Effectiveness of 1064-nm high-power laser therapy combined with thumb spica splinting in De Quervain’s tenosynovitis: a randomized double-blind sham-controlled trial

Abstract

Background

De Quervain’s tenosynovitis (DQT) is an inflammatory condition of the first dorsal compartment of the wrist that causes pain and impaired thumb function. High-power laser therapy (HPLT) has been proposed as a non-invasive modality for musculoskeletal pain management; however, evidence supporting its effectiveness in DQT remains limited. This study aimed to evaluate the effectiveness of 1064-nm HPLT combined with thumb spica splinting in reducing pain and improving hand function in patients with DQT.

Design

A randomized, double-blind, sham-controlled clinical trial.

Methods

Twenty-six patients with DQT were randomly assigned to receive either 1064-nm HPLT (8 W, 150 J/cm², total energy 1,580 J per session) combined with thumb spica splinting or sham laser therapy with splinting. Treatments were delivered three times per week for three weeks (nine sessions). Outcomes included pain intensity measured using the Visual Analogue Scale (VAS), lateral pinch strength (LPS), and hand function assessed with the Patient-Rated Wrist/Hand Evaluation Thai version (PRWHE-Thai). Assessments were performed at baseline, immediately after treatment (week 3), and at follow-up (week 6).

Results

Both groups showed significant reductions in VAS scores at weeks three and six compared with baseline, with no significant between-group differences. LPS slightly increased in both groups without statistical significance. PRWHE-Thai scores improved significantly in the sham group, while the HPLT group showed no significant functional gains. Splint compliance was comparable between groups.

Conclusions

The 1064-nm HPLT (8 W, 150 J/cm², total energy 1,580 J) combined with thumb spica splinting did not provide superior benefits compared with splinting alone in reducing pain or improving hand function in patients with DQT. Further studies are needed to determine optimal laser parameters and clinical indications.

Trial registration

This study was registered with Thai Clinical Trials Registry on 12/07/2021. (TCTR20210712004)

Background

De Quervain’s tenosynovitis (DQT) is an inflammatory condition affecting the tendon sheaths of the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) within the first dorsal extensor compartment at the radial styloid of the wrist. It is commonly associated with repetitive or excessive use of the wrist and thumb, which increases friction between the tendons and the surrounding sheath, ultimately leading to thickening of the extensor retinaculum. Clinically, patients typically present with pain at the radial aspect of the wrist near the base of the thumb, which worsens with wrist or thumb movement. Associated symptoms may include swelling, tenderness, and erythema over the radial styloid, often resulting in functional impairment of the thumb and reduced quality of life. Epidemiological studies have reported prevalence rates of approximately 0.5% in men and 1.3% in women, with the highest incidence observed in individuals in their fourth and fifth decades of life [21]. Another study reported slightly lower prevalence rates of 0.13% in men and 0.36% in women [20].

The diagnosis of DQT is primarily based on patient history and physical examination. Several provocative clinical tests have been described, with the Finkelstein test being the most widely used. In this test, the patient flexes the thumb into the palm while the examiner passively deviates the wrist ulnarly. Reproduction of sharp pain over the radial aspect of the wrist at the first dorsal compartment is considered a positive result [9].

Conservative management of DQT depends on the severity of the condition and typically includes nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroid injections, and rehabilitation approaches such as splinting, activity modification, physical modalities, manual therapy, and therapeutic exercise. The European Delphi consensus on multidisciplinary treatment guidelines for DQT emphasizes the importance of providing patients with structured education and instructions as a core component of management. However, patient education is recommended to be combined with other treatment modalities rather than used as a stand-alone intervention [12].

Laser photobiomodulation therapy [5] is a non-invasive and painless treatment modality commonly used in physiotherapy. The biological effects of laser irradiation depend on several parameters, including wavelength, irradiation mode (continuous or pulsed), pulse duration, power output, and energy density. These parameters influence cellular responses such as modulation of inflammatory processes, stimulation of tissue repair, and analgesic effects [23].

High-power laser therapy (HPLT) differs from low-power laser therapy primarily in its higher power output, typically exceeding 500 mW. Although the intrinsic penetration depth of laser light is mainly determined by the wavelength and optical properties of biological tissues, higher output power allows a greater amount of energy to be delivered to tissues at a given depth within a shorter period of time. This may enhance the amount of therapeutic energy reaching deeper structures while maintaining clinically practical treatment durations.

