Development of Depth Gage Instrument Brian Cost Justin Johnson Tyler Kibbee March 20, 2008

Project Description Design, build and test an improved depth gage instrument for a variety of orthopedic surgeries Achieve bi-cortical fixation using a compression stopper Ergonomic Grip Ease of use for surgeons Accuracy Proper depth and correct size screw used

Existing Industry Design Inadequate measurements Unable to engage far cortex of bone Poor repeatability Shaft warps from abuse Surgeons bend shaft in attempt to engage far cortex Permanent damage to gage renders it useless

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Company Background Small Biotech company started by Orthopedic surgeon 4 specialized product trays MaxLock™ CalcLock™ MaxTorque™ DRLock™ Serves Niche market Small bone surgery Hand and Foot specialists

Project Timeline SolidWorks 7.0 3D modeling Revise 3D models with advisor Create additional Model Simulation Shadow Surgeons at VUMC Product design input SLA plastic prototype Quick, cheap prototype for visual inspection 1 st SLA deadline: On order (pending design approval) Test SLA prototype Use saw bone models to conduct testing Prototype contract Prepare for FDA approval Might not be before 4/22/08

Current Status Materials obatined: Hand and Foot saw bone models Drill Bits, drivers Plates, screws Revised switch to compress tip Met with Doctors at VUMC Dr. Andrew Thomson Dr. Thomas Limbird

Our Depth Gage Design

Switch Demonstration

Tip Demonstration Before Compression (switch disengaged) After Compression (switch engaged)

FDA Classification Class I – Surgical devices Sec Depth gauge for clinical use. (a) Identification. A depth gauge for clinical use is a measuring device intended for various medical purposes, such as to determine the proper length of screws for fastening the ends of a fractured bone. (b) Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter, subject to the limitations in [52 FR 33702, Sept. 4, 1987, as amended at 66 FR 38815, July 25, 2001]

Experimental Testing Material testing Stainless steel  Autoclave Medical-grade Silicon  Autoclave, heat resistance Failure testing Pull-out strength  Amount of force needed to pull silicon through hole Silicon-strength testing  Bone pressing against silicon

Summary of Maude Database Results Malfunction Improper depth measurement Depth gauge does not read accurately. When used, the depth gauge reads long. Depth gauge for cortex screws was sticking and provided an incorrect measurement Translation mechanism failure The depth gauge is not sliding smoothly Depth gauge for cortex screws was sticking and provided an incorrect measurement Tip Failure A modified depth gauge reportedly broke during surgery. A ball-tip that was 3mm in diameter had fallen off and was left in the patient. Injury - None Serious Injury/Death - None

Complaints/Incidences of Malfunction

Feedback Derek Lewis, advisor Surgeons are used to ergonomics of old design—minimal changes Currently critiquing design with president of OrthoHelix Surgeons Design needs to be for one handed operation Needs to slide smoothly Switch needs to be relatively easy to flip

Future Work Awaiting SLAs Revision process Choose tip composition. Obtain remaining materials for scaled prototype Continue conference calls to share ideas and check in with our progress

Innovation Workbench Concept Map

Questions?