注射型磷酸钙骨水泥在椎体成形术中的组织学研究

目的 模仿椎体成形术观察注射型磷酸钙骨水泥(CPC)／聚甲基丙烯酸甲（polymethylmethacrylate，PMMA)植入椎体后的微观结构变化。方法 将PMMA和CPC植入到犬椎体，通过X线、CT、光镜、扫描电镜观察二种材料与椎体界面间的微观结构变化。结果 PMMA与椎体之间的结合是单纯的机械连接未能达到生物机械固定，CPC与骨界面间无排异反应的表现，是直接的骨小梁与生物材料之间的生物连接，CPC与椎体之间的结合是生物连接可达到生物机械固定的目的。结论 磷酸钙骨水泥是椎体成形术中治疗胸腰椎爆裂骨折一种比较理想的材料。     

CPC/PMMA双向骨水泥性能及生物相容性的初步研究

目的 将聚甲基丙烯酸甲酯骨水泥(PMMA)与磷酸钙骨水泥(CPC)制成一种注射型混合骨水泥,利用各自的特性,优势互补,从而使该混合骨水泥成为理想的椎体成形术及椎体后凸成形术填充材料.方法 实验材料为注射型PMMA骨水泥和注射型CPC骨水泥.首先将PMMA与CPC按质量比1∶2、1∶1、2∶1均匀混合,制成不同比例的混合骨水泥,然后将PMMA、CPC、混合骨水泥(1∶2、1∶1、2∶1)制成标准试件(直径6mm、高12mm),最后对试件进行力学性能、凝固温度、凝固时间、电镜扫描、X线衍射、动物肌肉内植入实验,初步评估混合骨水泥的性能及生物相容性.结果 PMMA与CPC在1∶1比例混合时理化性能满意,其抗压强度较CPC提高约120％,凝固过程中的最高温度低于45℃,凝固时间约12～14 min,微观结构与CPC相似,孔径在100～300μm之间分布最多(约70％),大部分孔与孔之间有10 ～ 20μm小孔贯通.动物肌肉内植入实验显示混合骨水泥(1∶1)的组织相容性满意,但降解速度缓慢.结论 PMMA与CPC在1∶1比例混合能有效克服单一材料缺点,优势互补,从而使该混合骨水泥有望成为理想的椎体成形术及椎体后凸成形术填充材料.     

CPC／PMMA双向骨水泥性能及生物相容生的初步研究

目的将聚甲基阿烯酸甲酯骨水泥(PMMA)与磷酸钙骨水泥(CPC)制成一种注射型混合骨 水泥,利用各自的特性,优势瓦补,从而使该混合骨水泥成为理想的椎体成形术及椎体后凸成形术填 充材料。方法实验材料为注射型PMMA骨水泥和注射型CPC骨水泥。首先将PMMA与CPC按质 量比1：2、1：1、2：l均匀混合,制成不同比例的混合骨水泥,然后将PMMA、CPC、混合骨水泥(1：2、1：1、 2：1)制成标准试件(直径6ram、高12mm),最后对试件进行力学性能、凝固温度、凝同时间、电镜扫描、 x线衍射、动物肌肉内植入实验,初步评估混合骨水泥的性能及生物相容性。结果PMMA与CPC 在I：1比例混合时理化性能满意,其抗压强度较CPC提高约120％,凝固过程中的最高温度低于 45℃,凝固时间约12—14 rain,微观结构与CPC相似,孔径在100—300¨m之间分布最多(约70％), 大部分孔与孔之间有10～201zm小孔冕通。动物肌肉内植入实验显示混合骨水泥(1：1)的组织相容 性满意。但降解速度缓慢。结论PMMA与CPC在I：1比例混合能有效克服单一材料缺点,优势互 补。从而使该混合骨水泥有望成为理想的椎体成形术及椎体后I九1成形术填充材料。     