HPLT has increasingly been incorporated into physiotherapy protocols for musculoskeletal pain management. In clinical practice, HPLT is often used in combination with other therapeutic interventions [7]. Although preliminary studies suggest potential benefits, the current evidence remains insufficient to establish HPLT as an effective non-invasive modality for musculoskeletal pain. Variability in study designs and reported outcomes highlights the need for well-designed randomized controlled trials with clearly defined outcome measures and adequate follow-up to better clarify the clinical effectiveness of HPLT [8]. Evidence regarding the use of HPLT specifically for the treatment of DQT remains limited, indicating the need for further research in this area.

Chongkriengkrai et al. [3] conducted a pilot randomized study to evaluate the effectiveness of high-intensity laser combined with splinting and therapeutic exercise in patients with subacute DQT. Nineteen patients were randomly assigned to either the HPLT group or the sham group. Each participant received nine treatment sessions delivered three times per week over three consecutive weeks. Outcome measures included pain intensity assessed by the visual analog scale (VAS), handgrip strength, and disability evaluated using the Thai version of the Patient-Rated Wrist/Hand Evaluation (PRWHE-Thai). Both groups demonstrated significant reductions in pain and improvements in disability scores at follow-up compared with baseline. However, no statistically significant differences in grip strength were observed between groups at any time point. In the pilot study 3, HPLT was applied according to the device protocol using two treatment phases. During the analgesic phase, the laser was delivered at 8 W power with an energy density of 8 J/cm2 and a total energy of 80 J in pulsed mode. In the biostimulation phase, the parameters were set at 8 W power, 80 J/cm2 energy density, and 800 J total energy in continuous mode, resulting in a total energy delivery of 880 J per session. This energy dose may have been insufficient to achieve optimal therapeutic effectiveness.

Based on these findings, the present study was designed to further investigate the clinical effectiveness of high-power laser therapy in patients with DQT by increasing the energy delivered while maintaining the same treatment area. Specifically, the total energy per session was increased from 880 J in the previous pilot protocol to 1,580 J. This adjustment was intended to enhance the therapeutic dose with the aim of improving pain reduction and hand function. The increase in energy delivery was informed by previous studies reporting improved clinical outcomes with laser doses of up to 4,000 J per session [16].

Therefore, the present randomized double-blinded controlled trial aimed to evaluate the effectiveness of 1064-nm HPLT in patients with DQT. The treatment protocol was modified from the previous pilot study by increasing the total energy delivered per session from 880 J to 1,580 J while maintaining the same treatment area. This adjustment was intended to investigate whether a higher therapeutic energy dose could produce greater reductions in pain and improvements in hand function compared with sham treatment.

Methods

The study was conducted in accordance with the Declaration of Helsinki, with ethical approval obtained from the Institutional Review Board of the Faculty of Medicine, Chulalongkorn university (IRB No. 508/64) and registered in the Thai Clinical Trials Registry on 12/07/2021. (TCTR20210712004) Written informed consent was obtained from all participants prior to participation. This randomized, controlled, double-blinded (patients and assessor) study was conducted in Physical Medicine and Rehabilitation, Department of Chulalongkorn University and King Chulalongkorn Memorial Hospital between October 2021 and January 2023.

Participants

Participants were recruited from the Department of Rehabilitation Medicine’s outpatient service from September 2022 to August 2023. They were diagnosed with DQT, based on symptoms of first dorsal compartment discomfort and tenderness, increased symptoms with thumb abduction or extension, and a positive Finkelstein’s test. All participants were willing to join the study and provided informed consent. Participants who had symptoms for less than 1-month, previous treatment with physical modalities within the past 4 weeks, local corticosteroid injection within the past 6 months, or surgery, and those with contraindications to HILT (such as metal implants, tumors, abnormal sensation, or tattoos) were excluded.

All eligible participants were randomly divided into two groups by an independent researcher using a computer-generated block randomization method. The allocation sequence was created and sealed in opaque envelopes. An investigator, who was unaware of the group assignments, enrolled the participants and conducted the assessments. The participants were also kept unaware of their group assignments.

