The Journal of & Surgery xxx (2016) 1–6

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The Journal of Foot & Ankle Surgery

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Case Reports and Series Aplastic Posterior Tibial in the Presence of Trimalleolar Ankle Fracture Dislocation Resulting in Below-the-Knee Amputation

Peter Andrew Bellezza, DPM, MS 1, Edward Elliott, DPM 2, Thomas Conlee, MD 3, John Randolph Clements, DPM 4

1 Resident, Division of Foot and Ankle Surgery, Swedish Medical Center, Seattle, WA 2 Resident, Division of Foot and Ankle Surgery, Department of Orthopaedic Surgery, Carilion Roanoke Memorial Hospital, Roanoke, VA 3 Vascular Surgeon, Jefferson Surgical Clinic, Carilion Roanoke Memorial Hospital, Roanoke, VA 4 Assistant Professor, Co-Section Chief, Division of Foot and Ankle Surgery, Department of Orthopaedic Surgery, Virginia Tech Carilion School of Medicine, Roanoke, VA article info abstract

Level of Clinical Evidence: 4 We present an interesting, but unfortunate, case of an 86-year-old female who sustained a trimalleolar ankle fracture dislocation that resulted in below-the-knee amputation after open reduction and internal fixation of the Keywords: fi below-the-knee amputation fracture. To the best of our knowledge, this is the rst case report describing popliteal variants that ultimately critical limb ischemia resulted in critical limb ischemia and below-the-knee amputation after foot and ankle trauma. The anatomic foot and ankle trauma variation altered the expected outcome from a relatively straightforward surgical case. We introduce the previ- lower extremity Allen test ously described lower extremity Allen test and describe how it can be a useful adjunct in the initial physical popliteal variants examination of lower extremity trauma. The ability to identify abnormal distal perfusion to the foot could provide enough insight to warrant evaluating the patient with angiography or computed tomography angiography. Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved.

Knowledge of anatomic variations in the branching pattern of the PT artery absent or rudimentary (4–6). Angiographic studies have is important because damage to its branches can be shown the incidence of a hypoplastic-aplastic PT artery ranges from limb threatening. Kim et al (1) proposed a new classification of the 0.8% to 3.8%. In anatomic studies, the incidence has ranged from branching pattern of the popliteal artery by modifying the original 1.5% to 11% (1,2,5,7–11). Compensatory hypertrophy of the PR artery classification system by Lippert and Pabst (2). They classified the with a hypoplastic or aplastic PT or AT artery might indicate a branching patterns into 3 categories and 3 subtypes (Table). The main variant arterial supply to the foot (1). This enlarged PR artery, the distinction of the new classification system is their third category. This “peronea magna” or “great” peroneal artery as described by Senior describes a normal branching pattern and sequence; however, the (6,12) either joins and reinforces the PT artery or replaces it in the proximal segments of the anterior tibial (AT) and/or posterior tibial distal leg and foot (4,6,12,13). When the PR artery has replaced the (PT) branches are congenitally absent or hypoplastic. Category III PT artery at the ankle, the distal aspect typically continues into the anatomic variants have the most clinical significance to vascular, sole as the . The is then orthopedic, and podiatric foot and ankle surgeons. The 3 major vari- usually absent (6,12,13). Cases have been reported in published ants in the popliteal branching pattern reported by Kim et al (1) are its studies that have documented the PR artery replacing the PT artery trifurcation (IB), high division with a normal branching sequence (IIA), but with the distal segment in the same anatomic location as the and the hypoplastic-aplastic PT with the distal PT replaced by the expected,butabsent,PTartery(1,14).Casesofahypoplastic- peroneal (PR) artery (IIIA). These major variants were also predomi- aplastic PT artery have also been documented in individuals with nantly seen in a review by Kropman et al (3). inborn foot deformations (15–17). In other cases, the arterial defect Normally, the popliteal artery divides into the AT and PT . might not be diagnosed for years and might only be recognized In some cases, it can bifurcate into the AT and PR arteries, with the incidentally (11,18). Detection of this anatomic variant on physical examination can be Financial Disclosure: None reported. deceiving and not easily determined. Chow et al (19) retrospectively Conflict of Interest: None reported. evaluated multidetector computed tomographic angiography (CTA) to Address correspondence to: John Randolph Clements, DPM, Department of determine donor and recipient site arterial suitability for vascularized Orthopaedic Surgery, Carilion Roanoke Memorial Hospital, 1906 Belleview Avenue fl Southeast, Med Education Building 202, Roanoke, VA 24014. free ap transplantation. They found 4 of 32 lower extremities (12.5%) E-mail address: [email protected] (J.R. Clements). had anatomic variants. These variants involved the popliteal, AT, PT,

