Knee osteoarthritis (OA) is a chronic degenerative joint disease characterized by progressive damage to the articular cartilage and underlying bone. OA generally affects all structures within a joint. In knee OA, the hyaline articular cartilage is lost, the capsule is stretched, and muscles around the joint are weakened [1]. The incidence of knee OA increases with age [1,2]. OA is strongly associated with aging. Knee OA affects most adults aged 65 years or older, with a prevalence of 33.6% (12.4 million) in the United States [3].

Knee OA is classified into two types according to its etiology: primary (idiopathic or nontraumatic) and secondary (typically caused by trauma or mechanical misalignment). Although the etiology of knee OA remains unclear, its incidence increases with age, genetics, and obesity. Moreover, it occurs more commonly in women [1,2]. It is clinically characterized by slowly developing joint pain and stiffness, fatigue, crepitus, joint locking, joint instability, and joint enlargement with limitations of motion. Patients often complain of knee stiffness or pain when sitting or standing for long periods [1,4]. As most patients exhibit nonspecific clinical symptoms, knee OA is diagnosed based on a patient’s age, disease duration, pattern of joint involvement, inflammation, and radiographs [5].

Several clinical studies have supported the effectiveness and safety of acupuncture treatment for knee OA [6-8]; however, randomized controlled trials on thread-embedding acupuncture (TEA) for knee OA are scarce. A study published in 2022 included 20 participants in the TEA group and 20 participants in the acupuncture group; the participants were treated for 6 weeks [9]. In that study, both groups exhibited significantly higher scores on the visual analog scale (VAS), Short-Form McGill Pain Questionnaire, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). However, the limitations of the study are that the treatment method was not clearly described and the acupuncture and TEA treatment points were different. In another study, TEA was performed to treat postoperative pain in patients with knee OA. In that study, the VAS scores of the TEA + electroacupuncture group were significantly lower than those of the daily management group [10]. Moreover, the Korean WOMAC (K-WOMAC) scores significantly decreased in both groups. However, in that study, the number of subjects was small. Moreover, the electroacupuncture group was set as the control group, making it difficult to determine the effect of acupuncture alone. In another study, 20 participants each were included in the polydioxanone TEA and acupuncture groups for 30 weeks. In that study, polydioxanone TEA improved muscle strength and knee pain by supporting and fixing the vastus medialis muscle in patients with knee OA [11]. However, a limitation of the study is that only a single muscle (vastus medialis) was treated. Therefore, the present study is designed to compare the effectiveness and safety of acupuncture and TEA at the same acupoints in patients with knee OA.

1. Objective

This study focuses on patients with knee OA. The objectives of this study are as follows:

1) To compare differences in pain levels, functional outcomes, and consumed medicine doses between an intervention group treated with TEA and a control group treated with acupuncture.

2) To compare the rates of adverse events (AEs) between the two groups.

2. Design

This is a randomized controlled pilot trial with a two-arm parallel design, assessor blinding, and an allocation ratio of 1:1 (Fig. 1). This study will be conducted from November 2023 to December 2024 at Daejeon Korean Medicine Hospital, Daejeon University. The protocol will be conducted in accordance with the principles of the Declaration of Helsinki. The study protocol has been approved by the Institutional Review Board of Daejeon Korean Medicine Hospital, Daejeon University (DJDSKH-23-BM-08). All participants will provide informed consent and sign an informed consent form before participating in the study.

Figure 1. Flow chart of the trial. TEA = thread embedding acupuncture.

A total of 60 patients aged 40-85 years who have knee OA will participate in the study. At the time of screening, potential participants will sign an informed consent form and undergo a clinical examination to ensure eligibility. A screening radiograph (both knees, anteroposterior and lateral) will be performed to evaluate knee joint alignment and assess the degree of degeneration based on the Kellgren–Lawrence grade. In participants with bilateral knee OA, the more symptomatic knee will be assessed and treated.

Eligible participants will have a baseline visit within 2 weeks for assignment, evaluation, and treatment. The participants will be randomly assigned to the TEA group or acupuncture group and treated with the allocated intervention for 4 weeks.

