New surgical tool keeps orthopedic procedures on target

Common orthopedic procedures, such as hip and pelvic fracture surgery as well as spinal fusion, require the accurate positioning of a thin metallic wire to guide the positioning of a fixating screw. However, the surgical procedure is often hampered by deflection, bending and even breakage of the guide-wire, which then requires repair while complicating and prolonging the recovery of patients.

"This is a significant challenge," said Prof. Meir Liebergall, head of the Department of Orthopedic Surgery at Hadassah Medical Center, "as complications in guide-wire positioning could lead to revision surgeries and increase hospitalization time and cost."

To address this challenge, Prof. Liebergall partnered with a multidisciplinary team of medical doctors, along with engineering and business students, from The Hebrew University's BioDesign: Medical Innovation program.

They identified a solution: by creating a system that provides real-time indication of deflection or bending of the guide-wire, the surgeon will be able to adjust the procedure before damage occurs.

The team developed BendGuide, an opto-electronic drilling system that monitors and detects minute changes in guide-wire trajectory during surgery. It allows surgeons to correct drilling trajectories during the procedure itself. The system eliminates guide-wire bending or breakage and significantly reduces operation time and enhances safety.

"This is an elegant technological solution to a complex problem," said Prof. Yaakov Nahmias, director of The Hebrew University's Alexander Grass Center for Bioengineering and the BioDesign program. "The group model and proof-of-concept experiments showed they could detect even miniscule changes in guide-wire trajectory."

BendGuide uses a fiber bundle with a reflecting laser beam that enables detection of small deflections in wire trajectory. At a fully-aligned state, the beam power hits the center of the detector array. When deflected, mirror misalignment causes the power to spread differentially across the fiber bundle.

The market for computer-aided navigation systems for surgery is growing fast. The potential market is estimated at $500 million annually in the United States alone. BendGuide aims to become an integral part of this market, which is expected to grow further with the aging population.