Magnetic Mini-Mover Procedure to Treat Pectus Excavatum

Pectus excavatum is the most common congenital chest wall abnormality in children. Surgical correction requires a big operation under general anesthesia which forces the sternum forward and holds it in place using a metal chest wall strut. Deformation of the chest wall under great pressure may result in complications and potential relapses as well as postoperative pain requiring hospitalization for regional and narcotic anesthesia for up to a week. An alternative principle for correction of chest wall and other deformities is gradual (bit-by-bit) correction using minimal force applied over many months (like moving teeth with orthodontic braces).

The hypothesis of this study is that constant outward force on the deformed cartilage in pectus excavatum will produce biologic reformation of cartilage and correction of the chest wall deformity.

The study investigators have developed a novel method of achieving gradual deformation/reformation of chest wall cartilage without the need for transdermal orthopedic devices or repeated surgeries. A magnetic force field is used to apply controlled, sustained force to promote biologic reformation of structural cartilage (the same principle as distraction osteogenesis). A magnet is implanted on the sternum and secured using a novel fixation strategy that can be accomplished through a 3-cm subxyphoid incision as a brief 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 external magnet allows individual adjustment in small increments of the distance (and, thus, force) and orientation of the force applied to the sternum. The low-profile, non-obtrusive anterior chest wall prosthesis is held in place by the force field between the two magnets.

The study objectives are to test the safety and probable benefit of this procedure in 10 otherwise healthy, young patients, between 8 years and 14 years of age, who have chosen to have this deformity corrected using this novel technique rather than the standard Ravitch or Nuss techniques. We will document the rate of correction by chest imaging and measurement of the Pectus Severity Index. The study investigators will document safety and efficacy with an EKG prior to implantation, one month post-implantation, and finally after the magnet is removed, as well as patient and family satisfaction with a post-procedure Quality of Life-type survey.

Residents of the United States with previously diagnosed pectus excavatum who are referred to the UCSF Pediatric Surgery Service for evaluation and treatment will be considered for participation in this study. Only patients with moderate to severe pectus excavatum who meet all the inclusion criteria will participate. The patient and family will be fully counseled and consented about the risks and benefits of participation in the study, and will be asked to sign an informed consent reviewed and approved by the UCSF Committee on Human Research.

Inclusion criteria

• Resident of the U.S.;
• Otherwise healthy male or female with pectus excavatum deformity;
• Between 8 and 14 years of age;
• Pectus Severity Index > 3.5 (normal 2.56); and
• Ability to read and speak English.

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;
• Inability to obtain pre-approval (authorization) from the patient's insurance carrier; and
• Inability or refusal to return to UCSF for weekly follow-up visits for the first month after surgery.