Carpal tunnel syndrome (CTS) is a neurological disorder caused by the compression of the median nerve in the carpal tunnel [1]. This condition is a common disorder in daily life that often occurs in workers who perform repetitive movements or fixed postures, such as athletes [1]. In modern times, CTS is also common in younger age groups such as adolescents and young adults because of the use of smartphones [2,3]. CTS can induce wrist pain, numbness, and uncomfortable tingling sensations in the fingers [4]. In addition, compression of the median nerve passing through the carpal tunnel can limit finger movements [1]. Conservative treatment for CTS typically involves reducing the frequency of wrist use to alleviate symptoms [1]. Efforts to relieve the symptoms include physical therapy, injection therapy, wrist splinting, and ultrasound therapy. In most cases, symptoms improve through conservative treatment, and if conservative treatment is ineffective, surgical treatment is considered [1,5].

This study aimed to review the types and effectiveness of orthosis used in the conservative treatment of CTS to provide basic information for clinicians who prescribe orthosis for CTS in clinical practice.

This study aimed to investigate the effectiveness of splints in patients with CTS by reviewing a recently published randomized controlled trial (RCT) on orthosis use. RCT studies published between January 1, 2016, and April 30, 2023, were searched using the MEDLINE database. The search terms were as follow: “splint,” “splints,” “splinting,” “orthosis,” “orthoses,” “carpal tunnel syndrome.”

Nine randomized controlled trials [6-14] have compared the effectiveness of orthoses with other conservative treatments for CTS. A brief description of the included studies is presented in Table 1.

Table 1 . Characteristics of included randomized controlled trials.

Study	Patients	Intervention	Outcome measures
Burton et al. 2023	N = 234, age = no information	Orthosis group: resting night splint set at a neutral angle (0–20 degrees) Injection group: one corticosteroid injection of 20 mg methylprednisolone acetate	BCTQ, NRS, EQ-5D-5L, healthcare utilization, patient incurred costs due to CTS, referral for CTS surgery, undergoing CTS surgery, employment status, work capacity
Chung et al. 2016	N = 181 (M:F = 23:158), age (mean ± sd) = 51 ± 9.48 years	Splinting only group: wearing the prefabricated wrist splint in a neutral position for 8 hours each evening Combination treatment group: - Electroacupuncture: needles inserted into 8 acupuncture points (TW-5, PC-7, HT-3, PC-3, SI-4, LI-5, LI-10 and LU-5) followed by electrical stimulation (10-20 mA, 20-40 Hz, continuous wave) - Prefabricated wrist splint: wearing in neutral position for 8 hours each evening	BCTQ, DASH Questionnaire, NRS, Semmes–Weinstein monofilament test, Dellon-modified pick-up test, maximal tip pinch strength
De Moraes et al. 2021	N = 100 (M:F = 17:83), age (mean) = 54.3 years	Orthosis group: forearm-palmar orthosis with the wrist immobilized in a neutral position while sleeping Injection group: 6.43 mg (1 ml) of betamethasone dipropionate, 2.63 mg of betamethasone disodium phosphate, and 0.5 ml of 2% lidocaine (xylocaine), totaling 1.5 ml	Remission of nocturnal paresthesia, Boston-Levine questionnaire, VAS, complications
Golriz et al. 2016	N = 24 (M:F = 4:20), age (mean ± sd) = 48.32 ± 12.85 years	Orthosis group 1: wrist splint in neutral position (0 degree) Orthosis group 2: neutral wrist splint with an extended trim line to control the metacarpophalangeal joints in 0-10 degrees of flexion	DASH Questionnaire, VAS, grip strength, key pinch
Lewis et al. 2020	N = 105 (M:F = 73:32), age (mean ± sd) = 49 ± 12 years	Experimental group: - Education: presentation and booklet regarding CTS pathophysiology, treatment options, posture and activity modification principles - Night splint: neutral wrist orthosis with a custom palmar stay - Home exercises: median nerve-gliding and tendon-gliding exercises Control group: no specific intervention	Global rating of change scale, participant satisfaction, BCTQ, DASH Questionnaire, self-report version of the Leeds Assessment of Neuropathic Symptoms and Signs scale, Patient-Specific Functional Scale, symptom distribution, complications
Sim et al. 2019	N = 41 patients with 56 wrists (M:F = 7:49), age (mean ± sd) = 52.43 ± 12.03 years	Splinting only group: a neutral wrist splint applied to the palm of the hand for more than 23 hours daily Combination treatment group: - Orthosis: a neutral wrist splint applied to the palm of the hand for more than 23 hours daily - Supervised exercises: median nerve-gliding and tendon-gliding exercises - Ultrasound therapy: set at a frequency of 1 MHz, intensity of 1.0 W/cm2 and pulsed mode of 1:4; each session consisted of 5 minutes of therapy for once a week	BCTQ
So et al. 2018	N = 50 (M:F = 7:43), age (mean ± sd) = 57.3 ± 9.34 years	Orthosis group: neutral wrist splint worn at night Injection group: 20 mg methylprednisolone acetate premixed with lidnocaine	BCTQ, patient satisfaction, nine-hole peg test, duration of sick leave of employed patients, use of analgesics, prognostic factors, complications
Wang et al. 2017	N = 52 (M:F = 11:41), age (mean ± sd) = 55.15 ± 9.23 years	Injection only group: a single ultrasound-guided carpal tunnel injection contained 1 ml of 10 mg (10 mg/ml) triamcinolone acetonide (Shincort) mixed with 1 ml of 2% lidocaine hydrochloride (xylocaine) Combination treatment group - Injection: ultrasound-guided carpal tunnel injection - Orthosis: wearing a customized volar thermoplastic wrist splint with the wrist immobilized in a neutral position while sleeping (and possibly during the day as well)	BCTQ, VAS, 6-point Likert scale, median nerve distal motor latency, sensory nerve conduction velocity, sensory nerve action potential amplitudes, compound muscle action potential
Willis et al. 2016	N = 50 (M:F = 10:40), age (mean ± sd) = 51.2 ± 12 years	Experimental group: dynasplint stretching for two 30-minute sessions each day Control group: stretching exercises, nonsteroidal anti-inflammatory medications, and instructions for reducing the potential movement causing the pain	Levine-Katz symptom survey, change in nerve conduction (sensory and motor latency)

