This study endeavored to evaluate the auxiliary effect of low-energy laser therapy (LLT) on pain, muscle performance, fatigue, and functional ability in children with juvenile idiopathic arthritis (JIA). Sixty patients with JIA were randomly allocated to the LLT group (n = 30, received LLT in addition to the standard exercise program) or the control group (n = 30, received standard exercise program only). Both groups were assessed for pain intensity, muscle performance, fatigue perception, and functional status.

Sixty patients with JIA were recruited from the Physical Therapy Outpatient Clinic of College of Applied Medical Sciences, Prince Sattam bin Abdulaziz University, and the Pediatric Rheumatology Clinic, King Khalid Hospital, Al-Kharj, Saudi Arabia. The study included patients who had a confirmed diagnosis of Polyarticular JIA (according to the criteria set forth by the International League of Associations for Rheumatology), aged 8-16 years, identified being stable cases, and did not participate in a regular exercise program (in the past six months). Patients who had fixed deformities, a history of joint surgery, or whose radiological investigations revealed erosive changes of bone, ankylosing, or fractures were excluded.

Outcome measures

1. Pain intensity: measures through the Visual Analogue Scale
2. Muscle performance: represented by the peak concentric torque of the right and left quadriceps muscle and measured through an Isokinetic Dynamometer.
3. Fatigue perception: tested by the Pediatric Quality of Life Inventory Multidimensional Fatigue Scale (PedsQL-MFS)
4. Functional status: the functional status was quantified using the cross-cultural validated version of the Childhood Health Assessment Questionnaire (CHAQ).

Patients in the control and LLT group received a 40-minute exercise program, three times a week, for three months in succession. Patients in the LLT group additionally underwent an articular application of LLT on the knee joint, each session before exercises (eight points on each knee, 30 seconds irradiation for each point, with a total irradiation dose of eight minutes per session. The treatment was conducted by two experienced pediatric physical therapists.

Inclusion Criteria:

• Confirmed diagnosis of JIA
• Polyarticular onset of JIA with bilateral involvement of the knee joint
• Age between 8 and 16 years
• Stable conditions (i.e., receive stable doses of medications in the past three months)
• Not participating in a regular exercise program in the past six months

Exclusion Criteria:

• Fixed deformities
• History of joint surgery
• Ankylosing or fractures
• Bone destruction (erosive changes of the knee joint)

This was a single-blind protocol. The researcher who collected the data was blind to the allocation of treatment