胸腰椎骨质疏松骨折行CPC灌注成形的力学实验

目的探讨磷酸钙骨水泥(calcium phosphate cement,CPC)注射椎体成形术后对胸腰椎骨质疏松骨折椎体的力学影响。方法建立前屈方向加载单椎体骨折模型,对胸腰椎骨质疏松骨折标本行CPC成形强化,骨折前、成形后分别行屈曲压缩力学实验。结果椎体内注射CPC能明显恢复骨质疏松骨折椎体的力学性质。骨质疏松性胸腰椎标本行CPC灌注成形可以恢复椎体的强度和刚度,分别增加16.92%(P<0.05)和22.31%(P<0.05)。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质。     

胸腰椎骨质疏松骨折行磷酸钙骨水泥灌注成形的生物力学实验

目的:探讨磷酸钙骨水泥(CPC)注射椎体成形术后对胸腰椎骨质疏松骨折椎体的力学影响。方法:将4具甲醛固定的老年尸体胸腰椎标本建立前屈方向加载单椎体骨折模型,将固液比为2.5∶1的自固化CPC对胸腰椎骨质疏松骨折标本行成形强化,骨折前、成形后分别行屈曲压缩力学实验。结果:在同样的载荷下,单椎体CPC成形后的椎体应变比骨折前小,有统计学差异(t=6.37,P<0.05),骨质疏松性胸腰椎标本行CPC灌注成形可以恢复椎体的强度和刚度,分别增加16.92%和22.31%(P<0.05)。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质。     

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。     

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.     

硫酸钙骨水泥在胸腰椎爆裂骨折椎体成形术中的生物力学性能

[目的]评价硫酸钙骨水泥(CSC)椎体成形术在胸腰椎爆裂骨折中的生物力学性能及临床应用价值.[方法]将16具新鲜小牛胸腰椎标本分为4组,A、B、C 3组制成爆裂骨折模型后分别实施CSC磷酸钙骨水泥(CPC)、聚甲基丙烯酸酯(PMMA)椎体成形术,D组为无骨折对照组.测量指标包括:爆裂骨折前、后与复位后及椎体成形术后的椎体前缘高度;达到完全填充时的3种骨水泥的注射量;生物力学检测4组标本的极限抗压强度及刚度.[结果](1)实验组12具标本均形成胸腰椎爆裂骨折模型,平均撞击能量为66.2 J;(2)CSC、CPC、PMMA的注射量分别为:4.4 ml±0.8 ml、3.7 ml±0.7 ml、4.0 ml±0.6 ml,组间无差别(P>0.05);(3)3种骨水泥均能有效充填爆裂骨折椎体复位后遗留的骨缺损,显著恢复了伤椎高度(P<0.01);(4)A、B、C、D组的极限抗压强度分别为:1 659 N±154 N、1 011 N±142 N、2 821 N±897 N及2 439 N±525 N.PMMA能够完全恢复骨折椎的抗压强度,CSC、CPC均只能部分恢复骨折椎的强度,但CSC优于CPC(P<0.01);(5)4组椎体的刚度分别为:(140±40)N/mm、(148±33)N/mm、(236±97)N/mm、(224±38)N/mm.CSC的刚度低于完整椎体68.0%,(P<0.05),但与PMMA、CPC无显著差异(P>0.05).[结论]经CSC椎体成形术的骨折椎强度优于CPC,刚度与PM-MA、CPC相当.将CSC椎体成形术作为一种辅助治疗方式用于胸腰椎爆裂骨折能满足力学要求,手术安全可行.     