All participants will visit the hospital 4 weeks after the last treatment. During the 4-week treatment period, the TEA group will receive TEA weekly for four sessions. The acupuncture group will receive acupuncture twice a week for a total of eight sessions. All patients will be assessed based on the VAS score, K-WOMAC score, EuroQol 5-Dimension (EQ-5D) score, range of motion (ROM), patient global impression of change (PGIC) score, and rescue medication dosage at baseline (before treatment), week 2 (during treatment), week 4 (after treatment), and week 8 (after treatment). All participants will be requested to refrain from seeking other forms of treatment during the study period. However, because of ethical considerations, the participants will receive rescue medication (acetaminophen 500 mg, maximum daily dose limited to 3,000 mg) during their participation in the clinical trial. On the day of the assessment, the participants will not be permitted to take the rescue medication before the evaluation. However, they may take the rescue medication after the evaluation. All treatments will be administered by a Korean medicine doctor.

3. Participants

1) Number of participants

This is a pilot study in a randomized controlled clinical trial. Therefore, instead of using a statistical calculation process, the number of participants has been set at 60 based on the number of participants predicted to be recruited during the study period, the minimum scope for research funding, and the effectiveness evaluation.

2) Recruitment

Sixty men and women aged 40-85 years will be recruited through websites, bulletin boards, brochures, local advertisements, and social media advertisements. Individuals who are interested in participating will visit the hospital for screening. The investigator will screen and determine whether the inclusion or exclusion criteria have been met. The study will be conducted randomly at baseline, assigning only those deemed suitable for the study. If a serious adverse reaction occurs in a participant after baseline or if the research team determines the test to be inappropriate, the participant will be excluded from the study.

4. Inclusion and exclusion criteria

1) Inclusion criteria

(1) Diagnostic criteria of the American College of Rheumatology for knee OA (3 months before screening) [12,13].

① Experiencing pain in one or both knees.

② Meeting at least three of the following criteria:

Age > 50 years, stiffness < 30 min, crepitus, bony tenderness, bony enlargement, and no palpable warmth.

(2) Knee pain during daily activities, with a VAS score of ≥ 40 mm [14].

(3) Kellgren–Lawrence grade 2 or higher on knee radiographic examination [15-17].

(4) Voluntary consent to participate after receiving an explanation of the research purpose and process [18,19].

(5) Ability to complete the case report form independently or with assistance [20].

(6) Age 40-85 years [21,22].

2) Exclusion criteria

(1) Presence of severe trauma to the knee (cartilage damage or cruciate ligament rupture) [17-19].

(2) Presence of infectious or inflammatory disease of the knee (bacterial arthritis, tuberculous arthritis, or gout) [14,18].

(3) Presence of a congenital knee deformity [19].

(4) A history of invasive procedures, such as knee replacement surgery or proximal tibial osteotomy (excluding knee arthroscopy), or a plan to undergo such a procedure within the study period [17,18].

(5) Receipt of intra-articular injection (steroids, hyaluronic acid, prolotherapy, or platelet-rich plasma) within the last 6 months [23-25].

(6) Receipt of TEA or other invasive treatment for the knee joint within the last 6 months or acupuncture or other Korean treatment within the last 2 weeks [19].

(7) Erythrocyte sedimentation rate (ESR) > 40 mm/h and rheumatoid factor (RF) > 20 U/ml.

(8) Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels more than three times higher than normal levels (8-40 IU/l and 5-43 IU/l, respectively) [19].

(9) Blood urea nitrogen (BUN) and creatinine levels more than three times higher than normal levels (5-23 mg/dl and 0.6-1.3 mg/dl, respectively) [19].

(10) Presence of musculoskeletal pain more severe than knee pain [19].

(11) Consumption of narcotic analgesics, anticonvulsants, or corticosteroids for pain control within the past week [17].

(12) Presence of acupuncture hypersensitivity, metal allergy, severe atopy, keloid skin, and other skin sensitivities [14].

