1. Department of Otorhinolaryngology, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, Korea.
2. Department of Otorhinolaryngology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Orthopaedic Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.