1. Department of Orthopaedic Surgery The 1st Hospital of Hebei Medical University Shijiazhuang Hebei P. R. China
2. Department of Orthopaedic Surgery The 1st Central Hospital of Baoding Baoding Hebei P. R. China
3. Department of General Medicine the 2nd Hospital of Hebei Medical University Shijiazhuang Hebei P. R. China
4. Department of Spinal Surgery The 3rd Hospital of Hebei Medical University Shijiazhuang Hebei P. R. China