This randomized controlled trial is designed to evaluate the effects of scapular repositioning in individuals with neck pain and scapular dysfunction. The main questions it aims to answer are:

1. Does scapular repositioning reduce neck pain, increase range of motion, and improve joint position sense and pressure pain threshold?
2. Which type of scapular repositioning technique is more effective?

Participants will be randomly assigned to one of three groups:

1. Active scapular repositioning: The examiner will first passively position the scapula in a neutral position on the posterior chest wall. The participant will then be instructed to actively maintain that position for 10 seconds. This procedure will be repeated for 10 repetitions, with a 10-second rest interval between each repetition.
2. Passive scapular repositioning: The examiner will passively position and hold the scapula in a neutral position for 10 seconds. This procedure will be repeated for 10 repetitions, with a 10-second rest interval between each repetition.
3. Sham scapular repositioning (control): The examiner will perform gentle shoulder movements that do not alter scapular positioning. Each movement will be held for 10 seconds, repeated 10 times, with a 10-second rest interval between repetitions.

All participants will undergo pre- and post-intervention assessments (immediately after the intervention and at 30 minutes post-intervention). The primary outcomes include neck pain intensity, cervical range of motion, cervical and shoulder proprioception, and pressure pain threshold. All outcomes will be compared between groups and across time points (pre- and post-intervention).

Inclusion Criteria:

• Chronic idiopathic neck pain for ≥3 months
• An average pain intensity over the past week ≥3 mm on a Visual Analogue Scale (VAS)
• A current score of at least 10/100 on the Neck Disability Index-Thai version
• Having altered scapular alignment ipsilateral to the more painful side of neck pain

Exclusion Criteria:

• History of neck injury or surgery
• History of shoulder girdle pain, fracture, surgery or dislocation
• History of neurological conditions (e.g. stroke, Parkinson's disease, brachial plexus injury)
• History of marked spinal abnormalities (e.g. kyphosis, scoliosis) and other musculoskeletal conditions that could affect the scapular movement (e.g. myofascial pain syndrome, fibromyalgia, inflammatory joint disease, and/or autoimmune diseases)
• Have participated in any specific training of the neck or shoulder girdle muscles in the last 6 months