Pedicle Screw Design and Cement Augmentation in Osteoporotic Vertebrae

Abstract

Polymethylmethacrylate cement augmentation clearly enhances pedicle screw fixation in osteoporotic vertebrae when tested in pure pullout. The technique used for cement injection and choice of specialty screws can have a significant impact on the magnitude of this effect. Fenestrated screws have the capacity to confine cement placement in the vertebral body and may provide enhanced safety from cement extrusion into the spinal canal. It is feasible to inject high-viscosity PMMA through this fenestration geometry, and higher-viscosity cement may enhance the fixation effect.

Percutaneous Cement-Augmented Screws Fixation in the Fractures of the Aging Spine: Is It the Solution?

“…One of the limits of these augmented screws was related to a high risk of cement leakage associated with a nonacceptable neurologic risk. Recent developments of partially fenestrated screws are one the solutions to these risks as it allows a cement injection in the first anterior third of the screw, increasing the pull-out strength with a decreased risk of leakage [9] (Figure 3). …”

“…In every case, fixation of the fracture was done using a posterior percutaneous transpedicular instrumentation using cement-augmented cannulated fenestrated screws (Longitude, Medtronic, or Mantis, Stryker). Screws used in this study were partially cannulated fenestrated screws that allow injection of the cement in the first third of the screw when compared to fully cannulated fenestrated screws [9]. Pedicle screws were systematically inserted under anteroposterior and lateral fluoroscopic guidance.…”

Augmented screws in angular stable plating of the proximal humerus: What to do when revision is needed?

“…Choma et al showed torque limits of augmented pedicle screws between 1.2 and 1.8 Nm in osteoporotic vertebrae. None of the tested vertebral bodies sustained failure of the cement-bone interface (Choma et al, 2012).…”

Surgical treatment of osteoporotic thoraco-lumbar compressive fractures: the use of pedicle screw with augmentation PMMA

“…Numerous studies demonstrate that PMMA augmentation can increase the screws' pull out strength in osteoporotic and normal vertebrae [18].…”