G.BonaldiNeuroradiologia, Ospedali Riuniti

Bergamo - ItalyA. Cianfoni

Radiology Dept., MedicalUniversity South Carolina; Charleston,

SC, USA

mail@bonaldi.org

Posterior Vertebral Arch Cement Augmentation to

Prevent Fracture of Spinous Processes after Interspinous

Spacer Implant

Intermittent neurogenic claudication

from spinal/foraminal

stenosis: pain/discomfort radiating to

buttocks/thigh/lower limbs, standing and

walking, exacerbated by lumbar extension, relieved by flexion

FACETS DEGENERATION PSEUDO-SPONDILOLISTHESIS

80

FACETS DEGENERATION FORAMINAL STENOSIS

Schematic of the X STOP in situ. The implant is placed between the

spinous processes. The lateral wings prevent anterior and lateral

migration, and the supraspinous ligament prevents posterior

migration.

The Treatment Mechanism of an Interspinous Process Implant for Lumbar Neurogenic Intermittent Claudication

Joshua C. Richards, et al. SPINE 2005;30:744–749

In extension, the implant significantly increased the canal area by 18% (231–273 mm2), the subarticular diameter

by 50% (2.5–3.7 mm), the canal diameter by 10% (17.8 –19.5 mm), the foraminal area by 25% (106–133 mm2), and the foraminal width by 41% (3.4 –

4.8 mm).

Conclusions: The results of this study show that the X STOP interspinous

process implant prevents narrowing of the spinal canal and foramina in

extension.

A randomized, controlled, prospective

multicenter trial comparing ...X STOP...with

patients treated nonoperatively.

191 patients were treated, 100 in the X STOP

group and 91 in the control group. A Multicenter, Prospective, Randomized Trial Evaluating the X STOP Interspinous Process

Decompression System for the Treatment of Neurogenic Intermittent ClaudicationTwo-Year Follow-Up Results

James F. Zucherman, et al. SPINE Volume 30, Number 12, pp 1351–1358, 2005

RESULTS

The X-STOP provides a conservative yet effective treatment for patients suffering from lumbar spinal stenosis.

A Multicenter, Prospective, Randomized Trial Evaluating the X STOP Interspinous ProcessDecompression System for the Treatment of Neurogenic Intermittent Claudication

Two-Year Follow-Up ResultsJames F. Zucherman, et al. SPINE Volume 30, Number 12, pp 1351–1358, 2005

...the success rate in the X-STOP interspinous process

decompression group was 78% at an average of 4.2 years postoperatively and are

consistent with 2-year results reported by Zucherman...

Interspinous process decompression with the X-STOP device for lumbar spinal stenosis: a 4-year follow-up study.

Kondrashov DG, Hannibal M, Hsu KY, Zucherman JF.J Spinal Disord Tech. 2006 Jul;19(5):323-7.

-z2

--z3

Bending moment

Bending moment

Extension with a rigid interspinous spacer

spacer

ICR

The rigid interspinous spacer will move the ICR posteriorly, modifying the loads on the different parts of

the S.U.

tension

compression

spaceruninstrumented

S.U. in extension

Back pain induced from pressure

originating in the facets and/or

posterior anulus of the lumbar spine may

be relieved by interspinous

decompression.The Effect of an Interspinous Process Implant on Facet

Loading During ExtensionCraig M. Wiseman, et al. SPINE 2005;30:903–907

InSpace

Superion(VertiFlex Incorporated)

APERIUS™ PercLID™ Systemby Kyphon (Medtronic)

Technique

Implant of rigid interspinous devices is contraindicated in osteoporotic patients.

But also elderly and/or osteopenic patients can be considered at risk for bone fragility and consequent fracture of spinous processes after device implant?

After 6 weeks

Polymethyl-Methacrylate (PMMA) bone cement augmentation of the posterior vertebral elements has been proven to increase stiffnessand failure load values of the augmented bony structures in a cadaveric study

A novel technique of intra-spinous process injection of PMMA to

augment the strength of an inter-spinous process devicesuch as the X STOP.

Idler C, Zucherman, JF, Yerby S, Hsu KY, Hannibal M, Kondrashov D. Spine. 2008;33:452-456.

Von Mises stresses of the structure

Table

Case 1Osteoporosis in Spinal

Process-

Osteoporosis in Lamina

Case 2Bone Cement in Spinal

Process-

Osteoporosis in Lamina

Case 3Bone Cement in Spinal

Process-

Bone Cement in Lamina

0.534E-7 0.513E-7 0.456E-7Strain

Stress [MPa] 41.679 39.877 37.679

Study Design: Non-randomized, historically controlled, clinical trial

To assess the safety, feasibility, and effectiveness of posterior vertebral arch cement augmentation in preventing delayed spinous processes’ fracture after interspinous spacer device implant in patients with risk factors for fragility fractures.

Patients were classified at risk of fragility fractures according to one of the following criteria:

•age >75 years•osteopenia (as defined by WHO on a bone scan with a T-score < -1.0)•history of prior fragility fracture•chronic steroid therapy.

Laminoplastyoperative technique

From June 2007 to March 2010, we implanted interspinous spacers in 35 eligible patients with risk factors for fragility fractures

16 patients did not undergo laminoplasty

19 patients laminoplasty was also performed

The combined procedure was uneventful in all 19 patients, except for minor paralaminar leakages, asymptomatic. No intraforaminal or intravascular leakages.

A symptomatic delayed spinous process fracture was diagnosed in 4 out of 16 patients who did not undergo laminoplasty (25.0%), while no fractures were diagnosed in the 19 treated patients (p=0.035).

CONCLUSIONLaminoplasty is feasible

and safe.It seems effective inpreventing delayed

fractures of the posterior arch after interspinous spacer placement, in

patientsat risk for fragility

fractures.

mail@bonaldi.org

Thank you

GRAZIE