Efficacy of soothing cream gel in the range of motion and chronic pain at the shoulder and elbow: protocol of a double-blinded, randomised, placebo-controlled trial

Abstract

Introduction

Upper limb problems have a significant impact on the global population leading to pain and restricted joint mobility, ultimately impacting their quality of life. Traditional treatments, such as non-steroidal anti-inflammatory drugs and corticosteroids, often come with undesirable side effects, prompting patients to seek alternative therapies. In this trial, we hypothesise that soothing cream gel (SCG) will improve range of motion and chronic pain in the shoulder and elbow. The objective of this trial is to evaluate the efficacy of SCG in improving the range of motion and chronic pain in the shoulder and elbow.

Methods and analysis

A double-blinded, randomised, placebo-controlled trial is conducted to compare the effects of SCG and placebo gel. SCG contains Vitis vinifera essence, Melaleuca viridiflora essential oil, etc, and is manufactured according to Good Manufacturing Practice standards. The placebo gel will be processed with similar appearance, texture and scent but will lack active ingredients. 70 participants with upper limb problems will be recruited from four study sites, including clinical centres and a sport department at the Chinese University of Hong Kong (CUHK). Participants will be randomly assigned to either treatment group or placebo group for 2 weeks. Primary outcome will be the range of motion in the upper limb, assessed by a goniometer, to measure active flexion and abduction for the shoulder, and active flexion and extension for the elbow. The primary efficacy analyses will be based on the full analysis set following the intention-to-treat principle.

Ethics and dissemination

The trial has obtained approval from the joint CUHK–New Territories East Cluster (CRE-2023.142), and the patient enrolment commenced in July 2023. Written informed consent will be obtained from all participants prior to participation. Study results will be disseminated through publication in peer-reviewed journals and presentations at conference.

Trial registration number

NCT05799391.

STRENGTHS AND LIMITATIONS OF THIS STUDY.

• This is a high-standard randomised clinical trial (double-blinded, placebo-controlled) for a topical-type investigational medicinal product.

• This study may provide the evidence of efficacy of the natural botanical products.

• The dosage is fixed for all participants, so it may not be enough for participants with larger affected areas.

• It is difficult for the participants to avoid having general massage other than the study intervention, which may interfere with the result.

Introduction

Upper limb problems are prevalent among the general population and often manifest as pain and limited mobility. The reported prevalence rates (the number of people affected with a disorder at a specified point in time) of upper limb problems vary between studies, ranging from 4% to 35% in 2003.¹ In 2014, up to 48% of working-aged adults in England reported experiencing upper limb pain,² with 14% experiencing persistent pain lasting for more than 6 months, and 10% reporting disabling pain that affected daily activities such as sleeping, dressing and doing household chores.³ These issues contribute to significant morbidity and sickness absence, and have a substantial economic impact.⁴ The prevalence rate of upper limb problems continues to rise, particularly among the working-aged population and athletes.

A cross-sectional study revealed that musculoskeletal pain was more common among individuals engaging in high levels of leisure physical activity, and the co-occurrence of multiple musculoskeletal pains was frequent among individuals participating in sports.⁵ Musculoskeletal pain can impair physical function, including handgrip strength. Calvo Lobo et al demonstrated statistically significant differences in the handgrip strength between patients with or without shoulder pain.⁶ A Korean trial found that patients with upper limb pain had lower handgrip strength and the stability of the strength test was also affected.^{7 8} Several studies have reported that athletes with greater handgrip strength tend to exhibit better sports performance or sporting ability.^9–12

Besides that, a decrease in the range of motion (ROM) is another problem. The internal and external rotation degrees of the shoulder in the pain group are less than in the non-pain group,¹³ which indicates that their activities will be limited or affected by the pain symptoms.

