胸腰椎爆裂性骨折模型的快速制備

·基礎研究·

胸腰椎爆裂性骨折模型的快速制備

程自申

作者單位:200003上海,第二軍醫大學附屬長征醫院脊柱外科

【摘要】目的探討快速制備胸腰椎爆裂性骨折模型的方法。方法取20個豬胸腰段3聯體標本,上下椎體行環氧樹脂包埋,中間椎體中部一側前1/3、2/3處用直徑為3.2 mm的鉆頭鉆孔,平行對穿椎體,造成中間椎體的有限性損傷,游標卡尺測量骨折前L1椎體前緣高度,記為完整椎體的高度(HInt)。將9 kg不銹鋼錘置于高0.5 m高處,沿引導桿垂直撞擊標本,若L1椎體無骨折跡象則升至0.6 m的高度,若有骨折跡象則將鋼錘降至0.4 m, 在0.5 m的基礎上以0.1 m遞增或遞減進行多次撞擊,直至L1形成爆裂性骨折,記錄撞擊總能量,撞擊總能量E=mgh1+mgh2+…+mghn。爆裂性骨折形成后再次測量L1椎體的前緣高度,記為HFr并對所形成的爆裂性骨折模型行影像學檢查。結果 骨折前椎體前緣高度為(27.405±1.453) mm,骨折后椎體前緣高度為(17.784±1.362) mm,骨折前后差異有統計學意義(P<0.05)。當撞擊高度為0.5 m時有4個爆裂性骨折模型形成,當累計撞擊高度為0.9 m時有13個爆裂性骨折模型形成；當累計撞擊高度為1.3 m時有3個爆裂性骨折模型形成。累計平均撞擊高度為0.865 m ；累計平均撞擊能量為76.313 J。影像學顯示所有標本椎體均造成典型爆裂性骨折。結論采用上下椎體包埋,中間椎體有限損傷,多次撞擊實驗可以制作典型胸腰椎爆裂性骨折的模型。

【關鍵詞】胸椎; 腰椎; 脊柱骨折; 模型,動物

作者簡介:程自申(1980—), 博士,醫師

【中圖分類號】R 683.2

DOI【】

收稿日期：(2014-12-21)

Rapid preparation of model for thoracolumbar burst fractureCHENGZi-shen.DepartmentofOrthopaedics,ChangzhengHospital,SecondMilitaryMedicalUniversity,Shanghai200003,China

【Abstact】ObjectiveTo investigate the method of rapid preparation of thoracolumbar burst fracture. MethodsTo produce 20 thoracolumbar 3-conjoined porcine specimens, the upper and lower vertebrae was resin-embeded by epoxy,and the middle vertebrae was drilled a hole by drill (3.2 mm) respectively on one side of the middle 1/3, 2/3 to create limited damage. L1anterior border height was measured by vernier caliper (HInt). The 9 kg stainless steel hammer was placed at 0.5 m. Then the specimen was impacted along the vertical guide rod. If the middle vertebrae had no signs of fracture, the stainless steel hammer was promoted by 0.1 m at the basis of 0.5 m. If the middle vertebrae had signs of fracture, the stainless steel hammer was descended by 0.1 m at the basis of 0.5 m. When the middle vertebral body formated the burst fracture, the total impact energy was recorded. After middle vertebral body formated the burst fracture, L1anterior border height was measured again (HFr). Then all the models were examined by radiographic methods. ResultsBefore fracture the height of anterior border was (27.405± 1.453) mm, and after the fracture, the height of anterior border was (17.784±1.362) mm, there has significant difference bewteen before and after fracture (P<0.05). When the impact height was 0.5 m, 4 burst fracture model were observed. When the cumulative impact height was 0.9 m, 13 burst fracture model were observed. When the cumulative impact height was 1.3 m, 3 burst fracture model were observed. The cumulative average impact height was 0.865 m, and the cumulative average impact energy was 76.313 J. The models of burst fracture was confirmed by radiological examination. ConclusionA typical thoracolumbar burst fracture model can be made when the middle vertebrae is limitedly injured, the upper/lower vertebrae resin-embed and impact is given for several times.