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。     

胸腰椎爆裂骨折模型中硫酸钙骨水泥椎体成形术的生物力学性能

[目的]评价硫酸钙骨水泥椎体成形术的生物力学性能并探讨用于胸腰椎爆裂骨折的可行性. [方法]16具新鲜小牛胸腰椎标本分为4组,每组4具,A、B、C 3组(实验组)标本在制成爆裂骨折模型后分别实施3种骨水泥(CSC、CPC、PMMA)椎体成形术,D组为无骨折对照组.测量爆裂骨折前、后、复位后及椎体成形术后的椎体前缘高度;测量达到完全填充时的3种骨水泥的注射量;生物力学检测比较4组标本间的极限抗压强度及刚度差别. [结果](1)实验组12具标本均形成胸腰椎爆裂骨折模型,平均撞击能量为66.2 J;(2)CSC、CPC、PMMA的注射量分别为:4.4 ml±0.8 ml、3.7 ml±0.7 ml、4.0 ml±0.6 ml,组间无差别(P>0.05);(3)3种骨水泥均能有效充填爆裂骨折椎体复位后遗留的骨缺损,显著恢复伤椎高度(P<0.01);(4)A、B、C、D组的极限抗压强度分别为:1 659 N±154 N、1 011 N±142 N、2 821 N±897 N及2 439 N±525 N.PMMA能够完全恢复骨折椎的抗压强度,CSC、CPC均只能部分恢复骨折椎的强度,但CSC优于CPC(P<0.01);(5)4组椎体的刚度分别为:140 N/mm±40 N/mm、148 N/mm±33 N/mm、236 N/mm±97 N/mm、224 N/mm±38 N/mm.CSC的刚度低于完整椎体(62.5%,P<0.05),但与PMMA、CPC差异无统计学意义(P>0.05). [结论]经CSC椎体成形术的骨折椎的强度优于CPC,刚度与PMMA、CPC相当.将CSC椎体成形术作为一种辅助治疗方式用于胸腰椎爆裂骨折能满足力学要求、手术安全可行.     

椎体成形术中骨水泥量对椎体机械性能的实验研究

目的探讨聚甲基丙烯酸甲酯(PMMA)和自固化磷酸钙骨水泥(CPC)的不同用量对骨质疏松性椎体强度和硬度的影响,明确恢复椎体强度及硬度所需的最小骨水泥用量。方法取5具老年女性(65～73岁)48个脊椎标本(T6～L3),分解后压缩并测量其强度和硬度,将3、5、7ml PMMA和CPC注入压缩后的椎体,再测其强度和硬度,并与原来的强度和硬度进行比较。结果所有椎体注入骨水泥后强度都得到恢复,注入5ml、7ml骨水泥后强度明显增加;注入PMMA后硬度都得到恢复,而注入CPC 5ml、7ml才能恢复椎体硬度。结论骨质疏松性椎体骨折后,注入骨水泥可有效恢复椎体的强度和硬度,此结果可有利于指导椎体成形术的临床应用。     

用于骨质疏松脊柱压缩骨折的新型可降解材料的体外实验研究

目的 研发一种用于治疗骨质疏松椎体压缩骨折的新型复合生物玻璃的磷酸钙骨水泥,并观察其体外材料学及生物学活性。方法 将不同质量百分比的生物玻璃（bioglass,BG）与磷酸钙（calcium phosphate cement,CPC )球磨后物理共混获得一种具有可注射、自固化、可降解的椎体成型替代材料。分别对该替代材料的凝固时间、流动性、力学强度进行测定并行材料体外成骨细胞粘附实验、增殖实验,观察其生物相容性。结果 随着新型替代材料中BG组分含量的增加,替代材料的凝固时间逐渐延长,同时,流动性较磷酸钙骨水泥改善明显。随着凝固时间的延长,替代材料固化后的抗压强度显著高于实验组CPC骨水泥。此外,与CPC相比,替代材料更有利于细胞的粘附、增殖及分化,具有良好的生物相容性。结论新型复合生物玻璃的磷酸钙的生物材料不仅具有可注射性和较高的力学强度,同时骨传导性能更好,有希望成为临床治疗骨质疏松椎体压缩骨折的一种新型椎体成形材料。     

An ex vivo biomechanical evaluation of an inflatable bone tamp used in the treatment of compression fracture