注射型磷酸钙骨水泥和PMMA在椎体成形术中的生物力学研究

目的:模仿椎体成形术观察注射型磷酸钙骨水泥(calcium phosphate cement CPC)/聚甲基丙烯酸甲酯(polymethylmethacrylate,PMMA)植入椎体后的生物力学改变.方法:将PMMA和CPC通过手术植入到犬椎体,经过8周和16周后分别取材,行X线、CT检查,并测定不同时间椎体的轴向抗压强度和抗扭转强度.结果:(1)植入早期,PMMA的抗压强度明显高于正常椎体和CPC(P＜0.01),CPC的抗压强度明显低于正常椎体和PMMA(P＜0.01).术后8周显示,PMMA的抗压强度有所下降(P＜0.01=0.009),CPC的抗压强度有所上升(P＜0.05=0.034),但与正常椎体相比仍差别显著.术后16周显示PMMA抗压强度继续下降(P＞0.05=0.710),CPC的抗压强度继续上升(P＞0.05=0.648),与正常椎体相比无显著性差异.(2)植入早期,PMMA的抗扭转强度明显高于正常椎体和CPC(P＜0.05=0.03),CPC的抗扭强度明显低于正常椎体和PMMA(P＜0.05=0.02).术后8周显示,PMMA的抗扭强度有所下降,但与正常椎体相比仍差别显著(P＜0.05=0.045),CPC的抗压强度有所上升与正常椎体相比差异不显著(P＞0.05=0.078).术后16周显示PMMA抗压强度继续下降(P＞0.05=0.137),CPC的抗压强度继续上升,与正常椎体相比无显著性差异(P＞0.05=0.847).结论:磷酸钙骨水泥是椎体成形术中治疗椎体压缩性骨折和胸腰椎爆裂骨折一种比较理想的材料,注入到椎体后,其生物力学强度有逐渐增强的趋势,而PMMA是机械固定,其生物力学强度有逐渐减弱的趋势.     

注射型磷酸钙骨水泥和PMMA在椎体成形术中的生物力学研究

目的模仿椎体成形术观察注射型磷酸钙骨水泥(calcium phosphate cement CPC)/聚甲基丙烯酸甲酯(polymethylmethacrylate,PMMA)植入椎体后的生物力学改变.方法将PMMA和CPC通过手术植入到犬椎体,经过8周和16周后分别取材,行X线、CT检查,并测定不同时间椎体的轴向抗压强度和抗扭转强度.结果(1)植入早期,PMMA的抗压强度明显高于正常椎体和CPC(P＜0.01),CPC的抗压强度明显低于正常椎体和PMMA(P＜0.01).术后8周显示,PMMA的抗压强度有所下降(P＜0.01=0.009),CPC的抗压强度有所上升(P＜0.05=0.034),但与正常椎体相比仍差别显著.术后16周显示PMMA抗压强度继续下降(P＞0.05=0.710),CPC的抗压强度继续上升(P＞0.05=0.648),与正常椎体相比无显著性差异.(2)植入早期,PMMA的抗扭转强度明显高于正常椎体和CPC(P＜0.05=0.03),CPC的抗扭强度明显低于正常椎体和PMMA(P＜0.05=0.02).术后8周显示,PMMA的抗扭强度有所下降,但与正常椎体相比仍差别显著(P＜0.05=0.045),CPC的抗压强度有所上升与正常椎体相比差异不显著(P＞0.05=0.078).术后16周显示PMMA抗压强度继续下降(P＞0.05=0.137),CPC的抗压强度继续上升,与正常椎体相比无显著性差异(P＞0.05=0.847).结论磷酸钙骨水泥是椎体成形术中治疗椎体压缩性骨折和胸腰椎爆裂骨折一种比较理想的材料,注入到椎体后,其生物力学强度有逐渐增强的趋势,而PMMA是机械固定,其生物力学强度有逐渐减弱的趋势.     

不同充填材料强化椎体在骨质疏松性椎体压缩骨折中的应用

目的分别以聚甲基丙烯酸甲酯骨水泥(PMMA)和注射型自固化磷酸钙人工骨(CPC)作为强化椎体的充填材料,采用椎体成形术和膨胀式椎体成形器(Sky)后凸成形术治疗骨质疏松性椎体压缩骨折,观察其临床疗效。方法对45例骨质疏松性椎体压缩骨折患者采用以下4种方法治疗:椎体成形术 PMMA(15例17个椎体),椎体成形术 CPC(13例16个椎体),Sky后凸成形术 PMMA(8例8个椎体),Sky后凸成形术 CPC(9例10个椎体)。根据患者术前和术后侧位X线片计算椎体高度压缩率和恢复率、椎体后凸角度和恢复率,并采用VAS(vasual analogscale)进行术前和术后疼痛评分。结果所有患者均未出现并发症。Sky后凸成形术椎体高度恢复率和后凸角度恢复率优于椎体成形术。椎体增强材料充填剂量各组间无显著性差异。椎体成形术与Sky后凸成形术手术时无显著性差异。VAS评分术前各组无显著性差异,术后充填PMMA者优于充填CPC者,术后6周两者间无显著性差异。结论用PMMA和CPC强化椎体是一种微创、安全、有效治疗骨质疏松性椎体压缩骨折的方法,应根据患者的具体情况选择治疗方法和椎体充填材料。     

