Experimental Study On Cavity Creation Of A Cavity During Vertebroplasty

Objective: Percutaneous vertebroplasty(PVP)has been widely used in clinic since it was invented.As a minimally invasive technique for the treatment of osteoporotic vertebral compression fracture(OVCF),it has the advantages of shorter hospitalization time,less cost and so on.More and more attention has been paid to the complications of vertebroplasty due to the severity of vertebral fracture and the amount of bone cement injection is different.Bone cement leakage,can lead to pulmonary embolism,and adjacent vertebral fracture are the most common complications of PVP.Therefore,reduce the leakage of bone cement in PVP is extremely essential.To evaluate the prevention of bone cement leakage by the application of small cavity technique during vertebroplasty,with vitro vertebral specimens as experimental subjects.Methods: Fifty vertebrae(T8-L5)were harvested from each of five elderly embalmed samples,which from the same area with the same race and age(62-68years).The fractures,tumors and congenital malformation were ruled out by X-ray.Bone mineral density was measured by bone mineral density instrument to remove non osteoporotic vertebral body.50 vertebrae(T8-L5),of which 2 did pre-test,were made into compression fracture models and randomly divided into two groups.The whole vertebral bodies were placed between two nickelclads.Preloading 100 N pressure,with the time of 5min,eliminated corrosion vertebral relaxation and creep effects and then loaded vertically with 5mm/min until the vertebral bodies were yielded.Group A received vertebroplasty.For patients receiving cavuplasty(group B),prior to cement injection,a small cavity was created in the vertebral body using the nasal foreign body forceps.It was introduced into the vertebral body through the needle,thus compressing aside the bone tissue in the vertebral body.Thisprocedure was repeated with alternating rotation and manipulation of the nasal foreign body forceps in a 360? circular manner creating an irregular cone-shaped cavity in the vertebral body.After cavity creation,the forceps was removed,and cement was injected through the needle.All specimens injected the same manufacturer,the same amount(2.5 ml)cement at a constant speed(2 ml/min).The cement leakage rate was calculated and distribution of cement was assessed with postoperative CT scan.Meanwhile,the volume of cement leakage in each group was measured quantitatively in milliliter(ml).Statistical software were employed to analyze the data.Leakage rate were compared by χ2 test among the two groups;the volume of the leakage were compared by t-test in two groups.The differences were regarded as statistically significant when P< 0.05.Results:1 Cement leakage was observed in 14(58.3%)vertebral bodies in group A and 5(20.8%)in group B,there was statistical significant differences(χ2=7.056,P<0.05);The cement leakage volume in group B [(0.23±0.02)ml]was significantly less than that in group A [(0.77±0.06)ml](t=18.732,P<0.05).2 CT scan displayed the cement distribution in group B was more uniform with greater regularity than that in group A.3 Postoperative CT scan,a total of 19 vertebral bone cement leakage occurs,the incidence was 39.6%(19/48).Conclusion: Creating a small cavity during percutaneous vertebroplasty is simulate to the percutaneous kyphoplasty(PKP),which use the small cavity volume.The bone cement first gathered in the small cavity,which accommodate part of the bone cement.Thus there will not make a high pressure when inject the bone cement into the vertebral body.The falling bone cancellous made by nosal foreign body forceps in the vertebral body close the bone cement leakage channel,while the surrounding trabecular bone is compacted,so the bone cement leakage reduce and the volume of cement leakage also decrease.This experiment confirmed that the creation of a smallcavity in the vertebral body prior to cement injection is an effective way to reduce cement leakage and make cement distribution more uniform during vertebroplasty.Because the number of samples is small and using the vitro specimens,our current conclusions are limited and still require a large number of laboratory and clinical studies to confirm our current results.