寰枢椎后路椎弓根螺钉固定的生物力学评价

目的：评价寰枢椎后路椎弓根螺钉固定的生物力学稳定性。方法：6具新鲜颈椎标本，按随机顺序，对每一标本先后行C1-C2椎弓根螺钉、Magerl螺钉、Brooks钢丝以及螺钉联合钢丝固定，在脊柱三维运动实验机上测量其三维运动范围。结果：Magerl螺钉或C1-C2椎弓根螺钉联合Brooks钢丝组成的固定系统的三维运动范围最小。C1-C2椎弓根螺钉固定的前后屈伸运动范围与Brooks钢丝固定无差异，但大于Magerl螺钉；其左右侧屈运动范围小于Brooks钢丝固定，大于Magerl螺钉；其轴向旋转角度明显小于Brooks钢丝固定，但与Magerl螺钉无统计学差异。结论：C1-C2椎弓根螺钉的三维稳定性与Magerl螺钉相当，联合Brooks钢丝固定可进一步提高其稳定性。     

Dorsal atlanto-axial screw fixation. A stability test in vitro and in vivo

Clinical and biomechanical testing of the stability of atlantoaxial fusions was studied. For biomechanical testing, four different techniques for posterior atlantoaxial fusion were tested: (1) wire fixation with one median graft; (2) wire fixation with two bilateral grafts; (3) transarticular screw fixation and two bilateral posterior clamps. Ten fresh human cadaveric specimens were tested. The loads applied were 6 pure moments. The motion of C1 relative to C2 in the intact, injured and mechanically fixed spine were measured and compared. In flexion/extension the difference between Brooks, Magerl and Halifax were not significant, but each was significantly less than the Gallie-system. For the anterioposterior translation the stabilization of all fixation techniques was about equal. In axial rotation measuring the translations between C1 and C2, the screw-fixation technique proved to be the most stable. For lateral bending, there was no significant difference between the different techniques, except for Galliefixation, but the screw-fixation technique allowed the least motion. In additional in vivo tests ten patients with posterior atlantoaxial fusion by the transarticular screw-fixation technique underwent bending X-rays of the upper cervical spine as well as computertomograms. Solid fusion was achieved in all patients. Both investigations proved the reliability of the multidirectional stability of the atlantoaxial screw fixation technique.     

Biomechanical evaluation of four different posterior atlantoaxial fixation techniques.

Four different techniques for posterior atlantoaxial fusion were tested in vitro: 1) wire fixation with one median graft (Gallie type); 2) wire fixation with two bilateral grafts (Brooks type); 3) transarticular screw fixation (Magerl); and, 4) two bilateral posterior clamps (Halifax). The experiment was designed to determine the immediate three-dimensional stability of the spinal construct. Ten fresh human cadaveric specimens were tested intact, injured, and instrumented with each of the fixation techniques. The injury consisted of a severe soft tissue injury model, in which the alar, transverse, and capsular ligaments were transected. The three-dimensional motions of C1 relative to C2 were measured as the specimens were subjected to loads of pure moments in flexion-extension, axial rotation, and lateral bending. Each fixation technique significantly decreased motion in all directions, as compared to the intact and injured spines. We found that the Gallie system generally allowed significantly more rotation in flexion, extension, axial rotation, and lateral bending than the other three fixation techniques. There was generally no significant difference between the amount of rotation with the other three fixation techniques. However, the Magerl technique tended to allow the least rotation. The anteroposterior translation of two points on C1 were about equal for all fixation techniques.     