骨质疏松致椎体压缩性骨折PVP治疗中CPC填充物的应用研究进展

经皮椎体成形术(PVP)可增加椎体强度、解除疼痛,在脊柱疾病治疗中有着广泛的应用,临床研究已证实采用磷酸钙骨水泥(CPC)作为骨填充物是种安全、可靠、生物相容性高的替代材料。但单纯CPC作骨填充物仍不理想,文章从现阶段磷酸钙骨水泥的临床应用出发,总结分析出磷酸钙骨水泥的常用方式及最新的改性研究进展,以期为临床应用提供参考。     

椎体成形术或后凸成形术生物活性充填材料的体内降解

目的 观察磷酸钙骨水泥(CPC)和硫酸钙骨水泥(CSC)在椎体内的演变过程,为椎体成形术或后凸成形术中寻找更为合适的充填材料.方法 对24只成年雌性绵羊的L2～L5椎体制作骨缺损,随机注入CPC、CSC和聚甲基丙烯酸甲酯(PMMA),其中剩余的椎体作为空白对照,并以L6椎体作正常对照.术后2周、12周和24周分别随机处死其中8只绵羊,进行大体观察、生物力学测试、不脱钙组织学分析.结果 CSC组和CPC组椎体被填充材料明显增强,但CSC组椎体力学性能自2～12周呈现下降趋势,而到24周时又出现回升.CPC组椎体力学性能自2～24周呈上升趋势.12周时3组新骨形成量差异不明显,CSC已被大部分吸收;植入24周时新骨形成量CSC组＞空白组＞CPC组,CPC出现了明显的吸收,而CSC仅有少量残留.结论 CSC与CPC初期均能明显增强椎体;随着时间的推移,CSC在体内降解迅速,而CPC在体内降解缓慢.     

三种骨水泥应用于椎体成形术的生物力学比较

目的:评价硫酸钙(CSC)、磷酸钙(CPC)与聚甲基丙烯酸酯(PMMA)3种骨水泥用于椎体成形术的生物力学性能。方法:将16具小牛胸腰段(T11～L1)标本分为4组,A、B、C组制成T12爆裂骨折模型,D组为无骨折对照组,测量爆裂骨折前、后和复位并分别注射CSC(A组)、CPC(B组)、PMMA(C组)行椎体成形术后椎体前缘高度,达到骨水泥完全填充时的骨水泥注射量;生物力学检测4组标本的极限抗压强度及刚度。结果:12具标本均形成胸腰椎爆裂骨折模型,平均撞击能量66.2J;CSC、CPC、PMMA注射量分别为4.35±0.80ml、3.72±0.73ml及3.95±0.63ml,3组间无显著性差异(P>0.05);3种骨水泥均能有效充填爆裂椎体复位后残留的骨缺损及恢复伤椎高度(P<0.01);A、B、C及D组的极限抗压强度分别为1659±154N、1011±142N、2821±897N及2439±525N,C组能完全恢复椎体的抗压强度,A、B组可部分恢复,但A组优于B组(P<0.01);4组标本的刚度分别为140±40N/mm、148±33N/mm、236±97N/mm及224±38N/mm,A组刚度低于D组(68.0%,P<0.05),但与B、C组无显著性差异(P>0.05)。结论:3种不同成分骨水泥中,PMMA的强度最高,CSC次之,CPC的强度最差,刚度方面三者间无明显差别;CSC用于椎体成形术能满足对椎体填充材料的生物力学要求,可作为椎体成形术中填充材料的选择之一。     

