经皮后外侧腰椎间孔入路椎间盘工作区域的解剖学研究

 目的 通过对健康成人尸体标本的解剖和测量, 对经皮后外侧腰椎间孔入路的椎间盘工作区域进行应用解剖学研究。方法 对 25具尸体标本(年龄 45~65岁, 身高 150~176 cm)进行腰椎椎间孔解剖学研究, 首先在矢状面上测量椎间隙后缘高度(h), 神经根与椎间盘平面的倾斜角(茁), 神经根后缘与椎间盘最后缘水平距离(d), 椎间孔在上、下终板平面上的神经根后缘与下位椎体上关节突外缘的距离(a1, a2);去除关节突后显露神经根与硬膜, 冠状面上在上、下终板平面上测量神经根内缘与硬膜外缘的距离(b1, b2)。结果 在椎间孔矢状面和冠状面上椎间盘区域分别为两个”梯形冶。矢状面上测量参数: h为(7.0±1.1) mm, 茁为 77.6°±8.4°, d为(3.4±2.3) mm, a1为(9.4±2.2) mm, a2为(10.8±4.6) mm。冠状面上 b1为(9.9±2.7) mm, b2为(17.7±2.1) mm。除神经根倾斜角度(β)逐渐缩小外, 其余参数均随腰椎节段而逐渐增大。结论 后外侧腰椎间孔入路的椎间盘工作区域可模拟为由矢状面和冠状面”梯形冶所合成的立体结构。通过对立体结构解剖的研究比较可以指导临床操作, 如椎间孔镜工作通道的大小及椎间孔穿刺针角度等。     

Morphometric aspects of extraforaminal lumbar nerve roots

OBJECTIVE: In the posterolateral extraforaminal and anterolateral retroperitoneal approaches to lumbar spinal lesions, the neural structures in the lumbar extraforaminal region are unfamiliar to many spinal surgeons. The purpose of this study was to determine the normal anatomic morphometric parameters for all lumbar nerve roots around their exits, from the intervertebral foramen to the surrounding bony structure. METHODS: A total of 15 adult fixed cadavers were studied. The extraforaminal course of the lumbar nerve roots and the forming plexus were measured segmentally, using standard calipers, and we selected the shortest distance from the bony landmarks to the nerve roots in the horizontal plane. The bony landmarks were the most medial superior border of the transverse process (TP), the most medial inferior border of the TP, the tip of the superior articular process, and the most dorsolateral margin of the intervertebral disc space. In addition, the angle of each root exiting from the intervertebral foramen was measured using a goniometer. RESULTS: The mean distance from the medial superior border of the TP to the upper segment of the nerve root was 5.1 to 6.4 mm at L2-L5. The mean distance from the medial inferior border of the TP to the corresponding nerve root was 8.5 mm at L2 and L3 and 6 mm at L4 and L5. The mean distance from the tip of the superior articular process to the most dorsal border of the descending nerve trunk was 19 mm at L2 and L3 and 22 mm at L4 and L5. The main lumbar nerve trunk was located close to the most dorsolateral surface of the vertebral body and the intervertebral disc space, and it was topographically arranged dorsoventrally from the L5 to L2 nerve components. The average widths of the nerve trunk were 10, 14, and 25 mm at L3-L4, L4-L5, and L5-S1, respectively. The mean angles of the exiting roots in the extraforaminal region were 16 degrees at L2 and L3 and 25 degrees at L4 and L5. CONCLUSION: The lumbar nerve component, including both the lumbar trunk and each exiting nerve root in the extraforaminal region (the so-called "danger zone"), was located anteriorly at a distance more than 5 mm from the TP, more than 19 mm from the superior articular process, and up to 25 mm from the intervertebral disc space. Based on our results, the danger zone occupied up to 25 mm forward from the intervertebral foramen at the lower lumbar segments. Therefore, during operations such as percutaneous posterolateral procedures and open posterolateral or anterolateral approaches, great care should be taken within 25 mm of the extraforaminal region, especially for the lower lumbar spine.     

Radiographic measurement for transforaminal percutaneous endoscopic approach (PELD)

Objective

A radiographic study to analyze the working zone and relationship of the nerve root to their corresponding intervertebral disc for transforaminal percutaneous approaches.

