High potential (or “border line indications”) of percutaneous vertebroplasty with scanner guidance
Tips and tricks
N.Amoretti, O.Hericord, ME Amoretti, PY.Marcy,P.Brunner,O.Hauger
Percutaneous vertbroplasty was first performed by Deramond in 1984 at the Amiens Centre Hospitalier Universitaire in France. It consists in the injection of acrylic cement in the vertebral body to reinforce it. The first indication was an aggressive angioma. Indications have been extended to metastatic vertebral state and to hyperalgic osteoporotic fractures. The evolution of material and experience of operators allowed for an expansion of the use to traumatic fractures and metastatic vertebrae reaching corticals, in particular posterior. The objective of this article is to present consolidation techniques allowing treatment of patients previously unable to be treated by vertebroplasty. Diverse techniques are necessary to increase the safety of the procedure, learning and control of simple vertebroplasties are compulsory before performing more advanced procedures.
Description of the techniques:
The common feature of the cases presented here is the double scannographic and fluoroscopic guiding system which allows for easier trocar positioning with better visualization of vertebral structures and lesions and to control the vertebral filling in real time to limit cement leaks (gangi et al, amoretti et al skeletal). This takes place in a interventional scanner room with surgical aseptic conditions
A preliminary MRI is necessary to analyze the vertebral level to treat, by visualization of a vertebral hypersignal in weighted sequence in T2 with fatty signal cancellation showing a secondary edema at the bodily lesion. In some cases, in particular metastatic or myelomatous, a complementary scan is useful thanks to higher spatial resolution, allowing better judgement on feasibility of intervention.
Patient setup
The patient is set in procubitus with a hyperlordosis ventral block. A volume acquisition on the whole rachis is performed. The multiplanar reconstruction allow for check of the level to treat and the way. The stone of the way is realized on the axial cuts allowing a tranpedicular approach, intercostal-vertebral of extra-vertebral depending on the level and the type of lesion to treat. A radio-opaque point is positioned on the skin in function of the marks established on the axial cuts of the scanner and confirmed by a new acquisition. The preparation of the material requires: a sterile table drape, a perforated sterile drape (used for angioplasties), a 22 gauges needle for under cutaneous anesthesia, 1% xylocain, a scalpel and two 13 gauges trocars for guided vertebroplasty and vertebral biopsy.
All the interventions are performed under local anesthesia according to the same protocol : the local anesthesia is performed by injecting 3 ml of 1% xylocain, 3 min are enough before inserting the 20 gauges shiba needle 20 cm at the point of contact of the periost under scopic guide. A scanner control in step by step mode allows for confirmation of correct positioning of the shiba needle.Approximately 3 ml of 1% xylocain is again injected at the vertebral point of entry to perform the periosted anesthesia. The removable connector of the Shiba needle is pulled out, leaving space for a true guide on which the trocar perforates and inserts to the contact with the bone, in particular at the precise level of the anesthesia. The progress of the trocar in the vertebral body is occurring under iterative scopic guidance. A scanner control can confirm the correct position of the distal end of the trocar at the level of the zone to treat. A biopsie is performed using the coaxial canulae.
The cement preparation is performed with a mixer in closed loop to avoid vapors. The 1 ml syringe’s luer lock are filled at the early liquid phase of the cement. We use a cement (cook ref) radio-opaque in which we mix 4 g of tungsten to increase opacity. This high radio-opacity enables a perfect visualization during vertebral filling and represents an additional safety aspect. The cement must posses variable phases of viscosity in time from liquid to paste. The working time must be longer than 10 min at room temperature, the exothermic reaction occurs around 60C in vivo.
Vertebroplasty technique for vertebra-plana.
The position of the patient in hyperlodosis in order to reduce the fracture and increase the intra-somatic space is important. We systematically perform a extra-pedicular access or intercosto-vertebral access so that the trocar as more mobility in the vertebrae. The progression of the trocar is performed under scopic guidance, the penetration must be strictly intra-corporeal in the same axis as the fracture. A scanner control confirms the position in the fractured zone, the bevel of the trocar is oriented toward the important residual bone surface. We fill a first part of the vertebrae with a few drops of liquid cement to judge and anticipate the positioning and the frequent discal leaks. Under continual scopy, we visualize a linear diffusion intra-vertebral of the cement. Then we wait a few minutes to allow polymerization and get a high viscosity cement that we will push slowly in the cannula with a needle. The large viscosity at the end of the procedure is a key element to the correct filling of these fractures. The injection can be performed by filling the canulae and pushing the cement with the trocar. In case of a cement that is too liquid and a too large pressure applied at the point of intra-corporeal injection, the cement comes back up in the perforated needle to limit the risk of leaks at the epidural level. A thick and old cement diffuses close to the distal end of the trocar. Similarly the progressive retreat of the trocar by pushing to the needle the rest of the cement allows for perfect cementing in the rest of the way.
