Purpose of This study to detect if there is correlation between the Cobb's angle and the forward head posture in patients with Adolescent Idiopathic Scoliosis.

And if there is correlation between the Cobb's angle and the cervical sagittal curve angle in AIS. And also if there is correlation between the Cobb's angle and deep flexors muscles endurance in AIS

The prevalence of sagittal profile imbalance in adolescent idiopathic scoliosis is not known exactly as little research is available in this context (Nasser et al., 2023) Thought based on previous studies that a forward head corrective exercise program combined with conventional rehabilitation improved three-dimensional scoliotic posture and functional status in patients with adolescent idiopathic scoliosis. (Alia Diab et al., 2012) Up to our knowledge there is no significant evidence that there is correlation between Craniovertebral angle (CVA) and idiopathic scoliosis by Cobb's angle.

So we need to make a simple assessment method of the severity of scoliosis and its impact on head position through a simpler method by observing the cervical curvature through photos for CVA, This can help to avoid unnecessary radiological examination. In addition, it also may help in paying the attention to the correction of cervical spines, head position and cervical muscles endurance during conservative treatment of scoliosis.

Also studying cervical sagittal alignment deformities will help in surgical operations to maintain or restore sagittal physiological curvature side by side with correction of coronal scoliosis angle in order to prevent adjacent segment degeneration after the fusion operation.

Inclusion Criteria:

• 1- Patients with AIS. 2- Patient with forward head posture CVA less than 48 degress. (Fard et al .,2021) 3- Patients aged between 10 and 18 years, (Upasani et al., 2007). 4- Patients who underwent Posterioanterior (PA) and lateral X-ray radiography, and Cobb angle >10°.(Nasser et al.,2023) 5- Patients with Lenke types (1 to 6). 6- No previous spine surgery ((Wang, et al., 2017).

Exclusion Criteria:

• 1- Patients with congenital scoliosis (including hemivertebrae, butterfly vertebrae, and failure of segmentation), (Shu-Man Han et al., 2022 and Nasser et al., 2023).

  2- Other developmental thoracic deformity (funnel chest etc.). 3- Scoliosis with definitive reasons (secondary to neurofibromatosis, Marfan syndrome, and syringomyelia).

  4- Patients with neurologic deficit or spondylolisthesis (Upasani et al., 2007).

  5- History of spinal trauma and infection, and metabolic bone disease.

Thirty four Male and female subjects with adolescent idiopathic scoliosis participating in this study will be assigned homogenously some of them with Cobb's angle below 45 degrees and others above 45 degrees (n=34) and they will sign a consent form.