Methods

100 MRIs of transverse and sagittal views of 37 males, 63 females (average age 45 years), 50 MRIs of coronal views of 22 males, 28 females (average age 42 years), and 100 X-rays, 46 males, 54 females (average age of 44 years) were used for image analysis. All radiologic measurements were obtained independently by two experienced radiologists. On sagittal plane, foraminal height, foraminal diameter, nerve root-disc distance and nerve root-pedicle distance were measured. On transverse plane, foraminal width, nerve root-disc distance, nerve root-facet distance and target angle (J°) were analyzed at the superior (s) and inferior (i) margin of the disc. On coronal plane, nerve root-disc distance and nerve root-pedicle distance were measured at the medial, middle and lateral borders of the pedicle.

Results

Sagittal plane; foraminal height and diameter decreased caudally. Transverse plane; foraminal width was larger at the superior margin of the disc. Nerve root-disc distance decreased caudally. The nerve root lied dorsal to the disc at L2–L3 and L3–L4, whereas at L4–L5 and L5–S1 it lied ventrally. Nerve root-facet distance was shortest at the superior margin. Target angles (Js°, Ji°) at L2–L3 and L3–L4 were wider at their superior margin than at their inferior margin. Coronal plane; nerve root-disc distance increased from L2–L3 to L5–S1 whereas nerve root-pedicle distances decreased, thus coursing more vertically.

Conclusions

At lower lumbar levels the exiting nerve root is at risks of injury. Hence, it is advised to enlarge the foramen for safe passage of endoscopic instruments and to minimize the possibility of nerve injury.

     

Modified cervical laminoforaminotomy based on anatomic landmarks reduces need for bony removal.

We describe a modified keyhole laminoforaminotomy (LF) using anatomic landmarks on the posterior aspect of the cervical vertebral body to decompress the intervertebral foramen with minimal bone removal. Twenty-four procedures were performed at C3-4, C4-5, and C5-6; 12 at C6-7; and 3 at C7-Tl. Facets and laminae structures were identified based on relative surgical perspectives. Bony resection was limited as follows: 1) inferior limit; inferior border of the superior facet; 2) superior limit, superior border of the superior facet; 3) lateral limit, a vertical line linking the junction of the lamina-facet to the lateral end of the superior limit; and 4) lateral aspect of the dural sac. Fluoroscopy was used to confirm that the intervertebral space was reached. The amount of bony removal was quantified for the superior and inferior laminae and facets. The length of the exposed nerve root was measured. The intervertebral foramen was exposed and the intervertebral disc reached in all specimens. Fluoroscopy showed that the center of the exposure remained at the same height with the intervertebral space. The mean length of the nerve root was 4.6 mm; the mean percentage of bony resection was 21.8%, 7.5%, 11.3%, and 11.5% for the superior and inferior laminae and facets, respectively. Opening the intervertebral foramen posteriorly consistently exposed sufficient nerve root length and allowed access to the intervertebral disc. The technique offers the most direct and safest method of decompressing the intervertebral foramen while minimizing bony resection. This simple surgical procedure may help reduce postoperative morbidity.     

Combined intra-extracanal approach to lumbosacral disc herniations with bi-radicular involvement. Technical considerations from a surgical series of 15 cases

Large lumbosacral disc herniations effacing both the paramedian and the foraminal area often cause double radicular compression. Surgical management of these lesions may be difficult. A traditional interlaminar approach usually brings into view only the paramedian portion of the intervertebral disc, unless the lateral bone removal is considerably increased. Conversely, the numerous far-lateral approaches proposed for removing foraminal or extraforaminal disc herniations would decompress the exiting nerve root only. Overall, these approaches share the drawback of controlling the neuroforamen on one side alone. A combined intra-extraforaminal exposure is a useful yet rarely reported approach. Over a 3-year period, 15 patients with bi-radicular symptoms due to large disc herniations of the lumbar spine underwent surgery through a combined intra-extracanal approach. A standard medial exposure with an almost complete hemilaminectomy of the upper vertebra was combined with an extraforaminal exposure, achieved by minimal drilling of the inferior facet joint, the lateral border of the pars interarticularis and the inferior margin of the superior transverse process. The herniated discs were removed using key maneuvers made feasible by working simultaneously on both operative windows. In all cases the disc herniation could be completely removed, thus decompressing both nerve roots. Radicular pain was fully relieved without procedure-related morbidity. The intra-extraforaminal exposure was particularly useful in identifying the extraforaminal nerve root early. Early identification was especially advantageous when periradicular scar tissue hid the nerve root from view, as it did in patients who had undergone previous surgery at the same site or had long-standing radicular symptoms. Controlling the foramen on both sides also reduced the risk of leaving residual disc fragments. A curved probe was used to push the disc material outside the foramen. In conclusion, specific surgical maneuvers made feasible by a simultaneous extraspinal and intraspinal exposure allow quick, safe and complete removal of lumbosacral disc herniations with paramedian and foraminal extension.     

