Redesign of Otologic Surgical Instruments Brian Chow and Joy Nystrom Mechanical Engineer: Ryan Josefovsky Advisor: Russ Johnson, PhD-Smith and Nephew BME 273 March 19, 2001

Ear Surgery Otitis Media (Middle Ear Infection) Upwards of 800,000 surgeries/year Around 11 million cases total Closure of Tympanic Membrane Perforations

Ear Surgery Otosclerosis Removal of Tumors Cochlear Implants 10-18% of women aged 30-50 7-9% of men aged 30-50 Removal of Tumors Cochlear Implants 14,000 Americans The Boys Town Research Registry for Hereditary Hearing Loss http://www.nidcd.nih.gov/health/pubs_hb/coch.htm#c

Potential Market 100,000 Ear, Nose, and Throat (ENT) Physicians 1000 Neurosurgeons

Problem Otologic surgery requires delicate maneuvering in limited space ossicles <3 mm cavities ~1 cm Current method requires large hand movement www.earsurgery.org

A large hand movement (1 cm) causes a small tip movement (4 mm). 1 inch 1 inch A large hand movement (1 cm) causes a small tip movement (4 mm). Movement requires compensation by user.

Proposal Create a system that will allow identical movement of the instrument in an ear of a patient with a fingertip-controlled drive mechanism Brackmann, Otologic Surgery

The Task Redesign the back end and drive mechanism for fingertip control Maintain tip movement identical to current instruments Back End/ Drive Mechanism Tip

The Task There are different kinds of tips grasping cutting spreading Courtesy of Smith and Nephew

Reasons Fingertip control allows for: Steadier hand control Higher precision with finger movement Better access to inner ear

Advantages Reduced motion of surgeon’s arm results in: A lowered margin of error A potential for reducing amount of training required for proficiency A potential for better ergonomics Similar cost

Research and Brainstorming

Patent Search New problem, few previous patents, little information Similar to laparoscopic surgery

Possible solutions Screw mechanism Pulleys (#5,976,122) Gears Slide Concentric Wheels Levers

Concentric Wheel Design Concentric wheels designed to scale motion. Solid metal shafts

Concentric Wheel Flaws Requires larger handle (about the size of a fountain pen) Finger moves in a sliding motion

Current Design

Advantages More compact Push-button mechanism Fewer, more stable parts

Future Work Obtain Specifications Complete design on CAD program Consult with manufacturing Evaluate safety of design

Questions?