周君琳 趙會 秦永超 陸鐵

·論著·

肱骨近端交鎖髓內(nèi)釘和鎖定接骨板治療肱骨近端骨折的生物力學研究

周君琳1趙會1秦永超2陸鐵1

目的 通過生物力學研究，對比兩種治療肱骨近端骨折內(nèi)固定結(jié)構(gòu)的力學特性，為臨床應用提供理論基礎。方法 將36根經(jīng)防腐處理的成人肱骨干隨機平均分為6組：試驗組(A1髓內(nèi)釘壓縮組、A2髓內(nèi)釘拉伸組、B1鎖定板壓縮組、B2鎖定板拉伸組)和對照組(C1壓縮對照組、C2拉伸對照組)。試驗前對所有肱骨干標本進行骨密度檢查，計算小組間有無顯著性差異以排除骨質(zhì)情況對固定穩(wěn)定性的影響。所有標本均拍攝前、后位及側(cè)位X線片，以排除術(shù)前骨折及其他骨病。試驗組按照統(tǒng)一標準制作肱骨近端3部分外科頸大結(jié)節(jié)骨折模型。A1、A2組使用施樂輝TRIGENTM鈦合金肱骨交鎖髓內(nèi)釘固定，肱骨遠端為2枚交鎖髓內(nèi)釘固定，肱骨近端為4枚交鎖髓內(nèi)釘固定。B1、B2組使用AO肱骨近端鎖定鈦板內(nèi)固定，肱骨遠端為3枚皮質(zhì)骨螺釘固定，肱骨近端為5枚松質(zhì)骨螺釘固定。C1、C2組不做骨折模型及固定。對A1、B1、C1組進行軸向壓縮試驗，對A2、B2、C2組進行軸向拉伸試驗，以固定失效為試驗終止點。分別記錄極限載荷和位移曲線，計算剛度。試驗結(jié)果用SPSS12.0版軟件進行統(tǒng)計學分析，P<0.05為差異具有統(tǒng)計學意義。結(jié)果 (1)A1、B1組的極限壓縮載荷低于C1組(t=2.712、t=2.389,P值均<0.05)，A1、B1組間比較差異無統(tǒng)計學意義(t=1.951,P>0.05)，A2、B2組的極限拉伸載荷低于C2組(t=3.194、t=3.201,P值均<0.05)，A2、B2組間比較差異無統(tǒng)計學意義(t=2.136,P>0.05)；(2)A1、B1組的剛度低于C1組(t=2.826、t=2.837，P<0.05)，A1、B1組間比較差異無統(tǒng)計學意義(t=2.004,P>0.05)，A2、B2組的剛度低于C2組(t=2.357、t=2.481,P值均<0.05)，A2、B2組間比較差異無統(tǒng)計學意義(t=2.108,P>0.05)。結(jié)論 肱骨近端交鎖髓內(nèi)釘和鎖定接骨板在抗壓縮和抗拉伸方面的生物力學強度無明顯差異，交鎖髓內(nèi)釘可以提供與鎖定板相近的固定強度。

肱骨近端骨折；內(nèi)固定；肱骨近端交鎖髓內(nèi)釘；肱骨近端鎖定接骨板；生物力學

肱骨近端骨折是老年骨質(zhì)疏松患者的一種常見骨折。相對于其他手術(shù)治療手段，目前最流行的是鎖定鋼板和髓內(nèi)釘內(nèi)固定，兩種內(nèi)固定手術(shù)方法各有優(yōu)缺點。對其術(shù)前內(nèi)固定方式的選擇，目前是創(chuàng)傷骨科醫(yī)師需要面臨的問題[1]。本研究體外模擬人體防腐肱骨近端骨折，分別應用肱骨近端鎖定接骨板和肱骨近端交鎖髓內(nèi)釘進行骨折固定。模擬內(nèi)固定術(shù)后肩關節(jié)的負重狀態(tài)，測量和計算骨折內(nèi)固定模型的軸向載荷及剛度，探討兩種內(nèi)固定器械的固定強度。從生物力學角度分析這兩種內(nèi)固定方式的特點。

資 料 與 方 法

一、肱骨標本的選取

選取甲醛浸泡的18具60～85歲尸體標本，取雙側(cè)肱骨標本共36根，其中男性標本14根，女性標本22根。修整標本，去除附著的軟組織。首先應用Definium8000型DRX線拍片機(美國通用公司)拍攝標本正、側(cè)位X線片，排除先天性畸形、骨折和腫瘤。應用UnigammaX-rayPlus骨密度儀(意大利I，acn公司)測量骨密度(統(tǒng)一劃定肱骨頭區(qū)域進行測量)[2]。