经口咽前路寰枢椎复位钢板内固定的生物力学研究

目的 研究经口咽前路寰枢椎复位钢板(TARP)的三维运动范围和螺钉拔出力的生物力学. 方法 12例C0～C3新鲜标本,6例用于三维运动测试,分七组:①完整标本(对照)组,②损伤组(去除C1前弓、C2齿突,破坏关节囊和横韧带等),③TARP组,④后路Brooks钢丝组,⑤Magerl经关节螺钉组,⑥Magerl+Brooks组,⑦前路经枢椎体寰椎侧块螺钉组,分别测量其三维运动范围(ROM).另6例(双侧,n=12)分解为单个椎体后用于螺钉拔出力测试,分三组:①寰椎组,②枢椎组,③C,(对照)组,测定最大拔出力、钉道长度和屈服长度.结果 TARP组和Magerl+Brooks组在各个方向上差异均无统计学意义(P>0.05),前者的ROM值略大于后者,二者抗屈伸、侧屈和旋转均强于其他三种内固定方法(P<0.05).寰椎与枢椎、寰椎与C3的最大拔出力之间差异均有统计学意义(P<0.05),枢椎和c3椎体最大拔出力之间差异无统计学意义(P>0.05)[最大拔出力分别为C1=(491.58 4±67.92)N,C2=(396.73±60.99)N,C3=(385.53±96.77)N].寰椎与枢椎、寰椎与C3椎体的钉道长度之间差异均有统计学意义(均为P<0.05),枢椎和C3椎体钉道长度之间差异无统计学意义(P>0.05).三组的屈服长度之间差异.无统计学意义(P>0.05).C1～C3的螺钉最大拔出力与钉道长度和屈服长度均呈显著正相关(P<0.05,r分别为0.810和0.652),但与钉道长度的相关性更高(P<0.05). 结论 TARP与目前临床应用的后路Magerl+Brooks术式等效,较其他三种固定方式(前路经枢椎体寰椎侧块螺钉、后路Magerl经关节螺钉和后路Brooks钢丝固定)具有更坚强的固定作用.TARP的寰椎和枢椎固定螺钉固定牢靠,钉道长度即进钉深度是影响螺钉抗拔出力的主要因素,屈服长度是影响螺钉拔出力的次要因素.     

Modified Gallie technique versus transarticular screw fixation in C1-C2 fusion

The effectiveness of a modified Gallie technique versus Magerl and Seeman transarticular screw fixation was compared in the management of 27 patients with symptomatic atlantoaxial instability. Twelve patients were treated using a modified Gallie technique and postoperative halo vest immobilization. Atlantoaxial arthrodesis occurred in seven (58%) patients, stable fibrous union occurred in one patient, and pseudarthrosis with recurrent instability developed in four (33%) patients. Average followup was 6.9 years. All 15 patients treated using Magerl and Seeman transarticular screw fixation and postoperative soft collar immobilization had atlantoaxial arthrodesis develop. Average duration of followup was 4 years. One patient sustained vertebral artery injury during preparation for screw placement. Magerl and Seeman transarticular screw fixation provides stability and more reliably produces atlantoaxial arthrodesis than the Gallie technique provides in patients with atlantoaxial instability without the need for rigid postoperative bracing. Potential for vertebral artery exists despite apparent accurate screw placement. To ensure that safe transarticular screw placement is possible, preoperative fine cut axial computed tomography with reconstructions is required to assess vertebral artery position and C2 isthmus anatomy. A proportion of patients have anatomy unsuitable for screw placement. Traditional wiring techniques are indicated in these patients.     

Gallie结合单侧Magerl内固定法治疗寰枢椎不稳的生物力学研究

目的 对Gallie+单侧Magerl内固定技术治疗寰枢椎不稳进行生物力学评估.方法 10具成年国人甲醛固定的枕颈(C0～C4)标本,对寰枢椎不稳模型分别行Gallie内固定、Gallie+单侧Magerl内固定、双侧Magerl内固定,在颈椎三维运动试验机上对颈椎施加2.0 N×M纯力偶矩,产生前屈/后伸,左/右侧屈和左/右旋转6种生理运动,测量其三维运动范围(ROM).结果 单侧Magerl+Gallie法固定,其屈/伸ROM为1.66度,侧屈为0.5l度,轴向旋转为6.22度,与Gallie固定法比较,ROM分别减少78%、86%、69%,差异有统计学意义(P＜0.05).双侧Magerl法固定,其屈/伸ROM变为1.48度,侧屈为0.46度,轴向旋转为5.38度,与单侧Magerl+Gallie法比较,ROM减少其差异无统计学意义(P＞0.05).结论 Gallie+单侧Magerl固定法治疗寰枢椎不稳的生物力学稳定性与双侧Magerl法接近.     

