VMO and VL muscle thick-
ness and fiber angle, a preliminary study was performed
on 10 healthy individuals to replicate these parameters
during maximal SLR contraction in the different posi-
tions. An examiner conducted the measurements for 1
week, and the mean values with the three-time measure-
ments were used to calculate the intraclass correlation
coefficient (ICC).
After confirming the interrater reliability, the researcher
performed all VMO and VL muscle thickness measure-
ments and fiber angle measurements at the resting posi-
tion through ultrasonography. Then, before conducting
the main test, the subjects received a warm-up period by
walking at their normal speed for 5 min on a treadmill
and stretching the quadriceps, hamstrings, calf, and hip
adductor muscles. Muscle stretching was done for 30 s,
and three repetitions of the stretch for each muscle [20].
These procedures were performed on participants by the
same physiotherapist. After preparing the participants,
the person was placed in a chair designed for this study
so that the subject was sitting with straight knees and
ankles in a neutral position (Figure 1). Individuals were
then asked to randomly perform different positions of
SLR maneuver with their maximum strength in 6 posi-
tions: internal, external, and neutral hip rotations with
or without contraction of ankle dorsiflexor muscles. To
perform different hip rotations, the people rotated their
hips so that the axis designed on the device, on which
the people’s feet rested, was parallel to the thumb toe.
The axes were designed at a 45° angle on both sides, and
participants were asked to create maximum internal and
external rotations of their hips. Next, the people applied
their full strength to the load cell in front of the ankle and
held the contraction for at least 5 s. Performing SLR in
a sitting position can lead to more activity of VMO and
VL rather than the rectus femoris.
All VMO and VL muscle thickness measurements and
fiber angles were performed in this position after ensur-
ing the lower limb was stable during the SLR maneuver.
Ultrasound imaging was performed by the Sonography
Capture software so that the software regularly recorded
ultrasound images during the 5 seconds when the par-
ticipants completed their SLR maneuver. This software
could perform ultrasonographic measurements of the
target muscles when the person had created the most
torque. The participant repeated each SLR maneuver 3
times at 1-minute intervals. When the measures related
to the first 6 positions were finished, the person rested
for 4 min. The same procedure was followed for the
other 5 SLR maneuvers randomly selected. Dependent
variables included VMO and VL thickness at rest and
contraction positions, VMO and VL fiber angle at rest
and contraction positions, and the ratio of VMO to VL
thickness at different contraction positions.
Figure 1. The designed chair to measure the ultrasonographic measurements
Mikaili S, et al. Ultrasonography of Knee Muscles During SLR. RJ. 2023; 24(2):284-307
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This study used the ultrasonography device (Honda
Co, Japan) with a frequency of 7.5 MHz and a 5-cm lin-
ear probe to measure the VMO and VL muscle thickness
and fiber angle. To calculate the thickness of the VMO
muscle, we placed the probe of the ultrasound device,
after its soaking in some gel, horizontally in the supra
medial of the patella when we ensured that the lower
limb was fixed. Then, we moved the probe along the
medial side of the patella toward the proximal and distal
to reveal the VMO fibers. After ensuring that the VMO
muscle image appeared on the monitor, we saved the
image. The maximum distance between the anterior
and posterior fascia of the muscle was considered as
its thickness [21]. To measure the VMO fiber angle, we
placed the ultrasound probe parallel to the muscle fibers
so that VMO fibers appeared parallel to each other in the
ultrasound image. In this case, the angle formed between
the longitudinal axis of the ultrasound probe and the line
connecting the anterior superior iliac spine to the patella
center was considered a VMO fiber angle [16]. To mea-
sure the thickness of the VL muscle, we first marked the
middle point of the distance between the lateral epicon-
dyle of the femur and the greater trochanter of the hip.
After ensuring that the lower limb was fixed, the probe
with a sufficient amount of gel was placed parallel to
the muscle at this point. After appearing the image of
the VL muscle on the monitor, we fixed the image. The
maximum distance between the muscle’s superficial and
deep fascia was considered the VL muscle’s thickness
[22, 23]. At this point, the angle formed by the connec-
tion of the VL muscle fibers to the deep fascia was de-
fined as the VL fibers angle [24]. To evaluate the results
more objectively, we calculated the means related to the
thickness and fiber angle of VMO and VL in different
contraction positions as a percentage of the total resting
position. Therefore, all statistical tests of contraction po-
sitions were performed on percentage ratios.
