肘关节镜前外侧入路的解剖学研究

吴关 鲁谊

·论著·

肘关节镜前外侧入路的解剖学研究

吴关 鲁谊

目的 初步探讨肘关节镜前外侧入路向前方的变化范围。 方法 选用10具新鲜上肢标本，在肘关节屈曲90°下，测量近端前外侧入路、前外侧入路、外侧入路与桡神经的距离；测量改良后3个入路前方5mm与桡神经的距离。结果 标准入路的近端前外侧入路、前外侧入路、外侧入路与桡神经的距离平均值分别为：12.8mm、8.5mm、3.8mm，改良后的近端前外侧入路、前外侧入路、外侧入路与桡神经的距离平均值分别为4.1mm、2.2mm、-0.5mm。结论 肘关节近端前外侧入路与前外侧入路之间的连线区可向前方5mm进行操作，越靠远端距离桡神经越近；前外侧入路与外侧入路距离桡神经较近，不建议向前方改变入路。

肘关节镜； 前外侧入路； 解剖学

从20世纪80年代开始，肘关节镜手术快速发展，得到了广泛应用。肘关节镜的手术指征包括：肘关节游离体、肘关节僵硬、肘关节滑膜炎、肘关节软骨损伤等。近年来，越来越多的学者尝试应用肘关节镜做更加复杂的操作，如韧带损伤修复、重建，骨折复位固定等。目前，已有多个介绍肘关节镜下行桡骨头骨折、肱骨小头骨折、尺骨冠状突骨折复位内固定的报道[1-5]。作者于近期开展肘关节镜下骨折复位内固定手术，发现由于骨折形态、位置多变，导致有时通过常规的肘关节外侧入路难以获得较满意的固定角度。由于肘关节本身间隙狭窄，周围神经解剖关系复杂，肘关节镜手术中神经损伤较为常见，且后果严重[6-14]。因此，作者拟通过解剖学研究，探寻在不损伤桡神经的前提下，肘关节前外侧入路是否可以比标准入路适当偏前，或者在比常规入路更加靠前的位置打入内固定物，以适应骨折固定的需要。

资 料 与 方 法

一、一般资料

选用10具新鲜上肢标本，均为男性，平均年龄58岁(43～78岁)。所有肘关节均无外部畸形、手术瘢痕及关节活动受限。试验工具包括解剖器械(手术刀、血管钳、组织剪、齿镊等)，直径4 mm斯氏针，20 ml一次性注射器，18-Gauge硬膜外针头，游标卡尺(精确度0.1 mm)。

二、方法

肘关节屈曲90°，上臂固定于操作台。将重要的体表标志逐一标记，包括肱骨外上髁、桡骨头等。标记标准的肘关节镜外侧入路以及实验选取的肘关节镜外侧入路，标准入路按照既往文献描述的标准点选择，改良入路标记为标准入路正前方5 mm。标准入路包括近端前外侧入路(肱骨外上髁近端2 cm，前方1 cm)、前外侧入路(肱骨外上髁前方1 cm)、外侧入路(肱骨外上髁远端3 cm，前方1 cm)。

用18-Gauge硬膜外针头由前内侧入路穿刺，向关节内注射生理盐水以扩张关节。在之前标记的3个标准入路及3个实验入路点上做小切口，以直血管钳扩张皮下组织，在肘关节屈曲90°、前臂中立位下，分别以直径4 mm斯氏针朝向关节中心插入。剔除从上臂下1/3到前臂上1/3的所有皮肤、皮下组织，解剖桡神经。

在肘关节屈曲90°下，以游标卡尺测量桡神经与相邻斯氏针的最短距离。如斯氏针紧贴桡神经，距离记为0；如穿过桡神经，距离记为负值。计算五组数据的平均值作为最终距离值。平均值>2 mm视为安全。