In addition to the physical impact, upper limb pain also affects patients’ psychological and behavioural functions.¹⁴ Numerous studies have demonstrated that pain has a significant detrimental effect on the quality of life of patients,^15–17 regardless of the pain category or affected site. Several studies used a 36-item Short Form Survey (SF-36) and Psychological General Well-Being Scale to measure the quality of life of patients and showed that patients with chronic pain tend to have lower quality of life scores compared with individuals with other conditions, such as gastrointestinal disorders, hypertension or psychiatric problems.^{15 18–21} Thus, effective treatment approaches are needed.

In general medical practice, oral non-steroidal anti-inflammatory drugs (NSAIDs) or NSAID gels are commonly prescribed for symptomatic relief. However, these treatments provide only short-term benefits.²² Therefore, we aim to investigate whether the therapeutic effects of soothing cream gel (SCG) can offer longer-lasting relief compared with NSAIDs. Corticosteroid injections have also been used for many years, yielding rapid response in approximately 90% of participants that can last up to 6 weeks. However, the relapse rates are high.^{23 24}

Given these circumstances, patients often seek non-pharmaceutical therapies or complementary medicine to alleviate symptoms. In general, these therapies can be categorised into three groups: peripheral therapies (eg, transcutaneous electrical nerve stimulation, hot–cold treatment, acupuncture and acupressure, exercises, positioning, immobilisation massage and hydrotherapy); cognitive–behavioural therapies (eg, relaxation–respiration techniques and dreaming, distraction, praying, meditation, yoga, hypnosis, biological feedback, behavioural therapy) and other therapies (eg, reflexology, herbal treatments, aromatherapy, chiropractic and musical therapy).²⁵ Two randomised clinical trials have investigated the efficacy of herbal gel in relieving shoulder pain and osteoarthritis in the hand or knee, respectively. Both trials demonstrated significant improvements in the pain Visual Analogue Scale (VAS) scores compared with the placebo group (p<0.001 and p<0.003).^{26 27} However, these trials had small sample sizes, highlighting the need for a larger trial.

In recent years, there has been an increasing trend of using natural remedies due to concerns about the side effects of conventional drugs or treatments. Numerous natural or botanical products have been entering the market.^{28 29} Topical herbal remedies are commonly employed for the treatment of various conditions such as common colds, muscle pain and rheumatism.^30–32 The SCG used in this study contains Vitis vinifera essence, Melaleuca viridiflora essential oil and Eucalyptus globulus essential oil. Vitis vinifera and Eucalyptus globulus have been reported to possess a broad spectrum of pharmacological and therapeutic effects, including antioxidant, anti-inflammatory and antimicrobial activities.³³ Eucalyptus globulus also exhibits central and peripheral analgesic effects.³² Melaleuca viridiflora is a compound extracted from Niaouli, with its pale yellow oil used as a potent antiseptic, particularly effective against yeast infections. It is widely used in cosmetic products, including skin care lotions, soaps, mouthwashes and toothpaste.³⁴

Among the available topical analgesics for the treatment of upper limb pain, a majority of them include opioids or NSAIDs. While the side effects associated with these products are generally lower compared with those administered orally, patients often exhibit reluctance in using opioids-containing or NSAID-containing products due to concerns about potential adverse health effects. Moreover, there is a paucity of clinical evidence supporting the use of natural herbal extracts for alleviating upper limb pain. Consequently, our study aims to explore a new treatment for those patients.

Objectives

To evaluate the efficacy of SCG in the ROM and chronic pain at the shoulder and elbow.

Hypothesis

‘The ROM of the participants’ shoulder and elbow can be improved and the pain symptom can be relieved after using the SCG’ is the hypothesis of this study.

Methods and analysis

Study design

This is a double-blinded, randomised, placebo-controlled clinical trial that will investigate the efficacy of the SCG in participants with chronic pain and limited ROM problems at the shoulder or elbow. Participants will be randomised into a treatment group or placebo group for 2 weeks and followed by a 2-week post-treatment period. Both investigators and participants were blinded to group allocation during the experiment and analysis. A total of 70 participants will be recruited in this trial and the primary outcome will be the assessment of ROM (figure 1).

Figure 1.