二、骨折內(nèi)固定模型的建立

按Neer標準[3]及Kwon等[4]所介紹的方法，制作肱骨近端3部分骨折模型。在外科頸平面用擺鋸對肱骨頭進行截骨，鋸片厚度1mm，在截骨面上確定結(jié)節(jié)間溝的位置，再沿結(jié)節(jié)間溝垂直于結(jié)節(jié)面向遠端鋸開，直至小結(jié)節(jié)基底水平(肱骨頭截骨面的內(nèi)側(cè)最低點)，在小結(jié)節(jié)基底水平垂直于肱骨干長軸將大結(jié)節(jié)由肱骨干近端截骨分離，復制肱骨近端3部分骨折模型見圖1。

圖1 肱骨近端3部分骨折模型

三、分組及內(nèi)固定方法

所有手術(shù)操作在首都醫(yī)科大學附屬北京朝陽醫(yī)院外科試驗室完成，所有手術(shù)均由同一個三人小組完成，術(shù)后復查X線片確定內(nèi)固定螺釘?shù)奈恢谩?/p>

將36根防腐處理成人肱骨干隨機平均分為6組：試驗組(A1髓內(nèi)釘壓縮組、A2髓內(nèi)釘拉伸組、B1鎖定板壓縮組、B2鎖定板拉伸組)和對照組(C1壓縮對照組、C2拉伸對照組)。(1)A1和A2組：制作骨折模型，骨折復位后，使用施樂輝TRIGENTM肱骨近端鈦合金交鎖髓內(nèi)釘固定(由北京施洛輝Smith&Nephew公司提供，其中主釘長度18cm，近端直徑9mm，遠端直徑7.5mm，近端彎曲4°；近端鎖釘10枚，長度36～60mm，直徑5mm，螺距2mm；遠端鎖釘3枚，長度30mm，直徑4mm，螺距2mm)，肱骨干端為2枚鎖釘固定，肱骨頭端為4枚交鎖螺釘固定。(2)B1 和B2 組：制作骨折模型，骨折復位后，于肱骨外側(cè)使用AO/ASIF鎖定肱骨近端鈦板內(nèi)固定(AO/ASIF五孔鎖定肱骨近端鈦合金接骨板及相關手術(shù)器械由PHILOS，Synthes公司提供，其中鈦板長度114mm，厚度3.7mm，近端鎖釘8枚，長度36～50mm，直徑3.5mm，遠端鎖釘4枚，長度30mm，直徑3.5mm)，肱骨干端為3枚皮質(zhì)骨螺釘固定，肱骨頭端為5枚松質(zhì)骨螺釘固定。(3)C1和C2組：不做骨折模型及固定。

6組標本均自肱骨髁上方10cm處橫行鋸斷，上下兩端置入圓柱形鋼管夾具內(nèi)，用甲基丙烯酸甲酯(自凝牙托粉)包埋備用，其中自凝牙托粉購于上海貝康公司。

四、生物力學測試方法及檢測指標

1.軸向壓縮試驗：A1、B1、C1組每組6個標本。將標本豎直放置于WDW4100微機控制電子萬能生物力學試驗機(中國長春試驗機研究所生產(chǎn))上，遠端完整地夾于試驗機下部的夾具中，調(diào)整上壓盤的位置，使之與標本近端完全接觸，模擬人體肩部負重狀態(tài)，持續(xù)加壓，設定加載速度為0.01mm/s，直至固定失效。固定失效判定：(1)出現(xiàn)新骨折；或者骨折縫明顯增寬；應力形變曲線中線性負載曲線出現(xiàn)偏離或中斷，出現(xiàn)其一即為固定失效。(2)固定失效時的載荷為極限壓縮載荷。(3)記錄壓縮位移曲線及極限壓縮載荷。

2.軸向拉伸試驗：A2、B2、C2組每組6個標本。將標本豎直放置于生物力學試驗機上，近端夾于試驗機上部的特制夾具中，遠端完整地夾于試驗機下部的夾具中，模擬人體重力拉伸的肩部受力情況，設定拉伸速率0.01mm/s，直至固定失效。固定失效判定：(1)出現(xiàn)新骨折；或者骨折縫明顯增寬；應力形變曲線中線性負載曲線出現(xiàn)偏離或中斷，出現(xiàn)其一即為固定失效。(2)固定失效時的載荷為極限拉伸載荷。(3)記錄拉伸位移曲線及極限拉伸載荷。