不同充填材料应用于山羊经皮椎体成形术的组织学研究

目的:研究聚甲基丙烯酸甲酯(PMMA)、磷酸钙人工骨(CPC)和复合重组人骨形态发生蛋白-2的磷酸钙人工骨(rhBMP-2/CPC)在山羊骨质疏松症模型上行经皮椎体成形术(PVP)后的组织学表现。方法:6～8岁雌性山羊8只,均行双侧卵巢切除术,术后4个月建立骨质疏松症模型。在C形臂X线机监视下,随机选取8只山羊的L2-L6的两节椎体行PVP,分别充填PMMA、CPC和rhBMP-2/CPC,保证每只山羊的两节穿刺椎体的充填材料各不相同,术后4个月处死所有动物,取出椎体,组织学观察。结果:8只山羊16个椎体的PVP均成功,共出现4个椎体的渗漏。肉眼观察:PMMA与松质骨界限清晰,一个椎体取材时交界面出现破碎和脱落现象;而CPC和rhBMP-2/CPC与椎体内松质骨界限不清,互相融合生长。HE染色光镜观察:PMMA与骨小梁松散结合,界限明显,未见PMMA吸收和新生骨形成;CPC均匀分布于骨小梁和骨髓组织内,有CPC吸收现象,同时可见有新生软骨样团块形成,并有新生骨组织形成向其中心长入;rhBMP-2/CPC除了CPC的表现外,可见成骨活动活跃。结论:在组织学上,rhBMP-2/CPC和CPC均具有降解活性和骨传导活性,优于PMMA。rhBMP-2/CPC还具有诱导成骨活性,可能成为PVP中强化骨质疏松性椎体的首选充填材料。     

Biomechanical evaluation of vertebroplasty using calcium sulfate cement for thoracolumbar burst fractures

OBJECTIVE: To evaluate the biomechanical performance of vertebroplasty using calcium sulfate cement for thoracolumbar burst fractures. METHODS: Sixteen bovine thoracolumbar spines (T11-L1) were divided into 4 groups (A,B,C and D). After burst-fracture model was created, 12 vertebral bodies in Groups A, B and C were augmented with calcium sulfate cement (CSC), calcium phosphate cement (CPC) and polymethylmethacrylate (PMMA) bone cement, respectively. Each anterior vertebral body height was measured with a caliper at 4 time points: intact conditions (HInt), post-fracture (HFr), post-reduction (HRe) and post-vertebroplasty (HVP). The filling volume of 3 different bone cements was also measured. Each vertebral body was compressed at 0.5 mm/s using a hinged plating system on a materials testing machine to 50% of the post-vertebroplasty height to determine strength and stiffness. Difference was checked using t test or One-way ANOVA. RESULTS: The average strike energy was 66.2 J. Vertebroplasty with different cements could sustain vertebral height.The average filling volume of bone cement in 3 groups was 4.35 ml (CSC), 3.72 ml (CPC) and 3.95 ml (PMMA), respectively, and there was no statistically significant difference among them (P larger than 0.05). Vertebroplasty with PMMA completely restored strength (116%) and stiffness (105%). CSC or CPC partly recovered vertebral strength and stiffness. However, greater strength restoration was got with CSC (1659 N) as compared with CPC (1011N, P less than 0.01). Regarding stiffness, differences between CSC (140 N/mm+/-40 N/mm)and the other two bone cements (CPC:148 N/mm+/-33 N/mm, PMMA:236 N/mm+/-97 N/mm) were not significant (P larger than 0.05). CONCLUSIONS: For a burst-fracture of calf spine, use of CSC for vertebroplasty yields similar vertebral stiffness as compared with PMMA or CPC. Although augmentation with CSC partly obtains the normal strength, this treatment still can be applied in thoracolumbar burst fractures with other instrumental devices in light of its bioactivation.     

Biomechanical evaluation of kyphoplasty and vertebroplasty with calcium phosphate cement in a simulated osteoporotic compression fracture

 Kyphoplasty and vertebroplasty with polymethylmethacrylate (PMMA) have been used for the treatment of osteoporotic vertebral compression fractures. We performed kyphoplasty and vertebroplasty with α-tricalcium phosphate cement (CPC) and PMMA to compare the biomechanical properties. Thirty osteoporotic vertebrae were harvested from nine embalmed cadavers. We randomized the vertebrae into four treatment groups: (1) kyphoplasty with CPC; (2) kyphoplasty with PMMA; (3) vertebroplasty with CPC; and (4) vertebroplasty with PMMA. Prior to injecting the cement, all vertebrae were compressed to determine their initial strength and stiffness. They were then recompressed to determine their augmented strength and stiffness. Although the augmented strength was greater than the initial strength in all groups, there was no significant difference between the two bone cements for either kyphoplasty or vertebroplasty. The augmented stiffness was significantly less than the initial stiffness in the kyphoplasty groups, but the difference between the two cements did not reach significance. In the vertebroplasty groups, the augmented stiffness was not significantly different from the initial stiffness. There was no significant difference between the two bone cements for either procedure when cement volume and restoration of anterior height were assessed. We concluded that kyphoplasty and vertebroplasty with CPC were viable treatment alternatives to PMMA for osteoporotic vertebral compression fractures. Received: July 18, 2002 / Accepted: November 6, 2002 Offprint requests to: S. Tomita     