M: male; F: female; BCTQ: Boston Carpal Tunnel Questionnaire; NRS: numeric rating scale; CTS: carpal tunnel syndrome; DASH Questionnaire: Disabilities of the Arm, Shoulder and Hand questionnaire;.

VAS: visual analog scale..

1. Orthosis for managing CTS

The basic function of an orthosis for managing CTS is to maintain the wrist in a neutral position to minimize pressure on the carpal tunnel [15]. It is important to keep the wrist in a neutral position, as the pressure in the carpal tunnel increases when the wrist is flexed or extended [16]. However, this posture can limit the wrist movement and cause discomfort during daily activities [15]. During sleep, the wrist is usually naturally flexed, increasing pressure on the carpal tunnel [8]. Therefore, orthoses for patients with CTS are typically prescribed during nighttime or sleep, but if requested or if symptoms worsen, they can also be prescribed during the day or during the patient’s active hours [15].

There are no clear guidelines on how long an orthosis should be worn to achieve optimal results [17]. However, recent research has shown that long-term use of orthoses may be less effective than expected. In a prospective cohort study by Gatheridge et al. in 2020 [17], the symptoms and functional severity of subjects who used a wrist splint to maintain the wrist in a neutral position for 6 and 12 weeks were compared. Symptom severity improved in both periods; however, functional severity improved significantly only in subjects who wore the splint for 6 weeks. This study suggests that wearing an orthosis for at least 6 weeks can result in significant clinical improvement, but extending it for another 6 weeks may not provide any additional benefits.

Various types of splints are commonly used to treat CTS and are classified according to their shape and materials. The types of orthoses used for managing CTS are differentiated based on their shape, including palmar splints that support the palm and underside of the forearm, dorsal splints that support the back of the hand and forearm, splints that only fix the wrist, and splints that fix the wrist and metacarpophalangeal (MCP) joints. In addition, their types can be divided based on the materials used, including rigid orthoses and soft orthoses, with rigid orthoses typically made of thermoplastic or metal and soft orthoses made of materials such as neoprene, spandex, and polyester.

