Kyphoplasty Technique

Dorn Spinal Therapy

Spine Healing Therapy

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After induction of general or regional anesthesia, the patient is placed in the prone position on a radiolucent table. Biplanar (C-arm) fluoroscopy (one for anteroposterior and one for lateral views) is utilized throughout the entire procedure. Entry into the vertebral body is via penetration with a Jamshidi needle either through a transpedicular or extrapedicular approach (slightly superior and lateral to the pedicle). The transpedicular approach is favored in the lower thoracic and lumbar spine whereas the extrapedicular approach is used in the middle to upper thoracic spine. A posterolateral entry into the vertebral body anterior to the transverse process and exiting nerve root is another approach that allows direct access to the anterior vertebral body, especially in the lumbar region. Once the vertebral body is penetrated, a guide wire is placed through the Jamshidi needle into the posterior portion of the vertebral body. A blunt cannula is then placed over the guide wire followed by a working cannula. The inner cannula is removed, which allows placement of a handheld drill into the vertebral body. The path created by the drill is directed toward the anterior half of the vertebral body allowing delivery of the inflatable bone tamp (Fig. 3). The proper position of the inflatable bone tamp (balloon) is identified by radiographic markers by anteroposterior and lateral fluoroscopy. The balloon should reside in the anterior half of the vertebral body. The balloon is then inflated, elevating the end plates in an attempt to restore vertebral body height. Inflation should be discontinued if the balloon comes in contact with any cortical surface or if the maximum volume of the balloon is reached depending on the size of the balloon (15 mm in the thoracic spine and 20 mm in the lumbar spine). The balloon is filled with a radiographic contrast medium to evaluate the size of balloon expansion. The contralateral balloon can now be placed allowing for symmetric elevation of the vertebral end plates. Once both bone tamps are in place, an alternating slow filling of each balloon is undertaken until the pressure manometer indicates a pressure of approximately 150 psi (maximum 220 psi).

FIGURE 3 Pictorial of the kyphoplasty technique. (A) A typical vertebral body compression fracture prior to kyphoplasty. (B) The inflatable bone tamp is inserted into the fractured vertebral body. (C) The balloon is inflated, elevating the vertebral end plates attempting to restore vertebral height. (D) The balloon is deflated and withdrawn leaving a void in the vertebral body. Polymethylmethacrylate (PMMA) is then inserted through the cannula. (E) The void is filled with PMMA. The vertebral body is now elevated and stabilized. Source: Courtesy of Kyphon, Inc., Santa Clara, California, U.S.A.

FIGURE 3 Pictorial of the kyphoplasty technique. (A) A typical vertebral body compression fracture prior to kyphoplasty. (B) The inflatable bone tamp is inserted into the fractured vertebral body. (C) The balloon is inflated, elevating the vertebral end plates attempting to restore vertebral height. (D) The balloon is deflated and withdrawn leaving a void in the vertebral body. Polymethylmethacrylate (PMMA) is then inserted through the cannula. (E) The void is filled with PMMA. The vertebral body is now elevated and stabilized. Source: Courtesy of Kyphon, Inc., Santa Clara, California, U.S.A.

The end point of fracture reduction occurs when (i) adequate reduction of the compression fracture is accomplished, (ii) pressure readings approach 220 psi, (iii) cortical proximity of the bone tamp occurs based on orthogonal fluoroscopic images, and (iv) maximum inflation volumes as read from the syringe barrel connected to the inflation device (4 cc for 15 mm length and 6 cc for 20 mm length tamps) occurs. Factors that ultimately determine the final pressure and volume of the balloon tamp depend on the volume and density of the vertebral body (trabecular microarchitecture), as well as the age (healing rate) of the compression fracture. Higher pressures are generally needed for more dense bone as well as for subacute fractures whereas low pressures are commonly experienced in less dense bone and acute fractures. The surgeon must be vigilant in detecting any evidence of a cortical breech or leakage of any contrast material from the balloon prior to the insertion of cement. Once the desired reduction is obtained or maximal pressure is achieved, the bone tamp is deflated and removed on only one side to prevent the occasional loss of reduction in more acute fractures. PMMA, which at present (2001) is not approved for use in the spine by the Food and Drug Administration, is then mixed with sterile barium and placed into a 20 cc syringe. The viscosity of the cement should be on the thicker side to prevent inadvertent leakage through any cortical defect or via a venous conduit. The volume of cement used normally exceeds the volume of balloon inflation by 1 cc. Under low-pressure injection force, the PMMA is delivered through the cannula into the created void under continuous fluoroscopic monitoring. Cement extravasation may occur if the PMMA is too runny and/or a cortical margin is violated. If cement extravasation is noted, injection is immediately halted and time should be given for further cement hardening before further cement injection is commenced. Although PMMA leakage is common, significant embolization of the lungs and significant canal intrusion are rare. Once cement injection is completed, and approximately two to three minutes pass, the cannulas are removed and the PMMA is allowed to further harden. A final anteroposterior and lateral image is obtained to document cement location and end plate elevation (Fig. 4).

Contraindications for performing kyphoplasty include (i) cases where there is significant vertebral body compression (i.e., the vertebral body height is smaller than the sagittal pedicle height), making the procedure difficult to perform; (ii) when an obvious defect is present in the middle column (posterior cortex) that may lead to inadvertent cement extravasation into the spinal canal; and (iii) an uncorrectable coagulopathy. A relative contraindication for this procedure is seen in the patient with multiple levels of compression where the painful level cannot be identified.

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