ORIGINAL RESEARCH
1 SAJSM VOL. 31 NO. 1 2019
Creative Commons Attribution 4.0 (CC BY 4.0) International License
Exploring the efficacy of low-level laser therapy and exercise for
knee osteoarthritis
A Kholvadia, BHMS, HMS (Hons), MA (HMS); D
Constantinou, MBBCH, BSc(Med)Hons, MSc Med, MPhil,
FFIMS, FACSM; P J-L Gradidge, B Sp Sc, B Sp Sc (Hons),
MSc Med, PhD
Centre for Exercise Science and Sports Medicine, Faculty of Health Sciences,
University of the Witwatersrand, Johannesburg, South Africa
Corresponding author: A Kholvadia (a.kholvadia@gmail.com)
Knee osteoarthritis (KOA) is a prevalent,
chronic disorder with functional, social and
economic burdens.[1] The World Health
Organization’s (WHO) Global Burden of
Disease 2010 study highlighted that, with Africa’s attention
on infectious disease, child and maternal health, the burden
of non-communicable diseases, such as KOA, has amplified.[2]
A prevalence of 33% has been observed amongst older rural
South Africans, whilst South Africans in urban areas show a
higher prevalence of KOA (55%).[3] Urbanisation has resulted
in increased life expectancy, increased ageing populations and
higher levels of obesity-making osteoarthritis the fourth
leading cause of disability by the year 2020.[2] Furthermore,
common KOA-related symptoms include pain and joint
stiffness which negatively influences disability and
functionality.[1,2]
Contemporary evidence for identifying, diagnosing and
managing KOA varies, depending on the stage of disease
progression and severity.[1] The main goal of management for
KOA is to alleviate the symptoms and delay the progression of
the disease,[4] with therapeutic modalities, including physical
therapy, pharmacological intervention, and surgery.[4] The
current treatment regimen for KOA aims at controlling pain
and improving the joint function to enhance functionality
through pharmacological intervention and physical therapies.[4]
With disease progression, surgical intervention is considered as
activities of daily living decreases.[4]
Physical rehabilitation is important as a tool for disease
management in the early phases of KOA diagnosis, particularly
as evidence shows that compared with sedentary patients,
those patients who underwent exercise therapy had
significantly better outcomes.[5] Contemporary evidence
demonstrates that low-level laser therapy (LLLT) (also known
as photobiomodulation) in particular, together with physical
therapy, has the potential for better outcomes than conservative
therapy alone.[6,7,8] Data from these studies observed that
participants in the group using LLLT and combined with
exercise experienced increased pain relief and improved joint
functionality and mobility. However, there are other studies
showing no pain relief with LLLT alone.[9,10] Given the
conflicting outcomes from these studies, the aim of this study
was to investigate the efficacy of combined LLLT and exercise
compared with exercise or LLLT alone in a South African
cohort of patients diagnosed with KOA.
Methods
Study design
A descriptive, intervention study design was used to evaluate
the differences between the groups participating in LLLT and
exercise alone, and a combination of the two modalities.
Participants were randomised into one of the three groups
using pre-sealed envelopes attached to the batch of documents
provided to prospective participants at baseline testing. A
single blind methodology was employed as the principal
investigator carried out the intervention programmes. The
study participants were unaware of the diverse intervention
modes of the study. Furthermore, a factorial design
experiment, which is a variation of the between-group design
experiment, was used. This study consisted of three treatment
variables which examined the independent and simultaneous
Background: Knee Osteoarthritis (KOA) is a prevalent,
chronic disorder with excessive functional, social and
economic burdens. The goal of treatment is to alleviate the
symptoms and slow the progression. Documenting the effects
of exercise and LLLT as co-modalities in the management of
KOA allows practitioners to implement this management tool
as part of KOA rehabilitation, resulting in the earlier discharge
from a supervised rehabilitation setting.
Objective: The purpose of this study was to determine the
effect of low-level laser therapy (LLLT) in the treatment of
knee osteoarthritis (KOA). A randomised controlled trial
(RCT) was conducted on 111 participants (aged between 40-75
years) diagnosed with KOA. Participants were randomised
into an exercise (n=39), LLLT (n=40), or a combined exercise-
LLLT (n=32) group.
