Traumatic Lower Extremity Arteriovenous Fistulae in Children

Posted on November 18, 2008

By Andrea L. Bowers, MD; Severino R. Bautista, MD; Rocco Bassora, MD; Robin Kaye, MD; Lawrence Wells, MD
ORTHOPEDICS 2008; 31:612

Traumatic arteriovenous fistulae are rare injuries in the pediatric population. Most are caused by penetrating injuries or are post-surgical in nature. Fistulae resulting from non-penetrating injuries are often missed early in the course of physical examination. This occurs due to the absence of clinical signs of arterial or venous injury, despite the close proximity of the affected vessels to point of injury. Likewise, signs and symptoms of post-surgical vascular injury may be difficult to discern from normal postoperative discomfort. The astute clinician must be on alert for unusual presentations of vascular injury to intervene in an expeditious manner.

This article presents a series of vascular complications following either blunt injury or surgical management of the lower extremity in children who presented to our facility between November 2004 and December 2005.

Case Reports

Patient 1

An 11-year-old boy sustained closed fractures of his left distal tibia and fibula after jumping and subsequently falling 9 feet from the roof of his backyard shed. He was initially seen at a local emergency room where his fractures were splinted, and approximately 12 hours following the injury, he was transferred to our institution for further evaluation and management. Radiographs of the left leg revealed completely displaced oblique fractures of the distal third tibia and fibula.

Physical examination revealed palpable pulses in a tense, swollen left leg. Clinically the anterior and lateral compartments were the most taut, and warranted immediate fasciotomy. The patient was emergently taken to the operating room.

Intraoperative compartment pressures measured in the left leg were found to be elevated with an anterior compartment pressure of 40 mm Hg, lateral compartment pressure of 29 mm Hg, superficial posterior compartment pressure of 19 mm Hg, and deep posterior compartment pressure of 31 mm Hg.

The patient’s blood pressure at presentation, consistent throughout his surgery and hospitalization, was 100s/60s with mean arterial pressures in the low 80s.

The tibial fracture was promptly fixed with a single 7/64 inch Kirschner wire. Intraoperative radiographs confirmed satisfactory alignment and position of the fracture fragments (Figure 1). Fasciotomies of the anterior and lateral compartments were then performed through an anterolateral skin incision that allowed access to both compartments. The incision was then carried down to the fascia overlying the anterior and lateral compartments, which was incised proximally and distally. The musculature of the anterior compartment was found to be pink, healthy appearing, and contractile, while the musculature in the lateral compartment demonstrated evidence of significant bruising.

Upon incising the fascia overlying the anterior compartment, brisk bright red hemorrhage was encountered. In an attempt to gain better exposure, the skin incision was extended proximally, however the source of bleeding could only be controlled by the tamponade effect of packing. Intraoperative vascular surgery consultation was then obtained. The superficial posterior compartment pressure measurement was only 19 mm Hg, and while the deep posterior compartment was 29 mm Hg, this was over 50 mm Hg less than the patient’s mean arterial pressure. After discussion with the vascular surgery team, it was agreed that posterior compartment release was not indicated given these measurements and the understanding that the significant source of pathology was the brisk anterior compartment bleed. Urgent embolization of the source bleed was thus prioritized.

The patient was stabilized and taken to interventional radiology where an arteriogram revealed a traumatic arterial laceration with resultant pseudoaneurysm and arteriovenous fistula of the anterior tibial artery and veins. Multiple 0.035” stainless steel coils were deposited into both the pseudoaneurysm and the anterior tibial artery just proximal to the pseudoaneurysm. A post-embolization contrast injection showed no filling of the pseudoaneurysm and no further evidence of the arteriovenous fistula (Figure 2).

The patient’s postoperative course was uneventful. He remained nonweight bearing while the bony fracture healed. The limb was immobilized first in a posterior splint for observation of his soft tissues then ultimately in a long leg cast. One year postoperatively, he remained asymptomatic without signs of vascular compromise.

Patient 2

A 16-year-old boy with bilateral lower extremity chronic exertional compartment syndrome had measured resting compartment pressures in excess of 20 mm Hg in all compartments. He elected to undergo staged endoscopically-assisted four-compartment fasciotomies through three incisions on each leg. The left-sided fasciotomies were performed without apparent complication, and the right-sided procedure 2 weeks after his first surgery. Each surgery was performed as an outpatient procedure.

On the third postoperative day, the patient removed his dressings, except Steri-strips, as instructed. He noted some mild erythema and blistering at the site where the dressings had contacted his skin. He also reported some malaise and subjective low-grade fevers. By the fifth postoperative day, he presented to the emergency room with blistering progressed with mild serosanguinous drainage and increasing pain despite ibuprofen and oxycodone. He reported no trauma to his extremity since his recent surgery.