Study design.

Study population

Participants will be recruited from the following clinics/Chinese medicine centres: (1) the Chinese University of Hong Kong (CUHK) Chinese Medicine Specialty Clinic and Teaching and Research Centre on CUHK campus; (2) Department of Sports Science and Physical Education, CUHK; (3) the two Integrative Medical Centres, Hong Kong Institute of Integrative Medicine at Shatin and Wan Chai. Advertisements through posters and internet platforms, such as CUHK mass mail, Facebook, emails and websites, will be made to facilitate recruitment. Potential participants who meet the eligibility criteria will be recruited. The participants’ enrolment began in July 2023 and the trial is expected to be completed in June 2025.

Inclusion criteria

• Age 18–60 years.

• Participates in regular physical activity, at least once a week for 30 min.

• Chronic pain in the shoulder or elbow longer than 3 months.

• 11-item Numerical Pain Rating Scale ≥4.

• Willing to provide written informed consent.

Exclusion criteria

• The patient had received previous physiotherapy, acupuncture, Tui Na massage or bone-setting treatment for distal upper limb pain within the past 2 weeks.

• The pain was due to a fracture or known complex regional pain syndrome.

• History of upper limb surgery.

• Known severe medical conditions (eg, rheumatoid arthritis; osteoporosis; cardiac, renal, hepatic, haematological diseases; vertigo; seizure; infection; malignancy; neurological impairment).

• Use of drugs with concomitant NSAIDs, any kind of painkillers or anti-inflammatory drugs 15 days prior to randomisation.

• Known impaired haematological profile and liver/renal function.

• Known allergic history to any topical cream.

• Known pregnancy or lactating.

• Unable to complete questionnaires.

Study outcomes

Please refer to table 1 for details.

Table 1.

Study outcomes

Primary outcome (compared with baseline)	Time of assessment
Range of motion of the shoulder and elbow measured by a goniometer	Week 2 and week 4
Secondary outcome (compared with baseline)
Scores on the Numerical Pain Rating Scale	Week 2 and week 4
Handgrip strength measured by a dynamometer	Week 2 and week 4
Scores on the back-scratch test	Week 2 and week 4
Scores on the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form	Week 2 and week 4
Scores on the American Shoulder and Elbow Surgeons Standardized Elbow Assessment Form	Week 2 and week 4
Scores on the quality of life measured by the 36-item Short Form Survey	Week 2 and week 4
Rescue drugs or treatments used for pain symptoms	Baseline–week 4

Patients’ visit schedule

Screening and baseline visit (day 0)

Potential participants will be invited to undergo a screening process, during which they will be provided with a written informed consent form (the informed consent form is shown in the online supplemental appendix). The participants will be thoroughly informed about the trial, including its details, benefits and risks, as well as the assessment and data collection procedures. The research team will ensure that the participants understand the study and address any questions or concerns they may have during the consent process. Both the participants and investigators must sign the informed consent form before any study procedure commences.

Medical and surgical history will be obtained, and all eligibility criteria will be verified by investigators. Baseline assessments, encompassing ROM, upper extremity strength, back-scratch test and questionnaires such as the Numerical Pain Rating Scale, American Shoulder and Elbow Surgeons (ASES) forms and SF-36 will be conducted. Those eligible participants will be randomised into either the treatment group (receiving SCG) or placebo group (receiving placebo cream gel) for 2 weeks. Blinded investigators will distribute the cream gel to the participants, providing them with instruction on how to apply the cream gel to the painful area. Participants will also be provided with a diary to record their compliance with the treatment.

Follow-up visit (week 2)

Participants will be scheduled for a follow-up visit precisely 2 weeks after the randomisation process. During this visit, outcome assessments will be conducted to evaluate the changes following the treatment. These assessments will include measurement of the ROM, upper extremity strength, back-scratch test, as well as completion of questionnaires such as the Numerical Pain Rating Scale, ASES and SF-36. The purpose of these assessments is to identify discernible differences resulting from the treatment intervention.