Methods: The Western Ontario and McMaster Universities
Osteoarthritis Index (WOMAC) scale was used to assess pain
and functionality. Knee range of motion was assessed using a
goniometer, and the one-minute timed sit–to-stand test
measured physical functionality at four time points: (T1)
baseline, (T2) post 12-session intervention, (T3) one-month
post intervention and (T4) three-month’s post intervention.
Knee circumference was measured using a measuring tape.
Results: WOMAC pain and functionality scale and knee
circumference scores decreased in all three groups (P<0.05),
but the combined exercise-LLLT group demonstrated better
outcomes than the LLLT or exercise alone groups respectively.
The combined exercise-LLLT group showed better acute and
long-term benefits with participants experiencing a 3.5
centimetre decrease in knee circumference, 24 point
improvement in the WOMAC pain and functionality scale,
and a four repetition increase in physical functionality.
Conclusion: The findings suggest that LLLT is a viable tool for
managing KOA when used in conjunction with physical
exercise.
Keywords: photobiomodulation, physical therapy,
degenerative joint disease
S Afr J Sports Med 2019;31:1-5. DOI: 10.17159/2078-516X/2019/v31i1a6058
mailto:a.kholvadia@gmail.com
http://dx.doi.org/10.17159/2078-516X/2019/v31i1a6058
https://orcid.org/0000-0002-1650-6116
https://orcid.org/0000-0002-3363-7695
https://orcid.org/0000-0001-5225-1184
ORIGINAL RESEARCH
SAJSM VOL. 31 NO. 1 2019 2
effect of the respective treatments on the outcome measures
of the knee’s range of motion (ROM), knee circumference,
WOMAC pain scale, and physical functionality. This research
design allowed the study to explore the effects of each
treatment separately, together with the effect on the variables
explored, thereby providing a rich and encompassing
multidimensional view. The data collection for the
randomised controlled trial (RCT) was conducted at a
biokinetics rehabilitation centre in Johannesburg, South
Africa.
Participants
Male and female knee osteoarthritis patients (n=120) from
Johannesburg, aged 40-75 years, and meeting all the study’s
inclusion criteria, were recruited to voluntarily participate in
this randomised control trial after being referred to the study
by various medical practitioners. Prospective participants
were excluded from the study if they were pregnant,
diagnosed with cancer or epilepsy and if they were physically
unable to complete one or more tests in the battery of physical
tests required for the study. The participants were randomly
allocated to an exercise group, a LLLT group or a combination
of exercise plus LLLT group respectively. Sealed envelopes
were used and attached to the initial testing documentation
after the baseline testing (T1) was completed. These pre-
sealed envelopes were marked and randomly attached to the
back of each batch of baseline testing forms indicating an
assignment to a prospective intervention group. There was a
dropout rate of 0%, 2.5% and 20% in the exercise, LLLT and
combination treatment groups respectively. One hundred
and eleven participants completed the study (exercise group,
n=39, LLLT group, n=40 and the combined exercise-LLLT
group, n=32).
All participants were thoroughly informed regarding
consent to participation and withdrawal, testing procedures
and intervention programmes. Written informed consent was
obtained from all participants prior to data collection (T1).
Ethics approval was obtained from the Faculty of Health
Sciences Human Research Ethics Committee (Medical) at the
University of the Witwatersrand (certificate number:
M161112).
Knee circumference
Knee circumference was assessed using a measuring tape
while the participant was supine; with the affected knee
supported by a towel to create a 30° flexion in the knee which
allowed the relaxation of the quadriceps muscle. [11] The site of
joint circumference measurement was proximal (two cm
above the mid patella), mid and distal (two cm below the mid
patella) recorded to the nearest millimetre (mm).
Pain and functionality management
The Western Ontario and McMaster Universities Arthritis
Index (WOMAC) is a self-administered questionnaire which
can be used to describe and evaluate pain and function in
patients with osteoarthritis of the knee. This questionnaire
was chosen for its validity and reliability as a tool in reporting
KOA.[12] The WOMAC measures five items for pain (score
range 0–20), two for stiffness (score range 0–8), and 17 for
functional limitation (score range 0–68). Questions regarding
physical functioning cover everyday activities such as stair use,
standing up from a seated or lying position, bending, walking,
getting in and out of a car, shopping, putting on or taking off
socks, lying in bed, getting in or out of a bath, sitting, and doing
heavy and light household duties. [12] The change in the
WOMAC score was used as the outcome variable of pain and
functionality during the study.