结 果

在肘关节屈曲90°下，标准入路的近端前外侧入路、前外侧入路、外侧入路与桡神经的距离平均值分别为：12.8 mm、8.5 mm、3.8 mm，改良后的近端前外侧入路、前外侧入路、外侧入路与桡神经的距离平均值分别为4.1 mm、2.2 mm、-0.5 mm。

讨 论

本研究的主要发现是肘关节前外侧入路可以根据术中实际情况加以改变，但是仅仅局限于近端前外侧入路至前外侧入路之间，向前的距离尽量不超过5 mm；对于前外侧入路与外侧入路之间的区域，为了避免桡神经损伤，尽量不选择向前方改变入路或进行操作。

肘关节镜入路周围神经密集，术中极易损伤周围重要神经[6, 10, 13-14]，其中最易受损的就是桡神经[7]，最可能损伤桡神经的入路是前外侧入路。肘关节前外侧入路主要包括近端前外侧入路、前外侧入路、外侧入路。外侧入路在早期应用较多，但学者们发现应用该入路术后患者易出现桡神经症状[8]。通过解剖学研究发现，该入路与桡神经最短距离在屈肘90°仅4 mm左右，且随着肘关节屈曲角度减小而进一步减小[1, 6, 15]。因此，越来越多的学者选用近端前外侧入路作为前外侧常规入路，该入路与桡神经的距离在屈肘90°下>10 mm，损伤几率明显减小，而且通过该入路可获得前方自上而下的视野，可清楚观察肘关节前间室及内侧结构[1, 10, 12]。

伸直肘关节会对肘关节前外侧入路与桡神经的距离产生显著影响。既往的解剖学结果表明，前外侧入路与桡神经的距离会随着肘关节伸直而减小[1,6,15]。本文中，改良入路的初衷是方便特殊类型骨折的处理，不需要伸直肘关节；或者该定点并不作为入路入点，而是作为打入内固定物的套管通路，不需要频繁屈伸肘关节，因此本文仅对屈肘90°位置进行测量。

肘关节骨折是肘关节镜较新的适应证，最早在肘关节镜下处理骨折可追溯到1997年[2]。肘关节镜可处理的骨折主要包括：肱骨小头骨折、尺骨冠状突骨折、桡骨头骨折等。Rolla等[3]介绍了关节镜下复位内固定Mason 2、3、4型桡骨头骨折的方法，得到了满意的短期效果。对于肱骨小头骨折，由于骨折块往往较大，因此复位、固定过程中常常需要2个甚至更多前外侧入路进行辅助操作[2]。Adams等[4]介绍了以导向器定位冠状突骨折端经骨固定的方法，但同样需要尽量靠近骨折端的外侧入路辅助骨折复位固定。因此，对于肘关节镜下骨折操作，为了避免潜在的桡神经损伤风险，熟知前外侧安全范围极其重要。

本研究尚有一些不足之处：(1)入路的定位较模糊，虽然经过测量，但不同实施者之间会有误差并影响实验结果；(2)本实验以4 mm斯氏针代替关节镜套筒插入关节，但是插入关节内的位置在所有标本中会有偏差，影响实验结果；(3)经过解剖后，神经张力会有变化，距离测量会有一定的误差。

综上所述，可以得到以下结论：肘关节近端前外侧入路与前外侧入路之间的连线区可向前方5 mm进行操作，但越靠远端距离桡神经越近，神经损伤风险越大；前外侧入路与外侧入路之间连线区域距离桡神经较近，不建议向前方改变入路。

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(本文编辑：李静)

吴关,鲁谊.肘关节镜前外侧入路的解剖学研究[J/CD]. 中华肩肘外科电子杂志,2016,4(2):99-102.

Anatomyofanterolateralportalsofelbowarthroscopy

WuGuan,LuYi.