2. Comparison of efficacy of orthosis and injection therapy

In 2018, So et al. [12] investigated the efficacy of night splint and steroid injections in 50 patients with CTS. Twenty-five patients received steroid injection therapy, whereas the other 25 received night splints. Using a sterile technique, 20 mg methylprednisolone acetate premixed with lidocaine was injected. A standard wrist-forearm polyethylene splint was used in this study, which immobilized the wrist in a neutral position and was recommended for use at night for 1 month. Therapeutic outcomes were evaluated at the end of the intervention, and symptom severity and functional status were measured using the Boston Carpal Tunnel Questionnaire (BCTQ). The patients were also asked whether they wanted to change their treatment method after the study period. The BCTQ scores showed a statistically significant improvement after treatment compared with before treatment in both the splint and injection groups; nonetheless, no significant difference was found between the two groups. Six of the total patients who received steroid injections wanted to receive splints after the intervention, whereas only three patients who were referred for splinting wished to receive injection therapy. This study demonstrates that both night splint and steroid injection therapies are effective in relieving CTS symptoms at 1 month, and that splint therapy can be a viable alternative for patients who do not want injections.

In 2021, de Moraes et al. [8] compared the effects of night splints and corticosteroid injections in 95 patients. Forty-five patients used a forearm-palmar splint to immobilize their wrists in a neutral position while sleeping, and 50 patients received corticosteroid injection therapy. Symptom severity and function were evaluated through follow-up assessments before intervention, 1 week, and 1-, 3-, and 6-month after initiating the intervention. The Boston-Levine questionnaire (BLQ) includes scales for symptom severity and functional status, and a visual analog scale (VAS) is used to evaluate pain. Additionally, the occurrence of nocturnal dysesthesia and its complications were assessed. During the entire follow-up period of 6 months after the intervention, both splinting and injection showed positive effectiveness in improving BLQ scores and reducing nocturnal sensory disturbances. However, at 1, 3, and 6 months after initiating the intervention, injection therapy was more effective than splinting. The VAS scores showed significant improvement for both treatment methods at 1 week and 1 month follow-up. However, at 6 months, greater pain reduction was observed among individuals when using the splint compared to those who received injection treatment. This study revealed that splints may be more effective than injection therapy for long-term pain relief.

In 2023, Burton et al. [6] randomly assigned night splints and corticosteroid injections to 334 patients with CTS and compared the effects of two treatments after 6 weeks of use. The wrist splint used was a prefabricated wrist splint (Beta Wrist Brace with CE markingl; Promedics Orthopaedic; Port Glasgow, UK) made of dual-compression rubber and featuring a detachable aluminum palm bar that kept the wrist in a neutral position with 0-20 degrees of extension. The results were assessed using the BCTQ, a scale for hand and wrist symptoms and dysfunction, and the numeric rating scale (NRS), a measure of pain severity. At 6 weeks and 6, 12, and 24 months of follow-up, both treatments improved the BCTQ and NRS scores compared to pretreatment. At 6 weeks after treatment, patients who received corticosteroid injections had significantly improved BCTQ and NRS scores compared to those who received treatment with an orthosis. However, at 6, 12, and 24 months of follow-up, there was no significant difference in symptom relief between the two treatments (P > 0.05). Therefore, this study suggests that the use of a wrist splint may be a good alternative to long-term invasive treatments for CTS.

3. Comparison of efficacy of two types of orthoses

In 2016, Golriz et al. [9] conducted a 6-week study of 24 patients with CTS to compare the effectiveness of a classic wrist splint and a wrist splint with an MCP unit. Both were thermoplastic palmar splints fixed with straps with the dorsal portion open. The classic wrist splint was designed to allow the free movement of all fingers, whereas the splint with the MCP unit was designed to support the MCP joints to maintain an extended position of the MCP joints. Patients were asked to wear splints during the day and night for 6 weeks. Pain, function, grip strength, and pinch strength were measured before and after wearing the splints to assess their effectiveness. Pain was measured using the VAS; function was evaluated using the Disability of the Arm, Shoulder, and Hand (DASH) questionnaire; and grip and pinch strength were measured using a dynamometer. Both splints significantly improved pain and function after 6 weeks of use; however, patients who used the splint with an MCP unit showed more significant improvements. Patients who used the splint with the MCP device had a 1.59-point greater reduction in VAS scores and an 8.91-point greater reduction in DASH scores than those who used the classic splint. The use of a splint with the MCP joint showed greater improvement in grip and pinch strengths compared to the use of classic splint. Therefore, immobilization of the hand and fingers by fixing the splint to the MCP joints is recommended to alleviate CTS symptoms.

