Treatment strategies and biomechanical analysis for ulna coracoid process fractures

Abstract

Abstract:

BACKGROUND: Fractures of the coronoid progress are common in patients with elbow dislocations, and often accompanied by elbow ligament and joint capsule laceration. The coronoid progress fracture often leads to elbow joint instability, if cannot get the correct therapy, will result in repeatedly elbow instability, dislocation, and cause long-term irreversible damage to the elbow.
OBJECTIVE: To review the literatures about coronoid fractures and relative anatomic and biomechanical studies.
METHODS: An electronic search of the Web of Science database was conducted for clinical and experimental researches about coronoid fractures and relative anatomic and biomechanics published from January 1990 to March 2013, the key words were “coronoid process of the ulna, coronoid fracture, treatment method, research progress”. The articles published earlier and repetitive researches were excluded.
RESULTS AND CONCLUSION: Coronoid process is an important primary stabilizer of elbow joint, The coronoid process combined with the soft tissues of ligaments, joint capsule and muscles that attached on the coronoid plays an important role in maintaining the elbow axial, varus, valgus and rotation stability. The selection of the treatment strategies for coronoid process fracture depends on the fracture type, degree of fracture fragments crush and injury of medial and lateral collateral ligament and the anterior capsule. Uncomminuted large fractures can be treated with open reduction and internal fixation; comminuted fractures can be treated with reduction and internal fixation by the largest fracture fragments, autograft reconstruction or artificial coronoid process replacement; the repair of small coronoid process fracture depends on the circumstances; if the elbow gets enough stability after repair of soft tissue injury, it cannot be addressed, if not, the elbow should be repaired with sutures or anchors. Earlier motion after operation is important to get better function, and the hinged external fixator can be used if necessary.

Key words: ulna fractures, elbow joint, dislocations, internal fixators

CLC Number:

R318

Liu Ren-hao, Zhou Nan, Bi Zheng-gang . Treatment strategies and biomechanical analysis for ulna coracoid process fractures[J]. Chinese Journal of Tissue Engineering Research.

Figures/Tables 7

2.1 纳入研究基本概况纳入的45篇文献包括尺骨冠状突骨折临床回顾性研究文章25篇，模拟冠状突骨折的试验性研究文章8篇，尺骨冠状突解剖学及生物力学研究性文章5篇，冠状突骨折治疗方法的对照性研究文章7篇。 2.2 解剖学及生物力学尺骨冠状突是肘关节重要的骨性稳定结构，冠状突的解剖存在相当于肘关节前方支持扶璧，在肘关节屈伸运动中维持轴向稳定并防止发生脱位和内外翻失稳。冠状突由尖部、体部、基底部组成，在体部和基底部内缘向内延伸出一骨性结构称为冠状突前内侧面，其上有内侧副韧带前束止点(高耸结节)，具有重要的抗内翻作用。前关节囊止点附丽在冠状突尖部远端约5.9 mm处，肱肌肌腱止点距冠状突尖部约12.1 mm[1]。冠状突和附丽在其上的软组织结构一同在维持肘关节轴向稳定、后内侧、后外侧旋转稳定及防止肘内翻上发挥着重要作用。 2.3 损伤机制冠状突骨折很少单独发生，常常合并前关节囊、韧带的撕裂和桡骨头、鹰嘴的骨折[2]，多见于肘关节脱位的患者，文献报道在肘关节脱位的患者中有2%-15%合并有冠状突骨折[3-4]。最常见的损伤形式是当高处坠落或摔倒时上肢处于外展位手掌撑地，身体相对于上肢产生外翻力和后外侧旋转力，致使关节囊和韧带结构由外向内逐渐撕裂，继而肱骨远端与冠状突碰撞导致冠状突尖部或体部横行骨折，同时多伴有桡骨头的骨折[5]。由于冠状突前内侧面是一个相对独立无支撑的结构，当受到轴向内翻力时易于损伤，O’Driscoll等[6]提出上肢外展位摔倒时手掌撑地，由前臂向肘部传递的轴向力、内翻应力和肘部后内侧旋转作用力的联合作用导致外侧尺骨副韧带撕裂，致使肱骨远端同冠状突前内侧面发生撞击，导致前内侧面骨折[6]，此种损伤多不合并内侧副韧带前束的损伤，见图1。"