【key words】Thoracic vertebrae; Lumbar vertebrae; Spinal fractures; Models, animal

J Spinal Surg, 2015,13(3):182-185

隨著對脊柱爆裂性骨折的深入研究,無論是脊柱爆裂性骨折的治療,還是脊柱器械的研制,都需要一個容易制作、重復性好的模型。脊柱爆裂性骨折的模型制作有很多方法,但大都與實際差距太大。本研究綜合文獻分析,找到一種重復性好又能接近實際的快速制備胸腰椎爆裂性骨折模型的方法,通過豬胸腰椎三聯體上下椎體包埋、中間椎體有限預損傷、多次自由落體撞擊的方式制作脊柱爆裂性骨折模型。

1材料和方法

1.1實驗材料和裝置

收集新鮮雄性成年豬(120～140 kg,平均128 kg)胸腰段3聯椎體(T14-L1-L2)20個,國產環氧樹酯及固定液(北京化工),自制撞擊裝置包括重錘9 kg (見圖1)。傾斜15°的楔形壓縮模具(見圖2)。

1:9 kg不銹鋼重錘2:引導桿3:防重錘彈跳鋸齒結構4:楔形壓縮模具5:椎體過度破壞保護裝置

1:Stainless steel of 9 kg2:Guide rod3:Sawtooth structure preventing heavy hammer bouncing4:Wedge compression mold5:Vertebral bodies protection device preventing excessive broken.

圖1自制撞擊裝置

Fig.1Impact device

圖2傾斜15°楔形壓縮模具

Fig.215° inclined compression mold

1.2方法

保留標本橫突(1 mm)、棘突、棘間韌帶、后縱韌帶及關節囊的完整性,大量清水沖洗干凈。所有標本均在DR機上拍攝標準前后位及側位X線片,以除外骨折、畸形或病理變化。雙層塑料袋包裹置入-20℃的冰箱中待用。實驗前將標本取出,常溫下(20℃)解凍24 h,將T14及L2分別包埋在邊長為5 cm、厚為3 cm環氧樹脂中,暴露椎間盤,使上下平面平行,完全固化后待用。對L1椎體中部的一側前1/3、2/3處用直徑為3.2 mm的電鉆鉆孔,平行對穿椎體,造成中間椎體的有限性損傷。游標卡尺測量骨折前L1椎體前緣高度,記為完整椎體的高度(HInt)。將標本置入撞擊裝置,固定。根據Panjabi等[1]“自由落體逐級撞擊原理”進行撞擊實驗。具體如下：將不銹鋼錘置于0.5 m高處,沿引導桿垂直撞擊標本,若L1椎體無骨折跡象則升入0.6 m的高度,若有骨折跡象則將鋼錘降至0.4 m,以0.1 m遞增或者遞減進行撞擊,直至L1形成爆裂性骨折。撞擊總能量E=mgh1+mgh2+…+mghn(m為鋼錘的重量；g為重力加速度；h為鋼錘低面距標本上椎體上平面的高度)。爆裂性骨折形成后再次測量L1椎體的前緣高度,記為HFr。若有骨折跡象時,行影像學觀察,至完整形成骨折模型為止,影像學包括X線、CT。

1.3統計方法

2結果

2.1L1椎體前緣高度的變化

20個標本L1前緣初始高度HInt為(27.405±1.453) mm；骨折后L1前緣平均高度HFr為 (17.784±1.362) mm,骨折前后椎體前緣高度差異具有統計學意義(P<0.05)。

2.2撞擊能量及撞擊累計高度

本研究20例標本,當不銹鋼錘升至0.5 m時有4個標本發生爆裂性骨折,余均有骨折跡象。當撞擊累計高度為0.9 m時有13個標本爆裂性骨折形成,當撞擊累計高度為1.2 m時其余3例均形成爆裂性骨折。撞擊累計平均高度為0.865 m；累計平均能量為76.313 J。

2. 3影像學觀察

所有標本中間椎體均形成重復性較好的爆裂性骨折的模型,AO分型[2]為A3型(見圖3)。正位X線片示左側的椎弓根受到破壞,側位X線片示中間椎體部分壓縮,矢狀面及橫斷面CT示骨折椎體有大量腔隙形成,并有骨折塊突入椎管內。

a,b:正側位X線片示中間椎體部分壓縮,椎弓根受到破壞c,d 矢狀面及橫斷面CT示骨折椎體有大量腔隙形成,并有骨折塊突入椎管內

a,b: Anteroposterior and lateral roentgenographs show middle vertebral body compression and broken rertebral pediclesc,d: Sagittal and transectional CT show lacuna formation in fractured vertebral body and fragment breaking into spinal canal.

