1. Feinberg School of Medicine, Northwestern University, Chicago, IL 60208, USA
2. College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA
3. Department of Orthopedics and Rehabilitation, University of Iowa, Iowa City, IA 52242, USA
4. Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
5. Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI 48109, USA
6. Department of Orthopaedic Surgery, Duke University, Durham, NC 27708, USA
7. Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104, USA