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

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The Journal of Foot & Ankle Surgery

journal homepage: www.j fas .org

Case Reports and Series

Aplastic Posterior Tibial Artery in the Presence of Trimalleolar AnkleFracture Dislocation Resulting in Below-the-Knee Amputation

Peter Andrew Bellezza, DPM, MS 1, Edward Elliott, DPM2, Thomas Conlee, MD 3,John Randolph Clements, DPM4

1Resident, Division of Foot and Ankle Surgery, Swedish Medical Center, Seattle, WA2Resident, Division of Foot and Ankle Surgery, Department of Orthopaedic Surgery, Carilion Roanoke Memorial Hospital, Roanoke, VA3Vascular Surgeon, Jefferson Surgical Clinic, Carilion Roanoke Memorial Hospital, Roanoke, VA4Assistant Professor, Co-Section Chief, Division of Foot and Ankle Surgery, Department of Orthopaedic Surgery, Virginia Tech Carilion School of Medicine,Roanoke, VA

a r t i c l e i n f o

Level of Clinical Evidence: 4

Keywords:below-the-knee amputationcritical limb ischemiafoot and ankle traumalower extremity Allen testpopliteal variants

Financial Disclosure: None reported.Conflict of Interest: None reported.Address correspondence to: John Randolph C

Orthopaedic Surgery, Carilion Roanoke Memorial HSoutheast, Med Education Building 202, Roanoke, VA

E-mail address: jrclements@carilionclinic.org (J.R.

1067-2516/$ - see front matter � 2016 by the Americhttp://dx.doi.org/10.1053/j.jfas.2016.08.006

a b s t r a c t

We present an interesting, but unfortunate, case of an 86-year-old female who sustained a trimalleolar anklefracture dislocation that resulted in below-the-knee amputation after open reduction and internal fixation of thefracture. To the best of our knowledge, this is the first case report describing popliteal variants that ultimatelyresulted in critical limb ischemia and below-the-knee amputation after foot and ankle trauma. The anatomicvariation altered the expected outcome from a relatively straightforward surgical case. We introduce the previ-ously described lower extremity Allen test and describe how it can be a useful adjunct in the initial physicalexamination of lower extremity trauma. The ability to identify abnormal distal perfusion to the foot could provideenough insight to warrant evaluating the patient with angiography or computed tomography angiography.

� 2016 by the American College of Foot and Ankle Surgeons. All rights reserved.

Knowledge of anatomic variations in the branching pattern of thepopliteal artery is important because damage to its branches can belimb threatening. Kim et al (1) proposed a new classification of thebranching pattern of the popliteal artery by modifying the originalclassification system by Lippert and Pabst (2). They classified thebranching patterns into 3 categories and 3 subtypes (Table). The maindistinction of the new classification system is their third category. Thisdescribes a normal branching pattern and sequence; however, theproximal segments of the anterior tibial (AT) and/or posterior tibial(PT) branches are congenitally absent or hypoplastic. Category IIIanatomic variants have the most clinical significance to vascular,orthopedic, and podiatric foot and ankle surgeons. The 3 major vari-ants in the popliteal branching pattern reported by Kim et al (1) are itstrifurcation (IB), high divisionwith a normal branching sequence (IIA),and the hypoplastic-aplastic PT with the distal PT replaced by theperoneal (PR) artery (IIIA). These major variants were also predomi-nantly seen in a review by Kropman et al (3).

Normally, the popliteal artery divides into the AT and PT arteries.In some cases, it can bifurcate into the AT and PR arteries, with the

lements, DPM, Department ofospital, 1906 Belleview Avenue24014.Clements).

