Due to the termination of the collaboration of ApiFix ltd. and the UMC Utrecht

The primary aim of this study is to investigate the limited efficacy of these innovative surgical solutions in treatment of Early Onset Scoliosis (EOS) in terms of maintaining reduction while maintaining spinal growth. The secondary aim is to compare both devices for these and other parameters as well as safety.

Rationale: EOS is a severe and potentially life-threatening disorder since a disturbance of spinal development leads to impaired development of the trunk, with cardio-respiratory failure as a result, often early in adult life. Several innovative solutions have been developed to treat growing children with severe EOS. The SDS device was developed internally at the dpt. of orthopedics at the UMC Utrecht, the Netherlands, the MID-C device was developed by the company ApiFix Ltd.

Objective: The primary aim of this study is to investigate the limited efficacy of these innovative surgical solutions in treatment of early onset scoliosis in terms of maintaining reduction while maintaining spinal growth. The secondary aim is to compare both devices for these and other parameters as well as safety.

Study design: A feasibility study using two prospective cohorts according to an open label randomized clinical trial (RCT) design. The study will be done in two tertiary referral centers (UMC Utrecht and Amsterdam UMC). Primary endpoints are maintenance of curve correction as well as complications. These data will be compared to a recently described cohort of patients that received a "standard treatment" (Magnetically controlled growing rod (MCGR)). The same endpoints as well as secondary outcomes, will be compared between the two new treatments.

Study population: Children with idiopathic(-like) early onset scoliosis with an indication for a growing rod implant.

Inclusion Criteria:

• Ambulant skeletally immature children, 6-12 yrs. of age, with open triradiate cartilages on X-ray
• Scoliosis diagnosis prior to the age 10
• Diagnosis of idiopathic or mild syndromic scoliosis (e.g. 22q11DS, Trisomy 21 or 9, Coffin-Siris)
• Progressive scoliosis qualified for growth system surgery
• One curve for treatment with an apex below Th5 and a proximal end vertebra below Th2
• The primary curve must be between 35 and 75 degrees coronal Cobb angle
• The primary curve must be non-rigid (i.e. the curve reduces on bending X-rays to <35 degrees or reduces >30% )
• Normal or hypokyphotic sagittal alignment (Th5 -Th12 < 50 degrees) on lateral X-rays

Exclusion Criteria:

• Patients with an obvious neuromuscular disease
• Patients that are severely mentally retarded
• Patients with a scoliosis that extends to the pelvis or the cervicothoracic region
• Patients with a main curve of more than 8 vertebra Cobb to Cobb
• Patients with a skeletal dysplasia that effects growth (e.g. achondroplasia, SED)
• Patients with a systemic disease which severely influences bone quality (e.g. osteogenesis imperfecta, metabolic diseases)
• Patients with soft tissue weakness (e.g. Ehler Danlos, Marfan, Neurofibromatosis, Prader Willi)
• Patients with an active systemic disease such as Juvenile Idiopathic Arthritis, HIV or oncologic treatment
• Patients with a previous surgical fusion of the spine

Participants are blinded to the medical device till the surgery. After the surgery participants are able to see which medical device is implanted on X-rays.