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Technique

Lumbar Procedure: Unipediculate approach "stay in the ring" technique
  • The patient is positioned prone. Some patients cannot remain in a prone position and are placed three-quarter prone; the flexibility of the C-arm system allows the operator to adjust for these differences.
  • Exclusive fluoroscopy guidance requires two fluoroscopic views to be able to appreciate the exact needle position. Biplane fluoroscopic equipment facilitates the rapid acquisition of guidance information in two planes. It takes longer with a single-plane than with a biplane system, but it is feasible to use a single-plane fluoroscopic system.
  • We use the unipediculate approach in percutaneous vertebroplasty which allows filling of both vertebral halves from a single puncture site (96% of cases) with no statistically significant difference in clinical outcome compared to bipediculate vertebroplasty.
  • To facilitate the procedure, the approach should be visualized on a preprocedural CT scan (or axial MR imaging). The entry point and its distance from the midline (spinous process) can be measured on the preprocedural CT scan or MR films. A paramedian line lateral and parallel to the midline is drawn depending on the measurement performed on the previous CT or MR scan (approximately 5 cm, see case 2). The site of insertion of the needle is the point of crossing the paramedian line with the level of the vertebral body (lateral fluoroscopy). This measured distance is marked on the patient skin.
  • Place a pilot spinal (22-gauge) needle into the soft tissues at marked level,
  • Advance spinal needle to the pedicle and confirm position. Use the Tandem technique to insert the vertebroplasty needle. In contradistinction to the needle position in the bipediculate approach, where the tip of the needle enters the pedicle inferolateral to the superior articulating facet, the needle tip in the unipediculate approach enters the pedicle lateral to the superior articulating facet.
  • Once the needle tip has passed through the pedicle switch to lateral fluoroscopy.
  • The vertebroplasty needle is advanced into the pedicle under anteroposterior (AP) fluoroscopic control; the principle is to stay in the ring of the pedicle in anteroposterior view (AP-wiew) until the needle has reached the posterior wall of the vertebra in lateral view (L-view). Once the needle has reached the vertebral body, the procedure is continued under lateral fluoroscopy projection. The needle is advanced until it approaches the anterolateral wall in the midline (see movie, case 2). The needle tip is advanced as far forward as the junction of the middle one-third to one-fourth of the vertebral body at middle vertebral height (see Fig 2 to 4).

Fig. 1: "Stay in the ring" ( the pedicle).

Fig. 2: The tandem technique. The appropriate fluoroscopic anteroposterior view for pedicular approach is a straight anteroposterior view, although some cases may require a 5°–10° angulation. The appropriate Lateral projection is a straight lateral view.

Fig. 3: The principle is to stay in the ring (the pedicle) in AP-view until the needle has reached the posterior wall of the vertebra in lateral projection.

Fig. 4: Use the AP-view to ensure the needle tip is joining the midline of the vertebral body and at the same time use the L-view to ensure the needle tip is advanced as far forward as the junction of the middle one-third to one-fourth of the vertebral body at middle vertebral height.