圖3爆裂性骨折模型

Fig.3Burst fracture model

3討論

隨著現代建筑業及交通運輸業的迅猛發展,近年來胸腰椎損傷特別是爆裂性骨折的發生率隨之上升。脊柱爆裂性骨折常伴有神經功能損害,遺留各種后遺癥,給家庭和社會造成很大的負擔。對脊柱胸腰椎爆裂性骨折的研究是一個重要的課題,因此臨床需要建立胸腰椎爆裂性骨折的模型。本研究成功建立了胸腰椎爆裂性骨折的模型。

在標本的選擇上,人的脊柱標本最為理想,但人脊柱標本來源受到限制,且受年齡、性別的影響,而且尸體標本長期受到福爾馬林的浸泡,力學性質發生了改變,所以目前胸腰椎爆裂性骨折標本的研究集中到小動物上,主要為小牛[3-6]和豬[7-9]。而且豬的標本有來源廣泛、均一性好、涉及倫理少、與人脊柱具有一定的相似性等優點[10-13]。本實驗選擇豬作為實驗標本,很好地解決了標本的統一性。

采用上下椎體包埋、中間椎體預損傷的方法,上下椎體可以得到更好的保護,避免上下椎體骨折,而且由于楔形模具的作用,應力主要集中到中間椎體前中薄弱處,容易制成中間椎體的爆裂性骨折模型。本組20例標本,骨折前中間椎體前緣椎體高度HInt為(27.405±1.453)mm, 骨折后中間椎體前緣椎體高度HFr為 (17.784±1.362) mm,兩者差異有統計學意義(P<0.05)。說明成功造成了中間椎體爆裂性骨折。而且在對椎體預損傷的方式上盡量減少對椎體的破壞,這樣更接近真實情況。在椎體預損傷上傳統采用椎體部分或全部切除來模擬爆裂骨折[14-16],但這種方法與臨床相差較遠。有文獻報道先通過線鋸切割或大量鉆孔對椎體產生預損傷,然后在力學實驗機壓縮或用落錘撞擊方法產生骨折[17-19],該方法能較好地控制骨折的部位和損傷程度,重復性較好,但對脊柱骨折形成機制缺乏深入了解,對目標骨折椎體損傷較大,雖有較好的重復性,卻很難模擬真實脊柱骨折情況。既要較好地模擬脊柱骨折的真實情況,又要有較好的重復性,椎體有限損傷是較好的解決辦法。而之所以只有目標椎體骨折,是因為對目標骨折椎體的上下椎體進行保護,可通過對上下椎體包埋實現。但單純對上下椎體保護,進行多次撞擊形成骨折模型的重復性較差,在實踐應用中效果較差。故本實驗采用對L1椎體中部的一側前1/3、2/3處用直徑為3.2 mm的電鉆鉆孔,平行對穿椎體,造成中間椎體的有限性損傷的方法。實驗中發現中間椎體仍能較好的形成爆裂性骨折模型,有較好的重復性,并能充分模擬爆裂性骨折的形成機制。

本實驗采用鉆孔有限預損傷及多次撞擊的方式提高到了制備模型的成功率,爆裂性骨折模型也具有較好的一致性。單次撞擊可重復性欠佳,為達到椎體的損傷程度一致,常采用多次撞擊的方式。在撞擊中,對累計撞擊高度和爆裂性骨折形成的數目進行分析,發現爆裂性骨折分布具有較好的對稱性,從另一方面也說明了多次逐級撞擊能較好的形成爆裂性骨折。

綜上所述,采用標本上下椎體進行包埋,中間椎體有限預損傷、多次撞擊方法能成功制作爆裂性骨折模型,模擬骨折形成機制。

參 考 文 獻

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[7] Tarsuslugil SM, O’Hara RM, Dunne NJ, et al.Experimental and computational approach investigating burst fracture augmentation using PMMA and calcium phosphate cements[J].Ann Biomed Eng, 2014, 42(4):751-762.