椎间孔外型腰椎间盘突出症的应用解剖和手术治疗

目的　探讨后侧肌间隙入路治疗椎间孔外型腰椎间盘突出症的解剖基础及其疗效。方法　在 34具经甲醛固定的成人尸体上 ,观测椎间孔外区腰椎节段血管与横突、腰神经前支的相对位置关系 ,椎弓峡部侧缘距腰神经前支的深度以及腰神经前支的走行等。 1993年 10月～ 1999年 10月 ,采用后侧肌间隙入路和外侧腹膜后入路治疗椎间孔外型腰椎间盘突出症共 11例。　结果　L1～L4节段动脉前支及伴行静脉 90 %以上位于相邻横突间隙上 1/2的腹侧 ,血管与腰神经前支毗邻并位于腹前方 ,L1～L5椎弓峡部侧缘至腰神经前支的深度约为 1 0～ 2 0cm ,腰神经前支与矢状面夹角约为 7°～ 2 5° ,越往尾侧 ,深度与角度逐渐增加。本组 11例中 10例随访 1年 11个月～ 8年 2个月 ,按照LBOS标准进行疗效综合评定 ,优 8例 ,良 2例 ,比较而言 ,肌间隙入路的手术时间、失血量、康复时间等相对较少。　结论　后侧肌间隙入路治疗椎间孔外型腰椎间盘突出症是一种安全有效的手术方法。     

经椎小关节入路手术治疗复发性腰椎间盘突出症

目的介绍经椎小关节入路手术治疗复发性腰椎间盘突出症的手术方法。方法采用后正中切口显露相应节段患侧的椎小关节,切除上一椎骨的下关节突,显露下一椎骨的上关节突关节面,再切除下一椎骨上关节突的内1/2进入椎管,切除残存的黄韧带,显露硬脊膜和神经根,松解黏连,扩大神经根管并切除膨出的纤维环,摘除髓核,与硬脊膜及神经根黏连的瘢痕组织不作切除。结果从2002—2009年采用此方法手术治疗复发性腰椎间盘突出症64例,经平均4.2年随访,全部病例均获得满意疗效。结论经椎小关节入路这种方法解剖清楚,操作方便,显露充分,创伤小,出血少,手术时间短。无一例出现硬膜撕裂、神经损伤等手术并发症。     

侧隐窝与腰骶神经根相对关系的临床研究

为揭示侧隐窝入口区之正常侧隐窝和狭窄侧隐窝与相应腰骶神经根的相对关系及其临床意义，作者对５０例正常者、４３例狭窄者和３２例狭窄症者腰骶椎ＣＴ扫描片编序拍摄输入计算机，由ＶＩ－ＤＡＳ图像分析系统统一按自行设计的测量法对入口区侧隐窝矢状径、上关节突间径和与侧隐窝相应的神经根距所设侧隐窝内口ａｂ线间径进行了测量。结果表明：正常情况下神经根均居侧隐窝内口ａｂ线侧隐窝一侧，但随着上关节突退变内聚程度逐渐加剧，使神经根靠近并跨越侧隐窝内口ａｂ线一侧，终致受狭窄侧隐窝的嵌夹。作者认为，侧隐窝入口区狭窄的真正临床意义在于直接危害神经根，但决定因素是上关节突增生内聚的程度，而侧隐窝矢径值量化的实用价值取决于上述变化情况。作者同时就导致侧隐窝狭窄并危害神经根的椎间盘膨出／突出、黄韧带肥厚／钙化、后方纤维环断裂／骨化等病理变化及相关问题作了分析。     

