Trial design
This single blind, randomized, and controlled trial, which was conducted at Razi University rehabilitation center in Kermanshah, Iran, lasted for eight weeks starting with February and ending in May, 2019. The assessors who measured variables for patients were blinded about the group allocation. This study included three steps: 1. Pre-tests 2. 8-week aquatic and TRX exercises for case groups, and the control group which just received drug regimens by the rheumatologist, and 3. Post-tests (Fig 1).
Participants
A total of 200 knee osteoarthritis’ patients were studied for eligibility among which 36 individuals met the eligibility criteria. 12 patients were allocated to the aquatic exercise, 12 to TRX exercises, and the rest to the control group. However, 111 patients didn’t meet the eligibility criteria and 53 declined to participate. Participants of the present research (200 female) were recruited from two groups: individuals who had regular referral from rheumatologist physicians, and those patients who waited for common physiotherapy in rehabilitation centers.
Participants were included if they had (1) the age of more than 40 years ,(2) American College of Rheumatology clinical criteria for knee OA(Altman et al., 1986), (3) Kellgren and Lawrence radiographic disease severity scale ≥ II, and (4) self-reported knee instability. Additionally, participants were excluded if they (1) had strokes, (2) had uncontrolled hypertension, (3) were unable to walk without assistant instruments, (4) had received other treatment interventions in the past three months, (5) had obesity (BMI>40kg/m2), (6) suffered from neuromuscular diseases like multiple sclerosis and Parkinson, (7) had lower extremity fracture, (8) concurrent hip osteoarthritis, (9) waited for arthroplasty,(10) or had cardiovascular diseases [7, 21].All the patients who had received injection in the 6-month-period prior to the study, or had had surgical procedures were excluded from the study. All the patients included in this study had bilateral arthritis, however, the knee in which they reported symptom of instability was assessed. All the patients in this study received the similar drug regimens including Meloxicam 7.5 milligram, Glucosamine Sulfate 750 milligram, and Calcium-D in daily manner.
The G.Power (Ver. 3.1, Heinrich Heine University) software was used to estimate the minimum sample size. According to the results of previous researches and based on the test power of 0.90, the effect size of 0.63 and the significance level of 0.05, the minimum sample size was determined to be 36 [22]. Finally, they were divided randomly into three groups including TRX (n=12), aquatic exercises (n=12), and control (n=12) groups (Table 2).
Study interventions
TRX exercises
The TRX ® Rip Trainer ™ (model)was used for performing the exercises. TRX training was completed by a TRX specialist, while an assistant coach also helped to prevent the patients from doing wrong exercises. The safety points were checked by trainer every session to avoid injuries before the exercises started. The TRX straps hanging down from anchor point, and Suspension AnchorTM were adjustable to execute various exercises. Exercises were designed based on the patients’ motion limitations like knee flexion and extension. Furthermore, TRX exercises were started at their easiest forms, and gradually but progressively turned to be more and more difficult. The difficulty level of exercises increased step by step by 1) Narrowing the base of support which increased the difficulty due to reducing stability2) Changing the angle of pull, in other words, the farther the person was from the vertical, the greater the resistance3) and the pendulum was used in ground exercises in which the feet were placed in the Suspension Trainer and the hands were off the ground (head or back was on the ground). The gravity center in relationship with the perpendicular gravitational pull determined the difficulty. 4)Using a one handle can increase the exercises difficulty.5-10 min introducing the sessions’ exercises and their correct techniques, 5-10 min warm-up, which was stretching exercises, and also 40-50 min TRX exercises were performed per session. Participants who had wrist pain through the planks’ tests, could put their forearm on the ground in order to prevent the wrist pain increasing. The TRX exercises protocol were followed for eight weeks, three times a week, and with the duration of 60 minutes for each session. Most of the exercises were focused on the core muscles, hip abductors, and leg muscles strengthening (Table 1) [23].
