1. Mechanical Engineering Department; Imperial College London; London SW7 2AZ United Kingdom
2. Department of Orthopaedic Surgery; Queen Elizabeth Hospital; Gateshead United Kingdom
3. Department of Orthopaedic Surgery; Newcastle Freeman University Hospital; Newcastle Upon Tyne United Kingdom
4. Musculoskeletal Surgery Group, Department of Surgery and Cancer; Imperial College London, Charing Cross Hospital; London United Kingdom