2.6 治疗方案 2.6.1 冠状突尖部骨折 Regan和/或O’DriscollⅠ型骨折。Ⅰ型冠状突骨折骨折块较小，大部分学者主张仅修复除冠状突外的其他损伤结构[10-14]。 Jeon等[13]通过最新实验研究发现单独ReganⅡ型冠状突骨折(已然包含Ⅰ型冠状突骨折)、单独前内侧面骨折、单独前外侧面骨折所造成的内翻外翻、内旋外旋角度变化均< 1°、位移< 1 mm，几乎不造成肘关节失稳，并提出在关节囊、韧带结构完好尤其是桡骨头完好时的情况下≤40%冠状突高度的冠状突骨折，肘关节仍可保持足够稳定性，可不需手术治疗。 Beingessner认为Ⅰ型冠状突骨折对肘关节运动力学和稳定性影响甚微，同完好肘关节相比在肘关节屈曲30°，90°，120°前臂分别置于旋前、旋后位时外翻角度仅有轻微改变，并且修复冠状突骨折亦并未纠正增长的外翻角度。因而建议在修复完成桡骨头和外侧尺骨副韧带后Ⅰ型冠状突骨折可不给予处理，若修复桡骨头和外侧尺骨副韧带后肘关节仍存在失稳可选择修复内侧副韧带，冠状突骨折不给予处理[10，12]。但是一些学者认为冠状突尖部骨折的产生预示着肘部存在失稳，往往伴随着尺骨外侧副韧带、肘关节内侧副韧带、前关节囊的损伤，尤其是当冠状突尖部骨折块附着在前关节囊上时，修复该冠状突骨折具有重要意义[15-17]。 Ⅰ型冠状突骨折的修复多采用Hotchkiss正上方入路劈裂屈曲旋前肌群掀起肱肌及其前半部分进入冠状突，应用“套索式缝线”穿过近端尺骨钻孔或应用锚钉将骨折块及附着在其上的关节囊给以固定[18-22]。 Hausman等[23]则成功地应用关节镜技术对4例伴有Ⅰ型和Ⅱ型冠状突骨折和韧带损伤患者进行了手术，并取得了满意的结果。该学者指出关节镜技术仅支持小块冠状突骨折，技术要点：①首先明确尺神经位置，并避免损伤。②多选择2个入口，于肘关节近端前内侧面钝性创造观察窗口，然后在关节镜的观察下于肘关节前外侧面建立操作窗口，为便于观察可在前外侧面再建立一个窗口放置关节内牵开器必要时开阔视野。③在关节镜视野下找到骨折块和骨折基部，于近端尺骨背侧做1 cm切口由后向前插入导针，确保导针位于骨折基部中央，然后用关节镜抓手解剖复位骨折块并将导针穿过，必要时可用2枚导针。④由背侧沿导针插入空心螺钉，退出导针。⑤外侧副韧带的损伤需采取外侧切口单独处理。与传统切开复位内固定相比关节镜技术减少了对骨骼血运的破坏及软组织损伤[19，23]。 2.6.2 冠状突前内侧面骨折 O’DriscollⅡ型骨折。冠状突前内侧面自尺骨近侧干骺端向内延伸出约 7 mm，无支撑结构支持，该解剖特点使其在受到轴向内外应力时易于骨折[5，21]。冠状突前内侧面骨折多合并尺骨外侧副韧带撕裂，较少合并桡骨头骨折和内侧副韧带损伤[1，15]。如前所述Jeon等[13]认为单纯前内侧面冠状突骨折对肘关节稳定性影响甚小，无需修复。 Doornberg等[24]通过病例回顾分析发现冠状突前内侧面骨折行有限治疗(未手术、术中未处理、未达到稳固固定)的患者均有不同程度的肘关节失稳、半脱位和骨性关节炎等并发症，而行坚强稳固固定的患者均获得了优良结果。因而建议大多数冠状突前内侧面骨折行手术坚强固定治疗，并指出非手术治疗仅适用于非常小的骨折(Ⅱa)、不合并肘关节半脱位、侧位内翻应力下X射线片下肱桡关节间隙无变化[24-26]。其他一些学者则认为Ⅱa和Ⅱb型在修复外侧尺骨副韧带后若肘关节稳定性良好则不需修复冠状突骨折[27]。Ⅱc型甚至个别Ⅱb型冠状突前内侧面骨折由于损伤了内侧副韧带前束，需手术治疗。修复冠状突前内侧面骨折的内侧入路选择有多种：①尺神经原始位置进入：先行尺神经前置，然后从尺侧腕屈肌两头的间隔进入，在分离解剖尺侧腕屈肌时应由远及近分离，防止损伤在高耸结节处附丽的内侧副韧带前束。