Knee range of motion (ROM)
Bilateral ROM was measured using a Baseline® goniometer to
the nearest degree (°) while the participant was supine.[11] For
flexion measurements the participant was asked to bring the
foot as close to the buttocks as possible. For extension
measurements, the participant was instructed to actively
straighten the knee.
Physical functionality
The one-minute timed sit-to-stand test was used to measure
physical functionality.[13] The participant was requested to sit
in the middle of a 50 cm high chair with his/her arms crossed
against the chest, feet flat on the floor and back straight up
against the backrest of the chair. The participant was then
instructed to sit and stand respectively. A stopwatch was used
to count down 60 seconds and the number of completed
repetitions recorded.
Intervention
There were three intervention groups, i.e. exercise, LLLT, and
a combined exercise-LLLT.
Exercise group
The exercise programme was conducted three times per week
and consisted of 12 sessions based on rehabilitation
guidelines.[5] The exercise protocol included four different
types of exercises, i.e. flexibility (quadriceps, calf muscles and
hamstrings), stability (quad setting, single leg balance),
strength and endurance (supine and prone straight leg raises,
abductor squeezes, step-ups, calf raises), designed to maintain
and improve knee functionality through improved muscular
strength, ROM and locomotor function of the knee joint. The
programme was self-paced, starting at a low intensity and
became progressively more challenging. The principal
investigator supervised all exercise sessions and determined
individual participant exercise progression.
Low-level laser therapy (LLLT) group
Participants in the LLLT group were exposed to three different
arrays as part of the LLLT protocol over a period of 12 sessions,
with each session progressing from 35 min to 45 min.[14] There
are no frequency protocol guidelines on the use of LLLT for
KOA, therefore sessions were scheduled for times a week to
maintain uniformity across all three intervention groups. A
circumferential application method was employed. Three
placements with medial and lateral applications overlapping at
the patella’s surface were used. The participant’s knee was set
at 60°-70° for optimal penetration of light from the light-
ORIGINAL RESEARCH
3 SAJSM VOL. 31 NO. 1 2019
emitting diodes (LEDs).[14]
Combined exercise and LLLT group
The combined exercise and LLLT group underwent a protocol
that included both the exercise rehabilitation and the LLLT
intervention programmes described above. The exercise
sessions were done preceding the LLLT intervention. These
sessions were scheduled for three times a week.
Statistical analysis
Statistical analysis was performed using Statistica v13.3
(TIBCO Software. StatSoft Inc.). After assessing the normal
distribution of the data using the Shapiro-Wilks test,
descriptive data were presented as mean ± standard deviation
(SD). The differences between baseline and post-study
period analysis of covariance (ANCOVA) are presented as
effect sizes (Cohen’s d) and the differences between study
groups were determined using ANOVA (analysis of
variance). Paired t-tests were used to measure differences
between baseline and post-intervention data for all variables.
Independent t-tests were performed to determine if the
intervention groups differed in basic participant
characteristics. Repeated measures ANOVA tests with
between-subjects effects (exercise vs. LLLT or exercise vs.
combination group) and within-group effects (T2, T3, T4)
were performed to indicate the differences in measurements
from baseline. Significance was accepted at p<0.05.
Results
Participant characteristics
The one hundred and eleven participants in the study were
randomly allocated into the three intervention groups
exercise (n=39), LLLT (n=40), and combined exercise-LLLT
(n=32) groups, respectively. Most of the participants were
women (n=85, 77%), with a mean age of 61.8 ± 5 years. The
exercise group exhibited the highest BMI at 36.1 ± 3.7 kg/m-2)
followed by the LLLT group (31.6 ± 4.5 kg/m-2) and the
combined exercise-LLLT group (29.6 ± 4.7 kg/m-2).