Interventions

Participants in the intervention group received 1064-nm HPLT using a class IV semiconductor laser device (BTL-6000, BTL Industries). The device emits laser radiation at a wavelength of 1064 nm with a maximum optical power output of 12 W and a spot size of 1 cm². The irradiation parameters were selected based on the manufacturer’s recommendations and previous clinical studies.

The treatment consisted of two phases:

Analgesic phase

Pulsed mode, 8 W, 8 J/cm², total energy 80 J applied for 40 seconds over the most painful area of the first dorsal compartment using a circular motion from the periphery toward the center.

Biostimulation phase

Continuous mode, 8 W, 150 J/cm², total energy 1500 J delivered over the treatment area using linear and zigzag scanning movements.

The total energy delivered per session was 1,580 J. Treatments were performed three times per week for three consecutive weeks (nine sessions). Both the patient and the therapist wore protective safety glasses during the procedure to prevent ocular exposure to laser radiation. In addition, patients were instructed to keep their eyes closed throughout the treatment session, ensuring that they could not see the red aiming beam of the laser device, thereby maintaining participant blinding. In the sham group, participants followed the same procedures as those in the HPLT group; however, the therapist did not activate the power button on the device, resulting in no laser emission from the treatment probe. Participants in both groups were blinded to treatment allocation and were unaware of whether they received active laser therapy or sham treatment. To maintain blinding, participants wore headphones and listened to music during the procedure to mask any operational sounds produced by the device. Furthermore, the audible signal associated with device activation was muted to ensure that both groups experienced similar treatment conditions. The device display, which showed treatment parameters such as energy output and treatment duration, was positioned away from the participants so that these indicators were not visible.

Both groups will receive guidance on appropriate practices for managing DQT from research assistants who are unaware of the participants' group assignments. The recommendations consist of avoiding repetitive activities that involve the wrist and thumb, as well as wearing a prefabricated thumb spica splint to restrict movement of the 1 st metacarpophalangeal joint. The splint should maintain a neutral wrist position, with 30° of carpometacarpal joint flexion and 30° of thumb abduction. Participants are encouraged to wear the splint for at least 6 hours each day over a period of 6 weeks and to keep a record of the total hours it is worn. The exercise program was delivered weekly by an occupational therapist for a total of six sessions, supplemented with individualized home exercise programs that were progressively adjusted to promote healing, enhance hand function, and prevent further injury. The program included range of motion exercises for the thumb, fingers, and wrist, as well as strengthening exercises targeting the thumb, handgrip, and wrist using elastic bands, weights, and rubber balls.

Participants in both groups will receive paracetamol at a dosage of 500 milligrams as a rescue medication, with a maximum dose of 15 mg/kg per dose, not exceeding 1000 mg at a time. They were advised to take the medication as needed for intolerable pain and to record the number of tablets taken each time. Evaluators will track the medication intake based on the number of doses administered.

Outcome measurement

Baseline demographic data collected included age, gender, body mass index (BMI), dominant hand side and duration of symptoms. Outcome assessments were measured at three time points: baseline, after the 9th treatment session, and 3 weeks following the final treatment (designated as week 0, week 3, and week 6, respectively). All assessments were conducted by the same evaluator, who was blinded to the randomization and treatment procedures.

-Visual Analogue Scale (VAS): [14]

Pain intensity was assessed using the Visual Analogue Scale (VAS), which enables participants to indicate their pain level on a 100-mm line, measured in millimeters. The starting point on the left side is 0, representing no pain at all, while the endpoint on the right side is 100, indicating the worst pain imaginable. This assessment measures the highest level of pain experienced during activity.

-Lateral pinch strength (LPS): [19]

LPS was assessed using a hand dynamometer (Jamar® Hydraulic Hand Dynamometer, USA). Participants were instructed to exert maximum force by pinching with their thumb against the device. They performed three consecutive trials, with a 60-second rest period between each trial. The average lateral pinch strength was calculated based on these three trials. Measurements were taken with participants seated, ensuring that their shoulders were abducted at 0°, elbows were flexed at 90°, and forearms were positioned neutrally.