4. Comparison of the efficacy of combination therapy with orthosis and other conservative treatment

In 2016, Chung et al. [7] investigated the effects of combining electrical acupuncture with a splint compared to using only a splint in the treatment of 181 patients with CTS. All the patients had chronic mild-to-moderate symptoms. Ninety patients underwent electrical acupuncture 13 times over 17 weeks and wore the splint continuously at night during the same period. Ninety-one patients wore splints at night for 17 weeks. The night splint was a modular splint (Medex Carpal Tunnel Splint W09), and the patients were instructed to wear it for 8 h each day. Pain and functional status were evaluated using the BCTQ, the degree of upper limb disability was assessed using the DASH questionnaire, pain intensity was measured using the NRS, finger sensation was evaluated using the Semmes-Weinstein monofilament test, dexterity was assessed using the Dellon-modified pick-up test, and maximum tip pinch strength was evaluated before and after treatment. After 17 weeks of treatment, only finger sensation showed significant improvement when only the night splint was used. However, when electrical acupuncture and a splint were used together, all measured variables showed significant improvement. This study demonstrated that combining electrical acupuncture with night splinting for the treatment of patients with chronic CTS has potential benefits.

In 2017, Wang et al. [13] compared the efficacy of steroid injection therapy alone and in combination with wrist splinting for CTS. Fifty-two patients with CTS participated in this study and underwent a 12-week intervention period. Improvements in the BCTQ and VAS scores were evaluated before the intervention and at 6 and 12 weeks after treatment initiation. All patients received one ultrasound-guided carpal tunnel injection at the beginning of treatment. Of these, 26 received a custom-made volar thermoplastic wrist splint that maintained the wrist in a neutral position. The splint was made by an occupational therapist, secured with Velcro, and did not limit finger movements. The patients were advised to wear splints while sleeping for 12 weeks or during the day, if possible. The outcome variables for all pain and function evaluated at 6 and 12 weeks after treatment were significantly improved in both the single injection and combined therapy groups. When comparing the two groups, there was greater clinical improvement in the combination therapy group; however, the difference was not statistically significant.

In 2019, Sim et al. [11] compared the effects of using a splint alone versus a splint combined with nerve and tendon gliding exercises and ultrasound therapy for the treatment of CTS. A customized volar splint made of thermoplastic material with an open dorsal area was fabricated by an occupational therapist and secured using Velcro and betapile straps. It was recommended that the splint be worn for 8 weeks, with only 1 h of removal allowed per day. Ultrasound therapy was performed once a week for 8 weeks, with each session lasting 5 min. Symptom severity and functional status scores measured using the BCTQ showed significant improvements for each intervention after 2 months. However, no significant differences were observed between the two interventions. Therefore, the combined therapeutic approach was not more effective than the use of a splint alone, making it inefficient in terms of time and cost. This study demonstrated that a splint alone can alleviate symptoms and improve hand function in patients with CTS.

In 2020, Lewis et al. [10] conducted a study to investigate how night splint, home exercises, and group education influence the decision to undergo surgery for CTS. The study included 49 subjects in the experimental group who received night splints, home exercises, and education and 51 subjects in the control group who received only standard care without a night splint. The splint used in this study was a customized wrist support device that placed the wrist in a neutral position and included a neoprene material with a custom thermoformable stay wrapped around the forearm, wrist, and medial palm. The subjects were instructed to wear the splint only at night. Education included information on CTS pathophysiology and treatment options, and home exercises included median nerve and tendon gliding exercises to reduce CTS symptoms and nerve swelling. The control group received surgical consultation provided by the hospital while on the surgical waiting list and did not receive the intervention received by the experimental group. The intervention lasted for 6 months, and at the 24th week, the decision to convert to surgery, satisfaction with CTS symptoms, and hand function improvement were evaluated. After the intervention, 29 of 49 subjects (59%) in the experimental group and 41 of 51 subjects (80%) in the control group underwent surgery. The satisfaction scores were 44 out of 70 in the experimental group and 33 in the control group; both the decision to convert to surgery and satisfaction showed significant differences between the two groups. Therefore, a combination of night splints, home exercises, and education can increase patient confidence in managing CTS symptoms and improve clinical outcomes related to symptom relief and hand function. Additionally, this approach may be considered a more cost-effective treatment option than surgical treatment.

