1. Department of Orthopaedic Surgery, The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen 518170, China
2. Department of Medical Ultrasonics, First Affiliated Hospital of Jinan University, Guangzhou 510070, China
3. Guangdong Provincial Key Laboratory of Orthopedics and Traumatology, Department of Spinal Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China