Multicenter Trial of Magnetic Mini-Mover for Pectus Excavatum (3MP)

This study is a Phase 3, multicenter, non-randomized study to evaluate the safety and efficacy of the next-generation outpatient Magnetic Mini-Mover Procedure (3MP) in 15 patients aged 8-14 years for the correction of pectus excavatum ('sunken chest'). 3MP for pectus excavatum uses a magnetically coupled implant to pull the sternum forward and gradually remodel the deformed costal cartilage. The Funding Source for this trial is the FDA Office of Orphan Products Development (Grant #R01 FD003341).

Pectus excavatum is the most common congenital chest wall abnormality in children. The investigators have developed a novel method of achieving gradual deformation/reformation of chest wall cartilage. A magnetic force field is used to apply controlled, sustained force to promote biologic reformation of structural cartilage. A magnet is implanted on the sternum and secured through a 2-inch subxiphoid incision as a one-hour outpatient procedure. The magnet (and sternum) is pulled outward by another magnet suspended in a novel, low-profile, lightweight device previously molded to the patient's anterior chest wall. The low-profile, non-obtrusive anterior chest wall prosthesis is held in place by the force field between the two magnets. In the single-center, FDA-funded trial (IDE G050196), the investigators tested proof of concept, safety and probable benefit of this procedure in 10. In this Phase III multicenter trial, the investigators will further test the safety and efficacy of the procedure in 15 otherwise healthy patients with moderate-to-severe PE, ages 8 to 14. The investigators will be using the next generation Magnetic Mini-Mover Magnimplant device (IDE G090006), a design the investigators believe is much improved in terms of safety and ease of implantation/explantation. Implantation of the Magnimplant will be accomplished in an outpatient procedure. The investigators will document the rate of correction by comparing chest X-ray measurement of the Pectus Severity Index prior to implantation, to that measured after the magnet is removed. Treatment will last 18-24 months, depending on correction and when the patient has completed his or her pubertal growth spurt, as documented by hand x-ray. Explant of the device will be accomplished in an outpatient procedure. The investigators will document safety with an EKG prior to implantation, one month post-implantation, and finally after the magnet is removed. The investigators will document efficacy by comparing pre- and post-treatment PSI, as well as by evaluating patient satisfaction with a post-procedure Quality of Life-type survey. Long-term follow-up will occur at 6, 12, 18, and 24 months after explantation.

Pectus excavatum, Chest wall deformity, Magnetic Mini-Mover Procedure, Pectus Severity Index, pediatric medical device, magnetic alteration, sunken chest

This is a non-randomized study in which otherwise healthy patients, ages 8-14, with severe pectus excavatum (PSI > 3.5) will undergo the interventional treatment arm by having outpatient surgery and the Magnetic MIni-Mover Magnimplant procedure is performed during which the magnetic implant is surgically placed. After 2 years of treatment with the implanted magnet and brace treatment, the Magnetic Mini-Mover Magnimplant will be explanted. After surgery and recovery, all subjects will be fitted for an orthotic brace, which houses the external magnet and records brace-wear compliance. They will undergo 3MP treatment for 18-24 months, enough to attempt to improve their PSI (< 3.25).

This is a non-randomized study in which otherwise healthy patients, ages 8-14, with severe pectus excavatum (PSI > 3.5) will undergo the Magnetic Mini-Mover procedure outpatient surgery. The Magnimplant or Magnetic Mini-Mover device implant will surgically implanted on the sternum. Patients will be required to wear a custom-fitted orthotic brace, which houses the external magnet and records brace-wear compliance. They will undergo brace treatment for 18-24 months, enough to attempt to improve their PSI (< 3.25). Patients will be seen in clinic at least monthly until treatment is complete and the magnimplant device will be explanted from their sternum.

All adverse reactions were recorded and reported, including complications from implantation of the device, complications from application of the external device over time (e.g., changes in skin; infection; changes in cardiac electrical function).

Comfort of the external brace directly affects compliance (i.e., bracewear) and compliance were be measured throughout treatment. In addition, the satisfaction of the patient and family will be measured using a standard Quality of Life (QOL) questionnaire administered 1 month after implanting the device and 1 month after removing the device.

Though not powered to determine efficacy, preliminary efficacy data, as measured by pre and post treatment Pectus Severity Index (Haller Index), was also collected. Pre-treatment Haller Index was assessed based on computed tomography (CT) of the chest. One month after implant removal, patients underwent repeat chest CT to evaluate chest wall correction.

. Patients were asked to fill out questionnaire at 2 intervals: 1 month after explant and 1 year after explant

Inclusion Criteria: Otherwise healthy male or female with pectus excavatum deformity Between 8 and 14 years of age (inclusive) Pectus Severity Index > 3.5 (normal 2.56). NOTE: A pectus severity index of 3.5 or greater qualifies as a moderate-to-severe deformity, and justifies operative intervention Ability to read, speak and understand English Onset of rapid growth of puberty documented by hand/wrist x-ray in early to mid-puberty (defined as bone age in females of 7-13 years, and males of 9-14 years) Exclusion Criteria: Other congenital anomalies (including significant skeletal anomalies such as scoliosis, bony fusion involving the cervical vertebrae) not directly related to pectus excavatum Bleeding disorders Heart disease (including arrhythmia) Persons with active implantable medical devices (AIMD) such as pacemakers Persons with a relative(s) or close family friend(s) living within their households and having a pacemaker Persons with arteriovenous malformations Chest deformity more complicated than pectus excavatum (e.g., Poland syndrome) Persons for whom a foreign body implant would pose a risk (e.g., immunodeficiency) Persons at increased risk for general anesthesia (e.g., history of malignant hyperthermia) Respiratory conditions that have required steroid treatment (e.g., prednisone) in the last 3 years Pregnancy Inability to understand or follow instructions Refusal to wear the external brace Refusal to undergo monthly chest x-rays Inability or refusal to return to UCSF for biweekly follow-up visits for the first month after surgery, and monthly thereafter until explant. Inability to obtain pre-approval (authorization) from the patient's insurance carrier

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Harrison MR, Estefan-Ventura D, Fechter R, Moran AM Jr, Christensen D. Magnetic Mini-Mover Procedure for pectus excavatum: I. Development, design, and simulations for feasibility and safety. J Pediatr Surg. 2007 Jan;42(1):81-5; discussion 85-6. doi: 10.1016/j.jpedsurg.2006.09.042.

Harrison MR, Gonzales KD, Bratton BJ, Christensen D, Curran PF, Fechter R, Hirose S. Magnetic mini-mover procedure for pectus excavatum III: safety and efficacy in a Food and Drug Administration-sponsored clinical trial. J Pediatr Surg. 2012 Jan;47(1):154-9. doi: 10.1016/j.jpedsurg.2011.10.039.