-Patient-Rated Wrist/Hand Evaluation Questionnaire (PRWHE): [13]

Hand disability was assessed using the Thai version of the PRWHE. This questionnaire consists of 15 items specifically designed to evaluate wrist pain and disability in daily activities. Participants used a rating scale from 0 to 10 to indicate their levels of wrist pain and disability. The questionnaire includes two subscales: the pain subscale, which comprises 5 items, and the function subscale, which consists of 10 items categorized into specific activities and usual activities. Each subscale has a maximum score of 50, resulting in a total possible score of 100 for the questionnaire. The PRWHE-Thai has demonstrated high internal consistency, reliability, and validity [1].

Statistical analysis

Statistical analyses were performed using SPSS (version 22.0, IBM Corp., Armonk, NY, USA). Descriptive statistics were used to summarize participant characteristics and outcome measures. Continuous variables are presented as mean ± standard deviation (SD).

To evaluate changes in outcome measures over time and to compare treatment effects between groups, a repeated-measures analysis of variance (RM-ANOVA) was conducted with time (pre-treatment and post-treatment) as the within-subject factor and treatment group as the between-subject factor. The group × time interaction was examined to determine whether the pattern of change over time differed between the treatment groups. Additionally, given the potential baseline differences in functional outcomes (PRWHE scores), an analysis of covariance (ANCOVA) was performed with baseline values included as covariates to adjust for possible baseline imbalance between groups. Statistical significance was set at p < 0.05. In addition to statistical significance testing, the clinical relevance of pain reduction was evaluated using the minimal clinically important difference (MCID) for the Visual Analog Scale (VAS). Based on previous literature, a reduction of ≥20 mm on the VAS was considered clinically meaningful [10]. The proportion of participants achieving the MCID was calculated for each group, and between-group differences in responder rates were compared using the chi-square test. Effect sizes were calculated using Cohen’s d to estimate the magnitude of treatment effects within each group. Effect size values of 0.2, 0.5, and 0.8 were interpreted as small, medium, and large effects, respectively. A post hoc power analysis was performed to estimate the achieved statistical power based on the observed between-group difference in VAS reduction at the end of treatment. The analysis was conducted assuming a two-sided significance level of 0.05.

Results

Of the thirty-seven participants initially screened according to the inclusion and exclusion criteria, twenty-six patients with DQT were enrolled in the study. Thirteen participants were randomly allocated to the HPLT group and thirteen to the sham group. No participants were lost to follow-up, as illustrated in the flow diagram (Fig. 1). All twenty-six participants were included in the final analysis for the primary outcome based on the groups to which they were originally assigned (intention-to-treat principle). No participants were excluded from the analysis, and no protocol deviations occurred. The majority of participants were female (23 females and 3 males), predominantly middle-aged. Baseline demographic and clinical characteristics were comparable between the two groups, except for the treated side, where a higher proportion of right-sided involvement was observed in the HPLT group compared with the sham group (Table 1).

Fig. 1.

Participants flow diagram

Table 1.

Baseline demographic of participants

	HPLT group (n=13)	Sham group (n=13)	p-value
Age, years, mean (SD)	43.85 (17.45)	51.46 (14.68)	0.325
Gender (Male/Female) (n)	2/11	1/12	0.780
BMI, kg/m2, mean (SD)	23.88 (4.25)	25.26 (4.17)	0.658
Symptom duration, months, mean ±SD	10.69±10.82	11.00±15.70	0.589
Dominant side, (right/left)	12/1	13/0	0.468

Table 2 presents the descriptive statistics of clinical outcomes at each assessment time point. At baseline, the mean VAS pain scores were 61.23 ± 16.57 mm in the HPLT group and 63.62 ± 10.52 mm in the sham group. Pain intensity gradually decreased in both groups over time, reaching 37.69 ± 31.80 mm and 33.85 ± 19.72 mm at week 6 in the HPLT and sham groups, respectively. Both treatment groups achieved a reduction in VAS pain scores exceeding the minimal clinically important difference (MCID) of 20 mm. The mean improvement in the HPLT group was 23.54 mm, while the sham group demonstrated a mean improvement of 29.77 mm at week 6. These findings indicate that clinically meaningful pain reduction occurred in both groups.

Table 2.

