1. Spectrum Research, Tacoma, WA, USA
2. VA Puget Sound Health Care System, Seattle, WA, USA
3. Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA, USA
4. Orthopedic + Fracture Specialists, Portland, OR, USA
5. Orthopaedic Associates of Michigan, Grand Rapids, MI, USA
6. Twin Cities Orthopedics, Edina, MN, USA
7. Orthopaedic & Spine Center of the Rockies, Fort Collins, CO, USA
8. Department of Mechanical Engineering, University of Washington, Seattle, WA, USA