Knee osteoarthritis variable outcomes
Knee circumference
Varying effects were observed in all three groups for the key
outcomes. However, the combined exercise -LLLT group
demonstrated improved efficacy for the outcome measures of
knee circumference While the post-intervention (12-week) knee
circumference decreased significantly in all groups (p<0.05),
this effect was highest in the LLLT group compared to the
combined exercise-LLLT and exercise groups (Table 2).
WOMAC pain and functionality scale
Table 2 shows that all groups experienced improvements in the
WOMAC pain and functionality scale, but this was most
noticeable in the combined LLLT-exercise group (p<0.05). The
values at baseline were comparative in all groups. However,
the exercise vs. LLLT had significantly greater effect sizes at T3
and T4 compared to the exercise and combined exercise-LLLT
groups.
Knee ROM
Knee extension ROM was significantly lower in the combined
exercise-LLLT and LLLT groups compared with the exercise
group at baseline (Table 1). Only the combination group
experienced significant improvements following the
intervention (Table 2). Baseline knee flexion ROM was higher
in exercise group compared with the LLLT and combined
exercise-LLLT group (p<0.005); however, the effect of the
intervention was only significant in the combined exercise-
LLLT group (Table 2).
Sit-to-stand
Baseline values for physical functionality (measured by the sit-
to-stand test) were similar across all three intervention groups.
Table 2 demonstrates that the combined exercise-LLLT group
had the greatest improvements in the sit-to-stand repetitions
following the intervention, and this effect was evident at the T3
and T4 time points.
Table 1. Baseline and post-intervention characteristics
Exercise (n=39) LLLT (n=40) Combined exercise-LLLT (n=32)
Baseline Post-intervention Baseline Post-intervention Baseline Post-intervention
Knee circumference
Proximal patella (cm)
41.4 ± 6.1 38.0 ± 6.1* 41.3 ± 6.1 40.0 ± 6.1* 43.5 ± 7.3 41.1 ± 7.4*
Knee circumference
Mid patella (cm)
36.6 ± 5.1 38.9 ± 4.5* 38.5 ± 4.8 40.3 ± 4.5* 40.0 ± 4.6 39.2 ± 3.9*
Knee circumference
Distal patella (cm)
37.4 ± 4.3 36.6 ± 4.2* 36.3 ± 4.7* 37.9 ± 3.1* 37.7 ± 4.6 37.5 ± 4.0*
WOMAC
56.6 ± 10.1 60.8 ± 9.8* 59.1 ± 10.2 61.5 ± 11.3* 56 ± 10.8 65.6 ± 9.9*
ROM extension (⁰)
2.1 ± 2.8 1.1 ± 1.9* 1.6 ± 2.5 1.4 ± 2.1* 1.4 ± 2.5 0.8 ± 1.6*
ROM flexion (⁰)
99.5 ± 14.6 102.3 ± 16.9 96 ± 17.4 103.7 ± 11* 95.2 ± 19.1 108.3 ± 11.9*
Sit-to-stand (reps)
17 ± 2.5 19.7 ± 3.5* 17.1 ± 2.9 19.6 ± 3.2* 17.4 ± 3.5 21.3 ± 4.1*
Data presented as mean ± SD. * indicates p<0.05 vs. baseline values
LLLT, low-level laser therapy; WOMAC, Western Ontario and McMaster Universities Arthritis Index; ROM, range of motion; ⁰, degrees; reps, completed
repetitions.
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SAJSM VOL. 31 NO. 1 2019 4
Discussion
This study aimed to evaluate the effect of utilising LLLT in
combination with exercise in comparison to the use of exercise
or LLLT as stand-alone therapies for the conservative
management of patients diagnosed with KOA. Varying effects
were observed in all groups for the key KOA study outcomes;
however, the combined exercise-LLLT group demonstrated
the best effects when compared with the exercise or LLLT
groups alone.
