Orthopaedics

Title: Nonlinear dynamic modeling of rotator cuff impingement syndrome

Investigators: Richard E. Hughes, Ph.D. and James E. Carpenter, M.D.

Abstract: Rotator cuff impingement, which is a painful disorder of the shoulder, affects many athletes, workers, and older people. Treatment of impingement syndrome typically proceeds with three months of physical therapy.  Surgical treatment is indicated if the patient does not respond to the physical therapy. The research question to be addressed is, “why do some patients respond to physical therapy and others do not?” We speculate that the shoulder behaves as a nonlinear dynamical system that can be described by a few variables and their rates of change.  We will investigate the behavior of the system by formulating a set of nonlinear differential equations and determining the characteristics of their stability. Data from imaging studies and biomechanical models of the shoulder will be incorporated. We hypothesize that this dynamical system has a small number of stable attractors and that the course of physical therapy depends on the initial conditions of the patient at the time of presentation to the clinic. This project will involve close interaction with clinicians, both orthopaedic surgeons and physical therapists.

The project will be co-mentored by Richard E. Hughes, Ph.D., who is a math modeler, and James E. Carpenter, M.D., who is an orthopaedic surgeon and Chair of the Department of Orthopaedic Surgery at the University of Michigan. The project will be conducted as part of the Shoulder Group of the Laboratory for Optimization and Computation in Orthopaedic Surgery (LOCOS). For more information about this laboratory and the collaborative shoulder research that Drs. Hughes and Carpenter have been conducting for the past nine years, see the LOCOS webpage.