Bone graft translation of four upper cervical spine fixation techniques in a cadaveric model

The goal of spinal fixation is to promote bony fusion by restricting motion at the site of the bone graft. Therefore, in order to evaluate the efficiency of various cervical fixation techniques, we determined the translations at the posterior arch of C1 for four C1-C2 posterior techniques: Gallie, Brooks, Magerl, and Halifax. Our model was the cadaveric specimen, with extensive soft tissue injury: transection of the alar, transverse, and capsular ligaments. Under three-dimensional physiological loading, we recorded the motion of C1 relative to C2, and calculated the translations at the surface of the graft in three dimensions, 10 specimens being tested intact, injured, and instrumented with each of the techniques. We assumed that translational laxity or neutral zone was the critical motion parameter and evaluated it, quantified herein as the neutral zone, at seven points at the graft site. The three-dimensional neutral zone translations were analyzed by their axial and shear components. We found that there was no significant difference with the fixation techniques in the average axial translation (Brooks: 1.1 mm; Magerl: 1.3 mm; Gallie: 1.5 mm; and Halifax: 0.5 mm). In shear, the Magerl averaged 1 mm, which was significantly less than the Gallie (2.1 mm). The Brooks (1.6 mm) and Halifax (1 mm) were not different from each other, Magerl, or Gallie. We propose that evaluation by translational laxity (neutral zone) at the graft site is a noteworthy concept in biomechanical analysis.     

Biomechanical assessment of transoral plate fixation for atlantoaxial instability

STUDY DESIGN: In an experimental study using human cadaver specimens the biomechanical data of anterior atlantoaxial plating according to Harms were evaluated. OBJECTIVES: The purpose of this study was to evaluate this method biomechanically. SUMMARY AND BACKGROUND DATA: The optimum fixation method to achieve fusion at the atlantoaxial joint after odontoid resection is still a matter of discussion. Isolated posterior surgical procedures for treatment of irreducible atlantoaxial kyphosis with spinal cord compression are associated with high rates of morbidity and mortality. Transoral atlantoaxial plate fixation has been designed by Harms as a fixation technique after odontoid resection. In a modification, this procedure has been combined with the posterior wire fusion according to Brooks. METHOD: Eight human cadaver craniocervical specimens were tested in flexion, extension, rotation, and bending with a nondestructive flexibility method using a nonconstrained testing apparatus. Five different groups were examined: 1) control group (intact); 2) unstable group (after dissection of the atlantoaxial ligaments and odontoidectomy), 3) Harms group (transoral atlantoaxial plate fixation) 4) Harms-Brooks group (transoral atlantoaxial plate fixation and dorsal atlantoaxial wire fixation); and 5) Magerl group (transarticular atlantoaxial screw fixation). In a second experimental series, failure loads of the Harms-Brooks and the Magerl fixation methods were determined. RESULTS: The angular displacement of the Harms-Brooks group and the Magerl group was less than in any other group. Stiffness values at 0-3.0 Nm loads in any direction were larger for the Harms-Brooks-and Magerl-fixated specimens than for the Harms, control, or unstable specimens. No statistically significant difference was observed between Harms-Brooks and Magerl reconstruction stiffness. Ultimate failure load in the Harms-Brooks group was higher than in the Magerl group. CONCLUSIONS: Experimentally, isolated anterior atlantoaxial plating was less stable than the combined reconstruction procedures. Transoral plate fixation according to Harms in combination with posterior wire fixation according to Brooks provided a failure load and stiffness equal to transarticular screw fixation according to Magerl.     