The decrease in knee circumference values and
improvements in the WOMAC pain and functionality scores
indicate structural enhancement in the joint. A decrease in
joint effusion was evident by the decrease in knee
circumference scores and an improvement in WOMAC pain
and functionality score, as supported by other authors such as
Fukuda et al. [7] , Alfredo et al.[8,6]. Improvements of between
11 and 12.9 points in a period of 2-6 months post-intervention
establishes a minimally clinical important difference (MCID)
when using the WOMAC as an evaluation tool.[15] The study
showed a greater than 11 point improvement (calculated mean
difference between baseline and post-intervention testing) in
both groups exposed to LLLT at T3 and T4. Functional
improvements were observed by the increased number of
timed sit-to-stand repetitions and improvements in knee
flexion ROM. The findings from this study set up a discussion
point for both structural and functional management traits in
KOA. This research study suggests that analgesia associated
with LLLT results in the anti-inflammatory properties on the
articular capsule as suggested by the World Association of
Laser Therapy (WALT), with similar results being produced,
resulting in both pain relief and a decrease in knee
circumference values.[6,7,8]
The main finding of this study is that of an adjunctive effect
of LLLT with the conservative exercise management of KOA.
The findings showed that the KOA outcomes significantly
improved across all three intervention groups (p<0.05), with the
Table 2. Temporal outcome measures for knee osteoarthritis (KOA) patients with different interventions
Exercise (n=39) LLLT (n=40) Combined exercise-LLLT (n=32)
Variable T2 T3 T4 T2 T3 T4 T2 T3 T4
Knee circumference
Proximal patella
(cm)
Mean
± SD
40.0 ± 6.1* 38.3 ± 6.4* 38.0 ± 6.1* 38.0 ± 6.1*† 36.7 ± 6.1*† 35.2 ± 6.2*† 41.1 ± 7.4* 39.6 ± 6.7*† 38.3 ± 6.7*
Effect
Size
0.2
(-0.2:0.7)
0.5
(-0.0:0.9)
0.6
(0.1:1.0)
0.3
(-0.1:0.8)
0.3
(-0.2:0.7)
0.4
(0.0:0.9)
0.2
(-0.6:0.3)
0.2
(-0.7:0.3)
0.1
(-0.5:0.4)
Knee circumference
Mid patella (cm)
Mean
± SD
40.3 ± 1.4 38.6 ± 4.5* 37.4 ± 4.5* 38.9 ± 4.5† 36.8 ± 4.2*† 36.0 ± 4.2* 39.2 ± 3.9† 37.0 ± 3.1*† 36.5 ± 3.7*†
Effect
Size
0.1
(-0.6:0.3)
0.4
(-0.9:0.0)
0.2
(-0.6:0.3)
0.3
(-0.1:0.7)
0.4
(0.0:0.9)
0.3
(-0.1:0.8)
0.2
(-0.2:0.7)
0.4
(0.0:0.9)
0.2
(-0.2:0.7)
Knee circumference
Distal patella (cm)
Mean
± SD
37.9 ± 3.8* 38.0 ± 4.4 37.4 ± 3.6* 36.6 ± 4.2† 36.4 ± 4.2† 36.0 ± 4.2† 37.5 ± 4.0 37.3 ± 4.0 36.5 ± 3.7*†
Effect
Size
0.1
(-0.6:0.3)
0.1
(-06:0.3)
0.0
(-0.5:0.4)
0.3
(-0.1:0.8)
0.4
(-0.1:0.8)
0.4
(-0.1:0.8)
0.1
(-0.4:0.6)
0.2
(-0.3:0.3)
0.3
(-0.2:0.7)
WOMAC
Mean
± SD
61.5 ±11.3* 65.3 ±13.1* 70.5 ±11.8* 70.8 ± 9.8*† 76.9 ± 9.2*† 80.7 ± 8.5*† 65.6 ± 9.9*† 72.0 ± 8.7*† 78.0 ± 8.5*†
Effect
Size
0.5
(0.9:0.0)
0.7
(-1.2:0.3)
1.3
(-1.7:0.8)
0.9
(-1.3:-0.4)
1.0
(-1.5:0.6)
1.0
(-1.4:-0.5)
0.4
(-0.8:0.1)
0.6
(-1.1:-0.1)
0.7
(-1.2:-0.2)
ROM extension (⁰)
Mean
± SD
1.4 ± 2.1* 0.7 ± 1.5* 0.3 ± 0.9* 1.3 ± 1.9* 0.6 ± 1.3* 0.2 ± 0.6* 0.8 ± 1.6*† 0.4 ± 1.0*† 0.9 ± 0.4*†