[8] Hartensuer R, Gehweiler D, Schulze M, et al.Biomechanical evaluation of combined short segment fixation and augmentation of incomplete osteoporotic burst fractures[J].BMC Musculoskelet Disord, 2013, 14:360.

[9] Gurwitz GS, Dawson JM, McNamara MJ, et al.Biomechanical analysis of three surgical approaches for lumbar burst fractures using short-segment instrumentation[J].Spine (Phila Pa 1976), 1993, 18(8):977-82. MM, Kifune M, Wen L, et al.Dynamic canal encroachment during thoracolumbar burst fractures[J].J Spinal Disord, 1995, 8(1):39-48.

[2] Magerl F, Aebi M, Gertzbein SD, et al.A comprehensive classification of thoracic and lumbar injuries[J].Eur Spine J, 1994, 3(4):184-201.

[3] Zeng ZL, Zhu R, Li SZ, et al.Formative mechanism of intracanal fracture fragments in thoracolumbar burst fractures: a finite element study[J].Chin Med J (Engl), 2013, 126(15):2852-2858.

[4] Cain JE Jr, DeJong JT, Dinenberg AS, et al.Pathomechanical analysis of thoracolumbar burst fracture reduction. A calf spine model[J].Spine (Phila Pa 1976), 1993, 18(12):1647-1654.

[5] Wilcox RK, Allen DJ, Hall RM, et al.A dynamic investigation of the burst fracture process using a combined experimental and finite element approach[J].Eur Spine J, 2004, 13(6):481-488.

[6] Wilcox RK, Boerger TO, Allen DJ, et al.A dynamic study of thoracolumbar burst fractures[J].J Bone Joint Surg Am, 2003, 85-A(11):2184-2189.

[7] Tarsuslugil SM, O’Hara RM, Dunne NJ, et al.Experimental and computational approach investigating burst fracture augmentation using PMMA and calcium phosphate cements[J].Ann Biomed Eng, 2014, 42(4):751-762.

[8] Hartensuer R, Gehweiler D, Schulze M, et al.Biomechanical evaluation of combined short segment fixation and augmentation of incomplete osteoporotic burst fractures[J].BMC Musculoskelet Disord, 2013, 14:360.

[9] Gurwitz GS, Dawson JM, McNamara MJ, et al.Biomechanical analysis of three surgical approaches for lumbar burst fractures using short-segment instrumentation[J].Spine (Phila Pa 1976), 1993, 18(8):977-82.

[10]Smit TH.The use of a quadruped as an in vivo model for the study of the spine-biomechanical considerations[J].Eur Spine J, 2002, 11(2):137-144.

[11]Wilke HJ, Geppert J, Kienle A.Biomechanical in vitro evaluation of the complete porcine spine in comparison with data of the human spine[J].Eur Spine J, 2011, 20(11):1859-1868.

[12]Sheng SR, Wang XY, Xu HZ, et al.Anatomy of large animal spines and its comparison to the human spine: a systematic review[J].Eur Spine J, 2010, 19(1):46-56.

[13]Turker M, Tezeren G, Tukenmez M, et al.Indirect spinal canal decompression of vertebral burst fracture in calf model[J].Arch Orthop Trauma Surg, 2005, 125(5):336-341.

[14]Chen HH, Wang WK, Li KC, et al.Biomechanical effects of the body augmenter for reconstruction of the vertebral body[J].Spine (Phila Pa 1976), 2004, 29(18):E382-387.

[15]Wahba GM, Bhatia N, Bui CN, et al.Biomechanical evaluation of short-segment posterior instrumentation with and without crosslinks in a human cadaveric unstable thoracolumbar burst fracture model[J].Spine (Phila Pa 1976), 2010, 35(3):278-285.

[16]Schreiber U, Bence T, Grupp T, et al.Is a single anterolateral screw-plate fixation sufficient for the treatment of spinal fractures in the thoracolumbar junction? A biomechanical in vitro investigation[J].Eur Spine J, 2005, 14(2):197-204.