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Table The patient returned 8 days later for definitive fixation. On Classification of branching pattern of popliteal artery admission, the examination findings were unchanged. The vascular Class Description examination revealed palpable PT and DP with a brisk capillary I Normal level of popliteal arterial branching fill time (CFT). The next day, she underwent open reduction and in- A Usual pattern: AT is first arterial branch; tibioperoneal artery follows and ternal fixation of the right trimalleolar ankle fracture with posterior bifurcates into PR and PT arteries (92%) lip fixation. The patient was positioned prone. The posterior B Trifurcation: AT, PR, and PT arise within 0.5 cm; no true tibioperoneal trunk was stabilized with a posterior malleoli plate and 3.5-mm locking and is present (2%) fi fi C Anterior tibioperoneal trunk: PT is the first branch, the tibioperoneal trunk nonlocking screws. The bula was stabilized with an anatomic bular follows and bifurcates into the PR and AT arteries (1.2%) plate, and the medial malleolus was fixated with 2 partially threaded II High division of popliteal artery cannulated screws (Fig. 2). No intraoperative complications were A AT arises at or above the knee joint (3.7%) noted. Shortly after the procedure, the nursing staff noted delayed CFT B PT arises at or above the knee joint and is the common trunk for the PR to the digits; however, the CFT returned when the foot was placed in a and AT arteries (0.8%) C PR arises at or above the knee joint and is the common trunk for the AT dependent position. The next day the patient was evaluated and and PT arteries (0.16%) found to have palpable PT and DP pulses and a brisk CFT. The patient’s III Hypoplastic or aplastic branching with altered distal supply pain was well controlled, and she was discharged to a local skilled A Hypoplastic-aplastic PT; distal PT replaced by PR artery (3.8%) nursing facility. B Hypoplastic-aplastic PT and AT arteries; dorsalis pedis replaced by PR artery (1.6%) The patient returned for a follow-up examination 1 week after C Hypoplastic-aplastic PT and AT arteries; PT and dorsalis pedis arteries being discharged from the hospital. The physical examination replaced by PR artery (0.2%) revealed nonpalpable pedal pulses, but the PT and DP pulses were Abbreviations: AT, anterior tibial; PR, peroneal; PT, posterior tibial. identifiable on ultrasound examination with a handheld Doppler probe. Ischemic changes were noted along the dorsal and lateral aspects of the foot. The hallux and third toe remained viable but and pedal arteries. All results were compared with their original demonstrated prolonged CFTs. The incision was well approximated. physical examination findings. Their physical examinations findings, No erythema, discharge, drainage, or dehiscence was present; how- in all cases, were not predictive of the presence of any arterial ever, full-thickness tissue necrosis had developed, consistent with dry anomaly. gangrene, along the lateral aspect of the right heel and measuring Significant negative outcomes can occur when anatomic variations 5 5 cm. The patient was readmitted to the hospital, and vascular of the popliteal artery have not been appreciated. Orthopedic, surgery was consulted. A lower extremity arterial duplex Doppler vascular, and podiatric foot and ankle surgeons should be aware that examination was ordered by the vascular surgery team, with the anatomic variants exist. However, the question remains whether we official impression of the study noting no hemodynamically signifi- necessarily need to perform preoperative vascular screening with cant arterial disease at the right lower extremity. Because of the angiography and/or CTA. No guidelines have been set for its use in foot degree of necrosis, the vascular surgery team consulted with the and ankle surgery and trauma. According to the published data, the interventional radiology staff to evaluate the limb with angiography routine use of angiography and/or CTA is controversial, even for cases with right lower extremity runoff. The official interventional radi- in which such imaging modalities are most commonly used, such as ology report (Fig. 3A,B) concluded: free flap reconstructive surgery (19). We present an interesting, but unfortunate, case of an 86-year-old Traumatic occlusion of the distal aspect of the right AT artery at female who sustained a trimalleolar ankle fracture dislocation that the level of the superior aspect of the talus with no reconstitution resulted in below-the-knee amputation after open reduction and in- of the DP artery ternal fixation of the fracture. This patient ultimately had a type IIIA Likely congenital absence of the PT artery popliteal variant (Table) that was not appreciated on physical exam- Traumatic segmental occlusion of the PR artery approximately ination. The incidence of this variant is approximately 3.8% according 10 cm above the ankle that was reconstituted approximately 5 cm to the published data. To the best of our knowledge, this is the first distally into the normal expected course of the PT artery and was documented case report discussing type III popliteal variants in foot the only significant arterial supply to the foot and ankle surgery. The angiogram revealed no trifurcation of the popliteal artery. The Case Report branch of the PT artery was congenitally absent. The branches of the AT and PR arteries were present (Fig. 3C). When reviewing Fig. 3A,B, The patient was an 86-year-old female who presented to the the interventional radiology report noted traumatic occlusion of the emergency department with a right ankle fracture dislocation. She AT artery. The prevailing explanation was that the AT artery had been had no secondary injuries. The right ankle was globally tender. The traumatically occluded. This could have resulted from either an iat- patient had full, painless range of motion at the right hip and knee. rogenic cause or intimal injury (20) not detected during the index The compartments were soft. Her skin was intact, with diffuse examination. It is also plausible that the AT artery was congenitally ecchymosis and edema localized to the ankle. Sensation was intact to hypoplastic; however, this would be difficult to prove definitively all lower extremity nerve distributions. The PT and dorsalis pedis (DP) without a previous arteriogram or CTA. The finding of a congenitally pulses distally were 2þ and palpable. Radiographs revealed a dis- aplastic PT artery is consistent with the IIIA popliteal variant using the placed trimalleolar fracture with the talus posteriorly dislocated. The Kim classification (1). This has an occurrence rate of 3.8%. This, fibula was comminuted and displaced. Fractures were present in the combined with the traumatically occluded AT and PR artery, single- medial and posterior malleolus (Fig. 1). The right ankle fracture was handedly eliminated all the supply to the foot, causing critical reduced and splinted without complications. Postreduction plain pedal ischemia. Peculiarly, the patient still exhibited pedal pulses radiographs confirmed the reduction. A noncontrast-enhanced identifiable on ultrasound examination with a handheld Doppler computed tomography scan of the right lower extremity was probe, although obvious clinical and angiographic signs of pedal obtained for preoperative planning. The patient was admitted for pain ischemia were present. The results of the angiogram demonstrated a control and social placement. result consistent with that described by Chow et al (19). The physical P.A. Bellezza et al. / The Journal of Foot & Ankle Surgery xxx (2016) 1–6 3