Mean and standard deviation of clinical outcomes at each time point

Outcome	Time point	HPLT group (n = 13) Mean ± SD	Sham group (n = 13) Mean ± SD
VAS pain (mm)	Baseline	61.23 ± 16.57	63.62 ± 10.52
	Week 3	40.62 ± 28.25	40.62 ± 18.68
	Week 6	37.69 ± 31.80	33.85 ± 19.72
Lateral pinch strength (kg)	Baseline	3.39 ± 1.04	2.95 ± 1.18
	Week 3	3.64 ± 1.15	3.16 ± 1.12
	Week 6	3.88 ± 0.98	3.25 ± 1.09
PRWHE score	Baseline	44.46 ± 13.85	57.54 ± 12.71
	Week 3	30.89 ± 21.49	38.54 ± 13.95
	Week 6	30.39 ± 25.21	35.85 ± 16.28

Values are presented as mean ± standard deviation

LPS showed a gradual increase in both groups during the study period. The mean pinch strength in the HPLT group increased from 3.39 ± 1.04 kg at baseline to 3.88 ± 0.98 kg at week 6, whereas the sham group improved from 2.95 ± 1.18 kg to 3.25 ± 1.09 kg. Lateral pinch strength (LPS) showed a slight increase after treatment (week 3) in both groups, with an average gain of 0.25 kg in the HPLT group and 0.22 kg in the sham group, neither of which reached statistical significance. (Table 2) Further increases in pinch strength were observed during the 3-week follow-up period (week 6), with gains of 0.49 kg in the HILT group and 0.30 kg in the sham group.

Similarly, PRWHE scores improved over time in both groups, indicating functional improvement. The HPLT group showed a reduction from 44.46 ± 13.85 at baseline to 30.39 ± 25.21 at week 6, while the sham group decreased from 57.54 ± 12.71 to 35.85 ± 16.28. The functional score of the PRWHE-Thai questionnaire demonstrated significant improvement in the sham group at both 3 and 6 weeks after treatment, whereas the improvement in the HPLT group did not reach statistical significance.

Repeated-measures ANOVA (Table 3) demonstrated a significant effect of time for pain intensity (p < 0.001), indicating that both groups showed significant improvement throughout the study period. However, neither the group effect nor the group × time interaction reached statistical significance (p > 0.05), suggesting that the pattern of improvement over time did not differ significantly between the HPLT and sham groups. Similar findings were observed for PRWHE scores, with a significant time effect (p = 0.002) but no significant group or interaction effects.

Table 3.

Repeated-measures analysis of treatment effects

Outcome	Time effect (p-value)	Group effect (p-value)	Group × Time interaction (p-value)	Effect size (partial η2)
VAS pain	<0.001	0.58	0.63	0.04
Lateral pinch strength	0.041	0.17	0.29	0.06
PRWHE score	0.002	0.12	0.34	0.05

Data were analyzed using repeated-measures ANOVA to evaluate the effects of time, group, and group × time interaction

In addition to mean changes in pain intensity, the proportion of participants achieving the minimal clinically important difference (MCID) of ≥20 mm on the VAS was analyzed. At week 3, 8 of 13 participants (61.5%) in the HPLT group and 9 of 13 participants (69.2%) in the sham group achieved the MCID threshold. At week 6, the proportions increased to 9 of 13 participants (69.2%) in the HPLT group and 10 of 13 participants (76.9%) in the sham group. No statistically significant difference in responder rates was observed between the groups (p > 0.05) (Table 4).

Table 4.

Proportion of patients achieving the minimal clinically important difference (MCID) at week 6

Outcome	MCID threshold	HPLT group (n=13) n (%)	Sham group (n=13) n (%)	p-value
Pain (VAS)	≥ 20 mm reduction	9 (69.2%)	10 (76.9%)	0.68
PRWHE score	≥ 11 point reduction	8 (61.5%)	9 (69.2%)	0.71
Lateral pinch strength	≥ 0.5 kg increase	6 (46.2%)	4 (30.8%)	0.41

Chi-square test was used to evaluate the differences of the between group

MCID Minimal clinically important difference, VAS Visual analog scale, PRWHE Patient-Rated Wrist/Hand Evaluation

Between-group effect sizes at week 6 were calculated using Cohen’s d (Table 5). The effect size for VAS pain was trivial (d = 0.15). A moderate effect size was observed for lateral pinch strength (d = 0.61). The PRWHE score demonstrated a small effect size (d = 0.26) (Table 5).

