|
上尺桡关节脱位意味着肱骨处桡骨脱位且尺骨脱位。X线片显示：这类脱位的尺骨出现在肱骨小头的对侧，桡骨头出现在滑车对侧。小儿肘关节脱位是一种罕见的损伤，仅占肘关节损伤的3-6％。此外，上尺桡关节脱位伴肘关节脱位是一种极为罕见的儿童创伤组合。自MacSween首次报道于1979年以来，仅有17例儿童的病例报道。由于X线片上的解剖关系常易被忽视，故初步诊断有时较困难。
我们报道了一例更为罕见的半脱位伴桡骨颈骨折及肘关节脱位。与先前的报道相比，我们在本病例中观察到了肘关节的反向不稳定性，因此该病例具有重要的临床意义。 一名5岁男孩自2米刚架摔伤致外展的左臂受伤，送往我院急救中心。患者主诉左肘疼痛并且活动受限。初步检查发现左肘疼痛、肿胀，无神经血管问题。左肘在前臂弯曲体位与旋后体位50°时较稳定。初次X光片诊断为肘关节后脱位及桡骨头骨折（图1）。静脉镇静下行闭合复位并采用长臂夹板固定肘部。然而，接下来的日子里疼痛并没有消失并且前臂旋转受限，特别是旋前受限。复位后进行了X光仔细检查，显示前臂肱骨头存在逆转型解剖关系。术前拍摄磁共振图像以评估相关的软组织损伤。桡骨头嵌于冠突与肱肌嵌入物之间（图2）。 
Fig. 1 Initial anteroposterior and lateral radiographs show elbow dislocation and translocation of proximal radioulnar joint with radial neck fracture 图1 初次X光正位片和侧位片显示肘关节脱位，上尺桡关节脱位伴桡骨颈骨折 
Fig. 2 Magnetic resonance image shows the radial head being caught between brachialis tendon and coronoid process 图2 磁共振图像显示桡骨头嵌于肱肌肌腱与冠突之间 再次施行闭合复位。全麻下，前臂可伸展和旋后，但旋前不超过中立位（图3）。我们对前臂桡骨头采用纵向牵引和强制旋后并手法复位，仍未能实现复位。在尺骨近端内侧面开25px的皮肤切口。通过该切口较易插入，并通过侧面推动桡骨近端行手法复位（图4）。复位之后，通过X光透视检查桡骨近端的稳定性。前臂旋后时桡骨近端半脱位，但前臂旋前已复位（图5）。桡骨颈骨折采用闭合复位较好后，肘部固定于90度屈曲并采用长臂夹板固定前臂45°旋前4周。在2个月的随访时，肘关节屈伸弧度几乎恢复；然而，前臂旋转仍受限。在6和12个月的随访时，X线片显示：可观察到尺骨近端前侧面完全愈合，无疼痛感，但出现异位骨化现象（图6）。肘关节运动和前臂旋转的范围已完全恢复（图7）。 
Fig. 3 Clinical photographs of forearm rotation under general anesthesia show limitation of pronation beyond neutral position (left) comparing with supination (right) 图3 全麻下，前臂旋转的临床图片显示：与旋后（右）相比，旋前不超过中立位（左） 
Fig. 4 Intraoperative fluoroscopy shows freer pushing the proximal radius laterally 图4 术中X光透视显示侧面推动桡骨近端较容易 
Fig. 5 Fluoroscopic images show that the radial headis reduced in pronation (left), but subluxated in supination (right) 图5 荧光屏图像显示：桡骨头旋前已复位（左），但桡骨头旋后半脱位（右） 
Fig. 6 Radiographs at 6 months after the injury show well reduced elbow with calcification at proximal ulna 图6 损伤后6个月X线片显示：肘关节复位较好同时尺骨近端钙化良好 
Fig. 7 Follow-up clinical photographs 6 months after the injury show full flexion/extension of the elbow and full supination/pronation of the forearm 图7 损伤后6个月随访的临床图片显示：肘关节完全屈曲/伸展以及前臂完全旋后/旋前 上尺桡关节脱位，也称为收敛型肘关节脱位，儿童损伤极为罕见。自第一例MacSween报道以来，仅出现过17例病例报道。
如果X线片评估不仔细，这种脱位很容易被忽略。17例病例报道中，7例病例意识到脱位时仍有一个显著的延误（5天至2个月）。延误诊断有几个原因。由于这种损伤的发生率很低，医生未考虑到脱位。临床上，肘关节脱位伴“弹响”复位，屈伸弧度抬高。然而，前臂几乎完全旋前锁定。影像学上，闭合复位后侧位片有时显示较好的关节复位外观。这一发现使我们忽略了正位片上的异常现象，其中桡骨与滑车连接，而尺骨与肱骨小头连接。在该病例中，我们开始也忽略了脱位。持续疼痛和前臂旋转受限的临床症状引起我们再次观察X光片，然后可诊断为脱位。在此之前，几乎有一半的病例文献诊断较晚。当脱位复原后，前臂旋转受限和持续疼痛的临床症状更明显时，正确的早期诊断很关键，这包括格外警惕和仔细检查典型的正位片和侧位片，以及临床猜测有关脱位的可能性。 这种损伤机制为过度旋前伸展型前臂坠落伤，桡骨近端面呈现轴向载荷。 Combourieu等人也提出了脱位的机制。上尺桡关节脱位被认为是由桡骨过度旋前，并且上尺桡关节周围韧带和软组织的实质性破坏所致，尤其是桡侧副韧带和环状韧带。然后桡骨通过损伤的肱前肌腱，沿着前面旋转。本病例MRI显示：桡骨头脱位嵌于冠突和肱肌肌腱之间。由于尺骨前侧异位骨化，则几周后可见肌腱病变出现。Isbister提出了一种不同的脱位机制。