Postoperative brachial artery entrapment associated with pediatric supracondylar fracture of the humerus: a case report

Background Severely displaced supracondylar fractures of the humerus in children are frequently associated with complications including neurovascular injuries, non-union, or compartment syndrome. In the current literature, no report exists about postoperative brachial artery entrapment in combination with an inconspicuous preoperative neurovascular examination. Case presentation We present a case of a 6-year-old white boy with a pulseless radial and ulnar artery after open reduction and internal fixation of a severely displaced supracondylar fracture of his right humerus (Gartland type III) using four K-wires. Remarkably, the preoperative neurovascular examination was inconspicuous. Doppler ultrasound of his brachial artery revealed no pulse when his elbow was in flexion and a faint pulse when it was in full extension 10 hours postoperatively. Revision surgery was performed immediately. On intraoperative examination, a kinking of his brachial artery caused by an entrapment of the tunica externa in the reduced fracture was seen and the artery was released by microsurgical arteriolysis immediately. At the final follow-up examination, positive palpable pulse with good capillary filling and, according to Flynn’s criteria, an excellent recovery of elbow function was observed 3 months postoperatively. Conclusions This case demonstrates a rare complication of postoperative artery entrapment with inconspicuous preoperative neurovascular examination. It strongly emphasizes the need for a standardized postoperative neurovascular assessment with fully flexed as well as fully extended elbow.


Background
Supracondylar fractures of the humerus are common elbow fractures in children [1][2][3][4]. Gartland's classification based on the degree of displacement of the distal fragment is used frequently [5]. Fractures with complete displacement of the distal fragment (Gartland type III) are frequently associated with various complications such as neurovascular injuries, non-union, or compartment syndrome that can lead to a Volkmann's contracture or even amputation of the affected limb [3,[5][6][7][8].
Preoperative neurovascular assessment scores (for example, Liverpool Upper-limb Fracture Assessment) have already been proposed to optimize evaluation of children presenting with upper limb injuries in Accident and emergency (A&E) departments [9]. The following case presents a rare vascular complication despite an inconspicuous preoperative neurovascular examination and emphasizes the importance of a thorough postoperative neurovascular assessment.

Case presentation
A 6-year-old white boy presented to our A&E department after a fall on his extended right arm from a height of 1 m. An initial examination revealed a severely displaced right elbow without penetration of the skin. A physical examination was hindered by his anxiety and pain. However, according to Liverpool Upper-limb Fracture Assessment, his neurovascular examination was reported as unremarkable. Palpable radial and ulnar pulses as well as no sensorimotor deficit were obtained. Radiographs in two planes showed a posterolaterally displaced supracondylar fracture of his humerus classified as Gartland type III (Fig. 1a). Surgical efforts under general anesthesia were initiated immediately. An initial attempt of closed reduction was unsuccessful. Hence, open reduction and internal fixation using four K-wires were performed immediately (Fig. 1b). No intraoperative complications were reported. On postoperative examination, arterial pulses were palpable in elbow extension with unaffected capillary filling. His arm was immobilized in a long-arm cast with elbow flexion of 90°. Reevaluation of his arterial pulses after immobilization was not documented.
Ten hours after surgery, he complained of acute pain in his right forearm. A physical examination revealed a coldness of his right forearm with poor capillary filling and absent arterial pulses while immobilized in the longarm cast with elbow flexed to 90°. The cast was removed and Doppler ultrasound revealed that there was no pulse while his elbow was in flexion and faint pulses with his elbow in extension. The immediately performed revision surgery (transverse arteriotomy and exploration with a Fogarty catheter) revealed no arterial thrombosis. After extending the surgical approach a kinking of his brachial artery caused by an entrapment of the tunica externa in the reduced fracture was observed (Fig. 2a). It was released with microsurgical arteriolysis (Fig. 2b).  Immediately, his radial and ulnar pulses were palpable with good capillary filling.
Postoperative immobilization was achieved using a long-arm cast with the elbow at 90°flexion for 6 weeks. Implant removal at 6 weeks was followed by intensive physical therapy to increase the range of motion (ROM). At the final follow-up examination at 3 months, the subjective elbow function had fully recovered. He had positive palpable pulses, a warm forearm with good capillary filling and, according to Flynn's criteria [2,10], an excellent recovery of elbow function as compared to the healthy contralateral side with 100 % ROM in extension/ flexion 10-0-150°, pronation/supination 90-0-90°, and no loss of carrying angle were observed. Figure 3 gives an overview of the case.

Discussion
Gartland type III fractures are highly correlated with primary neurovascular lesions [11][12][13][14]. Posteromedial displacement is associated with radial nerve injuries, whereas posterolateral displacement is associated with median nerve injuries. Brachial artery injuries occur in both types of displacement equally [15,16]. Typical vascular injuries are intimal tear, thrombus formation, and division or spasm of the vessel [17,18]. The initial therapy of pediatric supracondylar fractures with an absent radial pulse and a cold white hand is closed reduction and fixation with K-wires. If the initial attempt is unsuccessful in restoring the pulse, open reduction and vascular exploration is mandated [19]. Management of children with absence of their radial pulse with a well-perfused hand is still controversial [19][20][21]. Remarkably, no difference between early surgical treatment (8 hours or less following injury) and delayed surgical treatment (more than 8 hours following injury), with regard to the perioperative complication rates, is reported [22]. Due to serious primary neurovascular lesions and difficult physical examination in young patients, a standardized neurovascular assessment has already been proposed [9]. In the current literature, only a few reports about delayed neurovascular complications exist [23][24][25]. In fact, an excellent clinical long-term outcome can be expected if postoperative circulatory failure is treated immediately [24]. In general, artery entrapment syndromes, for example caused by a humeral bony spur, are usually clinically unapparent and symptoms only occur with specific movements, such as extension or flexion of the elbow [26,27]. Arguably, a thorough postoperative neurovascular assessment with fully flexed as well as fully extended elbow can detect a postoperative artery entrapment.

Conclusions
This case demonstrates a rare complication of a postoperative brachial artery entrapment despite inconspicuous preoperative neurovascular examination. This strongly emphasizes the need for a standardized postoperative neurovascular assessment in a full range of elbow motion.