Percutaneous vertebroplasty: An experience of 31 procedures
A prospective study of 31 percutaneous vertebroplasty procedures (PVP) in 22 patients treated during January 2000 to December 2001 is presented. PVP was performed using polymethylmethacrylate (PMMA) to treat vertebral collapse due to osteoporosis and vertebral metastasis, to obtain analgesia and spinal stabilization. We analyze the efficacy and complications related to the procedure. PVP is a safe, effective and a daycare surgery. It can be performed under local anesthesia and has minimal and manageable complications.
Vertebrae give support to the body in sitting, standing and walking. With increase in the life expectancy, an increasing number of elderly persons have vertebral collapse either due to osteoporosis or metastasis. Vertebral collapse frequently causes persistent and often excruciating pain which significantly impairs mobility and the quality of life. Osteoporosis, steroid medication, bony metastasis and vertebral hemangiomas are the main causes of vertebral collapse. External bracing, analgesics, rest and observation may ameliorate pain in some patients, but in others a constant administration of narcotics is necessary.
Surgical decompression and placement of polymethylmethacrlylate (PMMA) or autologous bone graft have been used in the past for the management of neoplastic compression fractures,,, giant cell tumors of long bones,, and vertebral heamangiomas. Percutaneous vertebroplasty was first performed in 1984 in France by Deramond et al,, in a vertebral angioma to obtain analgesia and spinal stabilization. Till date the published data has been from the western population and the general results have been excellent.
A prospective study was carried out in the department of Neurosurgery, King George's Medical College, Lucknow from January 2000 to December 2001. Eligible patients were treated for disabling back pain and/or impaired mobility secondary to vertebral collapse of varying etiology. All were refractory to conservative therapy.
The patients underwent an elaborate physical and radiological examination. Patients in whom the pain was not localized to the site of the fracture were excluded from the study. Patients having radiculopathy and compressive myelopathy or a suspicion of Pott's spine were also excluded from the study. Active infection in the areas of planned vertebroplasty was a contraindication for treatment.
The patient is placed in a prone position on the angiography table. Under appropriate monitoring, the patient is sedated using a cocktail of diazepam, promethazine and pentazocine (1 amp each) and/or midazolam. Using aseptic precautions, the vertebral body to be treated is localized under C-arm image intensifier. Local anesthesia using xylocaine is used for the overlying skin and tissues in the trajectory of injection. A small skin incision is made with no. 11 scalpel blade. A disposable 11-G Jamshidi needle is positioned with its tip in the center of oval and is advanced until the stylet tip abuts the bone. Under radiographic control the needle is advanced with a slight twisting motion through the cortex. Care must be taken not to violate the anterior cortical wall or the endplates. The stylet tip is placed at or near the junction of the anterior and middle third of the vertebral body in midline.
Before injecting the PMMA, venography is done to exclude needle placement directly within the basivertebral venous complex and to ensure continuity of the posterior vertebral wall as evidenced by containment of the contrast material within bony trabeculae. Injection of 5 ml of iohexol (omnipaque 300) was used to confirm the location of the tip of the needle.
Bone biopsy is performed through the same Jamshidi needle in cases where a malignant etiology is suspected. Codman Cranioplastic, type I (slow-setting) material (CMW Laboratories, Blackpool, England) was found to be the most suitable. The contents consist of a powder PMMA (polymethylmethacrylate) and a liquid PMMA (solvent monomer). The powder is placed into a bowl and mixed with 1 teaspoon (5 g) of sterile barium sulphate powder and/or 1 g tungsten powder to increase radio-opacity. One half of the liquid agent is aspirated into a plastic syringe and the remaining portion is left in the glass bottle. About 10 g of mixed powder is taken in a separate bowl and the liquid agent is added and thoroughly stirred to make a consistency of toothpaste. The material is then poured into a 2 ml plastic syringe, which is tightly attached to the shaft port of the Jamshidi needle and injected by one operator guided by pressure required to inject and under C-arm image intensifier control to see homogenous filling of vertebra, while the second operator loads another syringe [Figure - 1]. The injection pressure required to push the material increases over time as the vertebral body fills and the bone cement consolidates. If the passage of material into the venous system is noted, the injection is halted while the material attains a thicker consistency. The injection is continued until hemivertebral or holovertebral filling is achieved, no material can be pushed into the body or extravasation is observed into the veins or disc and epidural spaces. Upon completing the injection, the needle is removed. The contralateral hemivertebra is then treated in similar fashion, if vertebral filling is less than 50%. More than one vertebra can be treated in single setting, depending on the patient's tolerance.
After the procedure, the patient is placed in a supine position for 2 hours to allow setting of bone cement prior to axial loading. The patient is made ambulatory overnight and is discharged 24 hours later from the hospital following clinical and radiological assessment.