②若骨折块较小可选择前述的Hotchkiss正上方入路[18]，骨折块较大时也可将整个屈曲旋前肌群掀起，但需注意保护尺神经。依据骨块大小及骨质情况选择固定方式：①恐怖三联征的小块骨折及前内侧面小块骨折可用“套索式缝线”穿过近端尺骨的钻孔或应用锚钉将骨折块连同附着在其上的前关节囊固定于肘关节屈曲位，缝线于尺骨干骺端背面系紧[28-29]。②大块前内侧面骨折可应用冠状突塑型钢板或T型钢板固定均可取得较好结果[18，20]。 2.6.3 冠状突体部或基底部非粉碎性骨折 Regan Ⅱ型或Ⅲ型骨折。大多数Ⅱ型或Ⅲ型冠状突骨折破坏了肱尺关节协调的关节结构及附丽在其上的软组织稳定结构，常导致肘关节失稳[3]，往往需手术治疗。Ⅱ型或Ⅲ型非粉碎性骨折由于骨折块较大，在临床上易于诊断及手术固定，相对于冠状突尖部和前内侧面骨折处理起来反而简单且效果良好。术中麻醉状态下行肘关节稳定性的影像学检查有助于判断韧带损伤情况及手术入路的选择，内侧副韧带检查采取肩部外展前臂旋前位肘关节外翻应力下X射线摄像，外侧副韧带检查取肩部外展前臂选后卫肘关节内翻应力下X射线摄像，据影像学关节间隙的变化判断有无韧带损伤[18]。手术多取内侧入路，合并外侧副韧带损伤时联合使用外侧入路；亦有学者提出前方入路治疗冠状突骨折的文献，认为前方入路更为直观，且固定牢固尤其是对于单独的 Regan Ⅲ型冠状突骨折效果较好[25-26]；也可以选择后方正中切口，向上分别提拉起内外侧皮瓣行内外侧入路操作，该入路多应用于合并外侧副韧带损伤、鹰嘴骨折患者[30]。大块非粉碎性骨折块可采用多种固定方法如冠状突钢板、空心拉力螺钉或实心螺钉。另据文献报道采用螺钉固定骨块时由后向前插入螺钉的固定方式生物力学效果较好[31]。若伴有鹰嘴骨折用与鹰嘴塑形的后位钢板，冠状突骨折则通过板孔使用螺钉牢固固定[18]。外侧副韧带损伤者均需修复，多于其肱骨外髁起点处撕脱，撕脱的外侧副韧带可用锚钉或者穿骨缝线固定到肱骨外髁处，修复的关键在于将其缝合到肘关节的旋转中心，即肱骨小头外侧中心处，以恢复其等距解剖结构保证外侧副韧带在肘关节运动过程中处于恒定紧张状态[32]。中间撕裂损伤应用1#或2#的不可吸收性缝合线缝合，较少应用肌腱移植。冠状突骨折和外侧副韧带修复完成后，若肘关节获得足够稳定性，内侧副韧带可不给予修复，治疗后前臂置于旋后位避免外翻力，内侧副韧带多可自行愈合[10]。若存在不稳定则可考虑修复内侧副韧带，也可考虑应用铰链式外固定支架。外固定支架既保证了肘关节的稳定性的维持也可允许早期肘关节活动，有利于治疗后功能的恢复[3]。 2.6.4 粉碎性冠状突骨折粉碎性冠状突骨折为高能量损伤，临床处理困难，预后效果差，常伴有肘关节活动受限和骨性关节炎等并发症。对于可修复的粉碎新冠状突骨折可选择较大的关节面骨折块给予复位固定，重建肱尺关节的解剖结构，恢复冠状突的前方支持扶璧作用防止肘关节后脱位或半脱位。不可修复的粉碎性冠状突骨折，若同时伴有桡骨头骨折需要切除时，推荐应用切除的桡骨头重建冠状突[18，33-37]，见图6；若单纯冠状突粉碎骨折可选择应用同侧鹰嘴尖部骨软骨自身移植重建冠状突，但当伴随鹰嘴骨折时不可采用鹰嘴截骨重建；亦可选择应用三面皮质骨髂骨移植重建冠状突[34-35]，应用髂骨重建冠状突时髂骨移植物长2 cm，宽1 cm，高1 cm用 2.5 mm松质骨螺钉和垫圈将其固定并强调修复前关节囊和韧带结构以保证稳定性[35]。"

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