联合上颈段经颈静脉孔区入路的显微解剖学研究

目的 研究颈静脉孔区(JF)入路的显微解剖,利用该入路一期切除颅内外沟通型复杂病变.方法 成人尸头标本15例(30侧),在手术显微镜下进行联合上颈段经JF区入路的解剖操作,测量相关数据.结果 对C1～C4上颈段解剖,切除C1横突,游离椎动脉C1～C2段及水平段;充分切除颈静脉结节、颈静脉突及部分枕骨髁;迷路后切除乳突,显露半规管,轮廓化面神经垂直段,全程暴露乙状窦,打开颈静脉孔;扩大了JF区的显露并测得相关参数,如乳突尖间距枕髁外缘中点为(29.65±3.24)mm;枕髁后缘距舌下神经管内口为(10.10±0.81)mm;颈静脉球距面神经垂直段间距左为(6.8±0.35)mm,右为(4.6±0.33)mm.结论 此入路从多个方向对JF区充分暴露,使面神经、耳蜗、椎动脉、后组脑神经等结构得到保护,术中结合相关解剖参数可很好的完成一期全切JF区颅内外沟通型及延伸到上颈位的病变,提高治愈率、减少并发症、降低死亡率.     

髋臼前柱螺钉固定解剖学研究及导向器的设计

目的为经髋臼前柱螺钉固定提供解剖学依据。方法对22只成人尸体骨盆标本,共44侧髋臼进行解剖学研究,观测髋臼前柱横断面形状,测量髋臼前柱螺钉固定在髂骨翼外侧面的进针点、进针方向、钉道直径、进针点至闭孔沟的距离。结果髋臼前柱横断面呈近似直角三角形,钉道直径10.5±0.8mm;螺钉进针点位于髂骨翼后外侧面坐骨大切迹和髂前上棘连线上方9.2±2.4mm,距坐骨大切迹38.5±3.8mm;螺钉进针方向于水平面与中心线夹角为40.7±3.8°,矢状面向尾端成角54.2±5.5°。钉道长度84.1±6.2mm。并设计出髋臼前柱螺钉固定导向器。结论髋臼前柱可接受1枚直径6.5mm、长70mm的螺钉,螺钉进针点位于髂骨翼后外侧面坐骨大切迹和髂前上棘连线上方10mm,距坐骨大切迹40mm。螺钉进针方向于水平面与中心线夹角40°,矢状面向尾端成角55°。髋臼前柱螺钉固定导向器将提高前柱螺钉固定的安全性。     

The lumbosacral nerves in relation to dorsal S1 screw placement and their locations on plain radiographs

Seven adult cadaver lumbopelvises were harvested to study the anatomic relationship of the L4 and L5 nerves to S1 dorsal screw placement and the location of the L4, L5, and S1 nerves on plain radiographs. The mean lateral angle of S1 screw trajectory toward the L4 nerve was 31+/-8 degrees, and the mean screw trajectory length was 53+/-8 mm. The mean lateral angle of the screw trajectory toward the L5 nerve was 21+/-8 degrees, and the mean screw trajectory length was 38+/-4 mm. On both inlet and outlet radiographs, the lateral angle of the nerves increased from L4 to S1. The L4 nerve coursed over the middle third of the superior ala in the inlet view and the middle third of the lateral mass in the outlet view. The L5 nerve coursed over the inner third of the superior ala and inner third of the lateral mass. On the lateral view, the mean distances from the sacral promontory to the L4, L5, and S1 nerves along the anterior border of the sacrum were 4+/-7 mm, 12+/-5 mm, and 28+/-8 mm, respectively. This study suggests that S1 sacral screws be directed between 30 degrees and 40 degrees lateral to avoid compromising the lumbosacral trunk and sacroiliac joint.     

