Study design
This study will be a randomized controlled trial with a parallel-group design. A total of 112 eligible participants will be assigned to the quadriceps strength training (QT group); high frequency rTMS (HT group); sham rTMS and quadriceps strength training (ST+Q group); high frequency rTMS and quadriceps strength training (HT+Q group) at 1:1:1:1 ratio using stratified randomisation with gender and age as factors. A brief flowchart of the entire study is shown in Figure 1 and the schedule of events is provided in Table 1. The study protocol was approved by the Ethics Committee of Shanghai Seventh People’s Hospital (2022-7th-HIRB-065) and registered in the Chinese Clinical Trial Registry (ChiCTR2300067617).
Table 1 Schedule of enrolment, intervention and assessments
Note: "√" means things will be done. VAS, Visual Analog Scale; TQPEAK, peak torque; TQPEAK/BW, TQPEAK adjusted for body weight; agon/antag, agonist-antagonist ratio; KOOS, Knee Injury and Osteoarthritis Outcome Score; SF-36, 36-Item Short Form Survey. MRI, Magnetic resonance imaging.
Sample size calculation
The sample size calculation was conducted using the G*power software (v3.1.9.2). According to a prior two-way analysis of variance (ANOVA) F-test, with a power of 0.80 and effect size of 0.25, an alpha (α) level of 0.05, an estimated 88 participants will be required. Considering a 20% drop-out rate, the final sample size of each group will be 28, with a total of 112.
Participants
Inclusion criteria
- Meet the diagnostic criteria for KOA set by the ACR in 2019[16]
- Age between 40 and 60 years old
- Have a minimum score of 25 on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) total score
- Sign an informed consent form
Exclusion criteria
- Knee or hip arthroplasty
- Any uncontrolled non-musculoskeletal conditions that would make testing difficult and uncomfortable such as unstable heart conditions
- Neurological condition that affects lower-limb strength or walk (e.g., stroke)
- Have a contraindication for TMS use such as: existence of metal in the skull or implanted devices, epilepsy history, pregnancy
- Use of drugs that might affect cortical electrical activity (anticonvulsants, antidepressants or antipsychotics)
- Have a contraindication for MRI use such as:pacemaker, metal implant ect.
Drop-out criteria
- Inability to return for treatment for any reason
- Adverse events occur due to treatment
- Participants who receive other intervention to treat KOA or other that may interfere with the results of this study
Recruitment, enrollment and randomization procedures
All patients with KOA will be recruited from the orthopedics or joint surgery department of Shanghai Seventh People’s Hospital in China and communities around the hospital. Recruitment methods will include posters, online advertisements, and leaflets. We will communicate with prospective participants about the study details. After the patients voluntarily signs the informed consent, they will be invited to participate in the study. Recruitment will start from 1 October 2023, until when 112 participants are enrolled.
A total of 112 eligible participants will be assigned to four groups at 1:1:1:1 ratio using stratified randomisation with gender and age as factors in this research. The stratified randomisation will be achieved as follows: Firstly, participants will be invaded into men and woman two groups. Secondly, the two groups will be grouped by age including: men aged < 50; men aged≥ 50; women aged<50 and women aged≥50. In these four subgroups, the subjects will be randomly regrouped the QT group; HT group; ST+Q group and HT+Q group. Finally, all the four groups will be regrouped into new four groups to minimize the bias of the final results. The randomisation procedure is performed by an independent research assistant who is not involved in the data collection using Microsoft excel to generate the random number (https://www.microsoft.com).
Allocation concealment and blinding
Allocation concealment will be performed by using sealed, opaque envelopes which will hide a serial number. Additionally, an independent study researcher will open the envelopes in sequence after participates complete all baseline assessments to avoid selective bias. Due to the visibility of the quadriceps strength training intervention, physiotherapists and patients cannot be blind to intervention allocation. Therefore, the blinding will only be applied to the assessors and statisticians who responsible for data collection and final statistical analyses in this study to avoid implementation bias and measurement bias. Importantly, they will not participate in the participant recruitment process. The way to determine whether a blind method has been successfully implemented is by enquire the patient answer a question “Do you know which group you will be divided into before the follow-up evaluation is complete?” which is only using ‘yes or no’ to response. If the patient answer ‘yes’, we will ask he or she again “How did you know that?”.
Interventions
All participants will receive usual care management, including health education and physical therapy when necessary. Six qualified physiotherapists who have attained the physical therapist’s certification with over 5 years of experience will be trained beforehand, so as to instruct and guide patients in carrying out these exercises. The interventions in four groups will be carried out 5 days per week for a total of 12 weeks.
