PERCUTANEOUS VERTEBROPLASTY
INTRODUCTIONPercutaneous vertebroplasty is a technique of interventional radiology consisting in injecting acrylic cement by percutaneous way into an affected vertebra, in order to obtain an antalgic effect and consolidation of the vertebra. This treatment is carried out under neuroleptanalgesia.MECHANISM OF ACTION OF THE VERTEBROPLASTYVertebroplasty has two combined effects : the stabilization of the vertebral body and an antalgic effect.Vertebroplasty is considered to be a process of stabilizing the vertebral bodies. The injection of cement into the vertebra has an antalgic effect, by consolidating microfractures it thus decreases the mechanical constraints, related to the load ; It is also effective because it destroys the nerve endings of the normal bone by a cytotoxic effect or by the releasing of heat by the cement at the time of the treatment.
VERTEBROPLASTY TECHNIQUESPreoperative assessmentStandard full-face and profile radiograph measure the extent of vertebral packing, the level to which the pedicles of the posterior wall are affected, and the existence or the appearance of a modification of the rachidian curves.The MRI specifies to what point the vertebral body, the pedicles and the posterior arc are affected. It shows whether the posterior wall is ruptured, and whether epidural spread has occurred or whether spreading into the soft parts has occurred. The scan of the pathological vertebra is also of fundamental interest, because it is the only way to correctly evaluate the existence of a cortical lysis involving either the external cortical of the vertebral body, or the posterior wall. It also makes it possible to study the total texture of the vertebra, and see whether multiple microgeodes or an area where the pathology is condensed are present or totally absent. These are elements which significantly influence the distribution of cement throughout the vertebral body or its possible spreading outside its limits during the percutaneous injection.
The process allows for evaluation
of the possibility of using the transpedicular method.
Radiological equipmentX-ray control, by means of a digitized table provided with an arch.Alternative : Control scanner and mobile digitized amplifier. This technique has the advantage of being more precisely aimed under scanner control than under X-ray control of the vertebral body, in particular for small lesions. Vertebroplasty equipment 
Bevelled needles between 10 and 15 cm in length and with a diameter of 3 mm (10G) allowing for a biopsy by coaxial installation and a trocar of osseous biopsy (15G) at the same time which makes posible the taking of several samples for histological examination, if necessary. Needles of a finer gauge (15G) on the cervical and upper dorsal level require a finer needle (18G) to carry out a simultaneous coaxial biopsy.
Rachidian accessThis method depends on the level of the vertebra to be treated, the anatomical conditions and in certain cases, on the presence of osteosynthesis equipment.Cervical Rachis Anterolateral on a patient
in decubitus dorsal position, the radiologist's fingers penetrating between
the aerodigestive axis on the inside and the vascular axis on the outside.
Taking into account the size of the cervical vertebra, bilateral access is seldom necessary. Dorsal and lumbar RachisThe transpedicular method appears to be preferable, because it does not present a risk of a pleuroparenchymatal complication at the dorsal level or of a haematoma of the psoas at the lumbar level and there are less likely to be leakages outside the body through the puncture hole. (This method can not be used in the case of pedicular lysis or with osteosynthesis equipment).
Transpédicular, the patient is placed in strict procubitus position and the puncture is carried out full face, until the trocar is in the vertebral body, then profile. Postéro-side:
This method is also carried out in
procubitus.
(Help can be gained by the injection of physiological salt solution or xylocaïne with 0,5% to increase the trocar/pleura safety zone at the time of the progression of the anaesthesia needle and then the trocar.  Preparation of cement
Simplex Cement
(Howmedica). The mixture must be made of 4 volumes of methylmetacrylate
powder to 1 volume of solvent. To this mixture tungsten or tantalum powder
is added, in order to opacify the cement (usually 20 ml of powder, 5 ml
of solvent and 2 grammes of tungsten powder are prepared).
Cement injectionLuerlock 2 to 3 ml syringes fitted with gripping handles, under continuous profile scopic control.The methylmetacrylate injection is stopped as soon as the product arrives at the level of the posterior vertebral wall or as soon as there is a threatening spreading of the cement. It is sometimes necessary to modify the position of the needle, so as to obtain a better filling of the vertebral body. Once the vertebra has been satisfactorily filled, the needle is gradually withdrawn from the vertebral body. Radiological control Standard or digitized radiograph full-
face and profile, but also by computerized axial scanning with coronal
and sagittal rebuildings.
