title: Risk Factors for Ineffectiveness of Posterior Decompression and Dekyphotic Corrective Fusion with Instrumentation for Beak-Type Thoracic Ossification of the Posterior Longitudinal Ligament: A Single Institute Study.
abstract: BACKGROUND
  Thoracic ossification of the posterior longitudinal ligament (T-OPLL) is treated surgically with instrumented posterior decompression and fusion. However, the factors determining the outcome of this approach and the efficacy of additional resection of T-OPLL are unknown.
  
  
  OBJECTIVE
  To identify these factors in a prospective study at a single institution.
  
  
  METHODS
  The subjects were 70 consecutive patients with beak-type T-OPLL who underwent posterior decompression and dekyphotic fusion and had an average of 4.8 years of follow-up (minimum of 2 years). Of these patients, 4 (6%; group R) had no improvement or aggravation, were not ambulatory for 3 weeks postoperatively, and required additional T-OPLL resection; while 66 (group N) required no further T-OPLL resection. Clinical records, gait status, intraoperative ultrasonography, intraoperative neurophysiological monitoring (IONM), plain radiography, computed tomography and magnetic resonance imaging findings, and Japanese Orthopaedic Association (JOA) score were compared between the groups.
  
  
  RESULTS
  Preoperatively, patients in group R had significantly higher rates of severe motor paralysis, nonambulatory status, positive prone and supine position test, no spinal cord floating in intraoperative ultrasonography, and deterioration of IONM at the end of surgery ( P < .05). In preoperative radiography, the OPLL spinal cord kyphotic angle difference in fused area, OPLL length, and OPLL canal stenosis were significantly higher in group R ( P < .05). At final follow-up, JOA scores improved similarly in both groups.
  
  
  CONCLUSIONS
  Preoperative severe motor paralysis, nonambulatory status, positive prone and supine position test, radiographic spinal cord compression due to beak-type T-OPLL, and intraoperative residual spinal cord compression and deterioration of IONM were associated with ineffectiveness of posterior decompression and fusion with instrumentation. Our 2-stage strategy may be appropriate for beak-type T-OPLL surgery.
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Imagama
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Ando
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Zenya
authors.initials: Z
authors.lastname: Ito
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Hida
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Kenyu
authors.initials: K
authors.lastname: Ito
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Mikito
authors.initials: M
authors.lastname: Tsushima
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Yoshimoto
authors.initials: Y
authors.lastname: Ishikawa
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Akiyuki
authors.initials: A
authors.lastname: Matsumoto
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Morozumi
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Machino
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Kyotaro
authors.initials: K
authors.lastname: Ota
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakashima
authors.affiliation: Department of Orthopaedic Surgery, Aichi Medical Uni-versity, Nagakute-cho, Aichigun, Japan.
authors.forename: Norimitsu
authors.initials: N
authors.lastname: Wakao
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nishida
authors.affiliation: Department of Orthopaedic Surgery, Hamamatsu University School of Medi-cine, Hamamatsu, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Matsuyama
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ishiguro
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D019299:Decompression, Surgical / Q000379:methods*; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D017887:Ossification of Posterior Longitudinal Ligament / Q000000981:diagnostic imaging / Q000601:surgery*; D011446:Prospective Studies; D012307:Risk Factors; D013123:Spinal Fusion / Q000379:methods*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods; D017211:Treatment Failure; D016896:Treatment Outcome
keywords: Ineffectiveness of posterior decompression and fusion with instrumentation; Intraoperative neurophysiological monitoring; Intraoperative residual spinal cord compression; Positive prone and supine position test; Preoperative motor paralysis; Preoperative nonambulatory status; Thoracic ossification of the posterior longitudinal ligament