Implant Failure: STRATOS System for Pectus Repair.

BACKGROUND

Three European centers have recently reported dramatic failures of the STRATOS titanium system, approved in Europe and the United States since 2007 and meant for pectus repair, without detailed exploration of its causes.

METHODS

Failed implants (fractures or loosened crimp connectors) were surgically explanted from 12 patients and biopsies taken from surrounding discolored tissue. Detailed failure analysis was performed to find the cause of failures. Inductively coupled mass spectroscopy, scanning electron microscopy, and energy dispersive radiograph spectroscopy was used to determine titanium and to visualize titanium wear debris in histologic sections.

RESULTS

Implants failed in all patients by fracture of connecting bar, fracture of lateral bar at reduced cross-section, loosening of crimp connector, or different combinations of these. All fracture surfaces were clean and smooth without any signs of plastic deformation. Failure already started at 10 months after implantation and continued for 2.5 years. Biopsy of discolored tissue around the failures showed 0.4 mg to 105 mg titanium per gram tissue, and close observation showed titanium wear debris.

CONCLUSIONS

Combined tensile, compressive, bending, and torsional loading on the implant during each breathing cycle caused loosening and fatigue fractures, which led to failure. Excessive rubbing at the fracture and loosening site caused the release of large amounts of titanium in the surrounding tissue, which may lead to metallosis. Long and sharp pieces of failed implant in the cardiothoracic region is a grave danger to vital organs. All patients should be closely followed, and in our opinion, all implants should be removed. Serious reconsideration for clinical use of this implant is necessary.