At the follow-up visit, the occurrence of adverse events or serious adverse events will be assessed and documented. Additionally, the use of any rescue drugs or alternative treatments for pain relief during this period will also be recorded. To accommodate potential scheduling conflicts, a window period of ±3 days from the scheduled visit will be permitted if the participants are unable to attend the follow-up visit on the exact designated date. To ensure participants are reminded of the follow-up visit, a notification will be sent 1 week prior to the scheduled appointment.

End of study visit (week 4)

Participants will be scheduled for a post-treatment visit (2 weeks after the treatment was completed) to evaluate the various outcome parameters, including ROM, upper extremity strength, back-scratch test, and the completion of questionnaires such as the Numerical Pain Rating Scale, ASES and SF-36. Adverse events, serious adverse events, and rescue drugs or treatment will also be assessed and documented. Similar to the week 2 visit, a window period of ±3 days will be allowed.

Please refer to table 2 for details.

Table 2.

Patients’ visit schedule

Items	Screening & baseline	Treatment period	Post-treatment follow-up
	Day 0	Week 2 (±3 days)	Week 4 (±3 days)
Clinical assessment
Informed consent	✓
Eligibility	✓
Medical consultation and assessment	✓	✓	✓
Medical history	✓
Concomitant medication	✓	✓	✓
Vital sign (BP/pulse)	✓
AE/SAE assessment		✓	✓
Outcome assessment
Range of motion of the upper limb (shoulder, elbow)	✓	✓	✓
Numerical Pain Rating Scale	✓	✓	✓
Upper extremity strength	✓	✓	✓
Back-scratch test	✓	✓	✓
ASESp-S (for shoulder pain)	✓	✓	✓
ASESp-E (for elbow pain)	✓	✓	✓
SF-36	✓	✓	✓
Intervention
Administration of study products	✓	✓

AE/SAE, adverse event/serious adverse event; ASESp-E, American Shoulder and Elbow Surgeons Standardized Elbow Assessment Form–patient self-evaluation; ASESp-S, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form–patient self-evaluation; BP, blood pressure; SF-36, 36-item Short Form Survey.

Study intervention

Eligible participants will be randomised into either the treatment group or placebo group for a duration of 2 weeks. In the treatment group, participants will receive the SCG with a dosage of 1 g applied two times per day. The active ingredient of SCG consists of Vitis vinifera essence, Melaleuca viridiflora essential oil and Eucalyptus globulus essential oil. Each daily dose of SCG, amounting to 2 g, will be sealed within two aluminium sachets. Participants will apply one sachet of SCG to the affected area (either the shoulder or elbow) two times per day.

The placebo cream gel, designed for the placebo group, will consist of a natural base cream and edible pigment and flavouring agent. The ingredients of the placebo cream gel include aqua, alcohol denat, ethylhexyl stearate, hydroxyethyl acrylate/sodium acryloyldimethyl taurate copolymer, isohexadecane, polysorbate 60, sorbitan isostearate, CI 15985, CI 16255 and imidazolidinyl urea. Great care will be taken to match the appearance, texture and scent of the placebo cream gel to closely resemble that of the SCG.

Both the SCG and the placebo cream gel will be manufactured and packaged by a certified Good Manufacturing Practice manufacturer. It is important to note that since the study product does not meet the criteria outlined in the Pharmacy and Poisons Ordinance (Chapter 138) or fall under the definition specified in Regulation 36B of the Pharmacy and Poisons Regulations, a Certificate for Clinical Trial/Medicinal Test (the certificate) for a pharmaceutical product is not required.

Prohibited treatment/drugs

During the study period, the use of any painkillers, NSAIDs, anti-inflammatory drugs, traditional Chinese medicine specifically targeting pain symptoms, as well as treatments including occupational therapy, therapeutic massage, acupuncture therapy, and use of fascia gun or massage devices, are strictly prohibited. Participants will be instructed to refrain from using these interventions to ensure the accuracy and integrity of the study results. Compliance with these restrictions will be monitored throughout the duration of the study.