在轴向载荷与连续外翻应变下，尺骨嵌入了后外侧；而桡骨在关节内侧面插入尺骨。 合并伤包括桡骨头骨折、桡骨颈骨折、冠状突骨折和尺神经麻痹。伴行的骨折可使治疗方案变得复杂化，因此预后不太令人满意。桡骨头生长障碍是继小儿肘关节创伤后的一种常见的潜在结果。这一发现表明骨骺破坏是由于损伤时桡骨近端部位较大范围性脱位。临床发现该病例与先前的病例不同。复位前，前臂旋前受限比旋后更加显著。此外，旋后时可观察到上尺桡关节半脱位，复位后亦可。我们怀疑桡骨颈骨折表现不同的临床症状，并试图桡骨颈复位。然而，尽管桡骨颈干角复位，但不稳定性仍未改善。 闭合复位成功的病例报道仅有少数，其原因可能是延误诊断，明显的软组织嵌插可能阻碍复位，并且合并伤的存在需手术干预。本病例报告闭合复位失败后，通过内侧或外侧入路行切开复位术。我们推荐该病例报告中描述的一种小切口技术。这种方法可减轻肘关节额外软组织损伤并降低异位骨化的可能性。 早期诊断损伤失败后可能会导致肘关节运动严重受限并且出现显著功能障碍。早期诊断存在两个关键因素。一是典型的正位X光片仔细检查，X光检查显示上尺桡关节与肱骨之间连接异常。二是肘关节脱位闭合复位后的临床症状，其包括前臂旋转与肘关节活动的受限，甚至复位后不明原因的持续疼痛。
附英文原文： Introduction
The proximal radioulnar translocation means that both the radius and ulna are dislocated from the humerus. Then, trans-posed such that the ulna appears opposite to that of the capi-tellum, and the radial head appears opposite to the trochlea on radiographs. Dislocation of the elbow in children is an uncommon injury and only 3–6 % of all elbow injuries. In addition, proximal radioulnar translocation associated with elbow dislocation is an extremely rare combination of trauma to children. Since MacSween first reported in 1979, only 17 cases have been reported in children. Initial diag-nosis is sometimes difficult because the unexpected anatomi-cal relationship is easily overlooked in radiographs.
We report an even rarer subtype of this translocation associated with a radial neck fracture and elbow disloca-tion. This case had clinical importance in that reverse insta-bility was observed compared with the previous reports.
Case report
A 5-year-old boy was admitted to our emergency center after a fall from a 2 m jungle gym onto his outstretched left hand. The patient complained of left elbow pain and limitation of motion. Initial examination revealed a painful, swollen left elbow without neurovascular problems. The left elbow was held in 50° flexed position with the forearm in supinated position. The posterior elbow dislocation and radial head fracture were recognized at initial radiographs (Fig. 1). The closed reduction was performed under intravenous sedation and the elbow was immobilized with long arm splint. How-ever, the pain did not subside on the following day and the forearm showed limitation of rotation, especially pronation. The radiographs after reduction were reviewed carefully, and we realized the reversal anatomical relationship of the fore-arm bone with the humerus. Magnetic resonance image was taken before surgery to evaluate associated soft tissue injury. The radial head was incarcerated between the coronoid pro-cess and brachialis insertion (Fig. 2).