Table 5.

Between-group effect sizes (Cohen’s d) for pain, hand strength, and functional outcomes at week 6

Outcome	Time	Mean difference	Cohen’s d	Interpretation
VAS	Week 6	3.84	0.15	trivial
Lateral pinch	Week 6	0.63	0.61	moderate
PRWHE	Week 6	−5.46	0.26	small

Participants in both groups wore a thumb spica splint throughout the three-week treatment period and for an additional three weeks post-treatment, totaling six weeks. The average duration of splint use during the first three weeks was 10.15 hours per day in the HPLT group and 8.15 hours per day in the sham group. During the three-week post-treatment follow-up, the average wear time was 10.38 hours per day for the HPLT group and 7.85 hours per day for the sham group. Although patients in the HPLT group wore the splint for a longer duration, this difference was not statistically significant (Table 6).

Table 6.

Duration of thumb spica splint (hours/day)

	Group 1 HPLT (n=13)	Group 2 Sham (n=13)	p-value
	(Mean ± SD)	(Mean ± SD)
At week 0 to week 3	10.15±5.24	8.15±2.08	0.223
At week 3 to week 6	10.38±5.53	7.85±2.15	0.126

Repeated-measures ANOVA was used to evaluate the differences of the between group

No adverse events or unintended effects were observed in any participants during the study, regardless of whether they received HPLT, sham intervention, or used a thumb spica splint. Paracetamol consumption during the study period was low in both groups. During the treatment period (week 0–3), the median number of tablets taken was 0 (range 0–2) in the high-power laser group and 0 (range 0–5) in the sham group (p = 1.000). During the follow-up period (week 3–6), the median number of tablets used was 0 (range 0–2) in both groups (p = 0.593), with no statistically significant difference between groups.

Discussion

This study aimed to evaluate the additional effects of HPLT using a 1064-nm class IV laser system at a power of 8 watts and a total energy of 1,580 joules when combined with a thumb spica splint in treating DQT through a randomized double-blind controlled trial. The results showed a significant decrease in the VAS pain score at weeks three and six compared to pre-treatment in both the HPLT and sham groups, with no statistically significant difference between the groups. Similarly, LPS improved in both groups but did not reach statistical significance. Hand function, assessed via PRWHE, showed significant improvement in the control group at weeks three and six, while the HPTL group did not achieve statistical significance in this measure. These findings suggest that adding HPLT at 1,580 joules to a thumb spica splint does not provide additional benefits in reducing pain or improving hand function beyond the effects of splinting alone.

Our findings align with those of Chongkriengkrai et al. [3], who reported that an 8-watt HPLT at a total energy of 880 joules combined with a wrist splint was not superior to splinting alone in treating DQT. Given that our study nearly doubled the energy level to 1,580 joules. In comparing the findings of the present study with those of previous research conducted by Chongkriengkrai et al., it was observed that the effect of pain reduction, as indicated by the VAS score at three weeks post-treatment with HPLT utilizing an energy level of 1580 joules, demonstrated a more significant reduction in pain scores. However, at six weeks post-treatment, the results did not reveal any statistically significant differences. For the PRWHE questionnaire scores, the values did not show superiority with the increase in the energy used for treatment.

Conversely, Dundar EA and Sirzai H [6]. reported results that differed from ours. Their study, which investigated effectiveness of HPLT in DQT, found significant improvements in grip strength and pain reduction. They applied a different HPLT protocol, with a two-phase treatment plan over five weeks: the first seven sessions delivered 10 watts at 10 J/cm² (total 250 joules) in analgesic mode, followed by eight sessions at 6 watts and 120–150 J/cm² (total 3000-3750 joules) in biostimulation mode. In comparison to the dose of high-power laser energy using in the present study (1580 joules), Dundar’s study [6] utilized a considerably higher energy level of 3750 joules. This observation highlights the importance of determining the optimal energy dose that can yield therapeutic efficacy. At present, there is no standardized guideline for the use of high-power laser in the treatment of DQT, underscoring the need for further research to establish appropriate parameters, including parameter settings, treatment frequency, and the number of sessions, in order to achieve optimal therapeutic outcomes.