Table 1. TRX exercises protocol
First Month
|
Exercises
|
Days 1
|
1)TRX row, 2) TRX biceps curl, 3) TRX scapular retraction,
4)TRX standing roll out, 5) toe touches, 6) TRX hip press, 7) TRX hamstring curl, 8) walking high kick, 9) TRX Sit Up
Plank exercises 3 set 10 second
|
Days 2
|
1)TRX mid row, 2) TRX calf raise, 3) TRX kick back,
4) TRX standing push up plus, 5) clamshell, 6) lying side leg lift/ lateral raise, 7) Hamstring runner TRX, 8) TRX bent raise (single leg), 9) TRX side plank.
Plank exercises 3 set 15 second
|
Days 3
|
1) TRX high row, 2) TRX single leg reaching Roman deadlift, 3) TRX split fly, 4) TRX chest press, 5) lying leg raise, 6) TRX Routain, 7) supine plank TRX, 8) TRX bent leg raise, 9) TRX hip abduction.
Plank exercises 3 set 20 second
|
At the week1 and 2, All exercises 3 set 10 repetition.
At the week 3 and 4, All exercises 3 set 15 repetition.
|
Second Month
|
Exercises
|
Days 1
|
1) TRX T deltoid fly, 2) TRX standing hip drop, 3) TRX triceps press, 4) TRX standing calf raises 5) Flutter kicks 6) Side crunch leg raises 7) TRX supine plan/with pull through 8) TRX hip abduction, 9) TRX assisted sit up
Plank exercises 3 set 20 second
|
Days 2
|
1) TRX Y deltoid fly TRX hip press, 2) TRX torso rotation, 3) TRX overhead back extension, 4) TRX prone iron cross, 5) Side oblique crunch, 6) Swimmers, 7) supine TRX on elbow, 8) TRX saw 9) TRX oblique leg raises
Plank exercises 3 set 25 second
|
Days 3
|
1) TRX L deltoid fly, 2) TRX power pull 3) TRX bicep revers curl 4) TRX chest fly 5) Russian twist with medicine ball 6) Alternate heel touchers 7) TRX side plank/ top arm assisted pike 8) TRX pendulum, 9) TRX Pike
Plank exercises 3 set 30 second
|
At the week1 and 2, All exercises 3 set 10 repetition.
At the week 2 and 4, All exercises 3 set 15 repetition.
|
Days1: all exercises which were carried out in Sundays; Days2: all exercises which were carried out in Mondays; Days3: all exercises which were carried out in Wednesdays.
Aquatic exercises
Aquatic exercise intervention was accomplished for eight weeks, three times a week, 24 sessions in total, with each session lasting for exactly 90 minutes. So, each participant was obliged to experience 24 sessions of rehabilitation with 90 minutes of duration for each session during the conducting phase of the study. The water temperature was approximately 32 ° C (89° F), and the minimum water depth was considered1.3 meter. The water based exercises protocol included: 10 minutes’ warm-up along with walking (forward, backward, and sidewalk), and also stretching exercises for lower extremity muscles (quadriceps, hamstrings, tricepssurae, abductors and adductors of hip, and gluteal muscles), 20-minute strength exercises with elastic band and sandbag (gluteus, adductors and abductors of hip, quadriceps, hamstrings, and triceps surae muscles); 20 minutes of aerobic exercises (stationary running or deep water-running); 20 minutes of step training and proprioceptive exercises; 10 minutes of core exercises, and then 10 minutes of cool down. Resorting to previous study findings, we selected exercises of the present study with the purpose of improving function, pain, and balance [24, 25]. The aquatic exercises protocol was supervised by a certified physiotherapist in the pool (table 2).
