J Korean Neurosurg Soc.  2015 Jan;57(1):61-64. 10.3340/jkns.2015.57.1.61.

Radicular Pain due to Subsidence of the Nitinol Shape Memory Loop for Stabilization after Lumbar Decompressive Laminectomy

  • 1Department of Neurosurgery, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea. sbc@catholic.ac.kr
  • 2Department of Neurosurgery, Nowon Eulji Hospital, Eulji University, Seoul, Korea.
  • 3The Catholic Neuroscience Institute, College of Medicine, The Catholic University of Korea, Seoul, Korea.


A number of dynamic stabilization systems have been used to overcome the problems associated with spinal fusion with rigid fixation recently and the demand for an ideal dynamic stabilization system is greater for younger patients with multisegment disc degeneration. Nitinol, a shape memory alloy of nickel and titanium, is flexible at low temperatures and regains its original shape when heated, and the Nitinol shape memory loop (SML) implant has been used as a posterior tension band mostly in decompressive laminectomy cases because the Nitinol implant has various characteristics such as high elasticity and a tensile force, flexibility, and biological compatibility. The reported short-term outcomes of the application of SMLs as posterior column supporters in cervical and lumbar decompressive laminectomies seem to be positive, and complications are minimal except for the rare occurrence of pullout and fracture of the SML. However, there was no report of neurological complications related to neural compression in spite of the use of the loop of SML in the epidural space. The authors report a case of delayed development of radiating pain caused by subsidence of the SML resulting epidural compression.


Dynamic stabilization; Laminectomy; Nitinol; Pain; Shape memory loop

MeSH Terms

Epidural Space
Hot Temperature
Intervertebral Disc Degeneration
Spinal Fusion


  • Fig. 1 Radiologic findings of the patient. A : An anterior-posterior X-ray of the lumbar spine showing the placement of the shape memory loop and the posterior lumbar interbody fusion at the level of L4/5. B : A lateral X-ray of the lumbar spine. C : A sagittal T2-weighted image showing the encroachment of the shape memory loop (arrow) on the dural sac in the upper lamina of L4 and the lower lamina of L5. D : An axial T2-weighted image at the upper lamina level of L4.

  • Fig. 2 A : A sagittal reconstruction view of the CT-myelogram showing subsidence of the shape memory loop (arrow). An axial view of the CT-myelogram at the level of L4 (B) and L5 (C).

  • Fig. 3 A : An intraoperative photograph showing the placement of the shape memory loop. B : An intraoperative photograph showing the status of the upper limb of the shape memory loop at the level of L4 (right side). C : Drilling of the shape memory loop with a diamond burr. D : A photograph showing the presence of an epidural hole (arrow) made from the previous placement of the limb of the shape memory loop, causing dural compression.


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