寰枢椎前路复位钢板系统的研制及其生物力学

目的研制一种经口咽前路寰枢椎复位钢板内固定系统,评价其生物力学性能。方法研制各种型号经口咽前路寰枢椎复位钢板和复位器等配套器械。选12具新鲜成年颈椎标本,分别进行三维运动范围实验和螺钉拔出力实验。与其它内固定方法作比较分析。结果生物力学测试表明,三维运动范围,该钢板固定和Magerl Brooks固定在各个方向上均无显著差异(P>0.05)。其抗屈伸、侧屈和旋转均强于其它三种内固定方法。寰椎螺钉的最大拔出力显著高于枢椎和C3椎体固定螺钉,枢椎螺钉与C2螺钉等效。结论寰枢椎前路复位钢板系统设计新颖,具有良好的生物力学性能。能满足临床内固定需要。     

C1-C2 intra-articular screw fixation for atlantoaxial posterior stabilization

STUDY DESIGN: A trial of a new posterior stabilization technique for atlantoaxial instability and a report of preliminary results. OBJECTIVES: To describe a new posterior stabilization technique for atlantoxial instability. SUMMARY OF BACKGROUND DATA: Magerl's transarticular screw fixation is an accepted technique for rigid atlantoaxial stabilization, which reportedly has yielded many good clinical results. However, the technique is technically demanding and poses a risk of injury to the nerves and veins. METHODS: Eleven patients who had been treated with intra-articular screw fixation in combination with Halifax interlaminar clamp (OSTEONICS, Allendale, NJ) for atlantoaxial instability were observed. Results of their clinical examinations and biomechanical studies using resinous bones of a cervical spine model were reviewed. RESULTS: In all patients, occipital pain, neck pain, and neural deficit improved, and bony fusion with no correction loss was shown on radiography. To date, no vascular or neural complications have been found, and no instrumentation failures have occurred. In the biomechanical study, the Halifax with transarticular screw fixation had significantly greater flexion stiffness than the Halifax only or the Halifax with intra-articular screw fixation, but the torsion stiffness of the Halifax with intra-articular screw fixation was significantly greater than that of the other Halifax combinations. CONCLUSION: The preliminary results showed that this technique was effective in strengthening the rotational stability of the atlantoaxial fixation and was considered useful for atlantoaxial posterior stabilization.     

经寰枢关节间隙螺钉和寰椎椎板钩内固定的力学稳定性

目的评价双侧经寰枢关节间隙螺钉和寰椎椎板钩内固定的力学稳定性。方法将6具新鲜尸体颈椎标本（包括枕骨基底部和C1-C4颈椎节段）置于1．5Nm载荷下，测量C1，2节段的三维运动范围（range of motion，ROM）。标本依Gallie内固定、双侧经寰枢关节间隙螺钉和Gallie内固定、双侧经寰枢关节间隙螺钉内固定、双侧经寰枢关节间隙螺钉和寰椎椎板钩内固定、双侧寰椎侧块螺钉和枢椎椎弓根螺钉内固定的顺序实施固定，每次固定后测量三维运动范围。结果包含经寰枢关节间隙螺钉的内固定组在旋转和侧屈方向上具有最小的ROM，其中双侧经寰枢关节间隙螺钉和寰椎椎板钩内固定组在屈伸运动方向上也具有最小的ROM。寰椎侧块螺钉和枢椎椎弓根螺钉内固定组在旋转方向上ROM大于单纯经寰枢关节间隙螺钉内固定组，但在侧屈和屈伸方向上接近经寰枢关节间隙螺钉，差异无统计学意义；其在侧屈和旋转方向上ROM均小于Gallie内固定组，差异有统计学意义。结论双侧经寰枢关节间隙螺钉和寰椎椎板钩“三点”内固定具有最强的生物力学稳定性。虽然双侧寰椎侧块螺钉和枢椎椎弓根螺钉内固定在生物力学稳定性上不及“三点”内固定，但明显优于Gallie内固定。     

Anatomic and biomechanical assessment of transarticular screw fixation for atlantoaxial instability.