经皮椎体成形术结合体位复位治疗严重老年性脊柱压缩性骨折

目的探讨在体位复位辅助下椎体成形术治疗严重老年性脊柱压缩性骨折的疗效。方法36例老年性脊柱压缩性骨折患者，通过体位复位后，根据骨折椎体的形态，经双侧或单侧椎弓根穿刺充填自固化磷酸钙人工骨（CPC）。测量术前和术后侧位X线片椎体高度变化，记录分析视觉模拟评分（VAS）及骨折椎体形态变化。结果术后骨折处疼痛获得快速显著缓解，VAS评分改变从（7．8±2．5）分降至（1．8±1．4）分，椎体前缘高度和中间高度恢复明显。随访8—22（15±7）个月，短中期疗效满意，骨折椎体高度无明显丢失。结论经皮椎体成形术结合体位复位治疗严重老年性脊柱压缩性骨折是安全有效的。     

复合rhBMP-2可注射磷酸钙骨水泥在椎体成形术中应用的实验研究

目的 探讨自主研发的复合rhBMP-2可注射磷酸钙骨水泥(复合材料)替代注射型聚甲基丙烯酸甲酯(PMMA)应用于猕猴椎体成形术的可行性.方法 将4只成年猕猴分为Ⅰ、Ⅱ两组,每组2只.每组猕猴T10～L7的20个椎体经皮穿刺,按处理方法不同分为复合材料组(A组,8个椎体)、可注射型PMMA组(B组,6个椎体)和手术空白对照组(C组,6个椎体).分别于术后即刻和术后1、2,4、6个月行放射学检查.Ⅰ组于术后2个月、Ⅱ组于术后6个月处死,取出单个椎体,每个椎体取含材料骨样本2份,1份用于光镜检查,另1份用于扫描电镜.观察两种材料强化椎体的早期和后期效果和变化.结果 A组2个月时材料部分降解,未见界面缝隙、纤维增生、炎性浸润或硬化骨痂现象,大量类骨质形成并长人材料,可见新生血管;6个月后大部分材料吸收完全,大部分软骨钙化形成成熟骨组织,有完整的骨小梁及哈佛系统.B组2个月时未见材料降解,中度炎性浸润,纤维组织膜包裹,界面缝隙明显,未见新骨生长;6个月时,炎性浸润消失,纤维界膜变薄,界面缝隙变窄,仍无材料降解和新骨生长.C组2个月后椎体骨隧道被新生骨质填充,骨小梁排列紊乱,边界硬化骨痂形成;6个月后,骨小梁排列整齐,边界骨痂消失,不能辨认,骨重建完成.结论 复合rhBMP-2的注射型磷酸钙骨水泥植入椎体后能够获得良好的诱导生长活性,材料降解和新骨替代同步,周期接近于正常椎体的骨愈合,可望替代PMMA获得椎体成形后早期和远期更好的组织学效果.     

胸腰椎骨质疏松性骨折自固化磷酸钙骨水泥椎体成形的实验研究

目的探讨自固化磷酸钙骨水泥(calciumphosphatecement,CPC)注射椎体成形术后对胸腰椎骨质疏松性骨折椎体的力学影响。方法自愿捐赠的4具甲醛固定的老年尸体,取胸腰椎骨质疏松标本,平均年龄69岁,男、女各2具。每具标本随机取6个椎体,制备24个单椎体标本,建立前屈方向加载单椎体骨折模型。将CPC粉末与固化液以2.5g∶1ml调和制备CPC骨水泥,对骨折标本行CPC成形强化,每个椎体注射CPC约4ml。分别进行骨折前、成形后屈曲压缩力学检测。结果骨质疏松椎体标本骨折前最大载荷为1954±46N,位移长度为5.60±0.70mm,刚度为349±18N/mm;骨折间隙CPC填塞成形后最大载荷为2285±34N,位移为5.35±0.60mm,刚度为427±10N/mm,各指标骨折前和成形后比较差异均有统计学意义(P<0.05)。CPC加强成形后单椎体的承载能力强度较骨折前提高16.92%,刚度较骨折前提高22.31%。结论椎体内注射CPC能明显恢复骨质疏松骨折椎体的力学性能。     