Study assessments

Range of motion

For the shoulder measurement, the ROM for active flexion and abduction will be assessed using a goniometer while the participants are in a standing position. To measure flexion ROM, the test arm is placed at the side with the forearm pronated, and the movement is performed in the sagittal plane. For abduction ROM, the test arm is also positioned at the side, but with the shoulders externally rotated, and the movement is performed in the coronal plane. Participants will be instructed to move their arms as far as they can, taking into consideration any pain they may experience. Each movement will be performed three times, and the best value recorded will be used for the data analyses.³⁵

For the elbow measurement, both flexion and extension ROM will be assessed using a goniometer while the participants are in a standing position. The goniometer will be placed on the lateral epicondyle of the elbow, with the stationary arm positioned at the centre of the upper arm and pointing toward the middle third of the lateral edge of the acromion. The distal limb of the goniometer will be placed along the dorsal surface of the forearm. Participants will be asked to actively flex and extend their arm through its full ROM. Each movement will be performed three times, and the best value recorded will be used for the data analyses.³⁶

Numerical Pain Rating Scale

The Numerical Pain Rating Scale is a unidimensional measure used to assess pain intensity in adults. It consists of 11 items, and participants are asked to select a whole number on a scale of 0–10 that best represents the average intensity of their pain over the past week. The scale ranges from ‘0’, which represents one pain extreme (eg, ‘no pain’) to ‘10’, which represents the other pain extreme (eg, ‘pain as bad as you can imagine’ or ‘worst pain imaginable’).³⁷ This scale provides a standardised way to quantify and track pain levels throughout the study.

Upper extremity strength

Handgrip strength is commonly used test to assess the sports performance of athletes. It evaluates the strength of the hand and forearm muscles and is relevant to sport activities that involve various types of gripping actions, such as the precision grip (used for grasping sphere-shaped objects like balls) and the power grip (used for grasping cylindrical-shaped objects like rackets or paddles), among others. In this trial, handgrip strengths will be measured using a dynamometer (12‐0604 Digital Dynamometer, Jamar Plus, Bolingbrook, Illinois, USA) on the dominant hand of each participant. To ensure standardised testing conditions, participants will be instructed to hold the dynamometer with their arm at the right angle and their elbow positioned at the side of their body. During the measurement, participants will be asked to exert their maximum effort while squeezing the dynamometer. Three attempts will be made to obtain the highest recorded value of handgrip strength. This procedure allows for reliable and consistent assessment of handgrip strength across participants.³⁸

Back-scratch test

The back-scratch test is used to measure the overall ROM of the shoulders. It involves measuring the distance between or the overlap of the middle fingers of both hands behind the back using a ruler.^{39 40}

ASES Standardized Shoulder Assessment Form–patient self-evaluation

The ASES Standardized Shoulder Assessment Form–patient self-evaluation consists of 18 questions divided into 3 sections: pain, instability and activities of daily living (ADLs). Among the 18 questions, 11 self-report items represented functional ADL dimension (10 items) and pain dimension (1 item). The ADL section was scored on a 4-point graded ordinal scale, ranging from 0 (unable to do) to 3 (not difficult), and cumulative scores were collected. The pain section was derived from the 10-point graded VAS ranging from 0 (no pain) to 10 (maximum pain).^{41 42}

ASES Standardized Elbow Assessment Form–patient self-evaluation

The ASES Standardized Elbow Assessment Form–patient self-evaluation consists of three sections: pain, function and satisfaction. Patients are asked to indicate the specific spot of pain and intensity of pain on a VAS in different situations, such as the worst pain experienced, pain at rest, pain while lifting a heavy object, pain during tasks involving repeated elbow movements and pain experienced at night. The VAS ranges from 0 (no pain) to 10 (maximum pain). In the function section, patients are asked to rate their ability to perform 10 ADLs and their usual work and sporting activities with a scale from 0 (unable to do) to 3 (not difficult).⁴³