an College of Foot and Ankle Surgeon

PT artery absent or rudimentary (4–6). Angiographic studies haveshown the incidence of a hypoplastic-aplastic PT artery ranges from0.8% to 3.8%. In anatomic studies, the incidence has ranged from1.5% to 11% (1,2,5,7–11). Compensatory hypertrophy of the PR arterywith a hypoplastic or aplastic PT or AT artery might indicate avariant arterial supply to the foot (1). This enlarged PR artery, the“peronea magna” or “great” peroneal artery as described by Senior(6,12) either joins and reinforces the PT artery or replaces it in thedistal leg and foot (4,6,12,13). When the PR artery has replaced thePT artery at the ankle, the distal aspect typically continues into thesole as the lateral plantar artery. The medial plantar artery is thenusually absent (6,12,13). Cases have been reported in publishedstudies that have documented the PR artery replacing the PT arterybut with the distal segment in the same anatomic location as theexpected, but absent, PT artery (1,14). Cases of a hypoplastic-aplastic PT artery have also been documented in individuals withinborn foot deformations (15–17). In other cases, the arterial defectmight not be diagnosed for years and might only be recognizedincidentally (11,18).

Detection of this anatomic variant on physical examination can bedeceiving and not easily determined. Chow et al (19) retrospectivelyevaluatedmultidetector computed tomographic angiography (CTA) todetermine donor and recipient site arterial suitability for vascularizedfree flap transplantation. They found 4 of 32 lower extremities (12.5%)had anatomic variants. These variants involved the popliteal, AT, PT,

s. All rights reserved.

TableClassification of branching pattern of popliteal artery

Class Description

I Normal level of popliteal arterial branchingA Usual pattern: AT is first arterial branch; tibioperoneal artery follows and

bifurcates into PR and PT arteries (92%)B Trifurcation: AT, PR, and PT arise within 0.5 cm; no true tibioperoneal trunk

is present (2%)C Anterior tibioperoneal trunk: PT is the first branch, the tibioperoneal trunk

follows and bifurcates into the PR and AT arteries (1.2%)II High division of popliteal arteryA AT arises at or above the knee joint (3.7%)B PT arises at or above the knee joint and is the common trunk for the PR

and AT arteries (0.8%)C PR arises at or above the knee joint and is the common trunk for the AT

and PT arteries (0.16%)III Hypoplastic or aplastic branching with altered distal supplyA Hypoplastic-aplastic PT; distal PT replaced by PR artery (3.8%)B Hypoplastic-aplastic PT and AT arteries; dorsalis pedis replaced by PR

artery (1.6%)C Hypoplastic-aplastic PT and AT arteries; PT and dorsalis pedis arteries

replaced by PR artery (0.2%)

Abbreviations: AT, anterior tibial; PR, peroneal; PT, posterior tibial.

P.A. Bellezza et al. / The Journal of Foot & Ankle Surgery xxx (2016) 1–62

and pedal arteries. All results were compared with their originalphysical examination findings. Their physical examinations findings,in all cases, were not predictive of the presence of any arterialanomaly.

Significant negative outcomes can occur when anatomic variationsof the popliteal artery have not been appreciated. Orthopedic,vascular, and podiatric foot and ankle surgeons should be aware thatanatomic variants exist. However, the question remains whether wenecessarily need to perform preoperative vascular screening withangiography and/or CTA. No guidelines have been set for its use in footand ankle surgery and trauma. According to the published data, theroutine use of angiography and/or CTA is controversial, even for casesin which such imaging modalities are most commonly used, such asfree flap reconstructive surgery (19).

We present an interesting, but unfortunate, case of an 86-year-oldfemale who sustained a trimalleolar ankle fracture dislocation thatresulted in below-the-knee amputation after open reduction and in-ternal fixation of the fracture. This patient ultimately had a type IIIApopliteal variant (Table) that was not appreciated on physical exam-ination. The incidence of this variant is approximately 3.8% accordingto the published data. To the best of our knowledge, this is the firstdocumented case report discussing type III popliteal variants in footand ankle surgery.

Case Report

The patient was an 86-year-old female who presented to theemergency department with a right ankle fracture dislocation. Shehad no secondary injuries. The right ankle was globally tender. Thepatient had full, painless range of motion at the right hip and knee.The compartments were soft. Her skin was intact, with diffuseecchymosis and edema localized to the ankle. Sensation was intact toall lower extremity nerve distributions. The PT and dorsalis pedis (DP)pulses distally were 2þ and palpable. Radiographs revealed a dis-placed trimalleolar fracture with the talus posteriorly dislocated. Thefibula was comminuted and displaced. Fractures were present in themedial and posterior malleolus (Fig. 1). The right ankle fracture wasreduced and splinted without complications. Postreduction plainradiographs confirmed the reduction. A noncontrast-enhancedcomputed tomography scan of the right lower extremity wasobtained for preoperative planning. The patient was admitted for paincontrol and social placement.

