Percutaneous Vertebroplasty: Indications, Technique, and Results Sequence of Operations

Transcription

1 Percutaneous Vertebroplasty: Indications, Technique, and Results Sequence of Operations Technique: Sequence of Operations Materials Dual Guidance Local Anesthesia Puncture Vertebral Body Biopsy Vertebral Venography Acetabular Cementoplasty

2 Preparation of Cement Injection of Cement Materials 10-gauge beveled vertebroplasty needle (OptiMed medizinische Instrumente GmbH, Ettlingen, Germany.) for thoracic and lumbar spine, and 15-gauge needle for cervical spine Surgical hammer Acrylic cement (PMMA) (Simplex, Howmedica, Rutherford, NJ; Osteopal V, Biomet Merck, Sjobo Sweden; or Palacos low viscosity, Biomet Merck) Pressure syringe (Optimed) to facilitate the injection of the viscous cement tantalum or tungsten (acrylic cement is not sufficiently radiopaque) Sterile drapes, towels 22-gauge needle for anesthesia, scalpel Iodine, 1% lidocaine Figure S1a. 10-gauge needle for percutaneous cementoplasty. Figure S1b. Pressure syringe for percutaneous cementoplasty.

3 Figure S1c. Percutaneous cementoplasty tools: Surgical hammer, pressure gun, 10-gauge needle Figure S1d. Percutaneous cementoplasty materials: PMMA, pressure gun, tantalum, 10-gauge needle. Examples of Vertebroplasty Sets Depending on the manufacturer, a complete set or stand-alone components are available. The principal manufacturers of percutaneous cementoplasty material are Optimed, Cook (Bloomington, Ind), Stryker Medical (Kalamazoo, Mich), and Parallax Medical (Scotts Valley, Calif). Information on Cook and Optimed materials are available on the Internet. The following table provides the available sets and Web links to the manufacturers. Percutaneous Cementoplasty Sets Manufacturer Products Web Link Optimed Cook Cemento vertebroplasty system Osteo-Force high pressure injector set; Osteo-Site bone biopsy needle systeme/ The Cemento set contains the following: Needle o A 10- or 15-gauge, special beveled-edge needle with large metal wings for easy insertion and removal and easy rotation o Special needle alloy with reduction of artifacts at CT and excellent cement visibility in the cannula o Highly polished inner cannula for less cement friction, less exertion during injection, and faster injection of the viscous cement

4 o Shock resistant stylet Aspiration cannula with extra-large inner diameter for efficient and fast cement aspiration Cementogun o Screw applicator, pressure resistant; fast pressure buildup with precise speed control of the injection o Consistent cement delivery o Quick release lever that ensures immediate stopping of the injection o Easy and fast cement aspiration directly into the syringe with the aspiration cannula; extra-large caliber special Luer-Lock for efficient aspiration and injection of the cement Connecting tube; reduces radiation for the physician Figure S2a. 1. Cement aspiration cannula 2. Connecting screw 3. Cemento gun 4. Pressure resistant screw applicator 5. Flexible connector 6. Quick release lever (immediate stopping of the injection); easy and fast cement aspiration 7. Syringe 8. Head 9. Wings 10. Needle 11. Special beveled edge Figure S2b. Flexible connector.

5 Figure S2c. 10-gauge needle, handy metal wings for easy insertion and removal and easy rotation of the needle, special beveled edge. Figure S2d. Pressure gun. (1) Quick release lever (immediate stopping of the injection), (2) screw applicator (pressure resistant). Figure S2e. Quick release lever (immediate stopping of the injection), easy and fast cement aspiration directly into the syringe.

6 Figure S2f. 10-gauge needle, handy wings. Figure S2g. 10-gauge needle, shock resistant stylet. Figure S2h. Screw applicator (pressure resistant), consistent cement delivery, quick release lever, easy and fast cement aspiration directly into the syringe. Dual Guidance For minimally invasive technique, the best and safest guidance seems to be combined CT and fluoroscopy (10). This combination allows precise needle placement, reduces complications and increases the comfort of the operator. The dual guidance technique using CT and C-arm fluoroscopy is particularly useful in percutaneous cementoplasty (9,7 10). A mobile C-arm is positioned in front of the CT gantry. However, fluoroscopy and biplane fluoroscopy can be used by well-trained radiologists if access to the CT room is difficult (18) Figure S3a. Dual guidance CT and fluoroscopy.