Version 2 of SF-36 (1-week interval)

Quality of life is a crucial parameter when evaluating therapeutic interventions for patients experiencing upper limb pain. It encompasses various health-related factors, including physical, functional, emotional and mental well-being, as well as non-health-related elements like work, family, friends and overall life circumstances.^{44 45}

SF-36 is a generic instrument to measure general health status. It will be used to assess the patient’s health status using eight different dimensions including vitality, physical functioning, bodily pain, general health perceptions, role limitations due to physical health, role limitations due to emotional health, social role functioning and mental health. The possible score ranges from 0 to 100 points whereby 0 points represent the greatest possible limitation of health, while 100 points represent the absence of health restrictions.

Randomisation and blinding

This is a double-blinded randomised controlled trial. To ensure random allocation, a computerised random number generator will be employed to generate a random number table. The resulting random allocations will be placed into sealed opaque envelopes, each labelled with sequential study numbers. Two sets of the envelope will be prepared: one set will be used for randomisation at the study site, while the other set securely stored in the investigator’s office will be intended for emergency unblinding scenarios. Unblinding will only occur in specific circumstances, such as when clinical treatment decisions are necessary or in the event of an unexpected serious adverse event that requires disclosure of the intervention. The process of generating the random number table and creating the random allocation envelopes will be conducted by an independent staff. Each participant will be assigned a sequential study number, and subsequently, the research team will prepare the corresponding SCG or placebo gel based on the random allocation sequence. Throughout this trial, the Chinese Medicine Practitioner (CMP) investigators, study subjects and outcome assessors will be blinded to the allocated intervention to minimise bias and maintain the integrity of the study.

Adverse events

All participants will be suggested to inform the study team about any adverse reactions during the treatment and follow-up period. An adverse event is any undesirable medical event occurring in the subject within the trial period, whether it is related to the study intervention. The assessment of adverse events will be recorded according to the Common Terminology Criteria for Adverse Events (CTCAE) V.5.0, which is a standard assessment tool. Judgement on continuing, adjusting dosage or termination of the study intervention will be made by investigators.

Serious adverse events

A serious adverse event is an adverse event that results in one of the following outcomes:

• Death.

• Life-threatening situation.

• Inpatient hospitalisation or prolongation of existing hospitalisation.

• A persistent or significant disability or incapacity.

• A congenital anomaly or birth defect.

The definitions of causal relationship to study intervention are the same as those for adverse events. A standard serious adverse event form will be used to report the events within 24 hours after acknowledgement. The form is provided by the joint CUHK–New Territories East Cluster (NTEC) Research Ethics Committee at https://www.crec.cuhk.edu.hk/download/.

Sample size calculation

The primary outcome is the ROM of active shoulder abduction at week 2 measured with a digital goniometer. Because there is no previous clinical study about soothing cream for patients with chronic shoulder pain on ROM measured by a goniometer, the data from other studies on acupuncture or physiotherapy were used for estimation of clinically meaningful mean difference in ROM and SD.^{46 47} In this trial, the software Power Analysis & Sample Size and a linear mixed model will be used to calculate the sample size. In order to detect an estimated clinically meaningful difference of 20° in the ROM of shoulder abduction between treatment and placebo control groups, 28 participants in each group will be needed based on the assumed SD of 26.5 with a two-sided significance level of 0.05 and a power of 80%. Therefore, a total of 70 patients will be needed in this trial, presuming a 20% dropout rate.

Statistical analysis

The primary efficacy analyses will be based on the full analysis set (FAS) following the intention-to-treat (ITT) principle. Secondary efficacy analyses will be based both on the FAS and the per-protocol set. Continuous variables will be presented as mean value and SD or medians and IQRs, while categorical variables will be presented as frequency and percentage. Linear mixed models will be used to compare the primary and secondary outcomes between two groups and explore whether participant characteristics are associated with some outcomes. For the missing data, the last data carried forward will be used and ITT analysis will be used for missing data. All statistical tests will be two sided, and p<0.05 is considered statistically significant. The statistical software SPSS V.26.0 will be used for analysis.

