Cement Application

Dorn Spinal Therapy

Spine Healing Therapy

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Optimal visualization of the cement and permanent fluoroscopic control at time of application are crucial to the achievement of vertebroplasty. Early recognition of a cement leak enables the

FIGURE 11 Diagram showing that the needle tip should not cross the medial border of the pedicle on the anteroposterior view (left) before it has reached the posterior cortex of the vertebral body on the lateral view (centei).

FIGURE 12 Diagram showing an example of wrong needle track: needle placement is apparently satisfactory on the anteroposterior (left) and lateral (center) views. However, the medial cortex of the pedicle has been broken at the time of approach thus creating a path for cement leakage into the spinal canal.

FIGURE 12 Diagram showing an example of wrong needle track: needle placement is apparently satisfactory on the anteroposterior (left) and lateral (center) views. However, the medial cortex of the pedicle has been broken at the time of approach thus creating a path for cement leakage into the spinal canal.

injection to be stopped and prevents clinical complications. The following precautions are helpful for early detection of cement extravasation:

1. High-quality biplane (or C-arm) fluoroscopy as well as perfect C-arm positioning is essential.

2. Optimal opacification of the cement requires at least 30% barium sulfate or equivalent by weight (41) or addition of tungsten or tantalum powder (11,17). The greater the cement opacity is, the faster the operator will notice a cement leakage.

3. Refrigeration of the cement gives a longer working time.

4. It is important to use the recommended proportions of MMA polymer (powder) and monomer (fluid), respectively. It must be kept in mind that increasing the proportion of fluid (monomer) accelerates cement hardening. Once the polymer and the monomer are mixed, the mixture is stirred at a rate of one turn per second. A more rapid movement accelerates cement hardening.

FIGURE 13 Diagram showing an example of wrong needle placement: the needle tip is apparently contained within the vertebral body both on the anteroposterior (left) and lateral (center) views. However, the needle tip is actually partly in the prevertebral space due to the round shape of the vertebral body (right). This is more likely to occur in the case of a too-sagittal needle path.

FIGURE 13 Diagram showing an example of wrong needle placement: the needle tip is apparently contained within the vertebral body both on the anteroposterior (left) and lateral (center) views. However, the needle tip is actually partly in the prevertebral space due to the round shape of the vertebral body (right). This is more likely to occur in the case of a too-sagittal needle path.

FIGURE 14 Seventy-one-year-old man with L1 osteoporotic fracture with high level of pain despite high doses of morphinics. (A) Lateral radiographs showing marked wedge fracture of L1. (B) Sagittal magnetic resonance Tl-weighted image showing low signal intensity in L1 vertebral fracture. (C) Sagittal T2-weighted image showing intravertebral high fluid-like, signal intensity in L1 vertebral fracture. (D) Transverse computed tomography (CT) image through L1 vertebral fracture showing anterior vacuum phenomenon in L1 vertebral fracture. (E, F) Anteroposterior (E) and lateral (F) radiographs of L1 showing placement of the needle into the central part of L1 just posterior to the area of vacuum phenomenon. (G, H) Anteroposterior (G) and lateral (H) radiographs during vertebroplasty after cement injection showing cement filling of the L1 intravertebral cleft. There is some cement leakage in L1-L2 intervertebral disk and in the anterior prevertebral space. (I) Postvertebroplasty CT image showing cement distribution into the right part of L1 and replacing the vacuum phenomenon.

FIGURE 14 Seventy-one-year-old man with L1 osteoporotic fracture with high level of pain despite high doses of morphinics. (A) Lateral radiographs showing marked wedge fracture of L1. (B) Sagittal magnetic resonance Tl-weighted image showing low signal intensity in L1 vertebral fracture. (C) Sagittal T2-weighted image showing intravertebral high fluid-like, signal intensity in L1 vertebral fracture. (D) Transverse computed tomography (CT) image through L1 vertebral fracture showing anterior vacuum phenomenon in L1 vertebral fracture. (E, F) Anteroposterior (E) and lateral (F) radiographs of L1 showing placement of the needle into the central part of L1 just posterior to the area of vacuum phenomenon. (G, H) Anteroposterior (G) and lateral (H) radiographs during vertebroplasty after cement injection showing cement filling of the L1 intravertebral cleft. There is some cement leakage in L1-L2 intervertebral disk and in the anterior prevertebral space. (I) Postvertebroplasty CT image showing cement distribution into the right part of L1 and replacing the vacuum phenomenon.

5. The cement is injected when it has a tooth-paste consistency. To avoid the problem of an overly liquid cement, Wong and Mathis perform a "drip test" in which the operator waits until the cement balls up at the end of the needle and no longer flows downward from the tip (41).

6. Use of a screwing cement injection syringe also permits injection of a more viscous cement and more time for injection.

7. In the presence of a vascular bone, allowing 30 to 60 seconds or more for a small amount of PMMA from the first injection to set in the vertebral body before injecting all the PMMA, is helpful (Lawler GJ, personal communication to Peh and Gilula) (42).

8. If viscous cement clogs in the needle during the application process, the needle stylet can be used as a plunger to push the cement into the vertebral body with a high degree of control (41).

9. In cases of PMMA leakage, the cement injection is stopped, the needle tip is displaced, and the hardening of the first PMMA injected is awaited, so that it can serve as a plug (personal communication L. Gilula). This is easier to perform with cements that harden relatively slowly, as compared to plain PMMA such as Simplex®. Keeping the PMMA monomer in the freezer up to the last moment and maintaining it in an ice bath between use also allows more time for injection. The room temperature must be taken into account. High room temperature will result in accelerated cement hardening. 10. One should not try to obtain the perfect image (complete vertebral body filling) and it must be kept in mind that it is not necessary to completely fill the vertebral body. Clinical result is not closely dependent on the amount of cement injected (3). In addition, Belkoff et al. have shown that 2 to 4 mL of cement is sufficient to restore strength and stiffness of the vertebral body (43).

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