(13) Presence of factors that can affect hemostasis (consumption of anticoagulants, consumption of antiplatelet drugs, or presence of bleeding disorders) [14,17].

(14) Pregnancy, lactation, or a plan to become pregnant within the study period [14].

(15) Presence of uncontrolled diabetes or serious cardiovascular disease (myocardial infarction or congestive heart failure) [14].

(16) Receipt or requirement of active treatment because of a significant neuropsychiatric medical history, a history of alcohol or drug abuse, or a serious underlying disease [17].

(17) Interval of less than 1 month since the end of participation in another interventional clinical study (including human trials), or being selected for this clinical study but planning to participate in other interventional clinical studies (including human trials) while participating [18].

(18) Judged as inappropriate by the clinical research team [17].

5. Randomization and blinding

1) Randomization

A statistician who is not involved in the study will randomize the participants using a random number table generated using the statistical program SAS® version 9.4 (SAS Institute Inc., Cary, NC, USA). The randomization results will be delivered to the researchers in a sealed opaque envelope and stored in a double-locked cabinet. At the baseline visit, the researchers will open the randomization envelope in front of the participants. The opening date and researcher’s signature will be provided on the opened envelope, and it will be stored separately.

2) Blinding

As the treatment methods used in this study differ, the blinding of practitioners and participants will not be possible. However, assessors will be blinded to control bias. The evaluation will be performed by researchers who will not perform the intervention procedures or randomization.

6. Interventions

1) TEA group

In the TEA group, TEA will be performed once a week for a total of four sessions. Five visits will be performed, including one follow-up visit. Each session will last for approximately 10 min. The detailed procedures are described in Table 1 and Fig. 2 [9-11,26-32].

Table 1

Details of treatments based on the Standards for Reporting Interventions in Clinical Trials of Acupuncture (STRICTA)-thread embedding acupuncture.

Item	Detail
1. Acupuncture rationale	1a) Style of acupuncture: thread embedding acupuncture (TEA)
	1b) Reasoning for treatment provided: a textbook of acupuncture and moxibustion medicine, historical context, literature sources, and the consensus of doctors of Korean Medicine [9,10,32-32].
	1c) Extent to which treatment was varied: all participants will receive standardized treatment. No variation in treatment among patients.
2. Details of needling	2a) Number of needle insertions per participant per session: 10 needles
	2b) Names (or location if no standard name) of points used: ST34, SP10, EX-LE4, ST35, SP9, GB34, BL40, LR9, BL24, and GB30
	2c) Depth of insertion: - ST34: insert the 29G 60 mm TEA upward parallel to vastus lateralis. - SP10: insert the 29G 60 mm TEA upward parallel to the vastus medialis. - SP9: insert the 29G 30 mm TEA toward the medial epicondyle of the femur parallel to the medial collateral ligament. - GB34: insert a 29G 30 mm TEA into the lateral epicondyle of the femur parallel to the lateral collateral ligament. - EX-LE4: insert 29G 30 mm TEA medially along the joint surface. - ST35: insert 29G 30 mm TEA outward along the joint surface. - BL40: insert 29G 30 mm TEA downward parallel to popliteus. - LR9: insert the 29G 60 mm TEA upward parallel to the gracilis and sartorius muscles. - GB30: insert 29G 60 mm TEA the gluteus maximus. - BL24: insert a 29G 60 mm TEA forward and downward.
	2d) Response sought: De-qi
	2e) Needle stimulation: continuous stimulation by polydioxanone suture (slowly absorbable suture)
	2f) Needle retention time: remove needles immediately
	2g) Needle type: 29G 30 mm or 29G 60 mm polydioxanone TEA (Dongbang Medical co., Boryung, Korea)
3. Treatment regimen	3a) Number of treatment sessions: 4
	3b) Frequency and duration of treatment sessions: once a week for 4 weeks
4. Other components of treatment	4a) Details of other interventions administered to the acupuncture group: other interventions should not be permitted during the whole period.
	4b) Setting and context of treatment: the study will be conducted at Daejeon Korean Medicine Hospital, Daejeon University. The study participants will be outpatients.
5. Practitioner background	5) Description of participating acupuncturists: the doctor of Korean Medicine with more than 3 years of experience
6. Control and comparator intervention	6a) Rationale for the control or comparator in the context of the research question, with sources that justify this choice: - Based on a textbook of acupuncture and moxibustion medicine, historical context, literature sources, and the consensus of Doctors of Korean Medicine. - It is based on an RCT comparing the TEA and acupuncture groups [9] and an RCT comparing the TEA and electroacupuncture groups conducted in Korea in 2022 [10].
	6b) Precise description of the control or comparator: receive acupuncture treatment alone.