Adverse events will be categorised and the percentage of those experiencing some adverse events and serious adverse events will be documented. Χ² tests will be performed to examine differences in the proportion of total and categories of adverse events between groups.

Patient and public involvement

Patients or the public were not involved in the design, or conduct, or reporting, or dissemination plans of our research.

Data management

All collected study data will be entered into a secure database housed on a password-protected computer. Access to the database will be restricted to the research team, ensuring confidentiality and data security. Additionally, an independent staff member who is not directly involved in this trial will perform a double-check on the entered data, to verify their accuracy and integrity. The joint CUHK–NTEC Clinical Research Ethics Committee will conduct an audit after the completion of the trial.

Ethics and dissemination

This study complies with the Declaration of Helsinki and International Council for Harmonisation-Good Clinical Practice (ICH-GCP). The study was approved by the joint CUHK-NTEC Ethics Committee (CRE-2023.142). Prior to participation, all potential participants and/or their legal guardians will be fully informed about the study’s procedures, benefits and risks and participants’ rights. They will be assured that all information collected will be treated with strict confidentiality and maintained anonymity. Informed consent will be obtained from each participant and/or their legal guardians. All information will be encrypted and only the investigators involved in the study will have authorised access to the data. Access to the data will require a password for authentication. Participants will have freedom to withdraw from the study at any time without facing any consequence or providing a reason for their decision. The personal data of the participants will be retained for a period of 7 years and will be securely destroyed thereafter to protect privacy. To mitigate potential risks, clinical trial insurance will be obtained prior to the commencement of the trial. The study results will be disseminated through publication in peer-reviewed journals and presentations at scientific conference.

Discussion

Upper limb problems are prevalent worldwide and their incidence is increasing over time. These problems can be caused by various factors, such as improper posture, repetitive strain injury or even external injury. Common symptoms of upper limb problems include pain, soreness and limited ROM. These symptoms not only directly impact the affected area but also affect the patient’s sleep, mood and overall quality of life. While different treatments are available to alleviate these symptoms, they often come with potential side effects. In case of severe symptoms, corticosteroid injections are sometimes used as an alternative to oral treatments.

In recent times, there has been a growing interest in natural remedies and products for health-related issues. In this clinical trial, we will be evaluating the efficacy of the SCG for the treatment of upper limb problems. This gel is composed of essential oils derived from natural botanical sources, which have been reported to possess anti-inflammatory and analgesic properties. Among various modes of administration, we believe that topical application of medicinal products is safer and associated with fewer side effects compared with the oral administration.^48–50 Therefore, our objective is to explore an alternative product that can effectively alleviate the symptoms of upper limb problems through a randomised, double-blinded, placebo-controlled clinical trial. Additionally, this trial aims to provide further evidence regarding the efficacy of the natural botanical ingredients used in the SCG. We expect that the use of the gel will lead to improvements in the ROM and reduction of pain symptoms of participants with upper limb problems.

However, as this is a clinical trial, the dosage of the investigational medicinal product is fixed for all participants. Although we have made efforts to standardise the dosage to cover most affected areas of the participants, some individuals may require a larger amount of the SCG due to a larger affected area. Furthermore, some participants may have a preference for receiving a massage while applying the SCG to the upper limb. This preference may introduce a confounding factor that could potentially influence the positive outcome in this trial.

In this trial, we employed a placebo as the comparator to the active treatment. The placebo was carefully designed to closely resemble the appearance, texture and scent of the active treatment. To assess the credibility of the placebo, at the end of the follow-up period, we can ask the participants to guess which group they believe they were randomised to. This evaluation can provide insights into whether the participants were able to accurately distinguish between the active treatment and the placebo. It is an important measure to gauge the blinding efficacy of the trial and helps ensure the integrity of the study results.

Ethics statements

Patient consent for publication

Not applicable.