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下面我們將為大家提供四期連載內(nèi)容，本文為第一期，包括介紹、相關(guān)解剖和生物力學(xué) 介紹 肘關(guān)節(jié)三維結(jié)構(gòu)復(fù)雜，容易發(fā)生關(guān)節(jié)僵硬，且關(guān)節(jié)不穩(wěn)帶來的后果比較嚴(yán)重。有關(guān)肘關(guān)節(jié)周圍多發(fā)性骨折及軟組織損傷的病例多有報(bào)道，肘關(guān)節(jié)脫位合并冠狀突和橈骨頭骨折之所以獲得“恐怖三聯(lián)征”的稱號(hào)，主要?dú)w因于其治療困難及預(yù)后較差。“恐怖三聯(lián)征”常導(dǎo)致肘關(guān)節(jié)周圍骨性結(jié)構(gòu)和韌帶不穩(wěn)；因此，治療必須充分恢復(fù)肘關(guān)節(jié)的穩(wěn)定性以允許早期功能鍛煉，從而避免關(guān)節(jié)僵直。
相關(guān)解剖 肘關(guān)節(jié)由橈骨、尺骨上端和肱骨下端構(gòu)成，這三者由肱尺關(guān)節(jié)、肱橈關(guān)節(jié)和橈尺近端關(guān)節(jié)連接（圖1）。肱尺關(guān)節(jié)和肱橈關(guān)節(jié)屬屈戌（鉸鏈）關(guān)節(jié)，而橈尺近端關(guān)節(jié)屬車軸（樞軸）關(guān)節(jié)。恐怖三聯(lián)征會(huì)導(dǎo)致肱骨和前臂連接不穩(wěn)，但很少會(huì)破壞尺骨和橈骨（包括前臂骨間膜）之間的穩(wěn)定性。 Fig.1. Bony landmarks as seen on (A) anteroposterior (AP) and (B) lateral radiographs. 圖1 肘關(guān)節(jié)解剖標(biāo)記：A為前后位片，B為側(cè)位片。 雖然肘關(guān)節(jié)與肩關(guān)節(jié)都由肱骨參與組成，但肘關(guān)節(jié)不同于肩關(guān)節(jié)。相比于簡單的球形盂肱關(guān)節(jié)及其復(fù)雜的周圍軟組織穩(wěn)定結(jié)構(gòu)，肘關(guān)節(jié)的三維骨性解剖較復(fù)雜，而其軟組織結(jié)構(gòu)（包括內(nèi)外側(cè)副韌帶和前后部關(guān)節(jié)囊）則相對(duì)簡單。
內(nèi)側(cè)副韌帶（MCL）復(fù)合體由前束、后束和橫束三部分組成（圖2A）。前束和后束起于肱骨內(nèi)上髁的下方，而橫束并不跨越肘關(guān)節(jié)。前束止于冠狀突的高聳結(jié)節(jié)，是其中最為獨(dú)特和重要的。后束跨關(guān)節(jié)后面止于鷹嘴，而橫束起止點(diǎn)均在尺骨上，起于鷹嘴前端止于冠狀突。
外側(cè)副韌帶復(fù)合體同樣由三部分組成：外側(cè)尺骨副韌帶（LUCL）、橈側(cè)副韌帶和環(huán)狀韌帶（圖2B）。與內(nèi)側(cè)副韌帶復(fù)合體相似，前兩個(gè)韌帶的止點(diǎn)附著于上髁，而環(huán)狀韌帶起止點(diǎn)均在尺骨上，用于維持近端尺橈關(guān)節(jié)的穩(wěn)定。外側(cè)尺骨副韌帶止于尺骨旋后嵴，是抗內(nèi)翻應(yīng)力的主要穩(wěn)定結(jié)構(gòu)，有利于支撐橈骨頭，防止肘關(guān)節(jié)外側(cè)旋轉(zhuǎn)半脫位。橈側(cè)副韌帶的止點(diǎn)不直接與尺橈骨附著，而是止于環(huán)狀韌帶。 Fig.2. Ligamentous stabilizers of the elbow. (A) The medial collateral ligament.(B) The lateral collateral ligament complex. 圖2 肘關(guān)節(jié)的韌帶穩(wěn)定結(jié)構(gòu)：A為內(nèi)側(cè)副韌帶復(fù)合體，B為外側(cè)副韌帶復(fù)合體
生物力學(xué) 肘關(guān)節(jié)軸向負(fù)重時(shí)，主要承重的是肱橈關(guān)節(jié)（60％），而不是肱尺關(guān)節(jié)（40％）。肱尺關(guān)節(jié)高度咬合的結(jié)構(gòu)，主要功能在于維持穩(wěn)定而不是承重，其對(duì)肘關(guān)節(jié)整體穩(wěn)定性的貢獻(xiàn)可達(dá)50％。骨性結(jié)構(gòu)的穩(wěn)定，可讓最簡單的肘關(guān)節(jié)脫位在復(fù)位后保持穩(wěn)定。當(dāng)向后位移的外力作用于肘關(guān)節(jié)時(shí)，冠狀突尤為重要。由于冠狀突獨(dú)特的解剖結(jié)構(gòu)和前關(guān)節(jié)囊的附著，大的冠狀突骨折塊對(duì)肘關(guān)節(jié)不穩(wěn)造成很大影響，甚至是很小的骨折塊也意味著肘關(guān)節(jié)不穩(wěn)。后者在恐怖三聯(lián)征中是經(jīng)常出現(xiàn)的。冠狀突前內(nèi)側(cè)骨折相關(guān)損傷機(jī)制不同，在恐怖三聯(lián)征中較少見