Effect
Size
0.3
(-0.1:0.8)
0.6
(0.2:1.1)
0.9
(0.4:1.3)
0.1
(-0.4:0.5)
0.1
(-0.3:0.5)
0
(-0.4: 0.4)
0.3
(-0.2:0.8)
0.3
(-0.2:0.7)
0
(-0.5: 0.5)
ROM flexion (⁰)
Mean
± SD
103.7
±13.4*
108.1 ±
12.4*
111.4 ±
11.5*
102.3 ±
16.9*
107.4 ±
14.9*
109.5 ±
13.2*
108.3 ±
11.9*†
112.3 ±
11.3*†
115.2 ±
10.3*†
Effect
Size
0.3
(-0.7:0.2)
0.6
(-1.1:-0.2)
0.9
(-1.4:0.4)
0.1
(-0.4:0.5)
0.1
(-0.4:0.5)
0.2
(-0.3:0.6)
0.4
(-0.8:0.1)
0.4
(-0.8:0.1)
0.3
(-0.8:0.1)
Sit-to-stand (reps)
Mean
± SD
19.5 ± 3.0* 23 ± 4.5* 26 ± 3.5* 19.7 ± 3.5* 25.5 ± 3.0*† 25.5 ± 4.0* 21.2 ± 4.0*† 25.5 ± 3.0*† 30.0 ± 3.0*†
Effect
Size
0.9
(-1.4:-0.4)
1.6
(2.1:-1.1)
0.3
(-3.6:-2.3)
0.1
(-0.5:0.4)
0.7
(-1.1:-0.2)
0.1
(-0.3:0.6)
0.5
(-0.9:0.0)
0.7
(-1.1:-0.2)
1.2
(-1.7:-0.7)
Data presented as mean ± SD with effect sizes (95% CI). Bold font indicates effect size >0.02; * indicates p<0.05 (T1 vs T2, T1 vs. T3, T1 vs. T4) using independent tests;
† indicates p<0.05 exercise vs. LLLT, and exercise vs. combined exercise-LLLT.
LLLT, low-level laser therapy; WOMAC, Western Ontario and McMaster Universities Arthritis Index; ROM, range of motion; ⁰, degrees; reps, completed repetitions; T2,
post intervention; T3, 1 month post-intervention; T4, 3 months post intervention.
ORIGINAL RESEARCH
5 SAJSM VOL. 31 NO. 1 2019
LLLT group showing better short-term pain relief, but the
combined exercise-LLLT group demonstrated better long-
term reduction in pain symptoms. This implies a better
residual effect when exercise treatment is applied with a laser.
Indeed, fear of pain is the main reason for KOA patients
reducing their physical activity.[6] The combined exercise-
LLLT treatment can improve both functional strength (short-
and long-term), knee joint ROM and sit-to-stand scores
thereby contributing to improved activities of daily living and
quality of life. The findings of this study are supported by
work undertaken by Alfredo et al. [6] where the benefits of
combined intervention exposure were maintained for three
months post exposure to the intervention.
In this present study participants were recruited from one
geographic area and therefore further investigation is needed
to confirm the findings in other geographic areas.
Furthermore, participants were referred to the study by
multiple medical practitioners and therefore a standard
diagnostic criterion was not applied but it was rather a referral
based on each practitioner’s specific diagnostic criteria.
Conclusion
In conclusion, this 12-week RCT demonstrated that the
addition of LLLT with exercise strengthens the effects on KOA
outcomes, suggesting that the efficacy of LLLT as an adjunct
form of therapy should be included in the non-surgical
management of KOA. The data highlights the potential
carryover effect of this tool in diagnosed KOA patients;
however, further investigations are needed to confirm the
observed effect.
Author contributions:
A Kholvadia conducted the study, performed the statistical
analysis, and wrote the paper. All authors read, commented
and approved the final version of the manuscript.