7 Figure S3b. Dual guidance fluoroscopy and CT. A combination of CT and fluoroscopy for interventional procedures has been recommended (7 10). For fluoroscopy, a mobile C-arm is used, positioned in front of the CT gantry. By using a rotating fluoroscope and CT, the structure to be punctured can be visualized in three dimensions and with exact differentiation of anatomic structures, which in many cases is not possible with fluoroscopy alone. Two mobile monitors are placed in front of the physician, displaying the last stored image and the fluoroscopic image. The operator can switch from CT to fluoroscopy and vice versa at any time, as shown in the dual guidance movie. In percutaneous vertebroplasty, the intervention begins with CT and is followed by fluoroscopy. The needle is placed precisely and safely under CT guidance. The injection of the PMMA requires real-time imaging and is therefore performed under fluoroscopic control, as shown in the cement injection movie. This combination has many advantages. The possibilities for the simultaneous combination of the two imaging modalities are almost unlimited, and other applications in interventional radiology are possible. Note: Links to the movies can be found in the Supplemental Materials section of this article. Figure S3c. CT pathway.

8 Figure S3d. CT control. Local Anesthesia The procedure is performed with the patient under local anesthesia usually combined with neuroleptanalgesia. The skin, subcutaneous layers, muscles, and periosteum are infiltrated with local anesthetic (1% lidocaine ) by using a 22-gauge 9-cm-long needle. The procedure is illustrated in the local anesthesia movie. Note: Links to the movie can be found in the Supplemental Materials section of this article. Figure S4. Administration of local anesthesia. Puncture The patient is positioned prone or in lateral decubitus on the CT table. The entry point and the pathway are selected on the CT scan. After the patient is positioned and under neuroleptanalgesia and local anesthesia, the 10- or 14-gauge vertebroplasty needle is safely placed under CT guidance. The approach is anterolateral at the cervical level. The optimal approach is transpedicular at both the thoracic and lumbar levels, but the intercostovertebral route can be used at the thoracic level and the posterolateral route at the lumbar level. The use of CT for planning of the pathway and positioning of the needle allows medial positioning of the needle tip in the anterior third of the vertebral body. Contralateral access is seldom necessary to obtain a good vertebral filling. Cortical perforation can require the aid of a surgical hammer. When the needle is in the optimal position (needle tip in the anterior third of the vertebral body or in the anterior portion of the tumor), the imaging mode is switched to fluoroscopy. For fluoroscopic guidance, the patient is positioned prone. The appropriate fluoroscopic profile for the pedicular approach is a straight anteroposterior view, with 5 10 angulation. The pedicle is located with fluoroscopy and appears oval. The needle is advanced into the pedicle under fluoroscopic control. For an optimal approach, the entry point and its distance from the midline (spinous process) can be measured on the axial CT scan or MR image of the patient. The needle tip is positioned in the anterior part of the vertebral body. With this technique, the needle is placed in the ipsilateral half of the vertebra; a bipediculate approach is often necessary for optimal filling of the vertebral

9 body. After injection of the cement on one side, placement of the needle in the opposite pedicle prolongs the procedure and increases the risk of extravasation. Figure S5a. Drawing shows transpedicular route, axial view. Figure S5b. Drawing shows transpedicular route, sagittal view. Figure S5c. Drawing shows intercostovertebral route. Figure S5d. Puncture performed with surgical hammer. Figure S5e. Puncture is performed.