Table 2. Water-Based Exercise Program a
Type of exercise
|
Exercises
|
Set
|
Warm up
|
walking (forward, backward, sidewalk, with kickboard)
stretching exercise for lower extremity muscles :quadriceps, hamstrings, triceps surae, abductors and adductors of hip and gluteal muscles
|
3.10 (first 4 weeks)
and 10 seconds rest
3.12 (second 4 weeks)
and 10 seconds rest
|
Strength
|
Hip flexion, extension, and hyperextension, Hip abduction and adduction Knee flexion and extension, Double-Leg Calf Raise, Single-Leg Calf Raise, resisted hip extension, resisted hip abduction (resistance was considered water, noodle, and sand bag |
3.10 (first 4 weeks)
and 10 seconds rest
3.12 (second 4 weeks)
and 10 seconds rest
|
Aerobic
|
Bounce: Knee lift/knee-high jog, Inner thigh lift/ankle reach
Front, Leg curl/hamstring curl/heel-high jog, Kick front /straight leg Kick front/karate, Kick corner, Kick across, Kick side, Kick back, Cross-country ski, Bike on the noodle Jumping jack, Cross-country ski, Leap, Jazz kick/front, Jazz kick/corner, Pendulum |
3.12 (first 4 weeks)
and 10 seconds rest
3.15 (second 4 weeks)
and 10 seconds rest
|
Step and proprioceptive
|
Gait training in anteroposterior, lateral-lateral, and diagonal. Then they will go up and down step alternating legs.
Hand on hip as leg perform a rocking horse.
Knee chest (supine, prone, and standing)
Cross-country ski.
Also, step up and step down: forward and side ward.
|
3.10 (first 4 weeks)
and 10 seconds rest
3.12 (second 4 weeks)
and 10 seconds rest
|
Core
|
Stand and abduct and adduct the shoulder, Spinal rotation, standing with diagonal movement of hands with sand ball, Spinal rotation with sand ball , Bike on the noodle
|
3.10 (first 4 weeks)
and 10 seconds rest
3.12 (second 4 weeks)
and 10 seconds rest
|
Cool down
|
Deep breathing-forward and back ward tandem walking-static stretching interspersed with water walking- - figure 8 arm sweep with spinal rotation and shoulder abduction and adduction.
|
10 seconds for each stretch
|
a random selection of exercises from the following list was performed during each session.
|
Randomization and Blinding
Participants were randomized by the use of Random Number Generator Software (Research Randomizer, version 3.0), and also were allocated to three groups using Sequentially Numbered Opaque Sealed Envelopes (SNOSE) concealed allocation method. A physiotherapist who did not involve in the data collection and evaluation of the outcomes did the random allocation sequence, enrolled participants and assigned participants to interventions. Participants were distributedto TRX (n=12), aquatic exercises(n=12), and also control groups (n=12) by random (allocation ratio 1:1:1).
The assessors of this research were blinded about the exercises and interventions assigned to the groups, but there was no possible way for blinding the subjects to training as well as statistician towards the groups and their assigned exercises.
Study outcomes
We designed this research based on authors’ previous study and literatures results [2,6,7]. So, we assessed the effect of 8-week aquatic and TRX exercises on factors that may be affected by KI such as WOMAC stiffness subscale, balance, pain, KI, quadriceps strength and knee flexion ROM.
Knee pain
Knee pain intensity was measured by using 10-cm visual analog scale (VAS) with the scoring range between 0-10cm. “0” indicated the pain absence, “1” minimal pain, and “10” is extreme or intolerable pain. The participants were asked “how much pain do you have during your daily activities?” the VAS was used to measure the intensity of participants’ subjective pain before and after the interventions. A good reliability and validity was reported for the VAS (intraclass correlation 0.92) [26].
WOMAC stiffness
WOMAC is a reliable and valid instrument (ICC:0.80).Stiffness subscale had two items that were rated by the Likert scale of 0 (no symptoms)- 4 (extreme symptoms), with a total range of 0-8, and higher scores displaying worse symptoms [27].