Figure 2. Treatment point. TEA = thread embedding acupuncture.

2) Acupuncture group

In the acupuncture group, acupuncture will be performed twice a week for a total of eight sessions. Nine visits will be performed, including one follow-up visit. Each session will take approximately 30 min, with 15 min of treatment in the supine position and 15 min of treatment in the prone position. The detailed procedures are described in Table 2 and Fig. 2.

Table 2

Details of treatments based on the Standards for Reporting Interventions in Clinical Trials of Acupuncture (SRICTA)-acupuncture.

Item	Detail
1. Acupuncture rationale	1a) Style of acupuncture: acupuncture
	1b) Reasoning for treatment provided: a textbook of acupuncture and moxibustion medicine, historical context, literature sources, and the consensus of doctors of Korean Medicine [9,10,32-32].
	1c) The extent to which treatment will be varied: all participants will receive standardized treatment. No variation in treatment among patients.
2. Details of needling	2a) Number of needle insertions per participant per session: 10
	2b) Names (or location if no standard name) of points used: ST34, SP10, EX-LE4, ST35, SP9, GB34, BL40, LR9, BL24, and GB30
	2c) Depth of insertion: - ST34, SP10, SP9, GB34: in the supine position, insert 0.5 chon depth with a 0.25 × 30 mm needle. - EX-LE4, ST35: in the supine position, insert 0.3 chon depth with a 0.25 × 30 mm needle - BL40: in the prone position, insertion 0.3 chon depth with a 0.25 × 30 mm needle - LR9: in the prone position, insertion 0.5 chon depth with a 0.25 × 30 mm needle - BL24, GB30: in the prone position, insert 2 chon depth with a 0.30 × 60 mm needle.
	2d) Response sought: De-qi
	2e) Needle stimulation: manual acupuncture
	2f) Needle retention time: 15 min supine and 15 min prone. Total 30 min
	2g) Needle type: sterilized stainless steel needle measuring 0.25 mm in width and 30 mm in length, 0.30 mm in width and 60 mm in length (DB108C; Dongbang Medical Co., Boryung, Korea)
3. Treatment regimen	3a) Number of treatment sessions: eight
	3b) Frequency and duration of treatment sessions: twice a week for 4 weeks
4. Other components of treatment	4a) Details of other interventions administered to the acupuncture group: other interventions should not be permitted during the whole period.
	4b) Setting and context of treatment: the study will be conducted at Daejeon Korean Medicine Hospital of Daejeon University. The study participants will be outpatients.
5. Practitioner background	5) Description of participating acupuncturists: the doctor of Korean Medicine with more than 3 years of experience

1. Screening characteristics

Vital signs; demographic characteristics (participants’ initials, sex, date of birth, age, height, weight, occupation, exercise status, drinking status, and smoking status); physical examination findings; history of knee pain (duration, diagnosis, date of occurrence, and treatment history within the last 6 months); laboratory findings (AST, ALT, total protein, albumin, BUN, creatinine, alkaline phosphatase [ALP], and fasting blood sugar [FBS] levels; red blood cell [RBC], white blood cell [WBC], and differential counts; hemoglobin level; hematocrit; platelet count; ESR; C-reactive protein [CRP] level; RF; prothrombin time/activated partial thromboplastin time [PT/aPTT] [fibrinogen]; and urine human chorionic gonadotropin level [in women of childbearing potential]); knee radiographic findings; knee examination data (pain diagram and VAS score for knee pain); and suitability based on inclusion/exclusion criteria will be assessed at the screening stage.