Statistical analysis
The ICC was calculated to evaluate the reliability of
all dependent variables. For evaluating the normality of
data related to contractile positions, the Shapiro-Wilk
test was utilized. Due to the normality of all variables,
a 2-way mixed ANOVA test was used to compare the
healthy and PFPS groups. Also, analysis of variance
with repeated measures and the Bonferroni test were
performed for pairwise comparison to compare 6 differ-
ent positions in each group obtained by combining hip
rotations with or without ankle dorsiflexor contraction.
All analyses were performed using IBM SPSS software
version 24 at a significant level of P<0.05.
Results
A total of 20 healthy individuals and 20 subjects with
PFPS participated in the study, whose demographic in-
formation is shown in Table 1. At the beginning of the
study, there were no statistically significant differences
between the two groups in the demographic variables.
The ICC results showed that the reliability of dependent
variables during maximal SLR contraction was greater
than 0.95 (Table 2).
The values of the VMO and VL muscle thickness and
fiber angle, as well as the ratio of VMO to VL thickness
at rest (baseline position) for healthy and PFPS subjects,
are given in Table 3. The results indicated that the VMO
and VL muscle thickness and fiber angle and the ratio
of VMO to VL thickness in PFPS subjects were signifi-
cantly lower than in healthy individuals at baseline posi-
tion (P=0.01).
Mikaili S, et al. Ultrasonography of Knee Muscles During SLR. RJ. 2023; 24(2):284-307
Table 1. Demographic data of the subjects
Variables
Group
Mean±SD
P
Healthy PFPS
Age (y) 23±2.1 22.75±3.43 0.281
Height (cm) 170±6 169±8 0.473
Weight (kg) 64.65±3.61 64.1±4.63 0.321
BMI (kg/m²) 22.42 ± 1.65 22.41 ± 2.37 0.564
PFPS: Patellofemoral pain syndrome.
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In the between-group comparison of contractile posi-
tions, the results showed no significant difference in any
of the variables for the group factor (P>0.05, Table 4).
However, the main effect of contractile positions in both
healthy and PFPS groups during the SLR maneuver was
significant (P<0.05), and the results are presented below.
The independent effect of hip rotation without ankle
dorsiflexion contraction on VMO thickness changes
showed that hip rotation during SLR had a significant
effect on VMO thickness so that the existence of ex-
ternal hip rotation could significantly increase this out-
come in both groups compared to neutral and internal
hip rotations (P=0.01). On the other hand, the evaluation
of the combined hip rotation and ankle position showed
that performing SLR exercise with external hip rotation
and ankle dorsiflexion compared to SLR with neutral
hip rotation and no ankle dorsiflexion significantly in-
creased VMO thickness and fiber angle in both groups
(P=0.01) (Figure 2).
Also, a statistically significant effect was observed re-
garding the independent effect of hip rotations on chang-
es in VL thickness and fiber angle, so internal hip rota-
tion increased these outcomes in both groups compared
to the neutral hip position (P=0.01). Moreover, internal
hip rotation and ankle dorsiflexor contraction signifi-
cantly increased VL thickness and fiber angle compared
to SLR with a neutral hip position and no ankle dorsi-
flexion in both groups (P=0.01) (Tables 5 and 6).
Regarding the thickness ratio of VMO to VL in dif-
ferent SLR positions, the addition of ankle dorsiflexor
contraction to the exercise was an influential factor in
this ratio, so this variable during SLR with external hip
rotation and no ankle dorsiflexor contraction was signif-
icantly higher than SLR with external rotation of the hip
Table 3. Ultrasonographic measurements in rest position by the independent t test
Variables
Group
Mean±SD
P
Healthy PFPS
VMOT (mm) 20.82±4.13 19.93±1.62 0.011*
VMOFA (degree) 49.25±5.17 47.76±1.58 0.002*
VLT (mm) 19.59±2.60 19.16±1.32 0.001*
VLFA (degree) 22.4±3.44 20.94±2.76 0.114
VMOT/VLT 1.06±0.18 1.01±0.1 0.019*
Abbreviations: VMOT: Vastus medialis oblique thickness; VMOFA: Vastus medialis oblique fiber angle; VLT: Vastus lateralis
thickness; VLFA; Vastus lateralis fiber angle.