QT Group
In the QT group, the participants will receive 20 min quadriceps strength training intervention by using Biodex Multi-Joint System 3 dynamometer (Biodex Medicalt, Shirley, NY, USA). The 12 weeks intervention duration period has been chosen based on evidence that at least 12 sessions of supervised exercise are required for exercise to be effective in KOA, with a number of studies demonstrating symptom improvement in KOA after 8-12 weeks of exercise[17]. Thus, 12 weeks should be sufficient to show improvement in this population. We will modify the program according to the user’s manual to reduce the risk of participants and check the device for calibration errors. All participants will be informed how the test would be and its purposes. They will conduct two familiarization sessions before the formal intervention to ensure that they feel comfortable during the exercises and perform the technique correctly. After familiarization sessions, participants will be instructed to sit in an isokinetic dynamometer and the V elcro® fixation straps will be tied around the chest, hip and the distal thigh of the training limb to prevent compensatory motion occurs. the dynamometer axis will be aligned with the canter of the lateral femoral condyle. The lever arm will be adjusted according to the training leg length and the resistance will be applied anterior to the ankle joint. The training knee will be kept at a 90° flexed position and they will be instructed to extended knee at angular velocity of 60°/sec, 90 °/sec and 120°/sec with 15 repetitions in 3 sets. Rest periods of 30 seconds between each test extension and 2 minutes between each velocity will be given. Training will perform 5 days per week for 12 weeks. A regular physiotherapist will conduct all isokinetic testing with verbal stimuli. Outcome parameters will be assessed by an independent evaluator, who is experienced in handling isokinetic devices[18]. The peak torque (TQPEAK), TQPEAK adjusted for body weight (TQPEAK/BW) and agonist-antagonist (agon/antag) ratio will be the outcomes.
HT Group
In the HT group, the participants will receive 20 min high-frequency rTMS training intervention. The rTMS will be performed with a Super-Rapid Magstim Stimulator (The Magstim Co., Whitland, UK) including a figure-8 type coil. the reason why we choose the figure-8 type coil is not only because it has stronger focus, but it reduce risk of seizures and other side effects than the h-coil and circular type coil[19]. And all of the rTMS program will be performed as the recommendations of the International Federation of Clinical Neurophysiology[20, 21]. The coil will be placed in the M1 area on the opposite side of the pain and uniformly in the left when the patient had bilateral knee pain as in previous rTMS studies[22, 23]. To determine the coil position, we first will place the center of the helmet to install the figure-8 type coil at a point 1 cm lateral and 1 cm posterior from Cz. Then, we will identify the location and angle of the helmet by identifying the minimum stimulator intensity needed to cause a motor response in the targeted lower limb. We will keep the front surface of the helmet facing forward to ensure that the coil orientation is the same. The resting motor threshold (rMT) will be defined as the lowest intensity that produced five responses with peak-to-peak amplitude of at least 50mv in ten consecutive trials. We will determine the coil position and estimation of MT before the high-frequency rTMS session and the parameters are as follows: 10 Hz stimulation for 4s per session, with a 40s interval between sessions, 30 sessions per treatment, totaling 1200 pulses at 90% rMT over M1 of the target hemisphere.
ST+Q Group
In the ST+Q group, sham rTMS will be delivered with the coil angle rotated 90° and only one wing of the coil touching the scalp of the participant to avoid inducing real stimulation. The parameters, including noise, time, and frequency of the sham rTMS will be same as HT groups[24].Each patient will receive sham rTMS daily for five consecutive days.
HT+Q Group
In the HT+Q group, the participants will receive active High-frequency rTMS and quadriceps strength training intervention with randomization of treatment order. The parameters, including noise, time, and frequency of the High-frequency rTMS, will be the same as HT groups, and the detail of quadriceps strength training will be same as described above.
Outcomes
Participants will be assessed by other physiotherapists blinded to the group allocation at different time points based on different assessments shown in Table 1. Additionally, baseline age, gender, symptoms, disease severity, duration, previous treatment and medication will be recorded using a questionnaire (in week 0). Besides,all side effects during the study also will be recorded in real time.
Primary outcomes
VAS
The Visual Analog Scale (VAS) will be used as one of the primary outcomes to evaluate the improvement of knee pain, which consists of a 10-cm line, where 0 represents “no pain” and 10 represents “worst possible pain”. The participants will be asked to recall knee pain related to knee joint movement in the previous week and mark on the line. The reliability and validity of the VAS in application of musculoskeletal conditions is proved good[25].
Muscle strength
The maximal isokinetic muscle strength will be assessed by the Biodex Multi-Joint System 3 dynamometer (Biodex Medicalt, Shirley, NY, USA). Isokinetic exercise is a mode of speed-constant training, which can be used at low, moderate and high velocity for different evaluations and rehabilitation programs and provides reliable data. It is actually always used to quantify muscle strength, treatment and rehabilitation efficacy with mechanical or neurological instability of the knee or ligament injury[26].
Secondary outcomes
Knee Injury and Osteoarthritis Outcome Score (KOOS)
The Knee Injury and Osteoarthritis Outcome Score (KOOS, http://www.koos.nu) is a questionnaire which is a self-administered and participants need approximately 10 minutes to answer all questions[27]. Different from Western Ontario and McMaster Universities Arthritis Index (WOMAC), KOOS has a more comprehensive assessment including five subscales:pain, symptom (stiff),activity of daily living, physical function, quality of life. Every question has a minimum score of 0 and a maximum of 4 points. After the score of each part is calculated separately, it is converted into a percentage score by the conversion formula. 0 points of the converted percentage score means that the function of this part of the joint is very poor, while 100 points means that the function of this part of the joint is completely normal[28]. The KOOS shows good validity and reliability for patients with mild to moderate KOA[29].