五、統(tǒng)計學分析

結(jié) 果

一、操作前后肱骨標本大體和X線片

如圖2～4所示。

圖2 未操作前大體標本(A)和X線片影像(B)

圖3 AO/ASIF五孔鎖定肱骨近端鈦合金接骨板固定后大體標本(A)和X線片影像(B)

圖4 TRIGENTM肱骨近端鈦合金交鎖髓內(nèi)釘固定后大體標本(A)和X線片影像(B)

圖5 生物力學試驗照片

二、骨密度

如表1所示，各組之間差異無統(tǒng)計學意義(t=2.017，P>0.05)。

表1 六組骨密度測試結(jié)果比較±s)

三、壓縮試驗

如表2所示，A1、B1組的極限壓縮載荷低于C1組(t=2.712、t=2.389，P值均<0.05)，A1、B1組間比較差異無統(tǒng)計學意義(t=1.951,P>0.05)；A1、B1組的剛度低于C1組(t=2.826、t=2.837,P值均<0.05)，A1、B1組間比較差異無統(tǒng)計學意義(t=2.004,P>0.05)。

表2 三組壓縮試驗測試結(jié)果比較

四、拉伸試驗

如表3所示，A2、B2組的極限拉伸載荷低于C2組(t=3.194、t=3.201,P值均<0.05)，A2、B2組間差異無統(tǒng)計學意義(t=2.136,P>0.05)；A2、B2組的剛度低于C2組(t=2.357、t=2.481,P值均>0.05)，A2、B2組間差異無統(tǒng)計學意義(t=2.108,P>0.05)。

組別肱骨干(根)極限拉伸載荷(N)剛度(N/mm)A2組6599．5±35．5391．0±35．9B2組6691．4±51．2342．8±21．7C2組61068．0±108．5626．7±50．4

討 論

肱骨近端骨折是老年骨質(zhì)疏松患者臨床常見的骨折類型，對于大部分無移位或輕微移位的骨折，非手術(shù)治療可取得較好的臨床療效[5]。但是非手術(shù)治療不能對骨折部位進行有效的原位固定和減壓，手術(shù)治療可以實現(xiàn)有效的內(nèi)固定，并可以盡早進行功能鍛煉以恢復肩關節(jié)功能。肩關節(jié)是人體活動范圍最大的關節(jié)，肱骨近端骨折內(nèi)固定術(shù)后需要可以耐受各個方向活動受力，同時保持骨折斷端復位的穩(wěn)定，內(nèi)固定手術(shù)內(nèi)植物需要承擔活動范圍的多向應力，以保持肱骨的解剖長度和序列穩(wěn)定性[6]。本研究比較肱骨交鎖髓內(nèi)釘和鎖定接骨板內(nèi)固定術(shù)后的生物力學特性，發(fā)現(xiàn)肱骨近端交鎖髓內(nèi)釘和鎖定接骨板在抗壓縮和抗拉伸方面的生物力學強度無明顯差異，交鎖髓內(nèi)釘可以提供與鎖定接骨板相近的固定強度。

所有內(nèi)固定都有各自的優(yōu)缺點，交鎖髓內(nèi)釘可以通過閉合復位，與鎖定接骨板相比，可以有效的防止軟組織剝離破壞。另外，鎖定接骨板減壓和螺釘?shù)闹踩脒^程時間相對較長，且增加了術(shù)中出血量。但是，在植入肱骨髓內(nèi)釘?shù)倪^程中，會對肩袖造成損傷，造成術(shù)后肩部疼痛的長期殘留[7]。兩種內(nèi)固定方式都取得了積極可靠的臨床療效。當內(nèi)固定失敗的時候，經(jīng)常發(fā)生內(nèi)翻塌陷，是否可以有效地防止內(nèi)翻塌陷的發(fā)生，也是影響內(nèi)固定方式選擇的因素之一[8-10]。

在內(nèi)固定手術(shù)中，內(nèi)固定材質(zhì)的剛度通常不是內(nèi)固定選擇的影響因素。文獻回顧發(fā)現(xiàn)過度的堅強內(nèi)固定可以減小內(nèi)固定的微活動，后續(xù)影響骨痂的形成，并導致延遲骨愈合甚至骨不連的發(fā)生。而對骨愈合影響最小的內(nèi)固定角度、強度等參數(shù)尚且沒有定論，既往的生物力學研究主要集中在循環(huán)負荷加載、扭轉(zhuǎn)和其他的物理測試，而沒有進行軸向負荷測試[11-12]。Edwards等[13]比較了肱骨近端髓內(nèi)釘和3.5 mm鎖定鋼板的生物力學特性，發(fā)現(xiàn)鎖定鋼板優(yōu)于髓內(nèi)釘，但是他們僅僅進行循環(huán)負荷，而沒有進行純粹的軸向應力試驗直到固定失敗生物力學測試。在本研究中，不僅進行軸向壓縮試驗，也進行了拉伸試驗，發(fā)現(xiàn)兩者之間差異無統(tǒng)計學意義。

