Experimental Research And Clinical Use Of Percutaneous Vertebroplasty

Percutaneous vertebroplasty (PVP) was invented in 1987 in France Dr. Herve Deramond. It is a simple, minimally invasive procedure that offers a remarkable therapeutic option for patients suffering from osteoporotic or tumorrelated vertebtal fractures and pain. This interventional technique consists in the imageguided injection of a bone cement, most commonly polymethylmethacrylate (PMMA), into a fractured or disrupted vertebral body. Other than benign osteoporotic fractures, the main indications are primary malignant disease such as multiple meloma or lymphoma, metastatic disease and benign tumors of the bone particularly hemangioma. The European experience is more extensive in tumor therapy than osteoporosis. Pioneering physicians such as Jacque Chiras have driven the procedure, and developed referral bases in their own hospitals and inspired others to push the technique to the limit. This inversion may be because in North America we have primarily experienced the growth of a patient driven procedure here, with admirable, motivated, Web-sawy, osteoporotic people referring themselves to us directly. Our oncology colleagues have been slower to catch on and perhaps we as practitioners of the technique have shied away from these more challenging patients.With the extensive clinical application of PVP, more and more complications have been reported. This study on the complications of PVP in animals provides experimentation fundemention, on the other hand the methodology and efficacy ofvertebroplasty in the treatment of painful vertebral benign and malignant disease was discussed, and the long-term efficacy and safety of percutaneous vertebroplasty (PVP) was assessed.Part IAn Experimental Study of Effect of Injection of Bone Cement into SpinalEpidural Cavity on Spinal CordObjectives To investigate the effect of spinal epidural injection of bone cement on spinal cord and to prevent the complications after vertebroplasty.Methods A dose of 1.5 ~ 2 ml of polymethylmethacrylate (PMMA) was injected into the spinal epidural cavity in each of 12 dogs who were averagely divided into experimental and control groups. CT scan was proceeded in each of 12 dogs after injection. Six dogs in the experiment group received decompression of spinal cord by vertebrectomy removal of PMMA in the spinal epidural cavity and did not in the control group. The nerves function evaluation was performed and the spinal cords were subjeted to histologic examination 48 hours after the injection of PMMA.Results Bone cement distribute at anterolateral spinal epidural cavity . Tarlov score is 3.86 + 0.75 in experimental groups ,while 4.87 + 1.12 in control groups (p<0.05 for both comparisons).Contusion of spinal cord was induced by injection of PMMA into spinal epidural cavity, and the spinal cord injury was more serious in the control group than that in the experimental group(P<0.05).Conclusions Leakage of methylrnethacrylate during vertebroplasty may cause compression of adjacent structures and necessitate emergency decompressive surgery; thus, the procedure should be performed only if there is a surgical colleague who will consult or intervene if something untoward occurs. The bone cement is prevented from leaking into the vertebral canal when the vertebroplasty is performed. The decompression of spinal cord is performed as soon as the sympsom of spinal cord injury appears to rescues neurons in articulomortis, reversing the course of pathologic damages.Part IICardiopulmonary functional changes following cement injection in percutaneousvertebroplasty (PVP): an experimental study in dogs.Study design Vertebroplasty, the augmentation of vertebrae with polymethylmethacrylate, is a technique for treating osteoporotic compression fractures and achieving prophylactic stabilization of osteoporotic vertebral bodies at risk of fracture. However, there is concern that fat embolism and acute hypotension even the bone cement implantation syndrome could occur as in a variety of other orthopedic procedures.Objective To investigate the sequential occurrence of fat embolism and hypotension during vertebroplasty.Methods In six dogs, 1.5mL of polymethylmethacrylate was injected unilaterally into Li. Heart rate, arterial and venous pressures, blood gas values and blood volume of carotid artery were recorded before and for 25 minutes after injection.Results Injection of cement elicited a very rapid decrease in heart rate (within 2 ± 1 seconds) and a rapid increase in venous pressure (within 3 ± 1 seconds), which was followed by a fall in arterial pressure (within 4 ± 2 seconds). The injection resulted in an increase in partial pressure of carbon dioxide and breath rate, and a decrease in partial pressure of carbon dioxide and PETCO2 and pH .At the same time, the injection resulted in a decrease in blood volume of carotid artery momently.Conclusions The results suggest that immediately after cement injection, there was a reflex fall in heart rate and arterial pressure. There are potential cardiopulmonary complications during cement was used in PVP, which should be intensively cared. The key to safety is that the therapeutic response is not related tothe degree of filling but the risk of complication is. Procedural complications were mostly related to leakage of PMMA injection into the vertebral venous plexus. Such venous leaks caused compression of spinal cord or nerves or could also cause pulmonary embolism.PartmClinical use and Long-term follow-up of vertebral benign and malignant diseasetreated by percutaneous vertebroplasty.Objective To discuss the methodology and efficacy of vertebroplasty in the treatment of painful vertebral benign and malignant disease, and to assess the long-term efficacy and safety of percutaneous vertebroplasty (PVP).Methods A prospective open study was conducted. PVP were carried out between January 2003 and September 2004 for 8 patients with symptomatic vertebral benign and malignant disease that had not responded to extensive conservative medical therapy. Vertebroplasty was performed in 8 patients (ages 32~68,mean 54.5) with 9 diseased vertebrae . The neoplasm included metastatic lesion (n =4,5 vertebrae), vertebral body compression fractures (n =2,2 vertebrae), hemangioma (n=l) and neurilermmoma (n=l). 10G, 11G, 13G and 14G straight needles are available. Cervical lesions are the best accessed via a transoral approach at Q and C2, and via an anterolateral approach from C3 below.Under c-arm fluoroscopic monitoring , a needle was punctured to the vertebral body, then , methylmethacrylate (PMMA) bone cement mixture (with the ratio of powder/liquid/contrast agent as 3:2:1) was injected . We observe them in our holding area for 3 hours post procedure. Discharge instructions are given instructing the patient to cal us at 1 day at 1 week post procedure. A computed tomographic scan was obtained 1-8 hours aftermethylmethacrylate injection and was used to assess the percentage of lesion filling by methylmethacrylate and the leakage of methylmethacrylate into the epidural tissues, neural foramina, intervertebral disks, venous plexus, and paravertebral tissue.Results The successful puncturing with single manipulation was achieved in 9 vertebrae . PMMA leakage into adjacent paravertebral soft tissue occurred in 2 cases. All the patients were followed-up for more than half one year. The efficacy of the PVP was assessed by the changes over time in pain on the McGill-Melzack scoring system (MGM). The mean duration of follow-up was 11 months. The analgestic of pain relief was 6/8(CR), 2/8(PR).The results were significant for the MGM: 3.00+/-0.57 before PVP to 1.6+/-1.4 at the long-term follow-up (p<0.05). The solely statistically significant decrease for quality of life was noted for pain. No severe complication occurred immediately after PVP.Conclusions PVP appears to be safe and effective for treating persistent painful vertebral benign and malignant disease. Controlled studies with long-term follow-up are needed to evaluate the efficacy of percutaneous vertebroplasty (PVP).