To investigate the effect of cervical manual mobilization on head repositioning accuracy and postural balance in patients with chronic mechanical neck pain in a randomized controlled trial. Hypothesis: There is no difference between the intervention group (manual mobilization) and control group head repositioning accuracy and postural balance.

The aim of the study is to investigate the effectiveness of manual therapy to standing balance and head-neck proprioception sense in patients with chronic neck pain. The study will recruit 120 chronic neck pain patients and randomize the into 2 groups of 60. Group 1 will receive a course of manual therapy and infrared radiation for 15 minutes (twice weekly for 12 sessions). The other group (control) will receive infrared radiation therapy only. Manual therapy will be provided by experienced physiotherapists and assessed by a separate assessor. All outcome measures will be assessed at the beginning of study, upon completion of intervention, 3-month and 6-month after the completion of study. All measurements collected will be analysed by computerized statistical software in order to calculate the effectiveness of manual therapy and relationship among those outcome measurements.

Inclusion Criteria:

• Aged 18 to 65 years
• Presented with a complaint of neck pain (defined as pain in the region from the upper thoracic spine to the occiput and the surrounding musculature) for more than 7 weeks.
• Had not received neck pain treatment in the past 1 month

Exclusion Criteria:

• Onset of presenting neck pain episode after trauma (eg, whiplash)
• History of cervical injury of trauma since the onset of presenting neck pain episode
• History of cervical injury or trauma
• Neck pain due to fracture, tumor, infection, severe spondyloarthropathy, or other non-mechanical cause such as inflammatory arthritis;
• Progressive neurological deficit, myelopathy, herniated nucleus pulpous, or severe incapacitating pain;
• Being treated by electrical devices;
• Blood coagulation disorder or were using corticosteroids or anticoagulant medications;
• History of stroke or transient ischemic attacks;
• Vertebrobasilar artery insufficiency;
• Neurologic disease (eg, multiple sclerosis, Parkinson's disease, syringomyelia);
• Congenital anomalies involving the C-spine;
• Systemic disease (eg, diabetes mellitus);
• Pain involving third-party liability or Workers' Compensation.