如上所述，肱尺關(guān)節(jié)和肱橈關(guān)節(jié)均為鉸鏈關(guān)節(jié)，但二者屈/伸的軸線隨著位置的變化而變化，大約存在3°-6°的方向變化和1.4-2.0mm的位移。通常側(cè)位片顯示，該軸線從肱骨內(nèi)髁的前下部分（即MCL前束止點(diǎn)的前方）至所述滑車和肱骨小頭的中心。該軸的位置對(duì)置入鉸鏈?zhǔn)酵夤潭芫哂兄匾饬x。在該平面的正常屈曲運(yùn)動(dòng)范圍是0°-140°，雖然30°-130°即可滿足日常生活需要。
肩關(guān)節(jié)外展可以彌補(bǔ)有限的旋前，而旋后的缺陷卻無法彌補(bǔ)。前臂的旋轉(zhuǎn)也會(huì)影響肘關(guān)節(jié)的穩(wěn)定性。例如，肘關(guān)節(jié)旋后可以增加肱尺關(guān)節(jié)的接觸應(yīng)力和穩(wěn)定性，從而避免肘關(guān)節(jié)脫位。然而，在肘關(guān)節(jié)外側(cè)尺骨副韌帶損傷時(shí)，旋后也會(huì)加重后外側(cè)旋轉(zhuǎn)不穩(wěn)定，由此引發(fā)橈骨頭后外側(cè)脫位，反之引發(fā)尺骨頂端橫向傾斜。旋前位可防止這種外側(cè)旋轉(zhuǎn)不穩(wěn)。
外翻應(yīng)力下，橈骨頭緊靠肱骨小頭，并提供肘關(guān)節(jié)整體穩(wěn)定性的30％，當(dāng)MCL無力時(shí)提供的穩(wěn)定性增加。橈骨頭的復(fù)位幾乎能恢復(fù)全部肘關(guān)節(jié)的外翻穩(wěn)定性。MCL的前束在伸展時(shí)緊張，后束則在屈曲時(shí)緊張，兩者在肘關(guān)節(jié)整個(gè)運(yùn)動(dòng)中也對(duì)抗外翻應(yīng)力。
假設(shè)外側(cè)副韌帶（LCL）復(fù)合體在肘關(guān)節(jié)脫位時(shí)是第一個(gè)破壞的結(jié)構(gòu)。如上所述，外側(cè)尺骨副韌帶（LUCL）對(duì)防止后外側(cè)旋轉(zhuǎn)不穩(wěn)非常重要，是抗內(nèi)翻應(yīng)力的主要穩(wěn)定結(jié)構(gòu)。雖然LCL復(fù)合體中每束韌帶的確切貢獻(xiàn)仍存在爭議，但已經(jīng)證明僅重建LUCL能可靠地恢復(fù)后外側(cè)的穩(wěn)定性，這表明LUCL是肘關(guān)節(jié)的主要和關(guān)鍵的穩(wěn)定結(jié)構(gòu)。
恐怖三聯(lián)征的損傷機(jī)制是：軸向壓力作用于伴有前臂旋后的相對(duì)外展的肘關(guān)節(jié)（圖3）。該情況導(dǎo)致LUCL損傷，繼而橈骨頭后外側(cè)脫位，而軸向負(fù)荷同時(shí)導(dǎo)致橈骨頭和冠狀突骨折。其實(shí)，恐怖三聯(lián)征可以非常準(zhǔn)確地概括為終極的后外側(cè)旋轉(zhuǎn)不穩(wěn)。 Fig.3. The terrible triad pattern of injury is caused by a combination of valgus and axial compression with the forearm supinated. 圖3 恐怖三聯(lián)征是由外翻和軸向壓力與前臂旋后聯(lián)合所致。 附英文原文: INTRODUCTION The elbow is a 3-dimensionally complex joint where stiffness is poorly tolerated and instability is devastating. Although multiple periarticular fracture patterns and soft tissue injuries of the elbow have been described, the combination of coronoid process fracture, radial head fracture, and elbow dislocation has earned the moniker “terrible triad” by virtue of its challenging treatment and historically poor outcomes. This injury represents a failure of each bony and ligamentous stabilizer of the elbow; therefore, treatment must restore sufficient stability to permit early motion, thereby avoiding disabling stiffness.