经皮前路侧块螺钉内固定植骨融合治疗C1,2不稳

目的　创建一种经皮前路侧块螺钉内固定植骨融合治疗C1,2 不稳的手术方法。方法　取 4 0名正常人影像学测量寰枢椎正位、侧位片的标准角、安全角、椎动脉内壁至寰椎上下缘中点连线的距离等相应数据 ,并用自行研制手术器械 ,对 15例C1,2 创伤性不稳的患者。男 10例 ,女 5例 ;寰枢椎 (半 )脱位 7例 ,陈旧齿状突骨折伴脱位 1例 ;Jefferson骨折 3例 ;C1前弓骨折 4例。在C臂X光机监视下行经皮前路侧块螺钉内固定前路植骨融合技术治疗 ,并分析其治疗结果。结果　正位片上其标准角右侧为 2 4 0°± 3 7° ,左侧为 2 3 8°± 1 8°;安全角右侧为 15 2°～ 30 3° ,左侧为 14 8°～ 32 1°;椎动脉内壁至寰椎上下缘中点连线的距离右侧为 (5 6± 2 2 )mm ,左侧为 (5 8± 1 9)mm ;侧位片的标准角为 2 4 1°± 1 8° ;安全角为 12 6°～ 2 6 8°。 15例患者内固定均获得了满意效果 ,螺钉位置佳。无脊髓、椎动脉和食管损伤等并发症发生。穿刺创口无感染。结论　经皮前路侧块螺钉内固定治疗C1,2 不稳操作简单 ,出血少 ,创伤小 ,恢复快 ,可一期行侧块关节固定植骨融合。手术有一定风险 ,如使用合理的配套器械 ,并熟悉其解剖特点 ,在X线透视下正确选择进针点、角度和深度 ,操作规范 ,此技术是安全的。     

The course of the nerve root in the neural foramen and its relationship with foraminal entrapment or impingement in adult patients with lumbar isthmic spondylolisthesis and radicular pain

The purpose of this study was to demonstrate the course of a nerve root in the neural foramen and its relationship with foraminal entrapment or impingement in 19 adult patients with isthmic spondylolisthesis and radicular pain. Myelo-computed tomography and magnetic resonance imaging showed that the course of the nerve root was normal (ie, medial and then inferior, along the pedicle) in 10 patients and was deviated posteriorly in 9 patients. The patients with a normal nerve root course (N-NRC) had either a bony callus projecting medially into the spinal canal (n = 6) or a low mean percentile of vertebral slip (n = 4; 13.9 +/- 1.3). Those nine patients with a posteriorly deviated nerve root course (PD-NRC) had no medially projecting bony callus in the spinal canal but had a higher mean percentile of vertebral slip (n = 9; 31.5 +/- 10.1; P = 0.005). In the neural foramen, nerve roots of the N-NRC patients were entrapped craniocaudally between the pedicle and superior part of the intervertebral disc. In contrast, nerve roots of the PD-NRC patients were impinged ventrodorsally between the posterosuperior part of the intervertebral disc and either bony callus projecting inferiorly toward the neural foramen or fibrocartilaginous mass arising around the isthmic defect. The foraminal craniocaudal entrapment and ventrodorsal impingement highly agreed with the side of radicular pain (kappa= 0.73, P < 0.001). Our results demonstrate that the medially projecting bony callus and the percentile of vertebral slip affect the course of the nerve root in the neural foramen, which in turn determines the foraminal craniocaudal entrapment or ventrodorsal impingement. These two mechanisms, based on the course of the nerve root, correlate well with the side of radicular pain.     

Location of the vertebral artery in the cervicothoracic junction

Eight sectioned specimens and 8 cadavers were used to evaluate the location of the vertebral artery in the cervicothoracic junction. The results of the measurements showed that there was no significant difference between either sides at the C7-T1 junction in terms of all distances taken. The mean width of the vertebral artery was 2.9 mm at the levels of the C-7 and T-1. The sagittal distance between the vertebral artery and the posterior cortex was 16.8+/-3.0 mm at the C7 and 21.7+/-2.8 mm at T-1. The coronal distance between the vertebral artery and the midline of the vertebra was 17.5+/-1.8 mm at the C7 and 22.3+/-2.9 mm at the T-1. The mean angle between the line connecting the lateral border of the vertebral artery with the posterior midway of the lateral mass and the parasagittal line at C-7 was 14.1+/-6.1 degrees. The mean angle of the vertebral artery with respect to the midline was 22.8+/-6.4 degrees. This study suggests that the vertebral artery has closer anatomic relationship to the C-7 lateral mass. Care should be taken to avoid injury to the vertebral artery if lateral mass screw fixation at the C-7 is intended.     