Differential blood contamination levels and powder–liquid ratios can affect the compressive strength of calcium phosphate cement (CPC): a study using a transpedicular vertebroplasty model

Purpose

Calcium phosphate cement (CPC) is a potentially useful alternative to polymethylmethacrylate (PMMA) for transpedicular injection into osteoporotic vertebral fractures. Unlike PMMA, CPC is both biocompatible and osteoconductive without producing heat from polymerization, but it has lower compressive strength compared to PMMA. This in vitro model experiment analyzed how different CPC powder–liquid ratios (P/L ratios) and injection methods may minimize blood contamination in the CPC and, thereby its reduction in compressive strength.

Methods

(1) CPC of different P/L ratios of 4.0, 3.5, and 3.2 was equally mixed with different amounts of freshly obtained human venous blood, producing cylindrically shaped CPC samples. (2) Using a transpedicular vertebroplasty model containing blood in the bottom, CPC pastes of different P/L ratios were injected with the nozzle of an injection gun affixed either to the bottom (Bottom method) or to the top of the container (Top method). All cylindrical CPC samples thus obtained were immersed in simulated body fluid and then underwent compressive strength tests at 3 h–7 days post-immersion.

Results

In CPC equally mixed with blood, lower P/L ratios and a larger amount of blood contamination reduced compressive strength more significantly. Of the two methods of CPC injection, the ‘Bottom method’ produced significantly greater compressive strength values than the ‘Top method’.

Conclusions

When performing CPC-assisted vertebroplasty, a greater load bearing-support can be obtained by injecting CPC paste of a high P/L ratio of 4.0 into the deepest part of the space inside the vertebral body to minimize blood contamination.     

Vertebroplasty comparing injectable calcium phosphate cement compared with polymethylmethacrylate in a unique canine vertebral body large defect model.

BACKGROUND CONTEXT: Vertebroplasty was developed to mechanically reinforce weakened vertebral bodies. Polymethylmethacrylate (PMMA) bone cement has been most commonly used but carries risks of thermal injury and respiratory and cardiovascular complications. Calcium phosphate (CaP) offers the potential for biological resorption and replacement with new bone, restoring vertebral body mass and height. PURPOSE: To compare compressive strength, elastic modulus of the adjacent motion segments, and histologic response of vertebral bodies injected with either CaP or PMMA in a canine vertebroplasty model. STUDY DESIGN: By using a canine vertebroplasty model, two level vertebroplasties were performed at L1 and L3 and studied for 1 month (n=10) and 6 months (n=10). In each canine, one vertebral defect was randomly injected with either CaP cement (BoneSource; Stryker, Freiberg, Germany) or PMMA. METHODS: Twenty dogs had an iatrogenically created cavitary lesion at two nonadjacent levels injected with either CaP or PMMA. Canines from each group were tested mechanically (n=5) and histologically (n=5). Histology consisted of axial sections of the L1 and L3 vertebral bodies and high-resolution contact radiographs. Sections from each specimen were embedded in plastic without decalcification to study the bone-cement interface. Bone-cement interfaces were compared for evidence of necrosis, fibrosis, foreign body response, cement resorption, and new bone formation between the PMMA and CaP treatments groups. Mechanical compression testing was performed on specimens from the 1-month (n=5) and 6-month (n=5) time periods. The T13 vertebral body was used as an intact control for the destructive compression testing of L1 and L3. Each vertebral body was compressed to 50% of its original height under displacement control at 15 mm/min to simulate a nontraumatic loading situation. Force and displacement data were recorded in real time. RESULTS: Vertebral sites containing PMMA were characterized by a thin fibrous membrane. PMMA was detected within the trabeculae, vascular channels, and the spinal canal. Unlike PMMA, CaP underwent resorption and remodeling with vascular invasion and bone ingrowth. Woven and lamellar bone was found on the CaP cement surface, within the remodeled material, and on the surrounding trabeculae. Vertebral body compression strength testing revealed no significant difference in vertebral body height and compressive strength between PMMA and CaP. There was a trend for CaP-treated vertebrae to increase in compressive strength from 1 month to 6 months, whereas PMMA decreased compressive strength when compared with adjacent nontreated vertebrae. CONCLUSION: For both short and intermediate time periods, the injection of CaP cement can be an effective method to treat large vertebral defects. Early results indicate that CaP remodeling might result in the resorption of the majority of the cement with replacement by lamellar bone.