*P<0.05
Mikaili S, et al. Ultrasonography of Knee Muscles During SLR. RJ. 2023; 24(2):284-307
Table 2. Interrater reliability of sonographic measurements from two ultrasonography sessions
Variables SEM ICC
%95 CI
Lower Bound Upper Bound
VMO Thickness 0.32 0.96 0.86 0.99
VMO Fiber Angle 0.59 0.97 0.91 0.99
VL Thickness 0.68 0.98 0.93 0.99
VL Fiber Angle 0.44 0.98 0.93 0.99
Abbreviations: VMOT: Vastus medialis oblique, VLT: Vastus lateralis, ICC: Intraclass correlation coefficient, SEM: Standard error
of the mean.
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July 2023. Vol 24. Num 2
Table 4. Ultrasonographic measurements in two groups (ratio to the rest position)
Variables
Mean±SD
Healthy Group PFPS Group
VMOT (mm) VMOFA
(degree)
VLT
(mm)
VLFA
(degree) VMOT (mm) VMOFA
(degree)
VLT
(mm)
VLFA
(degree)
Rest condions 100±0 100±0 100±0 100±0 100±0 100±0 100±0 100±0
SLRNHNA 130.04±16.77 131.64±19.06 102.42±10.68 104.49±15.48 126.02±10.14 127.71±6.8 93.58±9.47 103.61±11.68
SLRNHAD 139.09±17.12 139.29±22.66 101.9±6.86 107.54±18.60 135.15±15.21 134.26±10.1 95.4±12.41 103.54±11.72
SLRIHNA 132.2±23.87 134.58±26.86 107.8±8.93 116.87±21.26 132.89±9.9 126.23±10.75 101.95±13.08 110.81±10.11
SLRIHAD 140.18±20.61 144.7±28.44 114.06±17.08 105.06±16.77 140.5±15.61 140.6±11.28 105.99±9.75 103.01±8.8
SLREHNA 136.1±23.15 140.94±36.13 109.45±12.69 121.36±22.46 134.19±11.19 129.16±8.57 101.13±14.09 109.25±15.52
SLREHAD 154.31±22.4 158.52±37.41 110.86±16.48 106.47±16.02 151.56±17.29 153.99±13.54 102.76±10.38 101.97±10.29
VMOT (mm) VMOFA (degree) VLT (mm) VLFA (degree)
P0.680 0.307 0.068 0.232
Abbreviations: SLRNHNA, straight leg raising in neutral hip position and with neutral ankle position; SLRNHDA, straight leg rais-
ing in neutral hip position and with ankle dorsi flexion; SLRIHNA, straight leg raising with hip internal rotation and with neutral
ankle position; SLRIHAD, straight leg raising with hip internal rotation and with ankle dorsi flexion; SLREHNA, straight leg rais-
ing with hip external rotation and with neutral ankle position; SLREHAD, straight leg raising with hip external rotation and with
ankle dorsi flexion; VMOT, vastus medialis oblique thickness; VMOFA, vastus medialis oblique fiber angle; VLT, vastus lateralis
thickness; VLFA, vastus lateralis fiber angle.
Mikaili S, et al. Ultrasonography of Knee Muscles During SLR. RJ. 2023; 24(2):284-307
15
Figure 2. Comparing VMO Thickness During Three Types of SLR Exercise in Healthy and PFPS Groups
Abbreviations: PFPS, patellofemoral pain syndrome, SLRNHNA, straight leg raising in neutral hip position and
with neutral ankle position; SLREHNA, straight leg raising with hip external rotation and with neutral ankle
position, SLREHAD; straight leg raising with hip external rotation and with ankle dorsi flexion; VMOT, vastus
medialis oblique thickness.
* P<0.05.
