Vertebral body stenting: a new method for vertebral augmentation versus kyphoplasty

Abstract

Vertebroplasty and kyphoplasty are well-established minimally invasive treatment options for compression fractures of osteoporotic vertebral bodies. Possible procedural disadvantages, however, include incomplete fracture reduction or a significant loss of reduction after balloon tamp deflation, prior to cement injection. A new procedure called “vertebral body stenting” (VBS) was tested in vitro and compared to kyphoplasty. VBS uses a specially designed catheter-mounted stent which can be implanted and expanded inside the vertebral body. As much as 24 fresh frozen human cadaveric vertebral bodies (T11-L5) were utilized. After creating typical compression fractures, the vertebral bodies were reduced by kyphoplasty (n = 12) or by VBS (n = 12) and then stabilized with PMMA bone cement. Each step of the procedure was performed under fluoroscopic control and analysed quantitatively. Finally, static and dynamic biomechanical tests were performed. A complete initial reduction of the fractured vertebral body height was achieved by both systems. There was a significant loss of reduction after balloon deflation in kyphoplasty compared to VBS, and a significant total height gain by VBS (mean ± SD in %, p < 0.05, demonstrated by: anterior height loss after deflation in relation to preoperative height [kyphoplasty: 11.7 ± 6.2; VBS: 3.7 ± 3.8], and total anterior height gain [kyphoplasty: 8.0 ± 9.4; VBS: 13.3 ± 7.6]). Biomechanical tests showed no significant stiffness and failure load differences between systems. VBS is an innovative technique which allows for the possibly complete reduction of vertebral compression fractures and helps maintain the restored height by means of a stent. The height loss after balloon deflation is significantly decreased by using VBS compared to kyphoplasty, thus offering a new promising option for vertebral augmentation.

Surgical procedure and initial radiographic results of a new augmentation technique for vertebral compression fractures

“…However, a significant loss of the restored height after balloon deflation prior to cement injection is a major disadvantage of percutaneous kyphoplasty. Recent studies have shown that the initial reduction achieved by the balloon is mostly lost after deflation [10], because the cavity created partially collapses before the bone cement can be injected [11]. Therefore, the expected spinal re-alignment cannot be completely achieved using percutaneous kyphoplasty [11].…”

Vertebral Augmentation with Nitinol Endoprosthesis: Clinical Experience in 40 Patients with 1-Year Follow-up

“…It has been observed during balloon kyphoplasty procedures that vertebral height restored during inflation of the bone tamp can be lost after balloon deflation due to elastic recoil of the vertebral body. This has been demonstrated in an in vitro study where anterior height loss was significantly higher in balloon kyphoplasty compared with vertebral body stenting (VBS): 12 versus 4 %, respectively (p = 0.003) [9]. Both kyphoplasty and VBS rely on balloon-assisted vertebral fracture reduction methods.…”

“…A comparative trial involving balloon kyphoplasty and a titanium implant was performed in a biomechanical in vitro study [9]. Significantly greater vertebral height loss (p \ 0.025) was detected after reconstruction with kyphoplasty repair compared with the titanium mesh implant.…”

“…A nitinol vertebral endoprosthesis has been designed to treat VCF, providing an intervertebral scaffold that maintains height restored during the procedure before cement injection. Less vertebral height loss compared with kyphoplasty has been demonstrated [9,10].…”

“…This device allows the preservation of cancellous bone and promotes cement interdigitation and perfusion, which ultimately result in height restoration and a potential for reduced fracture due to a reduction in the stiffness of the treated vertebrae. For these reasons and because of the possibility to reduce the volume of the cement used, nitinol implants may offer several advantages compared with kyphoplasty [9].…”