36-Item Short-Form Health Survey (SF-36)
The SF-36 is the secondary outcome measure which is a health-related questionnaire developed by the Boston Institute of Health and used to assess the quality of life (QOL) with high reliability and validity[30]. The scale is divided into physical health QOL and mental health QOL and including 36 questions in total. The former consists of physical function, social function, physical role function and emotional role function, The latter contains mental health, energy fatigue, pain, and general health. The scale assess QOL over the past month and the score of the SF-36 is 0–100 with higher scores indicating better QOL. [31].
motor cortex excitability
Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation tool is a commonly used to measure the functional level of cortex excitability and physiology in vivo[32-34]. The motor evoked potential (MEP) is an important index marker of corticospinal excitability which means when magnetic stimulation over M1, the descending pathway produces excitability and contralateral muscle contraction of the recorded value. The cortical silent period (CSP), which represents momentary suppression of MEP due to GABAergic. The short intracortical inhibition (SICI) and intracortical facilitation (ICF) which represent inhibitory and excitatory activation of interneurons within the motor cortex thought to probe GABAA-mediated inhibition and glutamatergic facilitation[35].
Magnetic resonance imaging (MRI)
MRI scan will use a 3.0-T GE scanner (General Electric, Milwaukee, WI, USA) with an eight-channel phased-array head coil at Medical Imaging Department of Shanghai Seventh People’s Hospital in China. Two independent MRI scans will be performed on each participant at baseline and after the 12-week intervention. Before the MRI evaluation, the scanner will require the participant to rest for 10 minutes and participants will be asked to stay awake with eyes closed during the entire MRI scan.
Resting state functional MRI images (Rs-fMRI) will be acquired with the following parameters: TR=2100 ms, TE=30 ms, flip angle=90°, voxel size=3.125 mm×3.125 mm×3.6 mm, 42 axial slices, field of view (FOV)=200mm×200 mm, phases=230. We also collected high-resolution T1-weighted structural images(T1WI), using a 3D-BRAVO sequence with the following parameters: TR=8.2 ms, TE=3.2 ms, flip angle=12°, FOV=220mm 20 mm, Matrix=256,256, slice thickness=1 mm[36]. The MRI outcomes include the following: grey matter (GM) density, white matter (WM), subcortical nuclei volumes, cortical thickness; functional connectivity (FC).
The DPARSF (http://rfmri.org/DPARSF) will be used to conduct fMRI data preprocessing[37] and the FSL tools (FMRIB Software Library) will be used to process T1WI structure data analysis [38]. The volumes of neocortical GM, total GM, and WM will be obtained by SIENAX (part of FSL 5.0)[39]. The normalized volumes of subcortical nuclei volumes will be estimated from FMRIB’s integrated registration and segmentation tool (part of FSL 5.0, FMRIB Software Library)[40]. The cortical thickness will be obtained using FreeSurfer (http:// surfer. nmr. mgh. harva rd. edu).
Safety and adverse events
Every adverse event during the study will be timely recorded and reported by the safety officer. All potential risks during the study are listed on the participant’s Informed Consent Form. All of them will complete an adverse effects questionnaire for TMS and MRI after intervention.
Availability of Data and Materials
The datasets will be generated and analyzed during the current study are available in the Clinical Trial Management, http://www.medresman.org. We will train all researchers which will record data in case report forms (CRFs) and sign them to ensure data quality. Any changes made on the CRF need to be indicated with a reason and date. Data collection and entry is performed by blinded and independent research assistants. Date storage will be in accordance with the protocols for maintaining security and privacy of data and will be protected by password.
Statistical analysis
Statistical analysis will be performed using IBM SPSS Statistics 25 (http://www.spss.com.hk). Intention-to-treat (ITT) analysis will be used to analyze the result which means the last observation will be used for interpolation when data missing. Continuous variables will be described as mean ± SD for normal distributions or median for non-normal distributions while categorical variables will be described as frequency. For continuous variables that meet the assumptions of a normal distribution and homogeneity of variance, we will use the Two-way of variance with repeated measures; the Wilcoxon test will be used if not. A chi-square test will be used for categorical variables. Pearson correlation coefficient will be performed to detect the correlation between the primary outcomes (VAS, TQPEAK) and secondary outcomes (MEP, FC). When analyzing data obtained by repeated measurements, we will use two-tailed multivariate analysis of variance. The results will be considered statistically significant when the P value is less than 0.05. The post hoc comparisons will be performed by the Bonferroni correction for multiple comparisons if necessary.
Patient and public involvement
The researcher briefly explained the study content and asked the KOA patients for their agreement to share name and telephone number. The KOA patients, physiotherapists and orthopedic doctor took part in preparation of the proposal with face-to-face interviews. The recommendation of a health professional influences the decision on whether to take part in a program. Exit the experiment had no consequences for further treatment.