Adolescent idiopathic scoliosis (AIS) is a common disorder of unknown etiology in which the vertebrae and discs gradually develop a curvature that is first detected in patients between 11 and 20 years of age. The deformity is 3-dimensional, with a coronal curve measured from radiographs by the Cobb angle .

The Cobb angle measurement of scoliosis represents the sum of the angular wedging of each vertebra and disc between the superior and inferior end vertebrae . Although a small curve is well tolerated and does not require treatment, a large curve can progress to the point that it is cosmetically unacceptable, interferes with chest wall mechanics, and produces cardiac and pulmonary compromises. The natural history of AIS apparently includes 2 stages: the initiation of the curve and its subsequent progression. The factors responsible for the initiation of the curve are unknown, but the subsequent progression of the curve is clearly associated with the adolescent growth spurt . The primary risk factors for progression include age at onset and the magnitude of the curve; young patients with large curves are at the highest risk .

Although numerous treatment methods have been recommended for patients with AIS, the only accepted treatment includes bracing for skeletally immature patients with curves between 25 and 40 degrees and operative correction with spinal fusion for patients with curves greater than 45 degrees. For many teenagers, the cosmetic and social concerns associated with bracing has caused compliance problems with wearing the brace and many patients only wear the brace at home . While operative intervention completely corrects the scoliosis or rib hump, it eliminates segmental spinal motion, and concentrates stresses at the ends of the fusion potentially leading to disc degeneration and back pain.

Despite satisfactory short-term results of operative instrumentation and fusion, a less invasive technique preserving more motion with a smaller scar represents a major improvement. Realizing this goal is contingent on treating curves early, before they progress to an irreversible deformity, and when there is still enough residual growth and remodeling potential.

ApiFix Ltd has developed a novel implant for less invasive treatment of AIS. The MID-C system is designed to correct the deformity step by step along a period of time, giving the skeletal and soft tissues time to accommodate any incremental correction.

The MID-C System inherent benefits are:

• Only two screws are used
• Incision size is much smaller
• Simpler operation with shorter operative time
• Less complications (attributed to the three points above).
• Minimal spinal mobility loss.

All the device components are made of materials well accepted in the orthopedic field and are fully biocompatible (see Investigator Brochure).

The unique concept of the system and the materials used may provide favorable results as follows: Smaller scare, quicker healing period and better spine mobility over the years.

This study is designed to demonstrate that the MID-C System is safe and effective.

The study is designed as an observational study with a 24-month follow-up period. Consecutive patients undergoing treatment of AIS by the MID-C system in daily practice will be included during a 24-month enrollment period.

Inclusion Criteria:

1. Adolescence aged 11 years old to 17 years inclusive
2. Minimum of 35 degrees Cobb angle, confirmed by X-ray. Lenke type 1 or 5, with flexible secondary curve.
3. Completed at least 6 months of conservative therapy (e.g., P.T., bracing, traction, or others).
4. Risser sign of 1 to 4
5. Appropriate candidate for posterior surgical approach
6. Subject has Good general health.
7. Subject has no hypersensitivity and allergies to Titanium
8. Subject guardians willing to sign a written informed consent form (ICF).

Exclusion Criteria:

1. Cobb angle over 55 degrees
2. Other non idiopathic scoliosis.
3. AIS which is not defined as Lenke type 1 or 5
4. Previous spine surgery.
5. Allergy to any component of the device.
6. Active systemic disease, such as AIDS, HIV, or active infection
7. Back or leg pain of unknown etiology Page 9 of 18
8. Systemic disease that would affect the subject's welfare or overall outcome of the study.
9. Mentally compromised

The study is designed as a European, observational study with a 12-month follow-up period. Consecutive patients undergoing treatment of AIS by the MID-C system in daily practice will be included during a 6-month enrollment period.