100
130.04 126.02
*
136.1 *
134.19
*
154.31
*
151.56
0
20
40
60
80
100
120
140
160
180
Rest Healthy PFPS
⁄ R (%)
SLRNHNA SLREHNA SLREHAD
Figure 2. Comparing VMO thickness during three types of SLR exercise in healthy and PFPS groups
Abbreviations: PFPS, patellofemoral pain syndrome, SLRNHNA, straight leg raising in neutral hip position and with neutral ankle
position; SLREHNA, straight leg raising with hip external rotation and with neutral ankle position, SLREHAD; straight leg raising
with hip external rotation and with ankle dorsi flexion; VMOT, vastus medialis oblique thickness.
* P<0.05.
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July 2023. Vol 24. Num 2
without ankle dorsiflexion in the two groups (P=0.01).
Nevertheless, no significant difference was observed in
the combined effect of hip rotation and ankle position on
this ratio (Figure 3).
Discussion
This study aimed to find the best position to activate
VMO muscle than VL in different positions of SLR ma-
neuver in two groups of healthy people and those with
PFPS. Various techniques, such as magnetic resonance
imaging, electromyography, and ultrasonography, are
used to study skeletal muscle structure and function;
ultrasonography, as a non-invasive, accessible, and in-
expensive tool, can easily examine these outcomes in
either static or dynamic positions [25]. In this study,
we utilized ultrasonography to evaluate VMO and VL
activation during the maximal SLR maneuver with dif-
ferent positions of hip rotation and ankle dorsiflexion.
Ultrasonography showed high reliability in examining
the structural features of VMO and VL during SLR.
VMO and VL muscle thickness and fiber angle in
the PFPS group were significantly less than in healthy
people at rest. This finding is consistent with the results
of Giles et al. (2013) and Dong et al. (2021), reporting
atrophy in the VMO and VL muscles at rest position
for PFPS patients compared to healthy individuals. The
Table 5. Bonferroni result, healthy group
Variables
SLR type
P
VLFA VLT VMOFA VMOT
SLRNHNA
SLRNHAD 1.000 1.000 0.901 0.042*
SLRIHNA 0.032*0.320 1.000 1.000
SLRIHAD 1.000 0.061 0.136 0.07
SLREHNA 0.003*0.071 1.000 1.000
SLREHAD 1.000 0.392 0.008*0.000*
SLRNHAD
SLRIHNA 0.432 0.110 1.000 0.725
SLRIHAD 1.000 0.037*1.000 1.000
SLREHNA 0.063 0.295 1.000 1.000
SLREHAD 1.000 0.214 0.025*0.002*
SLRIHNA
SLRIHAD 0.059 1.000 0.056 0.236
SLREHNA 0.013*1.000 0.773 0.295
SLREHAD 0.069 1.000 0.000*0.000*
SLRIHAD
SLREHNA 0.009*1.000 1.000 1.000
SLREHAD 1.000 1.000 0.014*0.000*
SLREHNA SLREHAD 0.006*1.000 0.001*0.000*
Abbreviations: SLRNHNA: Straight leg raising in neutral hip position and with neutral ankle position; SLRNHDA: Straight leg
raising in neutral hip position and with ankle dorsi flexion; SLRIHNA, straight leg raising with hip internal rotation and with neutral
ankle position; SLRIHAD, straight leg raising with hip internal rotation and with ankle dorsi flexion; SLREHNA, straight leg rais-
ing with hip external rotation and with neutral ankle position; SLREHAD, straight leg raising with hip external rotation and with
ankle dorsi flexion; VMOT, vastus medialis oblique thickness; VMOFA, vastus medialis oblique fiber angle; VLT, vastus lateralis
thickness; VLFA, vastus lateralis fiber angle.
*P<0.05.
Mikaili S, et al. Ultrasonography of Knee Muscles During SLR. RJ. 2023; 24(2):284-307
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July 2023. Vol 24. Num 2
reason for this claim was the presence of pain during
quadriceps contraction, which led to inhibition of this
muscle, resulting in atrophy in both VMO and VL mus-
cles in these patients [26, 27].
In between-group comparison, no significant differ-
ence in the VMO and VL muscle thickness and fiber an-
gle was observed in different positions of SLR maneu-
ver, and the trend of changes in the two groups followed
the same pattern by changing the hip rotation with or
without ankle dorsiflexor contraction. These results are
consistent with the findings of Lotfi et al. (2018), who
reported no significant difference in the electrical activ-
ity ratio of VMO to VL during the SLR maneuver be-
tween the healthy and PFPS groups [28]. The lack of
between-group difference could be young PFPS patients
in the present study with no chronic condition, and the
pattern of their knee muscles activity probably did not
substantially change compared to healthy individuals.