Physical examination revealed an exquisitely tender 4×8-cm area of warmth and erythema surrounding the incision at the mid-portion of the posterior medial border of the tibia. Two tense bullae and a third deroofed lesion were noted with mild serosanguineous drainage. The two lateral incisions were clean, dry, and intact. Compartments were soft and compressible, and there was no pain reported with passive stretch. Popliteal, posterior tibial, and dorsalis pedis pulses were all robust and capillary refill was less than two seconds. Mild swelling was noted of the posterior calf and 1+ pedal edema on the right side only.

The patient was afebrile (37.2°C) with laboratory studies notable for a hemoglobin of 9.9 mg/dL and mild elevations in both erythrocyte sedimentation rate of 29 and C-reactive protein of 3.1. The infectious disease team was consulted, and the patient was started prophylactically on intravenous clindamycin per their recommendations.

Radiographs of his right tibia and fibula revealed no osseous abnormality, but demonstrated mild soft tissue edema with a focus of subcutaneous emphysema medially. In light of the patient’s concerning physical examination, we sought to better characterize the nature of his soft tissue abnormalities. An magnetic resonance imaging (MRI) confirmed the presence of significant subcutaneous edema in the medial and posterior calf. In addition, a hematoma had formed deep to the soleus, which extended medially, measuring 12 cm in the craniocaudal dimension. At the inferior margin of the hematoma a well-circumscribed mass consistent with pseudoaneurysm was noted. Subsequent real-time ultrasound with duplex Doppler confirmed a hematoma with 2.0×1.8×2.2 cm pseudoaneurysm (Figure 3).

Interventional radiology where digital subtraction arteriography was used to identify the posterior tibial artery. The vessel and pseudoaneurysm, which were found to have no distal outflow, were infused with thrombin and embolized with multiple stainless steel coils. Once embolization was complete, absence of flow within the pseudoaneurysm was verified with repeat ultrasound and Doppler (Figure 4).

During his hospitalization, a 3-cm dehiscence of the posteromedial wound developed atop the subcutaneous emphysema. Given the generalized edema and the potential for excessive tension on a primary closure, a vacuum assisted closure dressing was applied, and eventually a split-thickness skin graft was performed to obtain final wound closure. Otherwise, the patient progressed well after the embolization. He ambulated easily with toe-touch weight bearing and crutches, and was discharged on oral clindamycin due to his wound drainage. At last follow-up, his wounds had healed with healing wounds, markedly reduced swelling, no pain, and he had progressed to weight bearing as tolerated.

Patient 3

An 11-year-old boy underwent in-situ pinning of a stable slipped capital femoral epiphysis at an outside facility. Four weeks later he presented to the emergency room with pain and swelling of the thigh on the surgical side, which, according to the patient’s parent, his primary surgeon had attributed to a “normal” postoperative course.

He reported no new injury or trauma to the leg since his surgery and reported compliance with nonweight bearing on the affected side. Ultrasound obtained at the outside facility revealed a pseudoaneurysm of the right femoral artery, and the patient was transferred to our tertiary care facility for further management of the vascular abnormality.

On presentation, the patient was afebrile, and his vital signs were stable. Physical examination was significant for a well-healed vertical scar on his anterolateral proximal thigh. There was no drainage, warmth, or erythema, although tenderness with some moderate edema in the area surrounding his scar. Femoral, popliteal, dorsalis pedis and posterior tibial pulses were palpable bilaterally, and the ankle-brachial index was greater than one on presentation.

The patient was admitted to the general surgery service with orthopaedic surgery as a consulting team. Plain films of the hip revealed a single, well-positioned, partially-threaded screw with washer transfixing the proximal femoral physis, some mild osteopenia, and no evidence of fracture.

A computed tomography (CT) angiogram and ultrasound were obtained to further define the pseudoaneurysm. Just distal to the level of the bifurcation of the right common and profunda femoral vessels, along the anterior proximal thigh, there was a large, round heterogeneously enhancing fluid collection measuring 6.6×11.4×18 cm, with a well-circumscribed central area of hyperdensity measuring as large as 7.9×5.4×5.0 cm. This collection appeared to be fed by a deep perforating branch of the profunda femoral artery. Furthermore, ultrasound revealed arterial and venous waveforms consistent with an arteriovenous fistula (Figure 5).

Computed tomography angiogram demonstrated a pseudoaneurysm, which arose from a lateral branch of the first deep femoral perforator, with an arteriovenous fistula draining into the superficial femoral vein. The bleeding profunda femoris branch was then selectively catheterized and embolized using multiple 3 mm×5 cm, 2 mm×3 cm, and 3 mm×2 cm stainless steel coils. Five coils were deployed, and a post-embolization completion angiogram demonstrated successful embolization and no opacification of the pseudoaneurysm or arteriovenous fistula (Figure 6).