STUDY DESIGN: Ex vivo biomechanical study using osteoporotic cadaveric vertebral bodies. OBJECTIVES: To determine if the inflatable bone tamp (tamp) restores height to compressed vertebral bodies and to compare the biomechanical properties of isolated, fractured osteoporotic vertebral bodies treated by kyphoplasty (tamp) or vertebroplasty. SUMMARY OF BACKGROUND DATA: Previous biomechanical studies have shown that vertebroplasty increases vertebral body strength and restores vertebral body stiffness, but does not restore vertebral body height lost as a result of compression fracture. METHODS: Compression fractures were experimentally created in 16 osteoporotic VBs assigned to either the tamp or percutaneous vertebroplasty group. The tamp treatment consisted of inserting balloon-like devices into the vertebral body, inflating the bone tamp, and filling the void with Simplex P (Howmedica, Rutherford, NJ) bone cement. The percutaneous vertebroplasty treatment consisted of directly injecting Cranioplastic bone cement (CMW, Blackpool, UK) into the vertebral body. Pre- and posttreatment heights were measured, and the repaired vertebral bodies were recompressed to determine posttreatment strength and stiffness values. RESULTS: The tamp treatment resulted in significant restoration (97%) of vertebral body height lost after compression, whereas percutaneous vertebroplasty treatment resulted in a significantly lower restoration of lost height (30%) (P < 0.05). Both treatments resulted in significantly stronger vertebral bodies relative to their initial state (P < 0.05). The tamp treatment restored vertebral body stiffness to initial values, but the percutaneous vertebroplasty treatment did not (P < 0.05). CONCLUSIONS: Tamp treatment resulted in significantly greater height restoration than did percutaneous vertebroplasty, without loss of vertebral body strength or stiffness.     

The biomechanics of vertebroplasty. The effect of cement volume on mechanical behavior.

STUDY DESIGN: Ex vivo biomechanical study using osteoporotic cadaveric vertebral bodies. OBJECTIVE: To determine the association between the volume of cement injected during percutaneous vertebroplasty and the restoration of strength and stiffness in osteoporotic vertebral bodies, two investigational cements were studied: Orthocomp (Orthovita, Malvern, PA) and Simplex 20 (Simplex P with 20% by weight barium sulfate content; Stryker-Howmedica-Osteonics, Rutherford, NJ). SUMMARY OF BACKGROUND DATA: Previous biomechanical studies have shown that injections of 8-10 mL of cement during vertebroplasty restore or increase vertebral body strength and stiffness; however, the dose-response association between cement volume and restoration of strength and stiffness is unknown. METHODS: Compression fractures were experimentally created in 144 vertebral bodies (T6-L5) obtained from 12 osteoporotic spines harvested from female cadavers. After initial strength and stiffness were determined, the vertebral bodies were stabilized using bipedicular injections of cement totaling 2, 4, 6, or 8 mL and recompressed, after which post-treatment strength and stiffness were measured. Strength and stiffness were considered restored when post-treatment values were not significantly different from initial values. RESULTS: Strength was restored for all regions when 2 mL of either cement was injected. To restore stiffness with Orthocomp, the thoracic and thoracolumbar regions required 4 mL, but the lumbar region required 6 mL. To restore stiffness with Simplex 20, the thoracic and lumbar regions required 4 mL, but the thoracolumbar region required 8 mL. CONCLUSION: These data provide guidance on the cement volumes needed to restore biomechanical integrity to compressed osteoporotic vertebral bodies.     

An ex vivo biomechanical evaluation of a hydroxyapatite cement for use with vertebroplasty.

