To operate on the heart, surgeons usually cut through the breastbone. After correcting the heart problem, they reconnect the sternum by piercing it with steel wires, pulling the bone segments together and twisting the wires tight. Because this half-century-old technique poses some risks to both the surgeon and the patient, undergraduates at The Johns Hopkins University have invented a less intrusive and potentially safer chest closure system that threads locking polymer clasps through the ribs.