5. Assessment of the impact of orthosis application on conversion to surgery

In 2016, Willis et al. [14] investigated the impact of dynasplint stretching (Dynasplint Systems, Inc., Severna Park, Maryland) on the decision to undergo surgery for CTS in patients scheduled for surgical treatment. They randomized 50 patients into an experimental group, which underwent dynasplint stretching for 60 days, and a control group, which received nonsteroidal anti-inflammatory drugs and home stretching exercises. The experimental group was advised to wear a customized splint twice daily for 15 minutes, gradually increasing the tension on the splint. The splint was designed to fit the length, width, and circumference of the patient’s hand and to stretch the transverse carpal ligament at a low intensity. Twelve months after the completion of the study, 72% (18 of 25) of the experimental group did not choose to undergo surgery, while 38% (9 of 25) of the control group avoided surgery. These results suggest that dynasplint stretching reduces the likelihood of surgery by approximately 50%, leading to cost savings in surgical treatment.

This study reviewed nine randomized controlled trials investigating the effects of orthoses on CTS published in the past 7 years. Among the nine studies [6-14] included in the review, three [6,8,12] compared the efficacy of injection therapy and splints and one [9] investigated the efficacy of two different types of splints. In addition, two studies [7,11] compared the effects of splints with and without other conservative therapies, and one [13] compared the effects of injection therapy alone with those of combined injection and splinting. The remaining two studies [10,14] investigated the impact of splint use on the decision to undergo surgical treatment.

Steroid injection therapy is primarily used in many clinical settings for managing CTS [18]. However, repeated steroid injections for CTS management carry the risk of accidental injection into the median nerve or flexor tendon, which can potentially cause nerve and tendon damages [13]. This review confirmed that orthoses show similar effects on pain relief and functional improvement as steroid injection therapy. The results of previous studies suggest that using orthoses for CTS treatment can reduce the psychological burden of invasive treatment on patients and alleviate some of the time and financial pressures associated with hospital visits. Orthoses can serve as efficient alternatives to injection therapy. In addition, combining ultrasound therapy or electrical acupuncture with orthosis did not result in significant clinical improvement in function or pain compared with orthosis alone. This indicates that using orthoses alone to manage CTS symptoms can provide sufficient clinical improvement. Moreover, experiencing orthosis before surgery can reduce the likelihood of surgery by approximately 50% [10,14]. Therefore, using orthoses for managing CTS has the potential to provide financial benefits over surgery, making it a potentially beneficial option in terms of cost.

The types of orthoses used in each study were as follows. One study [14] used a transverse carpal ligament stretching brace worn twice a day for 15 minutes per session, while the remaining eight studies [6-13] applied night splints. Among the studies that applied night splints, three [9,11,13] recommended wearing splints during the day as well. The most commonly used splint type was a volar splint that supported only the volar aspects of the forearm and hand or a soft orthosis that wrapped around the entire volar and palmar aspects of the forearm and hand. Neoprene is commonly used for soft orthoses and thermoplastics for rigid orthoses. The choice between rigid and soft orthoses depends on the patient’s preference and therapist’s experience [15]. When manufacturing a rigid orthosis, making perforations for breathability can increase the patient’s satisfaction with the orthosis [19].

This review examined the effectiveness of orthoses for treating CTS, a common upper extremity disorder. Orthoses may be an appropriate treatment method for relieving pain and improving hand function in patients with CTS. Using orthoses as a treatment option for CTS can reduce the psychological burden of invasive treatment in patients, as well as the time and financial pressures associated with hospital visits. However, as only a small number of randomized controlled trials were reviewed in this study, more studies should be reviewed in the future. In addition, guidelines should be developed for clinicians to prescribe appropriate orthodontic wear time and materials for patients with CTS.

This study received no external funding.

No potential conflict of interest relevant to this article was reported.