2. Assessment method

The participants will be assessed at baseline, week 2, week 4, and week 8 by an assessor blinded to the group allocation. The VAS score, K-WOMAC score, EQ-5D score, and ROM will be measured at baseline, week 2, week 4, and week 8. The PGIC score will be measured at week 2, week 4, and week 8. The rescue medication dosage will be recorded at each visit, starting from visit 2 (Table 3).

● = common to both groups; ◎ = only acupuncture group; ◉ = only thread embedding acupuncture group..

&md=tbl&idx=3' data-target="#file-modal"">Table 3

Schedule for the enrollment, intervention, and assessments.

		Study period
		Enrollment	Treatment phase								Follow-up phase
Visit	Thread embedding acupuncture group	Screening	V1	·	·	V2	·	V3	·	V4	V5
	Acupuncture group		V1	V2	V3	V4	V5	V6	V7	V8	V9
Week			W1		W2		W3		W4		8W (± 4 days)
Intervention
Thread embedding acupuncture			◉			◉		◉		◉
Acupuncture			◎	◎	◎	◎	◎	◎	◎	◎
Assessments
Visual analog scale		●	●			●				●	●
Korean McMaster Universities Osteoarthritis Index			●			●				●	●
Range of motion			●			●				●	●
EuroQol 5-Dimension			●			●				●	●
Patient global impression of change						●				●	●
Average dosage of rescue medication				◎	◎	●	◎	●	◎	●	●
Safety assessment			●	◎	◎	●	◎	●	◎	●	●

● = common to both groups; ◎ = only acupuncture group; ◉ = only thread embedding acupuncture group..

3. Primary outcome measurement

1) VAS

The VAS is an instrument used to measure a characteristic or an attitude believed to range across a continuum of values that cannot be easily measured directly. It is a horizontal line, usually 100 mm long, with 0 mm denoting “no symptoms” and 100 mm denoting “very severe symptoms” [33]. The knee pain felt by the participants while walking will be assessed using the VAS.

4. Secondary outcome measurement

1) K-WOMAC

The K-WOMAC has been developed to assess the pain, stiffness, and physical function of patients with hip and/or knee OA. It consists of 24 items divided into three subscales: pain (five items), stiffness (two items), and physical function (17 items) [34,35].

2) EQ-5D

The EQ-5D is a standardized measure of health status developed by the EuroQol Group. It serves as a simple, generic health measure for clinical and economic research. Participants are asked to rate their health status based on the following five categories: mobility, self-care, usual activity, pain/disability, and anxiety/depression [36].

3) Active ROM

The flexion and extension ranges of the knee will be measured in the supine position to determine the knee’s active ROM. Measurements will be performed using a goniometer (30 cm clinical ROM joint protractor; EFU&P Artner, China). The extension range will be measured with the leg held straight. The knee flexion range will then be measured with the thigh flexed at 90°. The knee ROM measurements are closely related to functional evaluation [37].

4) PGIC

The PGIC is a self-report measure that reflects a patient’s belief in the efficacy of treatment. It is a seven-point scale depicting a patient’s overall improvement rating. Patients can rate their change as “very much improved,” “much improved,” “minimally improved,” “no change,” “minimally worse,” “much worse,” or “very much worse” [38,39].

5) Rescue medication dosage

The participants of this trial will be provided with the necessary relief medications to manage uncontrolled knee pain. The dosage of the rescue medication will be checked at every visit, except at baseline. Evaluation of the dosage of the rescue medication will provide information regarding the analgesic effects of the intervention [40].

5. Statistical analyses

Research data will be analyzed using intent-to-treat (ITT), per-protocol (PP), and full analysis set (FAS) methods. Both ITT and PP methods will be used for safety analysis, and the ITT data will be used as the main data. The FAS and PP methods will be used for effectiveness analysis, and the FAS data will be used as the main data. Statistical analyses will be performed using two-tailed tests with a significance level of 5%. All statistical analyses will be performed using SAS® version 9.4 (SAS Institute Inc., Cary, NC, USA).