DepartmentofOrthopaedicTrauma,BeijingJishuitanHospital,Beijing100035,ChinaCorrespondingauthor:LuYi,Email:luyi_orthop@hotmail.com

Background From the 1980s, elbow arthroscopic surgery has been rapidly developing and widely applied. Indications for elbow arthroscopic surgery include: loose bodies, stiff elbow, elbow synovitis, and elbow cartilage injury etc. In recent years, more and more scholars try to apply elbow arthroscopy in more complex operations, such as ligament repair, reconstruction, and fracture fixation and so on. Currently, there are quite a few reports on reduction and fixation of radial head fracture, humerus capitellum fracture, ulna coronoid fracture under elbow arthroscopy. Recently, we started to conduct elbow arthroscopic fracture reduction and internal fixation, and found that due to the varying types of fracture morphologies and locations, the conventional lateral elbow approach sometimes cannot access satisfactory fixation angles. Due to the narrow space in the elbow joint and complex anatomical relationship of the peripheral nerves, nerve injury is common in elbow surgery and consequences are often serious. Therefore, we aim to explore better approaches to protect the radial nerve based on study of anatomical specimens. Here we used either an improved anterolateral elbow approach that entered at a more anterior position than the conventional approach, or we delivered implants at a more anterior position than the conventional approach to perform fracture fixation. Our findings are reported below.Methods Ten fresh upper limb specimens were selected, all males, mean age 58 years (43 to 78 years), all elbow joints free of external deformities, surgical scars or mobility limitation. Study tools included anatomical instruments (scalpel, forceps, scissors, toothed forceps etc.), 4 mm diameter Steinmann pins, 20 ml disposable syringes, 18-Gauge epidural needles, and vernier caliper (accuracy of 0.1 mm).Surgical procedure: flex the elbow at 90°, fix the upper arm on operation table, mark important anatomical landmarks individually including epicondyle of the humerus and radial head etc., mark the sites of conventional lateral elbow arthroscopic approach and experimental (improved) lateral elbow arthroscopic approach. Choose of the conventional approach was in accordance with previous literatures, and improved approach was 5 mm anterior to the conventional approach. Conventional approaches included proximal anterolateral approach (2 cm proximal and 1 cm anterior to the humeral epicondyle), anterolateral approach (1 cm anterior to the humeral epicondyle), and lateral approach (3 cm distal and 1 cm anterior to the humeral epicondyle). A 18-Gauge epidural needle was used for puncture via the anteromedial approach, inject normal saline into the joint to expand articular capsule, make a small incision on the previously marked 3 conventional approach sites and 3 experimental approach sites, expand subcutaneous tissues using straight forceps. Under 90° elbow flexion or forearm at neutral position respectively, insert a 4 mm diameter Steinmann pin into center of the joint, remove all skin and subcutaneous tissues of lower 1/3 upper arm and upper 1/3 forearm to dissect the radial nerve.Under 90° elbow flexion position, the shortest distance between the radial nerve and adjacent Steinmann pin was measured with a vernier caliper. If Steinmann pin was touched the radial nerve, distance was recorded as 0; if the pin was through the radial nerve, distance was recorded as negative. Final distance was calculated as average of 5 groups of measurement. An average of >2 mm was considered safe operation.Results Under 90° elbow flexion, average distances to radial nerve using the conventional approaches including proximal anterolateral approach, anterolateral approach and lateral approach were:12.8 mm,8.5 mm and 3.8 mm. These of the improved proximal anterolateral approach, anterolateral approach and lateral approach were 4.1 mm,2.2 mm and -0.5 mm respectively.Conclusions The connecting zone of the elbow proximal anterolateral approach and anterolateral approach can be moved anteriorly by 5 mm during surgical operation. The more distal, the closer to the distal radial nerve; anterolateral and posterolateral approach are too close to the radial nerve, so change of approach to anterior site is not recommended.

Elbow arthroscopy;Anterolateral approach;Anatomy

10.3877/cma.j.issn.2095-5790.2016.02.007

北京市卫生系统高层次卫生技术人才培养计划(2013-3-031)

100035北京积水潭医院运动损伤科

鲁谊，Email:luyi_orthop@hotmail.com

2015-09-24)