The procedure was performed in 22 consecutive patients (10 males, 12 females) involving 31 vertebrae (lower thoracic-13, lumbar-18). Eleven females were in the postmenopausal group (11 out of 12). Most patients were of the elderly age group with mean age of 59 years (range 35-78 years). Twenty patients belonged to the osteoporotic group (90.1%) whereas 2 patients belonged to the metastatic group (1 from carcinoma of the lung and 1 from carcinoma of the cervix). All the patients presented with severe intractable pain with varying degree of impaired mobility of relatively longer duration (mean 1½ yrs). Both the patients of the metastatic group presented with clinical and radiological features of spinal cord compression.
The procedure was successful in 21 patients. In 1 patient it was abandoned due to rapid extravasation of dye and bone cement in epidural space. The unilateral transpedicular approach was successful in the majority of vertebrae whereas the bilateral approach was needed in 4 vertebrae. The majority (68%) of the patients were treated for 1 level while 6 patients were treated for 2 levels and 1 patient was treated for 4 levels in 2 stages. The amount of bone cement injected per vertebral body varied from 2 ml to 8 ml with an average of 5 ml. Both the patients of the metastatic group required biopsy before PVP and underwent a decompressive laminectomy the following day.
The clinical response to the procedure was assessed immediately after the procedure and after 24 hours. The verbal expression of perceived pain, amount and/or type of pain medication given, and changes in the activity level (Odom's Criteria) were monitored. Twelve patients (57.1%) were cured completely whereas 8 (38.1%) obtained significant pain relief and improved mobility within 24 hours. One patient (4.8%) had no significant relief. In 1 patient the procedure was abandoned. Both the patients of the metastatic group improved completely in terms of neurological status and backache within 15 days.
Complications were encountered in 2 patients (9.1%). In 1 patient the procedure was abandoned due to extravasation of dye and bone cement in perivertebral veins and disc and epidural spaces. One patient developed allergic reactions in the form of severe itching and generalized eruptions after 24 hours. One patient had intense pain just after injection of bone cement. One patient developed retention of urine. Both the latter complications subsided within a week of symptomatic treatment. Follow-up of the patients was done at 6 months and 1 year, clinically and radiologically. No recurrence of pain and further vertebral collapse was seen during mean follow-up of 1 year [Table:1].
The western experience with percutaneous vertebroplasty has described 90-100% pain relief for the treatment of osteoporotic fractures.,, The complications of the treatment were 0-5.4% and most were minor. It has also been used in the treatment of symptomatic and aggressive hemangiomas and vertebral column metastasis. Our experience in performing vertebroplasty with no significant complications further validates these earlier studies. Osteoporosis is the most common etiology of vertebral collapse followed by malignancy, especially metastasis.,, Elderly age, postmenopausal status and prolonged steroid intake are the main factors accelerating osteoporotic collapse. All the findings in the present series are consistent with the previous studies.
Two types of patients are considered for treatment, those with chronic pain refractory to medical therapy and bracing and those with severe disabling pain caused by fractures. Severe cardiopulmonary disease, coagulopathy and cord compression are contraindications to vertebroplasty. Severe vertebral compression may also be a contraindication to treatment, because the vertebra may be compressed to such a degree that needle placement and cement injection becomes impossible. An absolute degree of vertebral compression that precludes treatment cannot be defined. An upper thoracic vertebra compressed by 50% may be impossible to treat safely, yet a lumbar vertebra compressed by 75% may still be treated because the remaining height is significant.
The majority of vertebral levels (87%) required unilateral PVP to achieve the adequate goal of homogenous vertebral filling with bone cement. When PMMA fills less than 50% of the vertebral body, a bilateral approach is required. Usually 2.5 ml to 11 ml with mean of 7 ml bone cement was required to achieve the goal. The magnitude of strength increased and the clinical result do not correlate with the volume of cement injected but depend upon distribution, which packs the trabecular network.
In a study conducted on 274 patients, successful results were obtained in more than 90% of cases of osteoporosis and vertebral angiomas, whereas successful results were obtained in more than 80% in malignant spinal tumors. The results in the present series were comparable to the previous studies in the osteoporotic group while it was different in the malignant group, though it couldn't be concluded exactly because of the small number of patients.
The complication rate for this procedure has been very low in other series,,,, ranging from 0% to 10% depending on the initial indications of PVP. The complications are uncommon in patients with vertebral angiomas (2% to 5%) and osteoporotic lesions (1% to 3%) and can be avoided by a good technique. In patients with spinal malignant tumors, the complications of PVP are more frequent (10%). Various complications like pulmonary embolism, bleeding, radiculopathy, neurological deficits, rib fractures, infections and anesthetic complications,, have been described but none of the above complications were seen in this study. Allergic reaction seen in 1 patient, might be due to dye or bone cement. Another patient experienced severe intense pain just after injection followed by retention of urine without sensory-motor deficit, which might be due to thermal injury (heat developed during bone setting) though the exact etiology remained elusive. Both the above complications have not been seen in earlier series.
Vertebroplasty is an effective new tool in the treatment of osteoporotic and neoplastic compression fractures.