10 For the thoracic spine, the intercostovertebral route can be used if the pedicles are too thin. The thoracic vertebrae are reached via an oblique posterolateral intercostal approach at an angle of 35 from the patient's sagittal plane, as recommended by Laredo et al (19). Figure S6a. Schematic shows posterolateral intercostal puncture approach at an angle of 35 from the patient's sagittal plane. Figure S6b. Schematic shows anatomic relationships in 35 oblique prone position. 1. Transverse process. 2.Costovertebral joint. 3. Disk. 4. Contralateral lamina.5. Vertebral body. 6. External edge of the articular process. 7. Line of pleural reflection. 8. Rib head. Cementoplasty needle under fluoroscopic control is shown in red. Other Procedures Vertebral Body Biopsy If a vertebral body biopsy is needed, it can be performed during the same operating time as vertebroplasty. After puncture, an 18-gauge biopsy needle (Ostycut; Bard/Angiomed, Covington, Ga) is used, under fluoroscopic control in coaxial mode to the Optimed vertebroplasty needle, to perform the samplings. Vertebral Venography Vertebral venography is performed only in hypervascularized lesions with overflow of blood. In all other cases, the contrast medium is washed out too slowly and can interfere with the injection of cement. Acetabular Cementoplasty Cementoplasty in the acetabula is done in the same way as in the vertebrae. First, the lesion is located and the pathway selected under CT guidance. The 10-gauge needle is then positioned in the metastasis under CT guidance, and the cement is injected under fluoroscopic control. Two to eight milliliters of PMMA is injected depending on tumor

11 size. The injection is stopped if the cement begins to leak. Sometimes two needles are necessary for good filling of the bone. Figure S7a. Vertebral body biopsy. Figure S7b. Vertebral body biopsy under fluoroscopic control. Preparation of the Cement The acrylic cement (low-viscosity Palacos, Osteopal, or Simplex) is prepared by mixing 40 g of PMMA powder and 20 ml of fluid monomer. Since the acrylic cement alone is not radiopaque enough, 3 g of tantalum (depending on patient morphology) is added to 20 ml of the mixture. Barium or tungsten can also be used. During the first seconds after mixing, the cement has a thin consistency. It then becomes pasty and thick. The cement has to be injected during its pasty polymerization phase to prevent distal venous migration. Normally, 2 7 ml of cement are injected with a 2-mL Luer-Lock syringe. PMMA is too viscous to be handled without difficulty in this conventional way because injection time is short and the operator must fumble with multiple syringes. The injection set on the market (Cemento; Optimed) allows aspiration and direct injection of the cement from the same syringe in a continuous flow with minimum effort. The cement preparation movie illustrates the procedure. Note: Links to the movie can be found in the Supplemental Materials section of this article.

12 Figure S8a. PMMA powder is mixed with monomer. Figure S8b. PMMA plus monomer is mixed with tantalum powder. Figure S8c. End product after mixing. Figure S8d. Syringe filling. Injection of the Cement This phase of the procedure is strictly controlled under lateral fluoroscopy. The injection of acrylic cement is stopped immediately whenever an epidural or paravertebral opacification is observed, to prevent spinal cord compression. When vertebral filling is insufficient, a contralateral injection is suggested to complete the filling. After vertebral filling, the mandrin of the needle is replaced, again under fluoroscopic control, before the cement begins to set (because the needle itself contains about 1 ml of cement). The needle is then carefully removed. Six to seven minutes after mixing, the PMMA begins to harden. During this hardening time, the cement becomes hot (about 90 O C).

13 The patient should be under neureuleptanalgesia to control pain. Monitoring of arterial pressure is necessary during the procedure because PMMA injections can induce transient hypotension. Total procedure time ranges from 20 to 50 minutes. In patients with osteoporosis and symptomatic hemangioma, optimal filling (2.5 4 ml) of the vertebral body is required to obtain both effects of percutaneous vertebroplasty: consolidation and pain relief. In patients with tumoral disease, percutaneous cementoplasty is usually performed for excruciating pain. In these cases, a small volume ( ml) of cement provides good pain relief. The cement injection movie illustrates the procedure. Note: Links to the movie can be found in the Supplemental Materials section of this article. Figure S9a. Injection of the cement. Figure S9b. Injection of the cement under fluoroscopic control. Figure S9c. CT guidance.