Also, because these patients did not have much severe
pain, they could probably activate the quadriceps mus-
cle as much as healthy people.
Based on the results, the independent position of the
external hip rotation compared with the two other hip
rotations led to a significant increase in the VMO mus-
cle thickness and fiber angle. This finding confirms that
reported by Sykes et al. (2003) study [9]. It may be due
Table 6. Bonferroni result, pfps group
Variables
SLR type
P
VLFA VLT VMOFA VMOT
SLRNHNA
SLRNHAD 1.000 1.000 0.017*0.439
SLRIHNA 0.126 0.007*1.000 0.474
SLRIHAD 1.000 0.000*0.000*0.006*
SLREHNA 0.852 0.078 1.000 0.056
SLREHAD 1.000 0.000*0.000*0.000*
SLRNHAD
SLRIHNA 0.134 0.049*0.045*1.000
SLRIHAD 1.000 0.000*0.015*1.000
SLREHNA 0.268 0.139 0.526 1.000
SLREHAD 1.000 0.010*0.000*0.217
SLRIHNA
SLRIHAD 0.030* 1.000 0.001*0.561
SLREHNA 1.000 1.000 1.000 1.000
SLREHAD 0.024* 1.000 0.000*0.001*
SLRIHAD
SLREHNA 1.000 0.691 0.005*0.420
SLREHAD 1.000 0.581 0.001*0.595
SLREHNA SLREHAD 0.476 1.000 0.000*0.005*
Abbreviations: PFPS: Patellofemoral pain syndrome SLRNHNA: Straight leg raising in neutral hip position and with neutral ankle
position; SLRNHDA, straight leg raising in neutral hip position and with ankle dorsi flexion; SLRIHNA, straight leg raising with
hip internal rotation and with neutral ankle position; SLRIHAD, straight leg raising with hip internal rotation and with ankle dorsi
flexion; SLREHNA, straight leg raising with hip external rotation and with neutral ankle position; SLREHAD, straight leg raising
with hip external rotation and with ankle dorsi flexion; VMOT, vastus medialis oblique thickness; VMOFA, vastus medialis oblique
fiber angle; VLT, vastus lateralis thickness; VLFA, vastus lateralis fiber angle.
*P<0.05.
Mikaili S, et al. Ultrasonography of Knee Muscles During SLR. RJ. 2023; 24(2):284-307
292
July 2023. Vol 24. Num 2
to the connections of the VMO muscle to the adduc-
tor magnus and the adductor longus; the fibers of these
muscles are placed on the surface, thereby performing
the SLR with hip external rotation by the collaboration
of adductors [1]. As a result of more activity of the ad-
ductor muscles, the VMO muscle also shows more ac-
tivity by increasing the values of the sonographic param-
eters of the present study. On the other hand, with the
hip external rotation, the VMO should overcome greater
gravitational force, resulting in greater torque produc-
tion in the quadriceps muscle. In this regard, Mikaili et
al. (2017) showed that greater force was produced in the
external hip rotation compared to the internal and neutral
rotations of the hip during the SLR maneuver in healthy
individuals [29]. However, Livecchi et al. (2002) found
that external hip rotation during SLR could not be used
as a specific exercise to activate VMO in healthy indi-
viduals [12]. In previous studies, surface EMG has been
utilized to evaluate the VMO and VL muscle activation
in SLR maneuvers with different hip rotations. How-
ever, in the present study, ultrasonography was applied,
which may be a reason for the controversy between the
results of this study and some previous studies.
