Résumé
BACKGROUND:In vitro experiments have demonstrated that the biodegradable mesh-like microporous baloon made of macromolecular materials has obvious advantage of anti-leakage, which is capable of maintaining calcium homeostasis, has no inhibitory effects on cel growth and on microscopic interdigitation formation between new bone and bone cement. OBJECTIVE:To evaluate the therapeutic effects of biodegradable mesh-like microporous baloon with calcium bone cement on vertebral fractures based on animal experiments. METHODS:The fracture model was established in 48 New Zealand rabbits, in which a bone dril was introduced after successful puncture at sites near left low extremity of the femur. These rabbit models were randomized into two groups: experimental group with calcium phosphate bone cement and biodegradable mesh-like microporous baloon and control group only with calcium phosphate bone cement. Clinical parameters such as blood cel count, biochemistry, and CT/X ray were examined at 1, 3 and 6 months after implantation of the baloon and bone cement. After that, the specimens were fixed for pathological analysis. RESULTS AND CONCLUSION:The operation was performed under general anesthesia with no eventful infusion of bone cement. The expansion of baloon was satisfactory without definite extravasation of bone cement in the experimental group. In the control group, cement diffusion was found with pulmonary embolism occurring in three New Zealand rabbits. No statistical significance for blood cel counts and biochemistry was found between pre- and postoperation or between two groups. The materials in the two groups had favorable biocompatibility with injured bones without obvious immunological response. In the experimental group, the baloon wal was thinned and partial bone tissues grew into the cement at 1 month; at 3 months, a large amount of bone tissues grew into the cement and cement volume diminished; at 6 months, the baloon disappeared and only a smal amount of cement left in the bone tissues. In the control group, it was difficult to determine when the cement degraded. The biodegradable mesh-like microporous baloon combined with calcium bone cement is superior to bone cement alone in the management of vertebral fractures.
Résumé
BACKGROUND:Percutaneous vertebroplasty and percutaneous kyphoplasty have become the mainstream clinical methods for the treatment of vertebral compression fractures. However, both of them have several shortcomings such as bone cement leakage, spinal stenosis, nerve compression, pulmonary embolism and other issues. OBJECTIVE:To verify the possibility of bone filing mesh container prepared by polyethylene terephthalate for the treatment of vertebral compression fractures. METHODS:The biological properties of bone filing mesh container were examined according to GB/T16886. After sample aging test, the tensile properties of the aged samples and the fresh prepared samples were compared. The expansion and bone cement leakage were evaluated by injecting bone cement into the bone filing mesh container and measuring the pressure. The initial strength and stiffness of the fresh pig vertebrae with calcium phosphate cement injection or with bone filing mesh container filed with calcium phosphate cement were compared. The in vivo bone tissue growth was periodicaly observed after the lumbar vertebra of 4-month-old pigs was implanted with the bone filing mesh container that was then ful of bone cement. RESULTS AND CONCLUSION: The bone filing mesh container had good biocompatibility. Bone filing mesh containers after 2-year storage had the same tensile strength to the fresh bone filing mesh containers. At ambient conditions, after bone cement injection, bone filing mesh containers could be expanded at 5-10 atm and therefore could play the role of uplift; at 7-10 atm, bone cement could leak out from the bone filing mesh container and enter into the interspace between surrounding bone tissues, thus playing the role of adhesion and fixation. The vertebrae after bone cement injection with or without bone filing mesh containers had the same initial strength and stiffness and exhibited bigger initial strength and stiffness than untreated vertebrae. Thein vivo animal experiments proved that bone filing mesh container had no obvious effect on the vertebrae. These findings indicate that the bone filing mesh container can be used to restore the height and strength of the fractured vertebrae. Moreover, it may eliminate bone cement leakage and therefore increase the surgery safety.