The demographic and clinical characteristics of the participants (sex, age, and weight) will be summarized by performing descriptive analyses. Each group will be compared by presenting the means and standard deviations for continuous data, followed by analysis using the independent t-test or Wilcoxon rank-sum test. The 95% confidence intervals will be presented as required. Categorical data will be expressed as frequencies and percentages and will be analyzed using the chi-square test or Fisher’s exact test.

The primary efficacy endpoint of this study will be the change in VAS scores at week 4 compared to baseline. The analysis will be performed using analysis of covariance, with pretreatment VAS scores and age serving as covariates and each treatment group serving as a fixed factor. Any clinical differences in sociodemographic characteristics and pretreatment participant characteristics between the groups will be corrected by adding these variables as covariates, if the differences are statistically significant. The secondary outcomes will be analyzed in the same manner as the primary outcome.

6. Safety

During screening, laboratory tests will be performed to ensure safety. At each visit, vital signs, changes in medical history and treatment medications, adverse reactions, and the criteria for discontinuation and withdrawal will be assessed. If an adverse reaction occurs, a hospital visit will be required for management, tests will be conducted if necessary, and the criteria for discontinuation will be checked.

Acupuncture can cause side effects, such as palpitations, dizziness, nausea, and vomiting, while TEA can cause allergic reactions and infections. If the thread is not properly embedded during TEA, an external infection may occur. The severity of adverse reactions will be measured according to the World Health Organization (WHO) adverse reaction evaluation criteria; if these criteria are not applicable, the threelevel classification method of Spilker [41] will be used instead. All information related to possible AEs and serious AEs (SAEs) will be reported.

7. Withdrawal and dropout

All patients will have the right to withdraw from the study at any time. Participation will end at any stage if a patient refuses to continue, withdraws consent, or violates the inclusion or exclusion criteria or the trial protocol. The trial will be halted if the principal investigator believes that there are unacceptable risks from SAEs.

Knee OA is one of the most common musculoskeletal diseases and a common reason for hospital visits [3]. Patients with knee OA often complain of limitations in activities of daily living and functional limitations resulting from knee pain, joint instability, and joint locking [2]. Considering the nonspecific characteristics of knee OA and its associated physical and social problems, it is important to identify and provide effective interventions based on scientific evidence to manage this disease.

The objective of managing knee OA is to relieve pain, improve function, and limit disability [16]. The treatment methods include nonpharmacological, pharmacological, and surgical methods. Acetaminophen and nonsteroidal anti-inflammatory drugs are widely prescribed as oral drug treatments and are known to pose a low risk. Moreover, glucosamine and chondroitin supplements are widely used to treat severe pain, despite their efficacy and long-term benefits being controversial [12]. Corticosteroids and hyaluronic acid are widely prescribed as intra-articular injection drugs. Corticosteroids are inexpensive and can relieve pain for 4 to 8 weeks, while hyaluronic acid can temporarily relieve pain for up to 3 months [13]. Furthermore, surgical options for knee OA include arthroscopy, cartilage repair, osteotomy, and knee replacement (arthroplasty) [12]. A conservative and minimally invasive method should be the initial choice of treatment for patients with knee OA. If this treatment is ineffective (as evidenced by no improvement in pain and function, severe degenerative changes in the joint, or loss of joint function), surgical treatment should be considered [13].

Acupuncture causes analgesia, induces sedation, and restores motor function by increasing the levels of endorphins, beta-endorphins, encephalins, and serotonin in plasma and brain tissue. Therefore, it is a widely used treatment option for pain disorders in Korean medicine [42]. Moreover, acupuncture can significantly reduce pain and improve function in patients with knee OA [43].