該研究的最大局限性是：目前還沒有肱骨近端處理的標準流程，因此也沒有肩關節(jié)的生物力學的基礎數(shù)據(jù)可以參考。另外，作者沒有進行模擬生理條件下肩關節(jié)多向運動的生物力學情況，在實際生理狀態(tài)下，扭力剪切以及環(huán)形運動都會影響到內(nèi)固定的應力效果，而在本研究中沒有進行模擬考慮。此外，在臨床工作中，大部分內(nèi)固定失敗的患者，不是因為進行單一動作導致的，而本研究中則是進行單一軸向壓縮和拉伸進行到內(nèi)固定失敗。

肱骨髓內(nèi)釘系統(tǒng)和鎖定鋼板在體外肱骨近端骨折模型上，抗壓縮和抗拉伸方面的生物力學強度無明顯差異，肱骨髓內(nèi)釘系統(tǒng)可以提供與鎖定鋼板相近的固定強度。

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(本文編輯：胡桂英)

周君琳，趙會，秦永超，等.肱骨近端交鎖髓內(nèi)釘和鎖定接骨板治療肱骨近端骨折的生物力學研究[J/CD]. 中華肩肘外科電子雜志,2016,4(2):87-92.

Biomechanicalinvestigationoncurrentfixationoptionsforproximalhumerusfractures:lockedintramedullarynailandlockedplate

ZhouJunlin1,ZhaoHui1,QinYongchao2,LuTie1.

1DepartmentofOrthopedics,BeijingChaoyangHospital,CapitalMedicalUniversity,Beijing100028,China;2DepartmentofOrthopedics,PekingUniversityFirstHospitalFengtaiHospital,Beijing100028,ChinaCorrespondingauthor:ZhouJunlin,Email：zhoujunlin@medmail.com.cn