The purpose of this study is to elucidate anatomically the atlantoaxial transarticular screw fixation described by Magerl in 1979 and compare it biomechanically with Gallie wiring. Five human C1-C2 specimens were tested in flexion/extension and rotation intact, then after wiring and screw fixation. Mean screw length was 39 mm, 25 mm in the C2 lamina and 14 mm in the lateral mass. Angular displacement of screwed specimens was significantly less than control or wired groups. Stiffness at 0-0.5 Nm loads was significantly greater for screwed specimens than for wired or controls (101 +/- 49 Nm, 10.3 +/- 9.2 Nm, and 1.96 +/- 0.18 Nm, respectively). All specimens withstood 5 Nm in flexion and extension without failure. Screw fixation provides stability comparable to Gallie wiring and is stiffer at low-range forces and rotational angles.     

经口咽前路寰枢椎复位钢板系统的研制与初步临床应用

目的 研制经口咽前路寰枢椎复位钢板系统(TARP),评价其生物力学性能,并进行初步的临床应用观察。方法研制设计一种新型的经口咽前路寰枢椎复位钢板系统,该系统包括蝶形钛合金钢板、自锁螺钉和寰枢椎复位器等配套安装器械。将此系统在12具枕骨～C3新鲜标本卜分别进行了三维运动测试(n=6)和拔出力实验(n=12),比较其生物力学性能,并初步临床应用3例。结果TARP系统设计有巧妙的即时复位饥制。 TARP、Brooks钢丝、Magerl经关节螺钉、前路螺钉以及Brooks钢丝 Magerl经关节螺钉等5组在屈伸方向的平均活动范同分别为4．0、6．2、5．1、6．6、3．7度;在侧屈方向的平均活动范围分别为2．3、3．6、2．7、4．2、1．8度;平均旋转活动范围分别为7．4、8．9、8．6、10．7、6．0度。结果显示TARP的生物力学性能与Brooks钢丝 Magerl经关节螺钉固定等效,较其他3种方法具有更坚强的固定作用。临床应用术后随访平均8．3个月,3例寰椎完全复位,伤口愈合良好,无感染,四肢麻痹消失,肌力恢复,病理反射消失?钢板螺钉未松动。结论TARP设计新颖独到,具有良好的生物力学性能,手术操作简便易行,能达到即时复位,固定效果好,具有良好的应用前景。     

Die atlantoaxiale Kyphose

Atlantoaxial kyphosis (AAK) is a rare sagittal deformity of the occiptoatlantoaxial junction. It is defined as a subgroup of anterior translatory atlantoaxial instability. AAK is a symptom of several ligamentours or bony disorders of the craniocervical junction; however, rheumatoid arthritis and trauma are the most common causes for AAK. AAK can be diagnosed on lateral radiographic views of the upper cervical spine if the angle between McGregor's line and the atlas plane is less than-15 degrees or the atlas-axis angle is greater 105 degrees. Treatment modalities for AAK depend on the ability to reduce the deformity. If closed reduction is achieved, posterior atlantoaxial fusion by sublaminar wiring according to Brooks or transarticular screw fixation according to Magerl are possible choices. Irreducible AAK can be treated with a combined transoral decompression, anterior plating according to Harms, and posterior wiring according to Brooks. This staged therapy for AAK was successful in our rheumatoid patient population with AAK.     

Atlantoaxial fusion using anterior transarticular screw fixation of C1–C2: technical innovation and biomechanical study

This study is an attempt to describe a new technique for anterior transarticular screw fixation of the atlantoaxial joints, and to compare the stability of this construct to posterior transarticular screw fixation with and without laminar cerclage wiring. Nine human cadaveric specimens were included in this study. The C1–C2 motion segment was instrumented using either anterior transarticular screws (group 1), posterior transarticular screws alone (group 2), or posterior screws with interlaminar cerclage wires (group 3). Using an unconstrained mechanical testing machine, the specimens were tested in rotation, lateral bending, and flexion-extension using nondestructive loads of ±2 N m. The specimens were also tested in translation using nondestructive loads of ±100 N. All values for the three groups with regards to anterior-posterior displacement, rotation, and lateral bending were similar as determined using a Kruskal–Wallis rank sum test with a significance level of p<0.05. The only significant difference was registered in flexion-extension where the cerclage wire added some strength to the construct. Anterior transarticular screw fixation of the atlantoaxial spine has several advantages over posterior fixation techniques, and is as stable as posterior transarticular fixation in all clinically significant planes of motion. The addition of posterior interlaminar cerclage wiring further improves resistance to flexion-extension forces. Anterior transarticular screw fixation of the atlantoaxial joint is a useful technique for achieving C1–C2 stabilization.     