References
1. Felson DT, Lawrence RC, Dieppe RA, et al. Osteoarthritis:
new insights. Part 1: the disease and its risk factors. Ann
Intern Med 2000; 133(8):635-646 [doi: 10.7326/0003-4819-133-
9-200011070-00015]
2. Woolf AD. Global burden of osteoarthritis and
musculoskeletal diseases. BMC Musculoskelet Disord 2015;
16(Suppl 1): S3. [doi: /10.1186/1471-2474-16-S1-S3]
3. Usenbo A, Kramer V, Young T, Musekiwa A. Prevalence of
arthritis in Africa: A systematic review and meta-analysis.
PLoS One 2015; 10(8): e0133858.
[doi:org/10.1371/journal.pone.0133858]
4. Michael JW, Schlüter-Brust KU, Eysel P. The Epidemiology,
Etiology, Diagnosis, and Treatment of Osteoarthritis of the
Knee. Dtsch Arztebl Int 2010; 107(9): 152-162. [doi:
10.3238/arztebl.2010.0152]
5. Fransen M, McConnell S, Harmer AR, et al. Exercise for
osteoarthritis of the knee: aCochrane systematic review. Br J
Sports Med 2015; 49(24):1554-1557. [doi: 10.1136/bjsports-2015-
095424]
6. Alfredo PP, Bjordal JM, Junior WS, et al. Long-term results of a
randomized, controlled, double-blind study of low-level laser
therapy before exercises in knee osteoarthritis: laser and
exercises in knee osteoarthritis. Clin Rehabil 2018; 32(2): 173-
178. [doi: 10.1177/0269215517723162]
7. Fukuda VO, Fukuda TY, Guimarães M, et al. Short-term
efficacy of low-level laser therapy in patients with knee
osteoarthritis: a randomized placebo-controlled, double-blind
clinical trial. Rev Bras Ortop 2015; 46(5): 526-533. [doi:
10.1016/S2255-4971(15)30407-9]
8. Alfredo PP, Bjordal JM, Dreyer SH, Meneses SRF, Zaguetti G,
Ovanessian V, et al. Efficacy of low level laser therapy
associated with exercises in knee osteoarthritis: a randomized
double-blind study. Clin Rehabil. 2012; 26(6); 523-533. [doi:
10.1177/0269215511425962]
9. Bjordal, JM, Johnson, MI, Lopes-Martins RA, et al. Short-term
efficacy of physical interventions in osteoarthritic knee pain: A
systematic review and meta-analysis of randomized placebo-
controlled trials. BMC Musculoskelet Disord 2007; 8:51. [doi:
10.1186/1471-2474-8-51]
10. Bülow, PM, Jensen, H, Danneskiold-Samsøe B. Low power Ga-
Al-As laser treatment of painful osteoarthritis of the knee. A
double-blind placebo controlled study. Scand J Rehabil Med
1994; 26(3): 155-159. [PMID: 7801065]
11. Jakobsen TL, Christensen M, Christensen SS, et al. Reliability
of knee joint range of motion and circumference measurements
after total knee arthroplasty: Does tester experience matter?
Physiother Res Int 2010; 15(3): 126-134. [doi: 10.1002/pri.450]
12. Salaffi F, Leardini G, Canesi B, et al. Reliability and validity of
the Western Ontario and McMaster Universities (WOMAC)
Osteoarthritis Index in Italian patients with osteoarthritis of the
knee. Osteoarthr Cartilage 2003; 11(8): 551-560. [doi:
10.1016/S1063-4584 (03)00089-X]
13. Huber EO, Meichtry A, de Bie RA, et al.. Construct validity of
change scores of the Chair Stand Test versus Timed Up and Go
Test, KOOS questionnaire and the isometric muscle strength
test in patients with severe knee osteoarthritis undergoing total
knee replacement. Man Ther 2016; 21: 262-267. [doi:
10.1016/j.math.2015.09.012]
14. Kahn F. Low Intensity Laser Therapy - in Clinical Practice.
Meditech International , 2006: 44–45.
15. Williams VJ, Piva SR, Irrgang JJ, et al. Comparison of reliability
and responsiveness of patient-reported clinical outcome
measures in knee osteoarthritis rehabilitation. J Orthop Sports
Phys Ther 2012; 42(8): 716-723. [doi: 10.2519/jospt.2012.4038].