Purpose: The Magnetic Mini-Mover Procedure (3MP) uses a magnetic implant coupled with an external magnet to generate force sufficient to gradually remodel pectus excavatum deformities. This is an interim report of the evolution of the 3MP during a Food and Drug Administration-approved clinical trial.
Methods: After obtaining Institutional Review Board approval, we performed the 3MP on 10 otherwise healthy patients with moderate to severe pectus excavatum deformities (age, 8-14 years; Haller index >3.5). Operative techniques evolved to improve ease of implantation. Patients were evaluated monthly by a pediatric surgeon and orthotist. Electrocardiograms were performed pre- and postoperatively. Sternal position was documented by pre- and postprocedure computed tomographic scan, interval chest x-ray, depth gauge, and interval photographs.
Results: There was no detectable effect of the static magnetic field on wound healing or cardiopulmonary function. No detectable injuries and minimal skin changes resulted from brace wear. Operative techniques evolved to include a custom sternal punch and a flexible guide wire to guide the posterior plate into position behind the sternum, reducing outpatient operating time to one-half hour. In 9 patients, the procedure was performed as an outpatient basis; and 1 patient was observed overnight. Three patients required evacuation of retained pleural air postoperatively, and 2 required an outpatient revision. A custom-fitted orthotic brace (Magnatract) was extensively modified to increase user friendliness and functionality while incorporating several novel functions: a screw displacement mechanism so patients can easily self-adjust magnetic force, a miniature data logger to measure force and temperature data every 10 minutes, and an interactive online Web portal for remote patient evaluation. All attempts to quantitate sternal position (radiographic, fluid volume, and depth gauge) were inadequate. Visual assessment remains the best indicator.
Conclusions: In this interim report, the 3MP appears to be a safe, minimally invasive, outpatient, cost-effective alternative treatment of pectus excavatum. Outcomes will be reported upon the completion of this phase II clinical trial.
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