STUDY DESIGN: Comparative ex vivo biomechanical study. OBJECTIVE: To determine the strength and stiffness of osteoporotic vertebral bodies subjected to compression fractures and stabilized via bipedicular injections of the following: 1) Simplex P (Stryker-Howmedica-Osteonics, Rutherford, NJ), 2) Simplex P formulated consistent with the practice of vertebroplasty (F2), or 3) BoneSource (Stryker-Howmedica-Osteonics). SUMMARY OF BACKGROUND DATA: Little is known about the mechanical stabilization afforded by new materials proposed for use with vertebroplasty. METHODS: Vertebral bodies (T8-T10 and L2-L4) from each of 10 fresh spines were harvested from female cadavers (81 +/- 12 years), screened for bone density (t score, -3.8 +/- 1.1; bone mineral density, 0.75 +/- 15 g/cm2), disarticulated, and compressed to determine initial strength and stiffness. The fractured vertebral bodies were stabilized via bipedicular injections of 4 mL (thoracic) or 6 mL (lumbar) and then recrushed. RESULTS: Vertebral bodies repaired with Simplex P resulted in significantly greater strength (P < 0.05) relative to their prefracture states, those repaired with BoneSource resulted in the restoration of initial strength for both the thoracic and lumbar level, and those repaired with F2 resulted in significantly greater strength (P < 0.05) in the thoracic region and restoration of strength in the lumbar region. All cement treatments resulted in significantly less stiffness compared with initial values. CONCLUSIONS: All three materials tested restored or increased vertebral body strength, but none restored stiffness. Both new materials show promise for use in percutaneous vertebroplasty, but they need clinical evaluation.     

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     

Biomechanical efficacy of unipedicular versus bipedicular vertebroplasty for the management of osteoporotic compression fractures.

STUDY DESIGN: Cadaveric study on the biomechanics of osteoporotic vertebral bodies augmented and not augmented with polymethylmethacrylate cement. OBJECTIVES: To determine the strength and stiffness of osteoporotic vertebral bodies subjected to compression fractures and 1) not augmented, 2) augmented with unipedicular injection of cement, or 3) augmented with bipedicular injection of cement. SUMMARY OF BACKGROUND DATA: Percutaneous vertebroplasty is a relatively new method of managing osteoporotic compression fractures, but it lacks biomechanical confirmation. METHODS: Fresh vertebral bodies (L2-L5) were harvested from 10 osteoporotic spines (T scores range, -3.7 to -8.8) and compressed in a materials testing machine to determine intact strength and stiffness. They were then repaired using a transpedicular injection of cement (unipedicular or bipedicular), or they were unaugmented and recrushed. RESULTS: Results suggest that unipedicular and bipedicular cement injection restored vertebral body stiffness to intact values, whereas unaugmented vertebral bodies were significantly more compliant than either injected or intact vertebral bodies. Vertebral bodies injected with cement (both bipedicular and unipedicular) were significantly stronger than the intact vertebral bodies, whereas unaugmented vertebral bodies were significantly weaker. There was no significant difference in loss in vertebral body height between any of the augmentation groups. CONCLUSIONS: This study suggests that unipedicular and bipedicular injection of cement, as used during percutaneous vertebroplasty, increases acute strength and restores stiffness of vertebral bodies with compression fractures.     

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.     

磷酸钙骨水泥在椎体成形术中的实验研究

目的 :模仿椎体成形术观察磷酸钙骨水泥 /聚甲基丙烯酸甲酯植入椎体后与椎体界面间的组织学差异。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 2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。结论 :磷酸钙骨水泥是椎体成形术中的一种比较理想的替代材料     

Biomechanics of vertebral compression fractures and clinical application

Local biomechanical factors in the etiology of vertebral compression fractures are reviewed. The vertebral body is particularly vulnerable to compression fracture when its bone mineral density (BMD) falls with age. However, the risk of fracture, and the type of fracture produced, does not depend simply on BMD. Equally important is the state of degeneration of the adjacent intervertebral discs, which largely determines how compressive forces are distributed over the vertebral body. Disc height also influences load-sharing between the vertebral body and neural arch, and hence by Wolff’s Law can influence regional variations in trabecular density within the vertebral body. Vertebral deformity is not entirely attributable to trauma: it can result from the gradual accumulation of fatigue damage, and can progress by a quasi-continuous process of “creep”. Cement injection techniques such as vertebroplasty and kyphoplasty are valuable in the treatment of these fractures. Both techniques can stiffen a fractured vertebral body, and kyphoplasty may contribute towards restoring its height. The presence of cement can limit endplate deformation, and thereby partially reverse the adverse changes in load-sharing which follow vertebral fracture. Cement also reduces time-dependent “creep” deformation of damaged vertebrae.