A Randomized Intra-Patient Controlled Trial of MagnetOs™ Putty vs Autograft in Instrumented Posterolateral Spinal Fusion in Idiopathic Scoliosis Patients

SUMMARY Rationale: Delayed union is a problem in adolescent idiopathic scoliosis (AIS) surgery, especially at the distal end of the construct. Surgeons therefore use local autograft or bone graft substitutes to prevent loss of correction and/or anchor failure and additionally restrict patients' activities during the first year. The concept of this study was developed after the promising results of the MaxA study (METC 18-311), where we compared the efficacy of BCP\<μm ceramic granules (MagnetOs™ Granules) to autograft in posterolateral fusion (PLF). This randomized intra-patient-controlled trial indicated superior spinal fusion rates for the BCP\<μm condition. The current investigational product (MagnetOs™ Putty) is made of the same MagnetOs™ Granules embedded in a fast-resorbing polymeric binder to improve surgical handling. If MagnetOs™ Putty allows better and faster fusion in scoliosis patients, it is possible to mobilize them faster and even abandon post-operative activity restrictions. Objective: The primary objective is to demonstrate superiority and safety of MagnetOs™ Putty compared to autograft regarding the posterolateral spinal fusion rate, in instrumented PLF in AIS patients. The secondary objectives encompass comparisons of posterolateral spinal fusion rates on different levels at various points in time, monitoring the changes in trunk rotation, evaluating quality of life and patient's experiences as well as improving the reliability of Hounsfield unit measurements. Study design: Multicenter, randomized, controlled superiority trial with intra-patient comparisons over a 1-year follow-up. Study population: 140 patients between 12 to 30 years with AIS qualified for scoliosis surgery with lowest instrumented vertebrae T12-L4. Intervention: According to a randomization scheme, one side of the caudal PLF will be grafted with the MagnetOs™ Putty and the other side with local bone. The rest of the surgical procedure will be according to standard care. Mai