TECHNICAL HITCHES AND COMPLICATIONSTechnical hitchesPuncture incidentsTranspedicular method: the major risk
of the transpedicular method is the lesion of the intern cortical of the
pedicle.
At the lumbar level, the theoretical risks are the puncture of the renal capsula, hematoma of the psoas and especially cement leakage through the puncture hole.
If the first posterolateral approach does not allow for a satisfactory positioning of the vertebroplasty needle, it is necessary to leave the first trocar in position and to carry out a second puncture to avoid cement leakage through the first cortical puncture hole. Cement leakage into the soft partsThis risk necessitates a permanent close scopic monitoring of the injection, in particular when the cortical rupture affects the pedicle or the posterior wall.On the level of the cervical rachis, anterior leakages through the puncture hole are commonplace, usually of small volume and only responsible for a transitory dysphagia in the very large majority of cases.
Cement leakage into the venous systemThis passage into the venous appears during the course of the injection and means that the injection must be stopped and that the repositioning of the needle might be necessary in order to be able to continue to fill the vertebral body.
(the early risk of cement passage into the veins explains why it is desirable to carry out a transosseous phlebography trough, the vertebroplasty trocar, when the lesion appears very vascularized (metastasis of the thyroid or cancer of the kidney, vertebral angioma). Leakage into the intervertebral discs In the cases of rachidian metastases
or osteoporotic packings, there is a direct communication between the intervertebral
disc and the vertebral body. This incident does not involve a real complication.
ComplicationsCompared with the frequency of these technical hitches, complications occur rarely.Local complications They can be of 3 types : local painful exacerbation, radiculalgia, neurological deficit. Increase in local painsThey yield in a few days under non-steroidian anti-inflammatory drugs or corticosteroids.Radicular complications The specific treatment can be a surgical
operation for ablation of the migrated cement fragment or marcaïnisation
under scanographic control.
Neurological deficiency complicationsThey are exceptional.Emergency surgical intervention relieves the compression and leads to neurological recovery. Infectious complicationsThe theoretical risk of spondylitis justifies draconian asepsis precautions, but probably also the pre-operatory injection of delayed action antibiotics or methylmetacrylate containing antibiotics.It is worth remembering that complications
are much more frequent in metastatic cases where the rate of occurence
is about 10%.
INDICATIONSAcrylic vertebroplasty makes it possible to obtain an antalgic effect in the majority of painful lesions of the rachis of tumoral or degenerative origin, which are responsible for an increased fragility of the vertebral bodies.The principal indications are metastases and rachidian localizations of hemopathies, vertebral angioma and osteoporotic or osteopenic packings. Vertebral AngiomaIn a patient presenting a brutal neurological or rapidly progressive symptomatology and in whom a vertebral angioma associated with a significant and compressive epidural component has been diagnosed, it is necessary to combine vertebroplasty and surgery.
In a patient presenting a progressive
neurological symptomatology or intense rachialgia without signs of nervous
compression and radiologically speaking an " aggressive " angioma with
epidural component, the vertebroplasty will be carried out by injection
of acrylic cement and supplemented at the same time by an injection of
pure alcohol after puncture of the posterior angioma arc or a angioma compartment
of the vertebral body not injected with cement.
Rachidian metastasesIn the case of a metastasis which is only slightly radio-sensitive (cancer of the kidney, cancer of the thyroid, malignant pheochromocytome), vertebroplasty also provides a simple means of obtaining a consolidation of the vertebral body.On the other hand, the goal of the vertebroplasty is to consolidate the body of a vertebra.
If the presence of an epidurite is
not in itself a countra-indication of vertebroplasty, this treatment being
able to relieve the local pain relating to the attack on the
vertebral body, it will not have any effect on the clinical signs in connection
with the epidurite.
This allows for a consolidation of
the anterior rachidian segment, whilst avoiding resorting to a corporectomy
which often seems to be out of proportion in polymetastatic patients or
those whose general condition is very poor.
Osteoporotic PackingsVertebroplasty is a therapeutic weapon of choice when medical treatment is insufficient to calm pain.The antalgic effect is excellent in more than 90% of cases and is very rapid since a resumption of the support is as often possible within 48 hours. |
