The Clinical Application Of Bone Filling Mesh Container (BFMCs) Kyphoplasty And Preparation And Testing Of A Biodegradable Reticular Balloon

BACKGROUND: Benign and malignant vertebral compression fractures (vertebralcompressive fractures, VCFs) can not only lead to restricting movement of patients, butalso affect the normal sequence of the spine, and reduce the effective volume of the thoraxand cardiopulmonary function, and decrease living quality of patients significantly. PKPis an effective method for treatment of benign and malignant vertebral compressionfractures.Ballon kyphoplasty （BKP） is based on the percutaneous vertebroplasty（PVP）.because it can reduce the risk of leakage of bone cement, at the same time,because of its clinical curative, less trauma and less complications and other characteristics,BKP has now become one of the main technical means of treatment of VCFS. But due to alack of mesh in the balloon, the CPC discontact with the bone tissues. Application of bonefilling mesh container(BFMCs）instead of the BKP. BFMCs-PKP become a new kind ofimproved technology.it can make the cancellous bone around the cement and boneformation micro bowstring, solve the problem of against the shear force of the vertebralbodies, To test and verify the curative effect of BFMCs-PKP.we have carried onControlled clinical studies of the PVP, BKP and BFMCs-PKP.Currently, Polymethylmethacrylate(PMMA) has been used in PVP, BKP andBFMCs-PKP,which has excessive inherent stiffness and may induce the adjacent-levelfractures after PMMA vertebral body augmentation.otherwise the BFMCs and PMMAhave no biological activity, there can produce complications when they had been in thevertebral body long-term, Calcium phosphate cement(CPC) has two main disadvantages:the water-induced collapsibility and poor mechanical properties, which limit its clinicaluse.In order to solve these problems, a biodegradable reticular balloon is designed, insidewhich was covered with a compound membrane in this study. With the degrade of reticularstructure and membrane,CPC is made contacted to vertebrae effectively and integratedbiologically.and to verify the possibility of biodegradable mesh-like microporous polymerballoon for the treatment of osteoporotic vertebral compression fractures.OBJECTIVE:1. To assess the effectiveness and security of BFMCs for the treatment ofvertebral compression fractures.2.With the degrade of reticular structure andmembrane,CPC is made contacted to vertebrae effectively and integrated biologically.andto verify the possibility of biodegradable mesh-like microporous polymer balloon for thetreatment of osteoporotic vertebral compression fractures. MATERIALS AND METHODS:1.90cases of painful vertebral body compressionfractures （from April2009to October2010）were randomly retrospective analysised:Agroup(BFMCs-PKP)、B group（BKP）、C group（PVP）。The indications included painfulosteopomtic venebral body compression fracture， spinal metastases and vertebralangioma．All of the cases were single segmental vertebral compression fractures and hadthe Experience the conservative treatment.Patients were evaluated with Visual AnalogueScale (VAS).the anterior height，midline height and Cobb’s Angle of the vertebrae bodywere measured preoperation and postoperation(3days,1month,3months,6months).2.Inthis study, a biodegradable macromolecular material, charactered by controlled degradationand excellent mechanical properties,is investigated with solution polymerization. Usingadvanced electrospinning and knitting technology, fiber network structure of the material isprepared to consoladate shape of balloon and increase its mechanical properties.Meanwhile,the compound biodegradable membrane can prevent the collapse and leakageof CPC effectively. The inosculation of CPC and vertebrae is achieved through thedegradation of membrane and fiber cancellate structure. This study will investigate themechanism and influence of the composition, structure, function and other parameters ofthe biodegradable macromolecular material. In addition, the biocompatibility, mechanicaland degradation properties,effectiveness of anti-collapsibility of the balloon will be studiedsystematically.3. Thirty-two vertebral bodies from pigs were randomly divided to fourgroups. For A group,2.5-3.0ml PMMA was injected into the body through a unilateralthoracic pedicle pathway; for B group,2.5-3.0ml CPC were injected by the same protocol;for C group, the biodegradable reticulated balloons filled with2.5-3.0ml CPC wereimplanted; D group, including normal vertebral bodies, was designed as controls. Leakageof bone cement was observed in each group. The load-shift curves were recorded by anelectronic universal testing machine (SCHENCK RSA-250).RESULTS:1.1case bone cement leakage happened in A group and B group,5caseshappened in group C without clinical symptoms. There was a significant difference in3d、1m、3m and6m postoperation of all groups (P<0.05) on VAS score compared withpreoperation,but it was not for postoperation with paired comparison (P>0.05).There wasno significant difference in paired comparison (P>0.05).There was a significant differencebetween the uplift of anterior and middle of Vertebral bodies postoperation of Groups Aand B （P﹤0.05）,the difference in the group C had no statistical significance（P﹥0.05）while a significant difference by comparing the group C with groups A and B（P﹤0.05）. There was a significant difference in the paired comparison pre-and post-operationbetween the Cobb’s variation of Groups A and B （P﹤0.05）.The difference was nosignificant in paried comparation postoperation （P﹥0.05）.There was no significantdifference between postoperation and preoperation（P﹥0.05）. There was no significantdifference in postoperative and preoperative group for C（P﹥0.05）while the differencewas no significant in postoperative group through pairwise comparison (P<0.05).Therewas a significant difference by comparing the Group c with Groups A and B （P﹤0.05）.2. Mesh-like microporous balloons presented with good fiber morphology, thicknessdistribution, and the presence of pores; on the coated balloon surface, there was absence ofspecific morphology and porosity. Compared with the coated balloon, the mesh-likemicroporous balloon showed better mechanical properties, liquid permeability and burstpressure, to prevent leakage of bone cement and promote osteoblast adhesion andproliferation. In addition, the degradation of the mesh-like microporous balloons was moreuniform and stable than the coated balloons, which may increase the calcium concentrationin the injured vertebrae and will be beneficial to the new bone growth and fracturehealing.3. The stiffness and strength of A group were significantly higher than those ofDgroup (P <0.05), and the stiffness and strength of B group were statistically lower thanthose of D group (P <0.05).The stiffness and strength of C group, otherwise, were similarwith those of D group (P>0.05). Cement leakage rate of C group was lower than that of Aor B group (P <0.05). Vertebral bodies implanted with biodegradable reticulated balloonsmay lead to similar biomechanical characters as the normal vertebral bodies and reduce thecement leakage rate.CONCLUSION:1. BFMCs-PKP is effctive and secure in the treatment of venebral bodycompression fhcture, but the BFMCs lacked the biodegradability, complications willappear in long-term follow-up．2. Mesh-like microporous balloons presented with goodfiber morphology, thickness distribution, and the presence of pores; on the coated balloonsurface, there was absence of specific morphology and porosity. Compared with the coatedballoon, the mesh-like microporous balloon showed better mechanical properties, liquidpermeability and burst pressure, to prevent leakage of bone cement and promote osteoblastadhesion and proliferation. In addition, the degradation of the mesh-like microporousballoons was more uniform and stable than the coated balloons, which may increase thecalcium concentration in the injured vertebrae and will be beneficial to the new bonegrowth and fracture healing.3.Vertebral bodies implanted with biodegradable reticulated balloons may lead to similar biomechanical characters as the normal vertebral bodies andreduce the cement leakage rate.