In the present study, LPS was evaluated, whereas previous investigations [6] predominantly assessed grip strength. Considering that pain in DQT is typically localized at the base of the thumb, LPS may serve as a more precise indicator of functional impairment. The results demonstrated a progressive improvement in LPS in both the HPLT and control groups at the third and sixth weeks; however, these changes did not attain statistical significance, which may be attributable to the limited follow-up duration.

The thumb spica splint, a widely accepted conservative treatment, is used to rest and immobilize the thumb, thereby reducing pain and improving functional hand mobility. By positioning the thumb in a functional and comfortable position, the splint helps minimize friction between the tendons and the tendon sheath, which may subsequently decrease local inflammation and mechanical irritation. 2 Splinting remains a well-established conservative therapy for DQT, primarily aimed at reducing inflammation, promoting rest, and limiting the movement of the APL and EPB tendons [18]. Previous studies [2, 17] have reported that immobilization with a thumb spica splint can effectively alleviate pain and improve functional outcomes in patients with DQT, particularly in the early or mild stages of the condition. Splinting reduces repetitive tendon gliding and mechanical stress across the first dorsal compartment, allowing the inflamed tissues to recover. In clinical practice, splinting is often recommended as part of first-line conservative management before considering more invasive interventions. Our findings reinforce the effectiveness of splinting as a conservative treatment modality for DQT. Patients who received splinting alone demonstrated meaningful improvements in symptoms, suggesting that adequate immobilization and rest may be sufficient to relieve tendon irritation in many cases. These results support the role of splinting as a fundamental component of conservative management and may explain why the addition of HPLT did not provide substantial additional benefit in some patients. Therefore, splinting alone may represent an effective and practical treatment option for symptom relief in patients with DQT, particularly when implemented appropriately and with good patient compliance.

Most recently, in 2025, a systematic review and meta-analysis investigating the efficacy of HPLT in the treatment of DQT was published [4]. Of the 1,462 reports initially identified, only three studies met the criteria for methodological quality assessment, namely those conducted by Chongkriengkrai et al. (2021, 2023) [3] and Dundar et al. (2023) [6]. Consequently, the current evidence remains insufficient to draw definitive conclusions regarding the therapeutic effectiveness of HPLT for DQT, thereby underscoring the need for further high-quality studies in the future.

In addition to statistical significance, the clinical relevance of pain reduction should also be considered. Previous studies have suggested that the MCID for pain measured by the VAS is approximately 10–20 mm [15]. In the present study, the mean reduction in VAS scores was 23.54 in Group 1 and 29.77 in Group 2, both exceeding the reported MCID threshold. These findings suggest that the observed improvements in pain intensity are not only statistically significant but also clinically meaningful for patients with De Quervain’s tenosynovitis.

In addition to statistical significance testing, effect size analysis was performed to evaluate the magnitude of the treatment effect between groups. At week 6, the between-group effect size for pain reduction was trivial (Cohen’s d = 0.15), indicating that the additional benefit of HPLT beyond standard conservative management was minimal. This finding is consistent with the comparable reduction in pain scores observed in both groups, suggesting that splinting and routine conservative care may have been the primary contributors to pain relief during the study period. For functional outcomes, the PRWHE score demonstrated a small between-group effect size (d = 0.26), indicating only a modest advantage of the intervention over the sham treatment. Although both groups experienced improvements in wrist and hand function, the magnitude of the difference between groups remained limited, which aligns with the lack of statistically significant between-group differences in the repeated-measures analysis. Interestingly, a moderate effect size was observed for lateral pinch strength (d = 0.61). While this effect did not reach statistical significance, likely due to the small sample size, the magnitude of the effect suggests a potentially meaningful improvement in hand strength associated with the intervention. This observation may indicate that HPLT could exert a greater influence on functional performance measures than on subjective pain outcomes. However, these findings should be interpreted cautiously and warrant confirmation in studies with larger sample sizes and longer follow-up periods (Table 5)

For the PRWHE, previous studies have suggested that the MCID ranges approximately between 11 and 14 points in patients with wrist and hand disorders [22]. In the present study, the mean PRWHE score in the HPLT group improved from 44.46 at baseline to 30.39 at week 6, representing a mean change of approximately 14 points. Similarly, the sham group demonstrated an improvement of approximately 21 points. These changes exceed the commonly reported MCID threshold, indicating that both treatment groups experienced clinically meaningful improvements in wrist and hand function. Although statistically significant differences between groups were not observed, the improvements exceeded the MCID threshold, suggesting clinically meaningful recovery in both groups.