Fig. 1. Displaced right trimalleolar ankle fracture with the talus posteriorly dislocated. The fibula was comminuted and displaced. examination findings in the present case were not predictive of any approximately 18 months after her below-the-knee amputation, she arterial anomaly present until noted on the angiogram. was living at home with her family and able to complete her activities The vascular surgery team offered the patient a bypass based on of daily living in an independent manner. the angiographic findings. However, because of the significant amount of soft tissue necrosis that had occurred, a high likelihood of Discussion failure was explained to the patient. Initially, the patient wanted to pursue limb salvage measures but then decided to proceed with Angiosomes below-the-knee amputation. The patient was doing well since the amputation. She was fitted for a prosthesis and participated in Throughout the preoperative and perioperative workup, no physical therapy once she was cleared by her vascular surgeon. At physical examination findings were present indicating the possibility 4 P.A. Bellezza et al. / The Journal of Foot & Ankle Surgery xxx (2016) 1–6

connected through the anterior perforating branch of the PR artery and the lateral malleolar branch of the AT artery. The flow of the PR artery can be retrograde from the AT artery by way of the lateral malleolar artery. The flow can also be antegrade, to provide a collat- eral support to the AT artery. Within the foot, the AT and PT arteries communicate directly by way of the anastomosis of the DP with the lateral plantar arteries (21).