Berg Balance Scale (BBS)
BBS, which was used to assess the balance consists of 14 different tasks, was assessing balance in sitting and standing position and in transfer. Each motor task was rated by the use of 5-point scale ranged from 0 to 4. The total score ranges from 0 to 56, where 56 represents normal balance. The test-retest reliability for the BBS was reported to be excellent (ICC= .71 to .99) [28].
Knee instability
Self-reported knee instability was evaluated according to giving way, and also shifting evidence, during the last month by Felson’s questionnaire [29]. Knee instability severity was graded based on the numerical scale (0 to 5) in response to the following question. The question was “What degree of giving way, buckling, or shifting of the knee would affect your daily routine activity?” The ratings were as follows: 5 = “I have no symptom”, 4 = “I have symptom, but it does not affect my ADL”, 3 = “Symptoms affect my ADL slightly”, 2 = “symptoms affect my ADL moderately”, 1 = “symptoms affect my ADL strongly”, 0 = “symptoms prevent me to perform all my everyday activities” [25]. The test-retest reliability of this self-report rating of KI was estimated by the use of an intra-class correlation coefficient (ICC =0.72) [30].
Knee Flexion ROM
The Bubble inclinometer device was used to measure Knee flexion ROM. The subjects were placed in prone position. Then the inclinometer was placed on the behind of the tibia. The test was conducted on the limb which had more involvement. Knee flexion was stopped in end-range of passive motion and further movement was restricted by pain. Three trials were recorded and the average value was used for analysis [31].
Knee extensors strength
Maximal isometric strength of the knee extensors (quadriceps muscle) was measured using the Baseline Pull-Push Dynamometer. This digital dynamometer measures the force up to a maximum of 199.9 kg. Measurements were used at 80˚- 90˚ of knee flexion. the instrument was calibrated according to the instructions, before any measurement. The patients were seated in a comfortable position with the backrest angled at 100˚. The shin pad was placed 2 cm between the above the medial and lateral malleoli. The instrument shaft remained horizontal to the anterior aspect of the mid shaft of tibia and horizontal to the posterior aspect over the musculotendinous junction of calf muscles. Subjects were then asked to hold that position while pushing against the dynamometer. Subjects were asked to push against the gauge pad as hard as possible when given the appropriate command. All measurements were performed with the limb segment in a position that was with gravity eliminated. Resting times between trials were approximately 60 seconds. Each contraction was held for six seconds. The peak force was recorded and average of records was considered as the quadriceps strength [32].
Ethical Considerations
This study's protocols were reviewed and approved by the research ethics committee of the Medical Sciences University of Kermanshah in Iran (Registration no.: IR.UMMS.REC.1397.718). The study’s protocol was also registered in the Iranian Registry of Clinical Trials (Registration no.: IRCT20181222042070N1). The subjects provided informed consent forms, and all the tests and measurements were carried out at the Sport Rehabilitation Laboratory of Razi University, Iran. As well, all the participants both completed and signed the consent form in person.
Statistical analysis
We analyzed BBS, Pain, WOMAC (stiffness), knee flexion ROM, quadriceps strength, and self-reported knee instability variables before and after the 8-week aquatic and TRX exercises.
First, we used Shapiro-wilks and Leven’s test for assessing the normal distribution of data, and also the variances homogeneity. When variances normality and homogeneity tests were confirmed, the data were considered to be parametric. Consequently, demographic and baseline parameters were analyzed by the one-way analysis of variance (ANOVA). Additionally, Tukey’s post hoc test was used for the pairwise comparisons. In order to compare the changes of each dependent variable over the time (t0=pretest, and t1=posttest) and between groups, the variables were analyzed by employing mixed-model repeated measures ANOVA using time and group as factors time ⁎ group (2⁎3). In the presence of significance, Tukey’s post hoc test pairwise comparisons were used. Also, we used Paired samples t-test for pretest to posttest assessing in each group. Statistical analysis was performed using statistical software, SPSS version 20.0 (IBM SPSS, Armonk, NY, USA). Statistical significance was determined at p-values less than 0.05. All results were reported as the mean ± standard deviation.