Adding ankle dorsiflexion to the SLR maneuvers sig-
nificantly increased the VMO and VL thickness and fi-
ber angle in healthy and PFPS groups. This finding is in
line with that of Choi et al. (2014) and Cha et al. (2014)
[10, 30]. From the point of view of neurophysiology
and according to the overflow principle in propriocep-
tive neuromuscular facilitation (PNF), the contractile
level of muscles can be affected by the contraction of
other muscles. This energy transfer is justified by the ir-
radiation principle, in which the torque resulting from
the contraction of other muscles is transferred to weaker
motor units [31]. Using the electromyographic exami-
nation of the abdominal muscles, Chon et al. (2010)
showed that the addition of ankle dorsiflexion to the ab-
dominal drawing-in maneuver increased the activity of
the abdominal muscles through the irradiation [32]. The
existence of a reflex relationship between the pretibial
muscle and the quadriceps muscle has also been shown
in the literature; for example, Kalantari et al. (2009) and
Rafsanjani et al. (2017) investigated this reflex relation-
ship, and their findings are consistent with the results
of the present study [33, 34]. Moreover, the extent and
intensity of this reflex vary at different positions of the
knee and the hip joints. As the knee extension and hip
flexion move closer to their terminal range of motion,
the incidence of this reflex reaches its maximum. This
reflex appears to occur more often in the SLR exercise
performed at their terminal range of motion of the knee
and hip. This event may explain the knee muscles’ in-
creased thickness, fiber angle during the SLR, and ankle
dorsiflexor contraction.
The results of our study also indicated that the hip in-
ternal rotation with ankle dorsiflexion during the SLR
maneuver compared to other positions significantly in-
creased in VL muscle thickness and fiber angle. Because
the VL muscle is placed on the surface resulting from
the hip’s internal rotation, it becomes more active during
Figure 3. The ratio of VMO thickness to VL thickness during types of SLR exercise in PFPS group
Abbreviations: PFPS, patellofemoral pain syndrome, VMOT, vastus medialis oblique; VLT, vastus lateralis thickness; HINROT,
hip internal rotion; NHP, neutral hip position; HEXROT, hip external rotation; NA, neutral ankle position; AD, ankle dorsiflexion.
16
Regarding the thickness ratio of VMO to VL in different SLR positions, the addition of ankle
dorsiflexor contraction to the exercise was an influential factor in this ratio, so this variable during
SLR with external hip rotation and no ankle dorsiflexor contraction was significantly higher than
SLR with external rotation of the hip without ankle dorsiflexion in the two groups (P =0.01).
Nevertheless, no significant difference was observed in the combined effect of hip rotation and
ankle position on this ratio (Figure 3).
Figure 3. The Ratio of VMO Thickness to VL Thickness During Types of SLR Exercise in PFPS Group
1.2
1.25
1.3
1.35
1.4
1.45
1.5
1.55
HINROT NHP HEXROT
⁄
Ratio in SLR
(PFPS group)
NA AD
Mikaili S, et al. Ultrasonography of Knee Muscles During SLR. RJ. 2023; 24(2):284-307
293
July 2023. Vol 24. Num 2
the SLR than other parts of the quadriceps. This result
was also confirmed by Serrao et al. (2005). They stated
that the internal rotation of the tibia increased the electri-
cal activity of the VL muscle in isometric knee extension
exercises [8].
This study evaluated the ratio of VMO to VL thickness
as a measure of VMO activation. In exercise therapy in
PFPS patients, the emphasis should be on specific VMO
strengthening [35]. The combination of hip rotations
and ankle dorsiflexion on the thickness ratio of VMO
to VL indicated no significant difference between the
healthy and PFPS groups. This result is consistent with
the results of Pattyn et al. (2011). They showed that the
ratio of the cross-sectional area of VMO muscle to VL
in PFPS individuals was not significantly different com-
pared to healthy individuals [36]. Similarly, atrophy in
both VMO and VL muscles in their distal part resulted in
no significant difference in the ratio of the cross-section
of VMO muscle to VL in PFPS patients than in healthy
individuals.
Study Limitations
One of the limitations of this study was that we just
included young participants. It is suggested that future
studies are conducted on older people and other muscu-
loskeletal knee injuries. Another limitation was the im-
mediate evaluation of exercise on sonographic param-
eters; thus, a high-scale design with a long-term exercise
program could help find the best exercise for greater
VMO activation in PFPS patients.
Conclusion
The present study indicated that by changing hip rota-
tions with or without ankle dorsiflexion during SLR, the
changes in VMO and VL thickness and fiber angle in the
two groups followed the same pattern. Moreover, per-
forming SLR in hip external rotation with ankle dorsiflex-
ion can be recommendable for the rehabilitation of PFPS.
Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of
Shahid Beheshti University of Medical Sciences (Code:
IR.SBMU.RETECH.REC.1400.217). The participants
were informed about the study objectives and were as-
sured that their information would remain confidential.
They all signed a written consent form.
Funding
This article was extracted from the PhD thesis of Saeed
Mikaili. The study was funded by Shahid Beheshti Uni-
versity of Medical Sciences.
Authors' contributions
Conceptualization: Saeed Mikaili and Khosro Khade-
mi Kalantari; Methodology, and data analysis: Minoo
Khalkhali Zavieh and Alireza Akbarzadeh Baghban; In-
vestigation: Saeed Mikaili and Mehdi Banan Khojasteh;
Editing and review: Aliyeh Daryabor; Supervision:
Khosro Khademi Kalantari.
Conflict of interest
The authors declared no conflict of interest.
Acknowledgments
The authors would like to thank the Vice-Chancellor
for Research of Shahid Beheshti University of Medical
Sciences for financial support and all participants for
their cooperation.
Mikaili S, et al. Ultrasonography of Knee Muscles During SLR. RJ. 2023; 24(2):284-307
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Citation
Mikaili S, Khademi Kalantari Kh, KhalkhaliZavieh M, Daryabor A, Banan Khojasteh M, Akbarzadeh Baghban A.
[ Ultrasonography of Knee Muscles During SLR With Different Positions of Hip and Ankle in Patellofemoral Pain Syndrome
(Persian)]. Archives of Rehabilitation. 2023; 24(2):284-307. https://doi.org/10.32598/RJ.24.2.3670.1
:
https://doi.org/10.32598/RJ.24.2.3670.1
Use your device to scan
and read the arcle online
1. Patellofemoral Pain Syndrome (PFPS)
2. Vastus Medialis Oblique (VMO)
3. Vastus Lateralis Muscle (VL)
4. Straight Leg Raising (SLR)
±±±
±
± ±
VAS
5. Visual Analog Scale(VAS)
6. Intraclass Correlaon Coecient (ICC)
LoadCell
SonographyCap-
ture
HondaCo
Japan
ASIS
P<SPSS
P<
7. Shapiro-Wilk Test
8. Two-way mixed ANOVA
9. Bonferroni
P=
P>
P<
P=
P
±
± ±
±±
± ±
± ±
%
P
±
± ±
± ±
± ±
± ±
± ±
P=
P=
P=
P=
±
±±±±±±±±
±±±±±±±±
±±±±±±±±
±±±±±±±±
±±±±±±±±
±±±±±±±±
±±±±±±±±
P
P=
10. Magnec Resonance Imaging (MRI)
P
P
PNF
11. Overow
12. Irradiaon
VMOTSLRPFPS
*
SLRNHNA: Straight Leg Raising in Neutral Hip position and with Neutral Ankle position, SLREHNA: Straight Leg
Raising with Hip External Rotation and with Neutral Ankle position, SLREHAD: Straight Leg Raising with Hip External
Rotation and with Ankle Dorsi flexion, VMOT: Vastus Medialis Oblique Thickness
VMOVLSLR
VMOVLSLR
SLR
P=
100
130.04 126.02
*
136.1 *
134.19
*
154.31
*
151.56
0
20
40
60
80
100
120
140
160
180
PFPS
VMOSLR(%)
⁄
R
(%)
SLRNHNA SLREHNA SLREHAD
VMOTSLRPFPS
*
VMOT: Vastus Medialis Oblique, VLT: Vastus Lateralis Thickness
HInRot: Hip Internal Rotion, NHP: Neutral Hip Position, HExRot: Hip External Rotation,
NA: Neutral Ankle Position, AD: Ankle Dorsi flexion
ثحب
VMOVLSLR
PFPSMRI
VMO VL
SLR
VMO VL SLR .
VMOVLPFPS
GileDongVMOVL
PFPS
VMOVL
SLR
1.2
1.25
1.3
1.35
1.4
1.45
1.5
1.55
HInRot NHP HExRot
VMOSLR(%)
⁄ Ratio in SLR
(PFPS Subjects)
NA AD
IR.SBMU.RETECH.
REC.1400.217
306
July 2023. Vol 24. Num 2
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