Armed Kyphoplasty: An Indirect Central Canal Decompression Technique in Burst Fractures

Abstract

Background and purpose: Burst fractures are characterized by middle column disruption and may feature posterior wall retropulsion. Indications for treatment remain controversial. Recently introduced vertebral augmentation techniques using intravertebral distraction devices, such as vertebral body stents and SpineJack, could be effective in fracture reduction and fixation and might obtain central canal clearance through ligamentotaxis. This study assesses the results of armed kyphoplasty using vertebral body stents or SpineJack in traumatic, osteoporotic, and neoplastic burst fractures with respect to vertebral body height restoration and correction of posterior wall retropulsion.

Materials and methods: This was a retrospective assessment of 53 burst fractures with posterior wall retropulsion and no neurologic deficit in 51 consecutive patients treated with armed kyphoplasty. Posterior wall retropulsion and vertebral body height were measured on pre- and postprocedural CT. Clinical and radiologic follow-up charts were reviewed.

Results: Armed kyphoplasty was performed as a stand-alone treatment in 43 patients, combined with posterior instrumentation in 8 and laminectomy in 4. Pre-armed kyphoplasty and post-armed kyphoplasty mean posterior wall retropulsion was 5.8 and 4.5 mm, respectively (P < .001), and mean vertebral body height was 10.8 and 16.7 mm, respectively (P < .001). No significant clinical complications occurred. Clinical and radiologic follow-up (1-36 months; mean, 8 months) was available in 39 patients. Three treated levels showed a new fracture during follow-up without neurologic deterioration, and no retreatment was deemed necessary.

Conclusions: In the treatment of burst fractures with posterior wall retropulsion and no neurologic deficit, armed kyphoplasty yields fracture reduction, internal fixation, and indirect central canal decompression. In selected cases, it might represent a suitable minimally invasive treatment option, stand-alone or in combination with posterior stabilization.

Fig 1.

Severe L3 vertebral body collapse (A) in a 74-year-old woman with osteopenia following minor trauma. Intraoperative myelogram through intradural injection of contrast agent at L1–L2 (arrow, A) shows an opacification defect of the dural sac dorsal to the retropusled fragment at L3 (arrowhead, A). On fracture reduction through balloon-expanded vertebral body stents (B), the myelogram shows greater opacification of the dural sac at L3 (arrowhead, B), a real-time indirect sign of ligamentotaxis and partial central canal clearance. C and D, Preoperative and postoperative midsagittal CT images used for measurement of vertebral body height at the maximum point of collapse (red arrows) and of posterior wall retropulsion (white arrows) perpendicular to the dashed white line connecting the postero-inferior corner of the cranial vertebral body and the postero-superior corner of the caudal one, representing the expected original posterior wall, now intersecting the PWR.

Fig 2.

Lung cancer metastatic T4 fracture in a 67-year-old man, with disabling back pain. MR imaging (A) and CT (B) show a lytic lesion, with vertebral body collapse and retropulsion of an osseous fragment (arrowhead, B), causing spinal cord compression, but the patient was neurologically intact. The patient underwent armed kyphoplasty with the SAIF technique (C–E) with bilateral stent and screw implant, with a decompressive surgery backup plan on standby. The procedure was uneventful, and the patient showed no neurologic worsening. Postoperative CT (F–H) shows a 3D view of the stent-screw-cement complex (F) and, most notably, the vertebral body height restoration and correction of posterior wall retropulsion (arrow, H) through ligamentotaxis. The patient was ambulating the same day and could undergo radiation treatment during the following days.

Fig 3.

Three different cases (A–C), (D–G), and (H–J). A–C, Treatment with the SpineJack of a traumatic incomplete burst fracture of T12 in a 55-year-old man with posterior wall retropulsion (arrow, A) and junctional kyphosis. Postoperative CT shows vertebral height restoration, central canal clearance through retropulsed fragment correction (arrowhead, C), and kyphosis correction. D–G, Treatment with the SAIF technique of a traumatic T10 fracture in a 78-year-old man with osteoporosis with >50% height loss and posterior wall retropulsion (arrow, D), with effective height restoration and posterior wall reposition (arrowhead, G). H–J, Treatment of an L1 osteoporotic fracture with bone subsidence (arrows, J) around the cement cast at 1-month follow-up, not compromising alignment and curvature. The patient was asymptomatic.

Fig 4.

Complete burst fracture of L1 following high-energy trauma in a 40-year-old man with marked vertebral body fragmentation (A–C) and posterior wall retropulsion (arrowhead, A). Sagittal fat-saturated proton density MR image (D) shows an epidural hematoma and compression of the conus medullaris, but the patient was neurologically intact. The patient underwent surgical treatment in a hybrid operation room, including, in sequence, L1 decompressive laminectomy, pedicular screw placement, fracture reduction and vertebral body augmentation with percutaneous bilateral SpineJack, and posterior stabilization with spinal rods (E and F). Postprocedural CT (G and H) shows fracture and kyphosis reduction and, most important, central canal clearance (arrow, H) through ligamentotaxis. Notably, no maneuvers of direct fragment impaction or of posterior fracture distraction were performed. Follow-up imaging with standing plain films at 6 months (I and J) and with CT at 12 months (K) shows preserved vertebral body height and alignment and osseous healing around the cement cast. In this case, a more invasive procedure of corpectomy and anterior column stabilization could be successfully avoided by armed kyphoplasty.