We show it is possible to measure the applied forces in middle ear surgery and that some of these forces are very large. Larger forces are seen in destructive procedures and in procedures performed by inexperienced operators. This project is an important first step in investigating the association between surgically applied middle ear forces and postoperative sensorineural hearing loss.

Surgery of the middle ear is a delicate process that requires the surgeon to manipulate the ossicles, the smallest bones in the body. Excessive force applied to the ossicles can easily be transmitted through to the inner ear which may cause a permanent sensorineural hearing loss. An instrument was required to measure the forces applied to cadaveric temporal bone ossicles with the vision of measuring forces in vivo at a later stage. A feasibility study was conducted to investigate a method of measuring force and torque applied to the ossicles of the middle ear. Information from research papers was gathered to determine the expected amplitudes. The study looked at commercially available transducers as well as constructing an instrument using individual axis transducers coupled together. A prototype surgical instrument was constructed using the ATI industrial automation Nano17 six axis transducer. The Nano17 allows for the measurement of force and torque in the X, Y and Z axis to a resolution of 1/320 N. The use of the Nano17 enabled rapid development of the surgical instrument. It meets the requirements for its use on cadaveric models and has the potential to be a useful data collection tool in vivo.