应用经关节螺钉固定在寰枢关节不稳中的生物力学研究与临床应用

目的 探讨后路经关节螺钉固定(Magerl技术)加植骨融合治疗寰枢关节不稳定的生物力学特性及其临床价值.方法 生物力学研究:取新鲜冰冻尸体标本30具,随机分成5组:完整标本组、寰枢椎不稳实验模型组、寰枢椎后路椎弓根螺钉固定组、寰枢椎经关节螺钉固定组及寰枢椎经关节螺钉联合Brooks钢丝固定组,每组各6具.标本施加±1.5N·m纯力偶矩作为加载的最大力矩,模仿前屈、后伸,左、右侧弯,左、右轴向旋转6种生理性运动,测量各种生理性运动的活动范围(ROM)和中性区(NZ)值.应用SPSS 11.0软件进行统计分析,比较组间差异.临床研究:2000年2月至2005年1月应用寰枢椎经关节螺钉(Magerl技术)固定、C1.2棘突间植骨融合术治疗寰枢椎不稳患者23例,男16例,女7例;年龄17～62岁,平均38.6岁;先天性畸形致脱位3例,外伤性脱位20例.所有患者进行定期随访和影像学检查,评估颈椎稳定性和植骨融合率.结果 标本生物力学测试结果表明:屈伸稳定性、侧弯稳定性和轴向稳定性均为寰枢椎经关节螺钉联合Brooks钢丝固定组＞寰枢椎经关节螺钉固定组＞寰枢椎椎弓根螺钉固定组＞寰枢椎完整标本组＞寰枢椎不稳模型组,组间差异有统计学意义.临床研究表明:23例共放置经关节螺钉46枚;无一例发生椎动脉损伤、脊髓损伤或舌下神经麻痹等并发症.23例患者均获随访,随访时间4～36个月,平均15个月;随访中2例患者主诉旋转活动部分受限;影像学检查提示所有患者植骨全部融合.结论 单纯的Magerl螺钉固定失稳的寰枢关节具有足够坚固的生物力学性能,临床上结合棘突间植骨可达到满意的骨性融合.     

A biomechanical study of unilateral posterior atlantoaxial transarticular screw fixation

The purpose of this study was to investigate the fixation of C1-C2 instability with the use of a unilateral screw. Transarticular screw placement across C1-C2 may be contra-indicated in up to 20% of specimens on at least one side because of anatomic variations or other pathological processes. Hence the current study looks into unilateral screw fixation of C1- C2 instability. Eight cervical spine specimens, C1 through C5, were harvested from fresh human cadavers (4 male and 4 female) of average age 67 years (54-80). C1 and C2-C5 vertebrae were potted to allow motion only at the C1-C2 articulation. Cutting the transverse ligament on both sides of the odontoid and the tectorial membrane destabilized the specimens. Transarticular screw fixation of C1-C2 was performed in a manner similar to the technique described by Magerl. The stability was tested after fixation with one transarticular screw together with a posterior graft and wire. Placement of the screw was randomized, resulting in half the specimens receiving screws on the right side and the remaining half on the left side. The stiffness of the C1-C2 articulation was tested in rotation, lateral bending, flexion, and anterior translation in random order. The rotational stiffness was 1.44 +/- 0.44 N-m/deg, while lateral bending stiffness values were 2.33 +/- 1.14 N-m/mm (right bending) and 2.81 +/- 1.36 N-m/mm (left bending). The stiffness value in flexion was 0.813 +/- 0.189 N-m/mm and in translation 67.1 +/- 25.1 N/m. It was found that stability after unilateral transarticular screw fixation was less than that previously reported after bilateral transarticular screw fixation, but similar to that found with modified Brooks posterior wiring, which has been shown to provide better stability than other posterior wiring methods, and fusion rates of 96% have been reported. We concluded that C1-C2 unilateral posterior transarticular screw fixation with supplemental posterior graft and wiring would confer adequate stability in cases where bilateral screw placement is contraindicated.     