Background Proximal humeral fracture is a common fracture in elderly patients with osteoporosis, locking plate and intramedullary nail fixation are the most popular methods for its surgical treatment at present. There are advantages and disadvantages for both methods of internal fixation treatment. Currently, the choice of internal fixation method is a problem faced by traumatic orthopedic doctors. In this study we used proximal humeral locking plate or interlocking intramedullary nail for fracture fixation in vitro human samples with anticorrosive treatment tosimulate theload condition of shoulder joint after internal fixation, measured and calculated the axial load and stiffness of the fracture model, and discussed the fixed strength of the two internal fixation devices. We also analyzed the characteristics of these two kinds of internal fixation methods from the perspective of biomechanics.Methods (1)Selection of humeralsamples.A total of 36 humeralsamples with antiseptic treatment wereselected from 18 specimens of 60-85 years old, including 14 male samplesand 22 female samples. The X-ray films of the samples were taken to exclude congenital deformity, fracture and tumor. We appliedUnigamma X-ray Plus bone mineral density instrument to measure bone mineral density (humeral head area were unified delimited), results in each group were recorded for variance analysis.(2)Construction of fracture model with internal fixation.According to Neerclassification and the method introduced by Kwon, we produced three-partproximal humeral fracture model. We cut the humeral head with a oscillating saw at the surgical neck plane, the thickness of saw blade was 1 mm, confirmed the position of intertubercular sulcus on the osteotomy plane, then saw the bone along intertubercular sulcus to the distal humerus, thedirection is perpendicular to the osteotomy plane, until to the base of the lesser tubercle level, cut the greater tuberosity from proximal humerusat the base of lesser tuberosity, the direction is perpendicular to the long axis of the shaft.(3)Grouping and internal fixation method.All operationswere performed by a same team in the surgical lab of Beijing Chaoyang Hospital affiliated to the Capital Medical University, postoperative X-ray filmswere taken to confirm the location of the internal fixation screws.Thirty-six embalmed adult shaft samples were divided into 6 groups randomly: the experimental group (A1 intramedullary nailing compression group, A2 intramedullary nail stretching group, B1 locking plate compression group, B2 locking plate stretching group) and control group (C1 compression control group, C2 stretching control group).A1 and A2 groups: (1)Producedfracture models, the fractures were fixed with TRIGENTM titanium alloylocking proximal humeral intramedullary nail (provided by Beijing Smith & Nephew company, of which the main nail length is 18 cm, proximal diameter is 9 mm, distal diameter is 7.5 mm, proximal bending is 4°, there were 10 proximal interlocking screws, the length is 36-60 mm, the diameter is 5 mm, there are 3 locking screws at distal humerus, the length is 30 mm, the diameter is 4 mm), humeral shaft were fixed with 2 locking screws, humeral headwere fixed with 4 locking screws.(2)B1 and B2 group: produced fracture models, the humeral fractures were fixed with AO/ASIFlateral titanium proximal humeral locking plate (AO/ASIF titanium alloy proximal humeral locking plate with five holesand related surgical instruments provided by the Synthes company, the length ofthe plate is 114 mm, the thickness is 3.7 mm, there are 8 proximal screws, length is 36-50 mm, the diameter is 3.5 mm, there are 4 distal locking screws, the length is 30 mm, the diameter is 3.5 mm), there are 3 cortical bone screws in the humeral shaft, 5 cancellous bone screws in the humeral head for fixation. (3)C1 and C2 groups: no fracture modelor fixation.All samples in 6 groups were sawed off from 10 cm above the humeral condyle,both ends were fixed in cylindrical steel pipe clamp, embedded with methyl methacrylate (Shanghai Nutrinen company).(4)Biomechanical test method and parameter.(A)Axial compression test: There were 6 samples in A1, B1 and C1 group respectively.Samples were place vertically on the electron universal biomechanical testing machine controlled by WDW4100 microcomputer (produced by Changchun testing machine institute, China), distalhumeral shift were fixed on the gripper at thebottom of the machine, modified the position of the pressure plate forcompletely contact with proximal of the samples, simulating theload state of human shouldersduring sustained compression, set the loading speed to 0.01 mm/s, until fixation failure.Fixation failure criteria: (a) new fracture occurred;fracture linesbroadening obviously;deviation or interruption of the linear load curve appeared in stress-strain curve, one of above is the mark of fixation failure. (b)fixationfailure load is same with the ultimate compression load. (c) record compressive-displacement curve and ultimate compression load.(B)Axial tensile test: There were 6 samples in A2, B2,C2 group respectively. Samples were placed vertically on the biomechanical test machine, with proximal humeral fixed to the gripper at the top of the machine, distal humeral shift fixedto the bottom of the tester, simulating human shoulder force of gravity stretch, set the stretching rate to 0.01 mm/s, until fixation failure. Fixation failure criteria: (a) new fracture occurred, fracture lines broadening obviously, deviation or interruption of the linear load curve appeared in stress-strain curve, one of above is the mark of fixed failures. (b) fixation failure load is same with the ultimate tensile load;(c) record tensile-displacement curve and ultimate tensile load.(5)Statistics processing.Data from density of bone samples and biomechanical test were analyzed by SPSS12.0 statistics software, the results were compared with variance analysis andttest,andP<0.05wasconsideredsignificant.ResultsTheultimatecompressionloadoffixationgroupswerelowerthanthatofthecontrolgroup(P<0.05),nosignificantdifferencebetweengroupsoffixations(P>0.05).Thetensileloadoffixationgroupswerelowerthanthatofthecontrolgroup(P<0.05).Thestiffnessofthefixationgroupswerelowerthanthatofthecontrolgroup(P<0.05).Nosignificantdifferencewasdetectedbetweenthefixationgroupswithdifferentloads(P>0.05).ConclusionsBiomechanicaltestingofmodernfixationoptionsforproximalhumeralfractureexhibitedthatthebiomechanicalstrengthincompressionandtensileresistanceissimilaraffordedbyPHNandLPHP,bothdevicescanprovidestablefixationinthetreatmentofproximalhumeralfractures.However,prospectiveclinicaltrialswithlongerfollowing-uparerequiredfordefinitiveassessmentoftheidealfixationchoiceforsurgicaltreatmentofproximalhumeralfractures.

Proximalhumerusfracture;Internalfixation;Proximalhumeruslockedintramedullarynail;Lockedproximalhumerusplate;Biomechanics

10.3877/cma.j.issn.2095-5790.2016.02.005

國家自然科學基金項目(81202124)

100028首都醫(yī)科大學附屬北京朝陽醫(yī)院骨科1；100071北京大學第一醫(yī)院豐臺醫(yī)院骨科2

周君琳,Email：zhoujunlin@medmail.com.cn

2015-07-20)