Four days after the embolization, ultrasound evaluation of the pseudoaneurysm and arteriovenous fistula verified residual hematoma but adequately embolized structures. At last follow-up, the patient was ambulating well with crutches with no further complication.

Discussion

An arteriovenous fistula is an abnormal communication between the venous and arterial system. Arteriovenous fistulae may be congenital or acquired secondary to trauma, tumor, or as a result of surgery.1,2 Classic clinical manifestations include pain, varicosity, palpable thrill or audible bruit locally, and diminished pulses distally. The main vessels in the thigh (circumflex femoral, profunda femoris, superficial femoral, and genicular arteries) and leg (anterior tibial, posterior tibial and peroneal arteries) have rich anastomoses at the level of the knee and ankle so that proximal vascular compromise may be masked by brisk pulses distally. For example, a complete laceration of the anterior tibial artery alone can still result in a palpable pulse in the foot and ankle.3 Hence, the diagnosis of vascular injury may not be established based on physical findings alone.

A fistula may also be an incidental finding in asymptomatic patients,4 or may exist for an extensive length of time before being recognized. Dissections, occlusions, pseudoaneurysms, and arteriovenous fistulas in the extremities may not be lethal, but can cause significant physiologic alteration and physical disability. Persistence of an arteriovenous fistula can lead to irreversible degenerative changes in the arterial wall and subsequent dilatation and thrombosis,5 leading to cardiac overload.6 Early treatment is still unequivocally the best management for all cases.4

Arteriovenous fistulae commonly are caused by traversing injuries, such as open fractures. Such injuries may produce bony fragments that impinge on adjacent veins and arteries causing extensive soft tissue damage. In those rare instances in which they occur with closed fractures from blunt trauma, the vessels along the fractured bones adjacent to the site of injury are usually the cause of an extensive bleed. However, it is rare to see a closed fracture in the distal tibia with an arteriovenous fistula markedly proximal and remote from the fracture, as presented here in our first case.

To our knowledge, limited reports in the literature exist regarding injury to the lower extremity vessels resulting in the formation of an arteriovenous fistula. Chong et al7 described 2 patients with femur fractures complicated by pseudoaneurysms of the profunda femoris artery. Ilijevski et al6 reported a single case of traumatic arteriovenous fistula with pseudoaneurysm involving a genicular artery and vein.

Ward and Carty8 reported a case of a traumatic arteriovenous fistula of the peroneal vessels following bone grafting for an non-united tibial fracture, and Haddad et al9 reported one that developed after a midshaft fibular osteotomy. Two incidences of pseudoaneurysm with an arteriovenous fistula following plantar fasciotomy have been described.10,11 In our review of the literature, the single report involving a child entailed a traumatic arteriovenous fistula with false aneurysm of the anterior tibial artery resulting from a small glass-fragment stab wound in the leg.12

Seaton2 showed that traumatic arteriovenous fistulae can have different presentations due to differences in location, size, and duration. With regard to timing, some reports revealed cases of traumatic arteriovenous fistulae from blunt and penetrating injuries treated only after they had developed into pseudoaneurysms, dissections, or occlusions in the lower extremities.

Kurihashi et al1 described a case of an adult who had a blunt injury to the leg that later developed into a peroneal arteriovenous fistula and was treated 15 months later. Huang et al13 also described a case of a long-standing arteriovenous fistula from a penetrating injury to the leg, which was treated 51 years later. With respect to location, Rozycki performed a retrospective study and concluded that blunt injuries in the lower extremities occur most commonly in the anteroposterior tibial arteries rather than in the superficial femoral arteries.

Here we describe three unique presentations of pseudoaneurysm/arteriovenous fistula of the lower extremity, each involving a different index vessel with presumably different mechanisms. The classic clinical manifestations of tenderness and edema were common among the three patients, although pulses were palpable in all cases and no bruits or thrills were appreciated. The underlying fistulae were not readily apparent but can exist in the absence of hard clinical signs and should remain in the differential of limb tenderness and edema.

The first patient presented with a distal tibia and fibula fracture that evolved into an apparent compartment syndrome and was transferred to our institution for definitive care. Measured compartment pressures indicated impending muscle ischemia requiring emergent fasciotomy. Adequate fasciotomy of the anterior, lateral, and posterior compartments provided release of the threatened muscular tissue,14 but did not address the continuous hemorrhage proximally.