[17]Baier M, Staudt P, Klein R, et al.Strontium enhances osseointegration of calcium phosphate cement: a histomorphometric pilot study in ovariectomized rats[J].J Orthop Surg Res, 2013, 8:16.

[18]Hartensuer R, Gehweiler D, Schulze M, et al.Biomechanical evaluation of combined short segment fixation and augmentation of incomplete osteoporotic burst fractures[J].BMC Musculoskelet Disord, 2013, 14:360.

[19]Mermelstein LE, McLain RF, Yerby SA.Reinforcement of thoracolumbar burst fractures with calcium phosphate cement. A biomechanical study[J].Spine (Phila Pa 1976), 1998, 23(6):664-670. TH.The use of a quadruped as an in vivo model for the study of the spine-biomechanical considerations[J].Eur Spine J, 2002, 11(2):137-144.

[11]Wilke HJ, Geppert J, Kienle A.Biomechanical in vitro evaluation of the complete porcine spine in comparison with data of the human spine[J].Eur Spine J, 2011, 20(11):1859-1868.

[12]Sheng SR, Wang XY, Xu HZ, et al.Anatomy of large animal spines and its comparison to the human spine: a systematic review[J].Eur Spine J, 2010, 19(1):46-56.

[13]Turker M, Tezeren G, Tukenmez M, et al.Indirect spinal canal decompression of vertebral burst fracture in calf model[J].Arch Orthop Trauma Surg, 2005, 125(5):336-341.

[14]Chen HH, Wang WK, Li KC, et al.Biomechanical effects of the body augmenter for reconstruction of the vertebral body[J].Spine (Phila Pa 1976), 2004, 29(18):E382-387.

[15]Wahba GM, Bhatia N, Bui CN, et al.Biomechanical evaluation of short-segment posterior instrumentation with and without crosslinks in a human cadaveric unstable thoracolumbar burst fracture model[J].Spine (Phila Pa 1976), 2010, 35(3):278-285.

[16]Schreiber U, Bence T, Grupp T, et al.Is a single anterolateral screw-plate fixation sufficient for the treatment of spinal fractures in the thoracolumbar junction? A biomechanical in vitro investigation[J].Eur Spine J, 2005, 14(2):197-204.

[17]Baier M, Staudt P, Klein R, et al.Strontium enhances osseointegration of calcium phosphate cement: a histomorphometric pilot study in ovariectomized rats[J].J Orthop Surg Res, 2013, 8:16.

[18]Hartensuer R, Gehweiler D, Schulze M, et al.Biomechanical evaluation of combined short segment fixation and augmentation of incomplete osteoporotic burst fractures[J].BMC Musculoskelet Disord, 2013, 14:360.

[19]Mermelstein LE, McLain RF, Yerby SA.Reinforcement of thoracolumbar burst fractures with calcium phosphate cement. A biomechanical study[J].Spine (Phila Pa 1976), 1998, 23(6):664-670.

(本文編輯于倩)

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《脊柱外科雜志》啟用“中國知網不端檢測”的聲明

近年的投稿中屢有學術不端行為出現，如抄襲剽竊、篡改他人學術成果、偽造或篡改數據、虛假署名、一稿多投等。這些無視學術規范的行為不僅違反了國家的有關法律、法規，而且給編輯工作造成了一定困擾。《脊柱外科雜志》一貫堅持“學術至上，質量第一”的原則，堅決抵制學術不端行為。為維護學術規范、保證期刊質量和學術聲譽，本刊愿與廣大作者、讀者一起，共同抵制學術不端行為，努力營造規范健康的學術風氣。因此，本刊特作以下聲明:

1.本刊將采用“學術不端文獻檢測系統”對初審稿件、刊前待用稿件進行不端檢測,對發現存在不端行為稿件堅決退稿，并視情節決定是否通報作者所在單位。

2.對已發表的論文一經查實有學術不端行為，本刊將第一時間刊登撤銷聲明，并立即終止該論文在各相關數據庫、文摘庫中的傳播。

3.本刊已加入“《中國學術文獻網絡出版總庫》刪除學術不端文獻系統”，該系統協助本刊對已發表論文的學術不端行為進行全面復核。