Interestingly, in some outcome measures, the sham group demonstrated slightly greater improvements than the HPLT group. Although these differences were not statistically significant, this observation warrants consideration. Photobiomodulation therapy has been reported to exhibit a biphasic dose–response relationship, often described by the Arndt–Schulz law, in which low doses of energy may stimulate biological activity, whereas excessively high doses may produce diminished or even inhibitory effects [11]. Therefore, it is possible that the energy parameters used in the present study did not represent the optimal therapeutic dose for achieving maximal clinical benefit. Further studies exploring different energy parameters and treatment protocols may help clarify the dose–response relationship of HPLT in the management of DQT.

This study has several limitations that should be acknowledged. First, the study design did not allow evaluation of HPLT as a standalone intervention, as all participants received wrist splinting as part of the conservative treatment protocol. Consequently, the independent therapeutic effect of HPLT without concomitant splint use could not be determined. It therefore remains unclear whether HPLT alone would provide clinical benefit for patients who are unable to tolerate wrist splinting. Second, the follow-up period in this study was relatively short. Therefore, the findings reflect short-term treatment effects only, and the long-term effectiveness of HPLT for DQT remains uncertain. Third, the sample size was relatively small. Interestingly, the sham group demonstrated slightly greater mean improvements than the HPLT group in certain outcomes, particularly pain reduction and PRWHE scores. These observations suggest that the additional benefit of HPLT beyond standard conservative management may be limited in this patient population.

In terms of external validity, the findings of this trial are most applicable to adult patients with DQT who have clinical characteristics similar to those of the study participants. Caution should be exercised when generalizing these results to patients with different comorbidities, more severe disease presentations, or to clinical settings where HPLT equipment or adequately trained personnel are not available.

Another limitation of this study is the relatively short follow-up period. The outcomes were assessed only up to six weeks after baseline, which primarily reflects the short-term effects of the intervention. As some therapeutic effects may develop over a longer period, the long-term effectiveness and sustainability of HPLT for DQT remain uncertain. Future studies with larger sample sizes and longer follow-up durations are needed to further clarify the long-term clinical benefits of this treatment.

Conclusions

The 1064-nm high-power laser therapy (8 W, 150 J/cm², total energy 1,580 J) combined with thumb spica splinting did not demonstrate superior clinical benefits compared with splinting alone in patients with De Quervain’s tenosynovitis. Although both groups experienced clinically meaningful reductions in pain, the addition of high-power laser therapy did not significantly enhance functional outcomes. Further adequately powered randomized controlled trials are required to determine the optimal role and treatment parameters of high-power laser therapy for this condition.

Abbreviations

DQT

De Quervain’s tenosynovitis

HPLT

High-power laser therapy

VAS

Visual Analogue Scale

PRWHE-Thai

Patient-Rated Wrist/Hand Evaluation – Thai version

APL

Abductor pollicis longus

EPB

Extensor pollicis brevis

LPS

Lateral pinch strength

NSAIDs

Nonsteroidal anti-inflammatory drugs

Authors’ contributions

Natthakun Sumanapun: Data curation, Investigation, Visualization, Writing-review. Jirapa Champaiboon: Data curation, Visualization. Kittima Paktranon: Investigation, Resources. Pimmas Srilabutr: Investigation, Resources. Jariya Boonhong: Conceptualization, Methodology, Funding acquisition, Project administration, Supervision, Writing - original draft preparation, Writing - review \& editing. All authors contributed to data interpretation, reviewed and approved the final version of the manuscript, and agreed to be accountable for all aspects of the work.

Funding

This study was financial support by the Ratchadapiseksompotch Fund of the Faculty of Medicine, Chulalongkorn University. The grant number is RA 64/66.

Data availability

The datasets used and/or analyzed during the current study available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

This study followed the Declaration of Helsinki and was approved by the Institutional Review Board of the Faculty of Medicine, Chulalongkorn university (IRB No. 508/64). Informed consent was obtained from all participants prior to participation.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.