Theorized Mechanism of Perfusion

In the present case, it was difficult to determine the exact mech- anism of blood flow, especially in the presence of an anatomic popliteal variant. Because the patient had a type IIIA popliteal variant, the PR was dominant to replace the aplastic PT artery. This became the primary vascular supply to the plantar aspect of the foot. If pulses were identifiable on ultrasound examination with the handheld Doppler probe, even on the day of the patient’s below-the-knee amputation, it is quite possible that antegrade arterial inflow was Fig. 2. The posterior malleolus was stabilized with a posterior malleoli plate and 3.5-mm occurring from the perforating branch of the PR, which was not fi fi locking and nonlocking screws. The bula was stabilized with an anatomic bular plate, traumatically occluded. The anastomosis with the lateral malleolar and the medial malleolus was fixated with 2 partially threaded cannulated screws. artery failed to supply antegrade or retrograde support owing to the traumatic disruption to the AT artery. of vascular insult leading to critical limb ischemia. The patient had Antegrade flow from the remaining aspect of AT artery then most pulses at the location of the PT and DP arteries that were identifiable likely traveled through the anastomosis of the first dorsal metatarsal on ultrasound examination with a handheld Doppler probe. The pedal artery between the DP and the lateral plantar artery. Retrograde flow pulses were faintly identifiable on the day of her below-the-knee at this anastomosis most likely explains the pulses identifiable on amputation. It is difficult to understand how this could occur when ultrasound examination with a handheld Doppler probe at the other both the AT and PR arteries were traumatically occluded. Angiosomes end of the traumatically severed PR. of the foot and ankle have been well described by previous in- vestigators (21–23). In the presence of popliteal variants, the angio- Angiographic Imaging somal vascular distribution to the foot and ankle can be significantly altered. No guidelines are available to justify the routine use of invasive Arterial connections around the ankle are complex and difficult to angiographic imaging after foot and ankle trauma. Intuitively, patients evaluate. Normally, the PT, AT, and PR arteries of the leg communicate with known peripheral arterial disease, claudication, or other meta- with each other at the level of the ankle joint. In the presence of a bolic conditions contributing to vascular disease require invasive popliteal variant, this predictable distribution becomes more convo- angiographic imaging before any surgical intervention. Patients with luted. In the normal anatomy, the AT and PR arteries are directly an ischemic foot or a Gustillo IIIb/IIIc fracture should be considered

Fig. 3. (A and B) Traumatic occlusion of the distal aspect of the right anterior tibial (AT) artery. Traumatic segmental occlusion of the peroneal artery approximately 10 cm above the ankle that was reconstituted approximately 5 cm distally. (C) No trifurcation of the popliteal artery was present. The branch of the posterior tibial artery was congenitally absent. The branches of the anterior tibial and peroneal (PR) arteries were present. P.A. Bellezza et al. / The Journal of Foot & Ankle Surgery xxx (2016) 1–6 5

Fig. 4. Initially, both the dorsalis pedis and posterior tibial arteries are compressed.

In the presence of foot and ankle trauma, performing a manual vascular examination at the bedside can be difficult owing to the localized soft tissue edema. An ultrasound examination using a handheld Doppler probe is a quick method to assess the blood flow to the foot at the AT, PT, and PR arteries. Haddock et al (30) described the lower extremity Allen test (LEAT) as an adjunct examination to the angiographic data available when determining the appropriate recipient vessel during the planning for free tissue transfer. This test is performed by placing a handheld Doppler probe at the first dorsal metatarsal artery in the first web space. Initially, both the DP and PT arteries are compressed (Fig. 4). A persistent signal indicates collateral flow through the PR. Haddock et al (30) did not describe the exact mechanism by which a signal remains but did note this would be highly unusual, because the PR artery usually reconstitutes at the DP , which has already been initially compressed. If the signal is not heard at the first interspace, pressure on the DP artery should be released (Fig. 5). A return of the signal would indicate adequate inflow at the DP artery. If releasing pressure on the DP artery does not result in a return of the signal, the PT artery should be released (Fig. 6). If the signal returns under these conditions, the distal foot is dependent on the PT artery for perfusion. The discussion of the LEAT demonstrates that simple digital pulse examination can be potentially misleading, because retrograde flow can yield palpable vessels in an otherwise healthy patient. This is the Fig. 3. (continued). high-risk patients necessitating angiographic imaging to assess the blood flow to the lower extremity. On the surface, our case was a straightforward trimalleolar fracture dislocation in an otherwise healthy elderly patient. Obviously, an angiogram or CTA would have been helpful in identifying the varia- tion in the vascular anatomy. However, no physical examination findings or patient risk factors were present to warrant the use of invasive angiographic imaging.

Lower Extremity Allen Test

Several methods are available to evaluate the vascular status of the lower extremity. These range from physical examination to invasive tests, such as angiography. Other common tests include ankle/brachial indexes, directional Doppler flow studies, toe pressure determination, and magnetic resonance angiography (24–29). Each of these tests helps define the anatomy and aid in the evaluation of healing fi potential. However, these tests could fall short in addressing speci c Fig. 5. If the signal is absent at the first interspace, pressure on the dorsalis pedis should functional changes in the lower extremity circulation (30). be released. Return of the signal indicates adequate inflow at the . 6 P.A. Bellezza et al. / The Journal of Foot & Ankle Surgery xxx (2016) 1–6

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