Thoracic pedicle: surgical anatomic evaluation and relations

This anatomic study investigated the thoracic pedicle and its relations. The objective was to emphasize the importance of the thoracic pedicle for transpedicular screw fixation to avoid complications during surgery. Twenty cadavers were used to observe the cervical pedicle and its relations. The isthmus of the pedicle was exposed after removal of whole-posterior bony elements, including spinous processes, laminas, lateral masses, and the inferior and superior facets. The pedicle width and height, interpedicular distance, pedicle-inferior nerve root distance, pedicle-superior nerve root distance, pedicle-dural sac distance, root exit angle, and nerve root diameter were measured. There was no distance between the pedicle and dural sac in eight specimens. There was, however, a short distance in 12 remaining specimens in the upper and lower thoracic regions. The distances between the thoracic pedicle and the adjacent nerve roots ranged from 1.5 to 6.7 mm and 0.8 to 6.0 mm superiorly and inferiorly at all levels. The mean pedicle height and width at T1-T12 ranged from 2.9 to 11.4 mm and 6.2 to 21.3 mm, respectively. The interpedicular distance decreased gradually from T1 to T5 and then increased gradually to T12. The mean root exit angle decreased consistently from 104 degrees to 60 degrees. The nerve root diameter was between 2.3 and 2.5 mm at the T1-T5 level and then increased consistently from 2.5 to 3.7 mm. All significant differences were noted at p < 0.05 and p < 0.01. The following suggestions are made based on these results. 1) More care should be taken when a transpedicular screw is placed in the horizontal plane. 2) Improper medial placement of the pedicle screw, especially in the middle thoracic spine, should be avoided, and the anatomic variations between individuals should be considered. 3) Because of substantial variations in the size of thoracic pedicles, utmost attention should be given to the findings of a computed tomographic evaluation before thoracic transpedicular fixation is begun.     

腰神经根解剖及其在经皮穿刺腰椎间盘摘除术中的临床意义

目的加深对腰神经根周围解剖的认识,选择经皮穿刺最佳途径。方法对３０具成人尸体腰神经根周围结构进行解剖学观察、测量和摹拟穿刺。结果测量三角工作区面积（ｍｍ２）：Ｌ４～５为１０４６５±２３６６,Ｌ５～Ｓ１为９１８１±１６７８;直视下穿刺针进入角度（°）：Ｌ４～５为４５３３±１８１,Ｌ５～Ｓ１为４０４３±３４９,外区为４８４±２５６;穿刺点距后中线距离（ｍｍ）：Ｌ４～５为６９８±５７,Ｌ５～Ｓ１为６０６±７０,外区为９７１±９９;闭合穿刺成功率：Ｌ４～５为１００％,Ｌ５～Ｓ１为９０％,外区为６０％。结论经三角工作区穿刺是经皮后外侧入路腰椎间盘摘除术的最佳途径;对Ｌ５～Ｓ１间隙穿刺有困难时,可经三角工作区的外区进行穿刺手术。     

Surgical anatomic evaluation of the cervical pedicle and adjacent neural structures

OBJECTIVE: Although several clinical applications of transpedicular screw fixation in the cervical spine have been documented recently, few anatomic studies concerning the cervical pedicle are available. This study was designed to evaluate the anatomy and adjacent neural relationships of the middle and lower cervical pedicle (C3-C7). The main objective is to provide accurate information for transpedicular screw fixation in the cervical region and to minimize complications by providing a three-dimensional orientation. METHODS: Twenty cadavers were used to observe the cervical pedicle and its relationships. After removal of the posterior bony elements, including spinous processes, laminae, lateral masses, and inferior and superior facets, the isthmus of the pedicle was exposed. Pedicle width, pedicle height, interpedicular distance, pedicle-inferior nerve root distance, pedicle-superior nerve root distance, pedicle-dural sac distance, medial pedicle-dural sac distance, mean angle of the pedicle, root exit angle, and nerve root diameter were measured. RESULTS: The results indicate that there was no distance between the pedicle and the superior nerve root and between the pedicle and the dural sac in 16 specimens, whereas there was a slight distance in the lower cervical region in the 4 other specimens. The mean distance between the pedicle and the inferior nerve root for all specimens ranged from 1.0 to 2.5 mm. The mean distance between the medial pedicle and the dural sac increased consistently from 2.4 to 3.1 mm. At C3-C7, the mean pedicle height ranged from 5.2 to 8.5 mm, and the mean pedicle width ranged from 3.7 to 6.5 mm. Interpedicular distance ranged from 21.2 to 23.2 mm. The mean root exit angle ranged from 69 to 104 degrees, with the largest angle at C3 and the smallest at C6. The mean angle of the pedicle ranged from 38 to 48 degrees. The nerve root diameter increased consistently from 2.7 mm at C3 to 3.8 mm at C6 and then decreased to 3.7 mm at the C7 level. Differences in measurements were considered statistically significant at levels ranging from P < 0.05 to P < 0.01. CONCLUSION: This study indicates that improper placement of the pedicle screw medially and superiorly in the middle and lower cervical spine should be avoided and that the anatomic variations between individuals should be established by measurement.     