The subchondral space must be perfectly filled, the pressure in this space being smaller, the diffusion is easy. Also, a gain in height is frequently observed in this type of lesions. The post-operation precautions are the same as for osteoporotic fractures.
Vertebroplasty technique in the burst fracture of A2 type in the Magerl classification (split-burst fracture)
Vertebroplasty in the split-burst fracture is a delicate intervention for numerous reasons. The fracture separates the vertebral body into two parts with a possible recess of the posterior wall. This intervention stays in the limits of the indications of vertebroplasty, it must be decided in conjunction with the neurosurgical or orthopedic team.
Numerous publications show the efficacy of this procedure (amoretti, huet) and the small rate of complication. In our experience, the coupling of scopy and scanner is fundamental. The axial cuts allow for visualization of the extremities.
The progression of trocars is done successively by controlling the scanners and lateral scopies. We use 13 gauges trocars, the penetration is performed manually, we avoid using a surgical hammer to limit he risks of displacements of bone fragments. We **transfixions the fractured centre with the two trocars bilaterally and symmetrically. , their ends being located medially to limit lateral leaks.
The cement is injected at the level of the anterior fragment of the fracture at its paste phase, then the trocars are slowly withdrawn at the level of the fracture while injecting progressively the cement and create a cement bridge with the anterior fragment and the fracture trait. A scanner control verifies that the end of the trocars is located perfectly in the fracture. The cement is injected slowly in the cannula and pushes with the needle of the trocar.
The lateral scopy controls real time diffusion of the cement in the fracture. The axial scannographic cuts confirm the correct diffusion in the fracture and the absence of para-vertebral leaks. The trocars are progressively withdrawn while injecting cement in the cannula with a needle. Standing up is authorized the day after with wearing corset. The clinical and radiological follow up is rigorous to avoid detecting all neurological sign of compression and appreciate the vertebral consolidation.
Vertebroplasty techniques in the case of lytic mestastatic lesions or myelomatic with pejorative invasion of the anterior or posterior walls.
The tumoral extension at the posterior wall with or without epidural inflammation constituted a few years ago a counter-indication to vertebroplasty. The experience of conventional radiology teams allowed to progressively reaching that limit. Numerous precautions are necessary to avoid complications.
In case of lytic tumoral lesion invading the anterior wall.
The trocar is positioned on the most posterior part of the tumor so that the filling is performed from back to front and to better control the anterior diffusion. A control scanner confirms the correct position of the trocar at the intra-tumoral level. The injection of the cement is performed at the end of the work, that is during the really thick phase. The filling is performed step by step slowly to fill the lesion completely. The injection of cement is performed under scopic control and verifies the absence of too anterior diffusion at the level of soft pre-vertebral parts. The cement viscosity is key, the risk of vascular leaks, in particular arterial, by neo vascular growing is possible, the cement going against of the blood flow (amoretti). The lateral scopy in this case can be taken into default, the vascular leak being projected at the level of the vertebral body. The cement embolus can also reach an medullar artery depending on the level.
In case of lytic tumoral lesion invading the posterior wall.
The major risk is compression of the spinal roots by the cement. An excellent radio-opacity of the cement is fundamental to perfectly limit its position and its diffusion under continuous scopic control.
We position the trocar at the level of the most anterior portion of the tumor and cross the adjacent bone. We slowly inject a few drops of cement at the level of the vertebrae not invaded, then as the cement is getting more dense, we withdraw while injecting cement.
The lesion must be filled as much as possible. An bilateral entrance way can be very useful for an optimal filling. In case of a pedicular contact, the withdrawal of the trocar is performed slowly while injecting the rest of the very thick cement little by little to create a bone bridge under scopic guidance. The risk to reach nervous root is important by extension in the foramen, a perfect control of the move s compulsory to avoid nervous complications.