RELEVANT ANATOMY The elbow supports the intersection of 3 bones, between which are 3 articulations: ulnohumeral, radiocapitellar, and proximal radioulnar (Fig. 1). The first two of these articulations are ginglymus (hinge) joints, whereas the last is a trochoid (pivot) joint. The terrible triad injury destabilizes the relationship between the humerus and the forearm bones, whereas the relationship between the ulna and radius (including the interosseous membrane) is rarely disrupted in this injury pattern.
While the elbow shares the humerus in common with the shoulder joint, its personality could not possibly be more different. Unlike the relatively straightforward spheroidal glenohumeral joint with its complex circumferential soft tissue stabilizers, the elbow has a complex three-dimensional bony anatomy but relatively simple soft tissue structure consisting of medial and lateral collateral ligaments as well as anterior and posterior capsular elements.
The medial collateral ligament (MCL) complex is composed of 3 bands: anterior, posterior, and transverse (Fig. 2A).The first two originate from the inferior aspect of the medial epicondyle, whereas the last one does not cross the elbow joint itself. The anterior band is the most distinct and significant of these bundles and inserts on the sublime tubercle of the coronoid. Inserting more posteriorly, on the olecranon, is the posterior band, whereas the transverse band is attached at both ends to the ulna, spanning the distance from the tip of the olecranon to the coronoid process.
Laterally, the collateral ligament complex is similarly made of up of 3 components: the lateral ulnar collateral ligament (LUCL), the radial collateral ligament, and the annular ligament (see Fig. 2B). Similar to the MCL complex, the first two components attach proximally on the epicondyle, whereas the annular ligament is a proximal radioulnar joint stabilizer that both originates and inserts on the ulna. The LUCL, which inserts on the crista supinatoris of the posterior proximal ulna, is a major stabilizer against varus stress and also supports the radial head like a sling, preventing posterolateral rotatory subluxation. The radial collateral ligament does not attach to the radius or ulna directly, but rather to the annular ligament.
BIOMECHANICS Load bearing across the elbow is predominantly at the radiocapitellar joint (60%), rather than at the ulnohumeral joint (40%). The latter, with its highly congruent configuration, is structured primarily for stability rather than for load bearing and contributes as much as 50% of the overall stability of the elbow. The stability conferred by these bony structures is what allows most simple elbow dislocations to remain stable after reduction. As displacing forces most commonly act on the elbow in a posteriorly directed manner, the coronoid is particularly vital. Large coronoid fragments destabilize the elbow considerably and even very small fractures may portend a great deal of instability by virtue of their unique anatomic shape and attachment to the anterior capsule. The latter are more common with terrible triad patterns. Fractures of the anteromedial coronoid are associated with a different mechanism of injury and are uncommon in terrible triad injuries.
As mentioned above, the ulnohumeral and radiocapitellar articulations are hinge joints, but their axis of flexion/extension varies with position, by approximately 3°to 6°in orientation and 1.4 to 2.0 mm in translation. On average, however, this axis runs from the anteroinferior aspect of the medial epicondyle (just anterior to the origin of the anterior band of the MCL) to the center of the trochlea and the center of the capitellum on lateral radiography. The location of this axis has important implications for the placement of hinged external fixators in particular. Normal range of motion in this plane is 0°to 140°of flexion, although most activities of daily living may be performed with a limited range of 30°to 130°.
Abduction at the shoulder does compensate for limited pronation, but no similar compensatory movement can substitute for supination. Forearm rotation also affects elbow stability. For example, supination of the elbow increases the joint reactive force at the ulnohumeral joint and increases stability against elbow dislocation. However, in the LUCL-deficient elbow, supination is also implicated in posterolateral rotatory instability, whereby the radial head subluxates posterolaterally, whereas the ulna tilts apex lateral. A position of pronation protects against this posterolateral rotatory instability.
In response to valgus stress, the radial head abuts the capitellum and provides approximately 30% of total elbow stability in this scenario, more so when the MCL is incompetent. Restoration of the radial head restores valgus stability to nearly that of the intact elbow. The MCL, with its anterior band taut in extension and its posterior band taut in flexion, also resists valgus stress throughout the range of elbow motion.
The lateral collateral ligament (LCL)complex is hypothesized to be the first structure to fail in dislocation of the elbow. The LUCL, as described above, is necessary to prevent posterolateral rotatory instability, and it is the major soft tissue stabilizer of the elbow, against varus stress. Although there is some controversy as to the exact contribution of each element of the LCL complex, it has been demonstrated that reconstruction of the LUCL alone reliably restores posterolateral stability, suggesting that LUCL is the primary critical stabilizer against this particular instability pattern.
The terrible triad injury pattern most commonly results from the axial loading of a relatively extended elbow with the forearm in supination (Fig. 3). This position encourages posterolateral escape of the radial head after failure of the LUCL, whereas the axial loading causes shearing of the radial head and coronoid process. In fact, the terrible triad can be conceptualized quite accurately as the ultimate posterolateral rotatory instability.
由MediCool醫(yī)庫軟件 趙婷 陸曉玲 編譯 原文來自： Terrible Triad of the Elbow Orthop Clin N Am 44 (2013) 47–58
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