Anatomic relationship of the cervical nerves to the lateral masses

Eight cervical specimens were transversely sectioned with slices approximately 2 mm to 3 mm in thickness to evaluate the anatomic relationship of the spinal nerves to the lateral masses. Results showed that the spinal nerve either does not appear or, when it does, is situated anteromedially to the superior facet on the cross sections through the upper portion of the superior facet. The anterolateral aspect of the superior facet is free from the spinal nerve. Cross sections through the lower pedicle of the vertebra showed that the spinal nerve rested on the transverse process anterolateral to the lateral mass. The mean distances between the posterior midline of the lateral mass and the posterior border of the spinal nerve measured 15 degrees in the lateral direction were 16.1+/-1.7 mm for C3, 16.5+/-1.8 mm for CA, 16.8+/-1.2 mm for C5, 16.3+/-2.0 mm for C6, and 8.5+/-0.9 mm for C7. This study suggests that the anterolateral corner of the superior facet and the anterior aspect of the lateral mass lateral to the origin of the transverse process would be safer zones for screw exit. Attention should therefore be paid to the screw orientation for the Magerl technique and to the screw length for the Roy-Camille technique. Care should be taken to insert the screw into the C7 lateral mass.     

Osseous anatomy of the scapula

Detailed anatomy and morphometry of the scapula were obtained to provide information for surgical procedures such as hardware fixation, drill hole placement, arthroscopic portal placement, and prosthetic positioning. Twenty-six measurements were made in 15 pairs of scapulas from cadavers. The average length of the scapulas from the superior to the inferior angle was 155 +/- 16 mm (mean +/- standard deviation). The thickness of the medial border 1 cm from the edge was 4 +/- 1 mm. The superior border was sharp and thin, and the suprascapular notch was present as a foramen in two scapulas. The distance from the base of the suprascapular notch to the superior rim of the glenoid was 32 +/- 3 mm. The length of the spine from the medial edge of the scapula to the lateral edge of the acromion was 134 +/- 12 mm. The anteroposterior width of the spine at 1 and 4 cm from the medial edge was 7 +/- 1 and 18 +/- 3 mm, respectively; the width at the lateral edge (spinoglenoid notch) was 46 +/- 6 mm. The acromion measured 48 +/- 5 mm x 22 +/- 4 mm and was 9 +/- 1 mm thick. The acromial shape was flat in 23%, curved in 63%, and hooked in 14% of scapulas. The distance from the glenoid to the acromion was 16 +/- 2 mm. The glenoid dimensions were 29 +/- 3 mm (anteroposterior) x 36 +/- 4 mm (superoinferior) and faced posterior by 8 +/- 4 degrees. Anteroposterior thickness of the head of the scapula 1 cm from the surface was 22 +/- 4 mm. The thickness of the coracoid was 11 +/- 1 mm. The average length of the coracoacromial ligament was 27 +/- 5 mm. Scapulas from male cadavers were significantly larger than scapulas from female cadavers in 19 measurements.     

CT三维重建在胸椎间孔穿刺定位中的应用

目的采用CT三维重建定位观察胸椎间孔,以确定胸椎间孔在椎板外侧的穿刺位置以及穿刺的深度。方法选取30例非胸椎病患者的CT三维重建胸椎图像,测量椎间孔所在水平面到上位胸椎棘突中点水平面之间距离、椎间孔外口到正中线距离以及椎间孔到棘突尖距离、椎间孔前后径和上下径。结果①T1-3椎间孔到各自上一椎体棘突中点平面为（20.5±3.0）mm,T4-6为（5.1±4.7）mm,T7-9为（4.4±2.0）mm,T10-12为（19.6±5.4）mm。②在T7处,椎间孔至正中线和棘突尖的距离最近,分别（15.2±4.8）mm和（44.3±5.9）mm,向上或向下逐渐增加。③椎间孔前后径为（9.8±1.4）mm。④椎间孔上下径（12.1±3.5）mm。结论胸椎间孔可以经上位棘突准确定位。