title: Paradoxical Radiographic Changes of Coflex Interspinous Device with Minimum 2-Year Follow-Up in Lumbar Spinal Stenosis.
abstract: Studies have yet to investigate long-term radiologic changes in lumbar spinal stenosis patients treated with interspinous device (Coflex). This study aimed to evaluate which radiologic parameters change significantly after surgery with Coflex and identify which parameter most affects the radiologic outcome.
  
  
  
  Of 101 patients with lumbar spinal stenosis treated by Coflex insertion on L4-5, the radiologic parameters of 30 patients were measured before and at least 2 years after surgery. On the basis of the development of bony erosion around Coflex, patients were divided into the erosion group (n = 14) or the nonerosion group (n = 16).
  
  
  
  The mean anterior disc height (ADH) and range of motion (ROM) were significantly decreased after surgery (15.161 mm vs. 13.788 mm and 9.63° vs. 7.13°). The erosion group showed substantially higher values in preoperative ADH, postoperative posterior disc height (PDH), and intervertebral foramen height (6.52 mm vs. 8.05 mm; 5.80 mm vs. 8.03 mm; 19.20 mm vs. 21.06 mm). Postoperative ROM and ROM ratio were higher in the erosion group (5.95° vs. 8.47° and 0.659 vs. 0.938). However, only ADH showed a significant change in the erosion group after surgery (15.86 mm vs. 14.29 mm). On the contrary, ADH and PDH, as well as ROM, were significantly decreased in the nonerosion group (14.55 mm vs. 13.34 mm; 6.52 mm vs. 5.82 mm; 9.46° vs. 5.95°).
  
  
  
  The preoperative state including relatively higher ADH, PDH, and larger ROM could induce erosion. The long-term preservation of disc height and ROM may also induce erosion. That reduction of most radiologic parameters seems to be natural after surgery, and insufficient reduction of disc height and ROM may induce adverse effects, which can increase the possibility of spinous process fracture or device malposition.
authors.affiliation: Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Nam
authors.initials: N
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Dong Ah
authors.initials: DA
authors.lastname: Shin
authors.affiliation: Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Keung Nyun
authors.initials: KN
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Do Heum
authors.initials: DH
authors.lastname: Yoon
authors.affiliation: Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Yoon
authors.initials: Y
authors.lastname: Ha
authors.affiliation: Department of Neurosurgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, South Korea.
authors.forename: Hyun Chul
authors.initials: HC
authors.lastname: Shin
authors.affiliation: Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, South Korea; Department of Brain and Cognitive Engineering, Korea University, Seoul, South Korea. Electronic address: yiseong@yuhs.ac.
authors.forename: Seong
authors.initials: S
authors.lastname: Yi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019299:Decompression, Surgical; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging; D007796:Laminectomy; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D019736:Prostheses and Implants; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D013130:Spinal Stenosis / Q000000981:diagnostic imaging* / Q000601:surgery*
keywords: Coflex; Disc height; Erosion; Lumbar spinal stenosis; Range of motion