TEA is a special type of acupuncture in which certain medical threads (catgut or polydioxanone) are inserted into subcutaneous tissues or muscles at specific points [44]. The embedded thread gradually softens, decomposes, and dissolves in the subcutaneous tissue or muscle over time. The absorption of TEA is known to last for the first 28 days and proceed for 6 months in the subcutaneous layer. Therefore, unlike acupuncture, which only provides stimulation during needle insertion, TEA can provide stronger and longer-lasting effects [1]. The treatment principle is explained in terms of physical and chemical effects. Physical effects include the effect of acupuncture stimulation and the effect of the thread being inserted into the body for a long period. Chemical effects include a sterile inflammatory response induced by tissue damage during the embedding procedure, thereby promoting tissue recovery in the affected area [45].

TEA is effective for all diseases that require long-term acupuncture and has a wide range of indications. It is particularly useful for painful disorders, including neuropathic, chronic inflammatory, nociceptive, and visceral pain [46,47]. However, only a few randomized controlled trials have compared the effectiveness and safety of TEA and acupuncture for knee OA. Therefore, well-designed clinical studies are warranted to compare the effectiveness and safety of TEA and acupuncture.

In this study, a pilot protocol will be used to evaluate improvements in knee pain, physical function, and quality of life in patients with knee OA after TEA treatment. As the severity of radiographic OA does not linearly correlate with that of pain, radiographic data will not be considered as the primary outcome. Instead, the VAS pain score will be considered as the primary outcome, hypothesizing that the VAS scores would differ between the two groups, in accordance with previous reports by Woo et al. [9] and Lee [10]. Moreover, the K-WOMAC score, EQ-5D score, ROM, PGIC score, and rescue medication dosage will be considered as the secondary outcomes to evaluate physical function and quality of life.

This study has several limitations. First, TEA and acupuncture cannot be blinded. However, the evaluator will be blinded, the treatment point for acupuncture and TEA will be the same, and the treatment method will be explained in detail to minimize bias. Second, as the study participation period is 8 weeks, long-term continuous treatment and follow-up may be necessary depending on the results. Third, patients with knee OA who have undergone surgery or have severe pain will be excluded. Hence, only patients with relatively mild symptoms will be enrolled. The results of this study could serve as a basis for future research designed to address the aforementioned limitations.

This study has the advantage of being able to compare the effectiveness and safety of acupuncture and TEA relatively accurately by applying them to the same area and excluding other treatments. The findings are expected to help future clinical research, including evaluating the feasibility of large-scale clinical studies of TEA for knee OA and calculating the appropriate number of subjects. The results of this study could serve as a basis for future research designed to address the aforementioned limitations.

In conclusion, This pilot clinical trial protocol aims to confirm the effectiveness and safety of TEA for knee OA by comparing TEA and acupuncture groups. The findings are expected to confirm the feasibility of large-scale clinical research on TEA and facilitate the provision of nonsurgical treatment options for knee OA.

We confirm that this manuscript has not been published elsewhere and is not under consideration by any other journal. All of the authors have read and approved the final manuscript and agree with submissin to Journal of Acuouncture & Meridian Studies.

This study was financially supported by grants from the project KSN23314113 of the Korea Institute of Oriental Medicine (KIOM), Republic of Korea.

All the authors were involved in the conception, design, and methodology of the protocol. Hyun Jin Jang drafted the manuscript. Ju Hyun Jeon and Jeong Kyo Jeong revised the manuscript for critically intellectual content. Chang-Hyun Han and HuiYan Zhao reviewed and edited the manuscript. All authors read and approved the final manuscript for submission.

This study has been approved by the Institutional Review Board (IRB) of Daejeon Korean Medicine Hospital, Daejeon University (DJDSKH-23-BM-08, 2023-10-16) and has been registered at the Clinical Research Information Service (identifier: The study protocol complied with the principles of the Declaration of Helsinki).

Informed consent will be obtained from all the subjects enrolled in the study.

The data from this trial will be accessible to other researchers upon reasonable request from the corresponding authors. The trial findings will be disseminated through open-access journals and national and international conferences.

The authors declare no conflict of interest.