title: Comparison of the clinical and radiologic outcomes obtained with single- versus two-level anterior cervical decompression and fusion using stand-alone PEEK cages filled with allograft.
abstract: BACKGROUND
  Although anterior cervical decompression and fusion with a stand-alone cage (ACDF-SAC) is accepted as a suitable procedure, the outcomes of the multi-level procedure remain controversial. The aim of this study is to compare the clinical and radiologic outcomes achieved with single versus two-level ACDF-SAC along with identification of the factors that contribute to loss in mean disc height (MDH) and change in cervical lordotic angle (CLA).
  
  
  METHODS
  A total of 109 consecutive patients who underwent ACDF-SAC for degenerative spondylosis were reviewed. Patients were divided into two groups according to surgical level (group A, single; group B, two) and were followed for at least 1 year. Clinical outcomes were evaluated using the visual analog scale (VAS) and Robinson's criteria. The fusion and subsidence rates, MDH, CLA, anterior, and posterior vertebral body height of the fused segments (AVBH, PVBH) were measured retrospectively from plain radiographs.
  
  
  RESULTS
  Clinical outcomes were similar in both groups, in terms of decreasing VAS score and a grade higher than "good" by Robinson's criteria. The fusion and subsidence rates for each group were found to be 92.2, 91.1, 14.1, and 20.0 %, respectively. The MDH (mm) increased by 1.44 ± 0.96 in group A, 1.57 ± 0.79 and 1.66 ± 0.69 for each surgical level in group B over the 12 postoperative months. The CLA (°) decreased by 1.70 ± 4.04 and 0.75 ± 6.12 over the 12 postoperative months from its presurgery value, the rate of kyphosis >5° was 26.6 and 22.2 % for each group. All compared values were not significantly different between the two groups. Correlation analysis revealed that the AVBH/PVBH ratio exhibited a positive correlation with CLA change in both groups (r = 0.368, 0.397; p = 0.018, 0.040).
  
  
  CONCLUSIONS
  The overall outcomes achieved with two-level ACDF-SAC were similar to those achieved with single-level ones. In addition, the AVBH/PVBH ratio might be a predictable marker for a postoperative kyphosis.
authors.affiliation: Department of Neurosurgery, Kyung Hee University Hospital, Kyung Hee University School of Medicine, 23 Kyungheedae-ro, Dongdaemun-gu, Seoul, South Korea, 130-872.
authors.forename: Man Kyu
authors.initials: MK
authors.lastname: Choi
authors.affiliation: Department of Neurosurgery, Kyung Hee University Hospital, Kyung Hee University School of Medicine, 23 Kyungheedae-ro, Dongdaemun-gu, Seoul, South Korea, 130-872. sungbumi7@hanmail.net.
authors.forename: Sung Bum
authors.initials: SB
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Kyung Hee University Hospital, Kyung Hee University School of Medicine, 23 Kyungheedae-ro, Dongdaemun-gu, Seoul, South Korea, 130-872.
authors.forename: Chang Kyu
authors.initials: CK
authors.lastname: Park
authors.affiliation: Department of Neurosurgery, Kyung Hee University Hospital, Gangdong, Seoul, South Korea.
authors.forename: Sung Min
authors.initials: SM
authors.lastname: Kim
mesh_terms: D000368:Aged; D001577:Benzophenones; D016025:Bone Transplantation / Q000379:methods; D002574:Cervical Vertebrae / Q000601:surgery*; D019299:Decompression, Surgical / Q000009:adverse effects / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016268:Internal Fixators / Q000009:adverse effects; D055959:Intervertebral Disc Degeneration / Q000473:pathology / Q000601:surgery; D007659:Ketones; D007738:Kyphosis / Q000473:pathology / Q000601:surgery; D008141:Lordosis / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019547:Neck Pain / Q000175:diagnosis / Q000209:etiology; D010147:Pain Measurement; D011092:Polyethylene Glycols; D011108:Polymers; D013117:Spinal Cord Compression / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D055009:Spondylosis / Q000473:pathology / Q000601:surgery; D016896:Treatment Outcome
chemical_list: D001577:Benzophenones; D007659:Ketones; D011108:Polymers; C063834:polyetheretherketone; D011092:Polyethylene Glycols
keywords: AVBH/PVBH; Anterior cervical decompression and fusion; Cervical lordotic angle; Mean disc height; Stand-alone cage