Low-Level Laser Therapy in the Treatment of Trigger Finger

Trigger finger develops as a result of a size mismatch between the flexor tendon or tendon sheath and the first annular (A1) pulley at the level of the metacarpal head. Although the A1 pulley is the most commonly affected site, triggering may also occur at the second and third annular pulleys (A2 and A3). The diagnosis of trigger finger is made clinically. Musculoskeletal ultrasonography is an adjunctive imaging modality that is increasingly used in the diagnosis of trigger finger. The ultrasonographic findings of trigger finger may include diffuse or nodular hypoechoic thickening of the A1 pulley and increased flexor tendon thickness.

Low-level laser therapy (LLLT) has been shown to be an effective, noninvasive treatment modality for pain reduction in various musculoskeletal disorders. Studies have investigated its effectiveness in the treatment of de Quervain's tenosynovitis, flexor tendon injuries, carpal tunnel syndrome, lateral epicondylitis, plantar fasciitis, and adhesive capsulitis. However, evidence evaluating the effectiveness of LLLT for the treatment of trigger finger remains limited. The literature includes a small, non-randomized, uncontrolled clinical study involving five patients. In addition, a case report described the application of a combination of LLLT, specific hand massage, and hand exercises in a patient with chronic trigger fingers and bilateral carpal tunnel syndrome. Although these studies reported favorable outcomes, high-quality evidence remains limited. To the best of our knowledge, no randomized controlled trials evaluating the use of LLLT for the treatment of trigger finger have been reported in the literature.

This study is a prospective, randomized, double-blind, sham-controlled clinical trial designed to investigate the effects of LLLT on clinical and ultrasonographic outcomes in patients with trigger finger. Adults with a clinical diagnosis of trigger finger who meet the eligibility criteria and provide written informed consent will be enrolled. Following randomization, participants will be assigned to either the active LLLT group or the sham LLLT group. Both groups will receive the same splint treatment during the intervention period. LLLT will be administered three times per week for 4 weeks, for a total of 12 treatment sessions, using a wavelength of 830 nm, an output power of 50 mW, continuous mode, and an energy density of 4 J/cm². Participants in the sham group will undergo the same treatment schedule, with the laser device remaining switched off throughout each session. To maintain participant blinding, participants in both groups will wear headphones and an eye mask during each treatment session. All participants will be provided with a metacarpophalangeal (MCP) joint blocking splint. The splint will block the MCP joint of the affected finger at 0° while allowing unrestricted movement of the interphalangeal joints. Participants will be instructed to wear the splint continuously for 4 weeks and to remove it only for personal hygiene. Compliance with splint use will be monitored using a daily diary in which participants will record the number of hours they wear the splint each day. The average daily wearing time will be calculated at the end of the treatment period. Participants will be allowed to continue their usual daily and work-related activities while avoiding movements that aggravate triggering symptoms or excessive use of the affected hand. Paracetamol will be permitted as rescue medication if needed, and its use will be recorded throughout the study.

Before treatment, demographic and clinical information, including age, sex, body mass index, affected hand, affected finger, symptom duration, and previous history of trigger finger, will be documented. Outcome measures will include pain intensity assessed with the Visual Analog Scale (VAS), triggering severity assessed with the Quinnell Classification, triggering frequency determined by the number of triggering events during 10 consecutive active full-fist movements, the Trigger Finger Assessment Scale (TFAS), the Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) questionnaire, hand grip strength, patient satisfaction, and ultrasonographic measurements of A1 pulley thickness and flexor tendon thickness. Ultrasonographic assessments will be performed by a single experienced investigator, who will be blinded to treatment allocation. All clinical outcome assessments will also be conducted by an investigator blinded to treatment allocation.

Inclusion criteria

• Applying to the outpatient clinic of the Department of Physical Medicine and Rehabilitation, Faculty of Medicine, Dokuz Eylül University
• A clinical diagnosis of trigger finger based on typical pain and tenderness over the A1 pulley accompanied by triggering of the affected finger
• Willingness to participate in the study

Exclusion criteria

• Multiple trigger fingers in the same hand
• Fixed deformity (Quinnell grade 4)
• Splint treatment, physical therapy, or steroid injection for the affected trigger finger within the previous 6 months
• Previous surgery for the affected trigger finger
• Musculoskeletal disorders or peripheral nerve injury involving the ipsilateral upper extremity
• Rheumatoid arthritis, carpal tunnel syndrome, Dupuytren disease, amyloidosis, or mucopolysaccharidosis
• Active infection, bleeding, skin lesions, or an implant at the treatment site
• Radiotherapy within the previous 6 months
• Photodermatosis, photosensitivity, or systemic lupus erythematosus
• Pregnancy, epilepsy, coagulopathy, active malignancy, or the presence of a cardiac pacemaker
• Cognitive impairment that precludes understanding of the study questionnaires.