title: Bone loss of the superior adjacent vertebral body immediately posterior to the anterior flange of Bryan cervical disc.
abstract: BACKGROUND
  No previous reports have mentioned bone loss of the superior adjacent vertebra immediately posterior to the anterior flange of Bryan cervical disc (Medtronic Sofamor Danek, Memphis, TN, USA), which plays a central role to prevent posterior migration of the device. The purpose of this study is to describe a new potential complication, bone loss immediately posterior to the anterior total disc replacement (TDR) flange on the superior adjacent vertebra following the Bryan cervical TDR and to discuss the possible mechanism.
  
  
  METHODS
  The authors retrospectively reviewed 37 patients undergoing cervical TDR with the Bryan cervical disc. The clinical and radiological outcome data were collected at 1, 3, 6, 12, 24, and 36 months postoperatively, and at last follow-up, which ranged from 42 to 113 moths (average, 60.1 months). Clinical evaluation included the visual analog scale and neck disability index, and the radiographic evaluation included measurements of the functional spinal unit range of motion on flexion and extension and identification of radiographic changes such as bone loss.
  
  
  RESULTS
  The Bryan TDR showed good mid-term clinical and radiological outcomes. Interestingly, however, bone loss was noted immediately posterior to the TDR flange on superior adjacent vertebra in 3 total patients; at 3 months (n = 2) and 6 months (n = 1). Although the bone loss was increased up to 6 months, this did not progress and no degradation of clinical and radiological outcomes occurred at last follow-up.
  
  
  CONCLUSIONS
  Bone loss immediately posterior to the anterior TDR flange on the superior adjacent vertebra can occur in the early postoperative period due to possibly stress shielding effect. However, it did not result in clinical changes or increased rates of graft failure at last follow-up. A long-term follow-up study is mandatory to evaluate the long-term effects of the bone loss.
authors: Department of Neurosurgery, Ajou University, Suwon, Korea.
authors: Sang Hyun
authors: SH
authors: Kim
authors: Department of Neurosurgery, Kunkuk University, Chungju, Korea.
authors: Young Sun
authors: YS
authors: Chung
authors: Department of Neurosurgery, Barrow Neurological Institute, Phoenix, AZ, USA.
authors: Alexander E
authors: AE
authors: Ropper
authors: Department of Rehabilitation Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
authors: Kyung Hoon
authors: KH
authors: Min
authors: Department of Orthopedics, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
authors: Tae Keun
authors: TK
authors: Ahn
authors: Department of Neurosurgery, CHA Bundang Medical Center, CHA University, 59, Yatap-ro Bundang-gu, Seongnam-si, Gyeonggi-do, 463-712, Korea.
authors: Keun Soo
authors: KS
authors: Won
authors: Department of Neurosurgery, Severance Hospital, Yonsei University, 50, Yonsei-ro, Seodaemun-gu, Seoul, 120-749, Korea. cistern@me.com.
authors: Dong Ah
authors: DA
authors: Shin
authors: Department of Neurosurgery, CHA Bundang Medical Center, CHA University, 59, Yatap-ro Bundang-gu, Seongnam-si, Gyeonggi-do, 463-712, Korea. hanib@cha.ac.kr.
authors: In Bo
authors: IB
authors: Han
mesh_terms: D000328:Adult; D001851:Bone Diseases, Metabolic / Q000209:etiology*; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000209:etiology* / Q000601:surgery*; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D011183:Postoperative Complications / Q000209:etiology*; D011859:Radiography; D012189:Retrospective Studies; D059145:Total Disc Replacement / Q000009:adverse effects*; D016896:Treatment Outcome
keywords: Bryan disc; Cervical disc disease; Disc degeneration; Total disc replacement