Vertebroplasty in the case of a fracture on posterior material implants
This type of vertebral fracture raises the problem of the entrance way and of the reduced visibility in lateral scopy of the filling of the secondary vertebral at the artrodesis material. The scannographic volume acquisition and the spotting has a large importance to guide the progress of the trocar without being blocked by the arthrodesis screws. The trocar path is outside the screws. An iterative scanner control checks the correct lateral position and the progression in the vertebrae to position at the level of the third anterior and third posterior. The filling is performed in the same way as standard vertebroplasty, the visualization of the cement by continuous lateral scopy is blocked by the osteosynthesis material, for this reason the injection must be done very carefully by alternatively controlling with scanner cuts the correct diffusion of the cement. The scanner control can also be blocked by the artifacts of the osetosynthesis material. Moreover in the cases of osteopenic fractures on arthrodesis, a low density line can exist around the screws showing a potential mobility of the material. In this case, the scanner guide can be very useful to position the tip of the trocar in front of this line. Thus, the vertebroplasty has the additional function to fix the intra vertebral corporeal arthrodesis.
Only the scannographic cuts allow to confirm the correct diffusion around the screws. The clinical results in out series are stackable to the vertebroplasties in the frame of the hyperalgic osteopenic fractures.
Vertebroplasty in the case of an intra-spongy hernia symptomatic hyperalgic.
This situation can occur when a collapse of the spongy bone holding the upper disc and able to provoke a large bone edema under chondral tissues. The principle of the vertebroplasty consists in consolidating the portion of the bone below the intra spongy hernia. The indication and the results of the consolidation of the vertebrae in this kind of bone damage has already been published (simonetti European Radiology) and showed a significant enhancement of the analog pain scale at the first day.
The vertebroplasty technique in this context can present a unique difficulty: the precision of positioning of the cement adjacent to the hernia with intra-discal passage. The scannographic volume acquisition determines in a first step the ideal path for the distal end of the trocar is located under the median portion of the hernia. The filling of the spongy bone is performed with a viscous cement which will fill the whole lower part to the hernia. The injection will be performed under continuous scopy and will avoid any disc passage. The rotation motions of the cannula bevel of the trocar can be very useful to better spread the cement.
Discussion:
Our university center has performed since 2001 ,more thatn 2500 vertebraoplasties of all indications.
The first prescriber were the oncology services in the frame of metastatic hyperalgic vertebral lesions. The first cases were patients escaping from all therapeutic on an analgesic, functional or oncologic point of view. In view of the very satisfactory results of our series and the coherence with the literature data, the prescribing oncologic physicians positioned vertebroplasty on the forefront of the therapeutic arsenal in association with the classical therapies. The evolution of the techniques and the acquisition of experience have expanded the indications for patients which couldn’t be treated with extreme damage to the vertebral body and the posterior axis, and numerous patients could benefit from a vertebral consolidation significantly enhancing their quality of life. Looking at the low complication rate even in the most difficult cases, the benefit/risk ratio is considered very good by the prescribers.
In the same manner, the rheumatology physicians took care of their patients for hyperalgic vertebral fractures after waiting several months the failure of a conservative heavy treatment including prolonged bed rest, use of a corset uncomfortable for the patients, and antalgic treatment up to class 3 of the oms (morphinics in particular). This late address put us in front of extreme cases of vertebral fractures going to the vertebraplana. The experience and the acquired technique, the vertebroplasty realization in these extreme cases brought a real enhancement for the patient immediately after the operation. Thus the rheumatologists faced patients very demanding not understanding why they waited so long to perform this rapid, painless procedure under local anesthesia and immediately efficient. The number of days without pain loss was not well perceived by the patients, therefore the rheumatologists have progressively offered a vertebral consolidation in shorter delays. In view of the satisfactory results and the sustainable clinical enhancement and the satisfaction of the patients, the vertebroplasty has imposed itself as a forefront and modern therapeutic. The contradictory studies published in the New England Journal have not altered the trust in the technique, these studies showing more than anything that when the vertebroplasty is not indicated on common criterions, the results were the same as placebos.
The end of this mini invasive tecnic takes its true meaning when the intervention is associated to an efficient and well tolerated local anesthesia. Avoiding the general anesthesia and its complications. Thus a population of fragile patients until now counter indicated to general anesthesia and to interventions have had access to the micro-invasive procedures: in particular the older patients, and those whose vital prognostic at short and middle term was bad, and for those whose ratio benefit/risk of the invasive intervention is low. Thus interventional spinal radiology associated to the advantages of the local anesthesia allowed to widen the action to patients who didn’t have access until now to conventional surgery under general anesthesia. These supplementary arguments motivate the physicians facing this type of pathology to offer a vertebroplasty to their most fragile patients.
The per-cutaneous vertebroplasty is an procedure that cannot be ignored in the therapeutic arsenal of the osteopenic and secondary vertebral fractures.
The evolution of the material and the mode of guidance enable realization of this intervention in optimal conditions of safety and ease. Numerous expert centers chose this technical evolution for the clear enhancement of the tolerance of this procedure and the speed, ease and safety of the gesture.