The unusual amount of hemorrhage prompted our team to seek a specific source via angiography, which revealed the definitive diagnosis of arteriovenous fistula. While the mechanism for arteriovenous fistula formation in this patient is not known, it is plausible that a traction or stretch injury of the structures in the anterior and lateral compartments along with the vessels tethered over the interosseous membrane resulted in the injury described.

While tibia and fibula fractures are common in childhood and result from a variety of low and high-energy mechanisms, few are associated with compartment syndrome or primary vascular injury. This case exhibits the relationship of closed distal tibia and fibula fractures with a ruptured arteriovenous fistula, accompanying pseudoaneurysm and impending compartment syndrome. This scenario highlights the necessity of careful physical examination and persistent investigation for unexplained sources of bleeding. The role of prompt intraoperative vascular consultation and angiography is further emphasized here.

Preemptive discussion with interventional radiology and vascular surgery to verify their availability should be contemplated before initiating surgical intervention in cases that might potentially unveil arteriovenous anomalies. As suggested by Rozycki and Maull,15 outcomes can improve with vigilant physical examination and use of arteriography in patients with lower extremity injuries accompanied with compartment syndrome.

In a Japanese study of victims who underwent fasciotomies after sustaining blunt trauma to the thigh, 5 of 9 thighs were found by subsequent angiography to have arterial injury.16 We concur with their recommendation that postfasciotomy arteriogram should be pursued for blunt limb injuries with compartment syndrome and hemodynamic instability. Arteriography, nonetheless, is an invasive endeavor with its own subset of risks and complications and may be too aggressive for the hemodynamically stable patient. However, when symptoms persist beyond fasciotomy, arteriography should be considered for both diagnostic and potential treatment purposes.

The second patient illustrated an elective fasciotomy for chronic exertional compartment syndrome complicated by a pseudoaneurysm of the posterior tibial artery. The patient had bounding pulses distally, and initial presentation was consistent with a postoperative wound infection, although the extent of soft tissue derangement led us to pursue further characterization of the edema and emphysema seen on plain radiographs. Without MRI, the underlying vascular lesion could have remained undetected and possibly progressed to even more threatening complications. Ultimately the lesion was definitively characterized by Doppler ultrasound and angiography. This highlights the use of diagnostic imaging, especially in a limb that has no visible signs of arterial injury. The workup of an arteriovenous fistula may include angiography, Doppler examination, duplex scanning, CT scan, and MRI/MR angiography.6,17-20

Due to the invasive nature of angiography, unless the limb is imminently threatened, the aforementioned ancillary studies may prove safer in the initial workup of an equivocal lesion. Angiography, however, remains the gold standard for both detection of vascular injuries and the management of the source vessel via embolization. When we suspect a vascular injury, our protocol is to first obtain plain radiographs, followed by ultrasound/Doppler, then reserve arteriography for ultrasound-positive lesions or for impending hemodynamic instability.

Another key point to be taken from this case is that elective procedures are not without inherent risks and can subject the patient to complications potentially more threatening than the initial problem. This must be emphasized when obtaining informed consent from a parent or guardian on the minor’s behalf.

Unlike the early presentations seen in the prior two cases, the last case of the patient with slipped capital femoral epiphysis presented >4 weeks after surgery. The slipped capital femoral epiphysis pinning had been performed at an outside facility, and per patient report, he had been told by his surgeon that his residual pain was to be expected after such a surgery. The source of his thigh pain and swelling was an underlying pseudoaneurysm of a deep perforating artery with an arteriovenous fistula draining into the superficial femoral vein. The vascular injury presumably occurred at the time of surgery, perhaps during dissection onto the femoral neck or while approaching with the guide pin or cannulated screw.

At our institution, we make every effort to limit our approach to the area lateral to an imaginary line connecting the anterior superior iliac spine to the superior pole of the patella while facing directly forward.21 In this manner we seek to minimize any potential vascular trauma to deep vessels. This scenario further demonstrates the need for the clinician to listen carefully to a patient’s symptoms and to always seek other sources before presuming benign postoperative phenomena. It is concerning that this patient’s symptoms seemed to have been dismissed by primary surgeon and progressed for 4 weeks after surgery before diagnosis and intervention. The physician must remain on alert for morbidity well beyond the immediate postoperative period.

References

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Authors

Drs Bowers, Bautista, Bassora, Kaye, and Wells are from the Division of Orthopedic Surgery, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania.

Drs Bowers, Bautista, Bassora, Kaye, and Wells have no relevant financial relationships to disclose.

Correspondence should be addressed to: Lawrence Wells, MD, Division of Orthopedic Surgery, The Children’s Hospital of Philadelphia, Wood Bldg, 2nd Fl, 34th St and Civic Center Blvd, Philadelphia, PA 19104-4399.

Posted in Trauma