Closed reduction was planned again. Under general anesthesia, forearm can be extended and supinated, but can-not be pronated beyond the neutral position (Fig. 3). Longi-tudinal traction and forced supination of the forearm with manual reduction on the radial head failed to achieve reduc-tion. A 1 cm skin incision was made on medial aspect of the proximal ulna. Freer was inserted through the incision, and manual reduction of proximal radius was performed by pushing it laterally (Fig. 4). After reduction, stability of the proximal radius was checked under fluoroscopy. The proximal radius was subluxated in supination of the fore-arm, but reduced in pronation of the forearm (Fig. 5). After closed reduction for radial neck fracture using freer, the elbow was immobilized at 90° flexion and 45° pronation of the forearm in long arm splint for 4 weeks. At the 2-month follow-up, flexion-extension arc of the elbow was almost recovered; however, forearm rotation is limited yet. At the 6 and 12-month follow-up, the radiographs showed com-plete healing without pain but heterotopic ossification was observed at anterior aspect of the proximal ulna (Fig. 6). The range of elbow motion and forearm rotation was com-pletely recovered (Fig. 7).
Discussion
Proximal radioulnar translocation with elbow dislocation, also known as convergent elbow dislocation, is exceedingly rare in children. Ever since MacSween reported the first case, there have been only 17 cases reported.
This dislocation can be easily overlooked if the radio-graphs are not carefully evaluated. In seven cases among the 17 reported cases, there has been a significant delay (from 5 days to 2 months) in recognizing the translo-cation. There are several reasons for delayed diagnosis. Because the incidence of this injury is very low, a physician does not think about translocation. Clinically, the dislo-cated elbow is reduced with “clunk” and flexion-extension arc is improved. However, the forearm is locked in almost complete pronation. Radiologically, the lateral view may sometimes give an appearance of a well reduced joint after closed reduction. This finding makes us to over-look the abnormal finding on the anteroposterior view, in which the radius is articulates with the trochlea, while the ulna is articulating with the capitellum. In this case, we also initially missed the translocation. Clinical sign of con-tinuous pain and limited rotation of forearm led us to look at radiographs again, and then translocation could be diag-nosed. This follows the pattern in the literature with almost half of the cases being diagnosed late. The key to a cor-rect early diagnosis is extra vigilance and careful inspec-tion of the true anteroposterior and lateral radiographs, as well as clinical suspicion about the possibility of transloca-tion, when clinical signs of restricted forearm rotation and pain continue even after reducing the dislocation.
The mechanism of this injury is a fall onto the hyper-pronated outstretched hand, producing an axial load on the proximal aspect of the radius. Combourieu et al. also suggested the mechanism of translocation. The proximal radioulnar translocation is thought to be caused by hyper-pronation of the radius with substantial disruption of the ligaments and soft tissues regarding the proximal radioul-nar joint, especially the radial collateral ligament and the annular ligament. The radius then spins along the anteriorly through the injured brachialis anterior tendon. MRI of this case shows that the dislocated radial head is incarcerated between the coronoid process and brachialis tendon. The tendinous lesion becomes visible after a few weeks because of heterotopic ossification at the anterior aspect of the ulna. Isbister proposed a different mechanism for transloca-tion. Under axial loading and continuous valgus strain, the ulna passed posterolaterally; whereas the radius crossed over the ulna in the medial aspect of the joint.
Associated injuries are radial head fractures, radial neck fracture, coronoid process fracture and ulnar nerve palsy. Concomitant fractures can complicate the treatment plan, and hence the out-come can be less satisfactory. Growth distur-bance of the radial head is a common potential outcome following elbow trauma in children. This finding sug-gests a disruption of epiphyseal vessel due to the wide displacement of the proximal part of the radius at the time of injury. The clinical finding in this case is different from the previous cases. Limitation of fore-arm pronation was more prominent than supination before reduction. In addition, subluxation of the prox-imal radioulnar joint was observed in supination even after reduction. Radial neck fracture was suspected as a reason of different clinical finding and reduction of the radial neck was attempted. However, instability did not improve although neck-shaft angle of the radius was restored.
Successful closed reduction had been reported in only a minority of cases. The reason may be late diagnosis, significant soft tissue interposition preventing reduction, and the presence of associated injuries which necessitate operative intervention. Open reductions through medial or lateral approach were performed in reported cases when the closed reduction failed. We suggest a mini-open technique described in this case report. This method can lessen the additional soft tissue injury to the elbow and chance of het-erotopic ossification.
Failure to diagnose this injury early may lead to severe restriction of elbow motion with significant functional impairment. There are two keys to a early diagnosis. First is careful inspection of the true AP radiograph, which shows abnormal articulation between the proximal radi-oulnar joint and humerus. The second is clinical sign after closed reduction of elbow dislocation, limitation of forearm rotation and elbow motion, and unexplained continuous pain even after reduction.
由MediCool医库软件 余娟 陆晓玲 编译
原文来自：
Proximal radioulnar translocation associated with elbow dislocation and radial neck fracture in child: a case report and review of literature
Arch Orthop Trauma Surg (2013) 133:1425–1429
|
