Michael Dahl Medical Device Research on the Spine

Graduate Research

My graduate work was primarily spent at the Applied Biomechanics Laboratory under Dr. Randal Ching. My masters project included doing the initial biomechanical testing for the first ever compliant cervical prosthetic intervertebral disk, known as the Bryan Cervical Disk System, made by Spinal Dynamics (now Medtronic-Sofamor-Danek). We tested the dynamic biomechanical properties of the implant, and compared its characteristics to those of a normal and fused spine. Medtronic-Sofamor-Danek contracted me to do an analysis of the implant core materials to satisfy FDA requirements. The results were published in JBE (My first paper!).

Dahl MC, Rouleau JP, Papadopoulos S, Nuckley DJ, Ching RP . Dynamic characteristics of the intact, fused, and prosthetic-replaced cervical disk. Journal of Biomechanical Engineering. 2006. Dec;128(6):809-14.

A side project I did in collaboration with Dr. Sundar Srinivasan incorporated modeling bone formation using a technique called agent based modeling. This is a unique form of computational modeling that examines emergent behavior in a system defined by basic parameters. It allows the researcher to examine the parameter space to determine which characteristics and variables are the most prominent in a system, which allows for more focused empirical research.

A couple orthopaedic surgeons from Harborview Medical Center contacted me about developing a study to determine the difference between various techniques of removing equipment from football players with cervical spine injuries. Apparently there are multiple schools of thought as to the correct way to remove equipment from a compromised individualThis was a fun and enlightening project and the research was submitted to the Journal of Applied Biomechanics.

Dahl MC, Ananthakrishnan D, Nicandri G, Chapman JR, Ching RP. Helmet and shoulder pad removal in football players with unstable cervical spine injuries. Journal Applied Biomechanics. 2009 May;25(2):119-32.

Now for my doctorate thesis I was looking at the Agility Total Ankle Prosthesis. This research was conducted at the Applied Biomechanics Laboratory under Dr. Randal Ching, along with collaboration with Dr. Stephen Benirschke, Dr. Patricia Kramer, and Dr. Sigvard T Hansen of Harborview Medical Center. I was testing the efficacy of a device I developed that can measure the amount of implant osteointegration non-invasively. This study included bench top and cadaveric testing with a small clinical cohort of patients. As a side project, I looked at some wear patterns in the prosthesis polyethylene bearing itself using Atomic Force Microscopy.

After conducting the small scale clinical trial on patients scheduled for a revision procedure, we found that we could predict the amount of implant osteointegration beforehand in the clinic. Hopefully this research will eventually assist patients who are rehabilitating from total joint implant surgery, and allow the surgeon to more accurately track the ingrowth of the device. This new technology received a provisional patient and was submitted to the Journal of Biomechanics.

U.S. Patient Application (No. 12/427,575) entitled: Method and Apparatus for Evaluating Osteointegration of Medical Implants.