Paradoxical Radiographic Changes of Coflex Interspinous Device with Minimum 2-Year Follow-Up in Lumbar Spinal Stenosis.
OBJECTIVES
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.


METHODS
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).


RESULTS
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°).


CONCLUSION
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.
['Lee|Nam|N|', 'Shin|Dong Ah|DA|', 'Kim|Keung Nyun|KN|', 'Yoon|Do Heum|DH|', 'Ha|Yoon|Y|', 'Shin|Hyun Chul|HC|', 'Yi|Seong|S|']
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 D007796:Laminectomy D008159:Lumbar Vertebrae D008297:Male D008875:Middle Aged D011183:Postoperative Complications D019736:Prostheses and Implants D011859:Radiography D016059:Range of Motion, Articular D013130:Spinal Stenosis
Coflex Lumbar spinal stenosis Erosion Disc height Range of motion