经口咽前路寰枢椎复位钢板治疗难复性寰枢椎脱位

目的 设计经口咽前路寰枢椎复位钢板系统(transoralpharyngeal atlantoaxial reduction plate,TARP)，评价其生物力学性能，观察临床应用效果。方法 研制设计一种新型的经口咽前路寰枢椎复位钢板系统，该系统包括-蝶形钛合金锯板、自锁螺钉和寰枢椎复位器等配套安装器械。将此系统在12具C0-C3新鲜标本上分别进行了三维运动测试(n=6)和拔出力实验(n=12)，比较其生物力学性能，并临床治疗难复性寰枢椎脱位患者5例。结果 TARP系统设计有巧妙的即时复位机制。TARP的生物力学性能与现行的寰枢椎融合Magerl Brooks固定等效，较其它三种方法(前路经枢椎体寰椎侧块螺钉、后路Magerl经关节螺钉和后路Brooks钢丝)具有更坚强的固定作用，TARP的寰椎和枢椎固定螺钉固定牢靠，具有良好的抗拔出性能。经难复性寰枢椎脱位的临床应用，TARP能达即时复位作用，手术操作可行，效果显著。结论 TARP设计新颖独到，具有良好的生物力学性能，手术能达即时复位，固定效果好，为临床提供了—个崭新的治疗方法。     

Biomechanical study of angle-stable anterior atlanto-axial spondylodesis plate

The optimum fixation method to achieve atlantoaxial fusion after odontoid resection is still subject to discussion. Isolated posterior surgical procedures for treatment of irreducible atlantoaxial kyphosis with spinal cord compression are associated with a high rate of morbidity and mortality. Transoral atlantoaxial plate fixation has been described by Harms as a fixation technique after odontoid resection. The purpose of this study was to compare biomechanically a new anterior atlantoaxial locking plate (AALP) with the Harms plate and the atlantoaxial transarticular screw fixation described by Magerl. Sixteen human cadaver craniocervical specimens were tested in flexion, extension, rotation, and bending with a nondestructive flexibility method using a nonconstrained testing apparatus. Five different groups were examined: (1) control group (intact) (n = 16), (2) unstable group (after dissection of the atlantoaxial ligaments and odontoidectomy) (n = 16), (3) Harms group (transoral atlantoaxial plate fixation) (n = 8), (4) AALP group (anterior atlantoaxial locking plate fixation) (n = 8), and (5) Magerl group (transarticular atlantoaxial screw fixation) (n = 16). Stiffness in any direction was significantly higher in the AALP specimens and those fixated with the Magerl method than in the Harms, control, or unstable specimens. The difference in stiffness between the AALP and Magerl reconstruction groups was not statistically significant. Experimentally, the AALP was significantly stiffer than the Harms plate. The AALP provided stiffness equal to transarticular screw fixation according to Magerl. A question that cannot be answered by this in vitro study concerns the level of rigidity required to obtain long-term stability and fusion by atlantoaxial fixation methods. However, it may be assumed that the more spinal motion is eliminated the greater the chance of definite spinal fusion. Therefore, it seems reasonable that the most reliable and rigid fixation method would be the method of choice.     

后路寰枢椎经关节螺钉内固定治疗陈旧性齿状突骨折

[目的]对后路寰枢椎经关节螺钉内固定治疗陈旧性齿状突骨折进行回顾总结。[方法]33例陈旧性齿状突骨折经Anderson-D＇Alonzo分类Ⅱ型31例，Ⅲ型2例，无Ⅰ型病例。所有患者行后路寰枢椎经关节螺钉内固定植骨融合术，其中9例同时行Gallie法内固定。[结果]术后进行颈椎正侧位片随访6～52个月（平均7．9个月），32例获牢固骨性愈合，融合率97％。[结论]后路寰枢椎经关节螺钉内固定是治疗陈旧性齿状突骨折简单有效的方法。