title: Late instrumentation failure after total en bloc spondylectomy.
abstract: OBJECTIVE
  The object of this study was to investigate failures after spinal reconstruction following total en bloc spondylectomy (TES), related factors, and sequelae arising from such failures in patients with malignant spinal tumors.
  
  
  METHODS
  Fifteen patients (12 males and 3 females, with a mean age of 46.5 years) with malignant spinal tumors who underwent TES and survived for more than 1 year were included in this analysis (mean follow-up 41.5 months). Seven patients had primary tumors, including giant cell tumors in 4 patients, chordoma in 2, and Ewing sarcoma in 1. Eight patients had metastatic tumors, including thyroid cancer in 6 and renal cell cancer and malignant fibrous histiocytoma in 1 patient each. Seven patients without prominent paravertebral extension of the tumor were treated using a posterior approach alone, and 8 patients who exhibited prominent anterior or anterolateral extension of the tumors into the thoracic or abdominal cavity were treated using a combined anterior and posterior approach. Spinal reconstruction after tumor resection was performed using a combination of anterior structural support and posterior instrumentation. The relationship between instrumentation failure and clinical and radiographic factors, including age, sex, history of previous surgery, preoperative radiotherapy, tumor histology, tumor level, surgical approach, number of resected vertebrae, rod diameter, number of instrumented vertebrae, and cage subsidence, was investigated.
  
  
  RESULTS
  Six patients (40%) with spinal instrumentation failure were identified: rod breakage occurred in 3 patients, and breakage of both the rod and the cage, combined cage breakage and screw back-out, and endplate fracture arising from cage subsidence occurred in 1 patient each. All of these patients experienced acute or chronic back pain, but only 1 patient with a tumor recurrence experienced neurological deterioration upon instrumentation failure. Cage subsidence (≥ 5 mm), preoperative irradiation, and the number of instrumented vertebrae (≤ 4 vertebrae) were significantly related to late instrumentation failure.
  
  
  CONCLUSIONS
  Late instrumentation failure was a frequent complication after TES. Although patients with instrumentation failure experienced back pain, the neurological sequelae were not catastrophic. For prevention, meticulous preparation of the graft site and a longer posterior fixation should be considered.
authors.affiliation: Department of Orthopaedic Surgery, Keio University, Tokyo, Japan. morio@sc.itc.keio.ac.jp
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Kota
authors.initials: K
authors.lastname: Watanabe
authors.forename: Takashi
authors.initials: T
authors.lastname: Tsuji
authors.forename: Ken
authors.initials: K
authors.lastname: Ishii
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakamura
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Chiba
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
mesh_terms: D000328:Adult; D001175:Arthrography; D001416:Back Pain / Q000209:etiology; D001863:Bone Screws / Q000009:adverse effects; D002292:Carcinoma, Renal Cell / Q000556:secondary; D002817:Chordoma / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D005870:Giant Cell Tumors / Q000601:surgery*; D051677:Histiocytoma, Malignant Fibrous / Q000000981:diagnostic imaging / Q000556:secondary; D006801:Humans; D016268:Internal Fixators / Q000009:adverse effects*; D007680:Kidney Neoplasms / Q000556:secondary; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D019637:Orthopedic Procedures / Q000009:adverse effects* / Q000295:instrumentation; D019651:Plastic Surgery Procedures; D012512:Sarcoma, Ewing / Q000601:surgery*; D013125:Spinal Neoplasms / Q000175:diagnosis / Q000556:secondary / Q000601:surgery*; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000556:secondary; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D017211:Treatment Failure; D055815:Young Adult