The patient returned 8 days later for definitive fixation. Onadmission, the examination findings were unchanged. The vascularexamination revealed palpable PT and DP pulses with a brisk capillaryfill time (CFT). The next day, she underwent open reduction and in-ternal fixation of the right trimalleolar ankle fracture with posteriorlip fixation. The patient was positioned prone. The posterior malleoluswas stabilized with a posterior malleoli plate and 3.5-mm locking andnonlocking screws. The fibula was stabilized with an anatomic fibularplate, and the medial malleolus was fixated with 2 partially threadedcannulated screws (Fig. 2). No intraoperative complications werenoted. Shortly after the procedure, the nursing staff noted delayed CFTto the digits; however, the CFT returned when the foot was placed in adependent position. The next day the patient was evaluated andfound to have palpable PT and DP pulses and a brisk CFT. The patient’spain was well controlled, and she was discharged to a local skillednursing facility.

The patient returned for a follow-up examination 1 week afterbeing discharged from the hospital. The physical examinationrevealed nonpalpable pedal pulses, but the PT and DP pulses wereidentifiable on ultrasound examination with a handheld Dopplerprobe. Ischemic changes were noted along the dorsal and lateralaspects of the foot. The hallux and third toe remained viable butdemonstrated prolonged CFTs. The incision was well approximated.No erythema, discharge, drainage, or dehiscence was present; how-ever, full-thickness tissue necrosis had developed, consistent with drygangrene, along the lateral aspect of the right heel and measuring5 � 5 cm. The patient was readmitted to the hospital, and vascularsurgery was consulted. A lower extremity arterial duplex Dopplerexamination was ordered by the vascular surgery team, with theofficial impression of the study noting no hemodynamically signifi-cant arterial disease at the right lower extremity. Because of thedegree of necrosis, the vascular surgery team consulted with theinterventional radiology staff to evaluate the limb with angiographywith right lower extremity runoff. The official interventional radi-ology report (Fig. 3A,B) concluded:

� Traumatic occlusion of the distal aspect of the right AT artery atthe level of the superior aspect of the talus with no reconstitutionof the DP artery

� Likely congenital absence of the PT artery� Traumatic segmental occlusion of the PR artery approximately10 cm above the ankle that was reconstituted approximately 5 cmdistally into the normal expected course of the PT artery and wasthe only significant arterial supply to the foot

The angiogram revealed no trifurcation of the popliteal artery. Thebranch of the PT artery was congenitally absent. The branches of theAT and PR arteries were present (Fig. 3C). When reviewing Fig. 3A,B,the interventional radiology report noted traumatic occlusion of theAT artery. The prevailing explanation was that the AT artery had beentraumatically occluded. This could have resulted from either an iat-rogenic cause or intimal injury (20) not detected during the indexexamination. It is also plausible that the AT artery was congenitallyhypoplastic; however, this would be difficult to prove definitivelywithout a previous arteriogram or CTA. The finding of a congenitallyaplastic PT artery is consistent with the IIIA popliteal variant using theKim classification (1). This has an occurrence rate of 3.8%. This,combined with the traumatically occluded AT and PR artery, single-handedly eliminated all the blood supply to the foot, causing criticalpedal ischemia. Peculiarly, the patient still exhibited pedal pulsesidentifiable on ultrasound examination with a handheld Dopplerprobe, although obvious clinical and angiographic signs of pedalischemia were present. The results of the angiogram demonstrated aresult consistent with that described by Chow et al (19). The physical

Fig. 1. Displaced right trimalleolar ankle fracture with the talus posteriorly dislocated. The fibula was comminuted and displaced.

P.A. Bellezza et al. / The Journal of Foot & Ankle Surgery xxx (2016) 1–6 3

examination findings in the present case were not predictive of anyarterial anomaly present until noted on the angiogram.

The vascular surgery team offered the patient a bypass based onthe angiographic findings. However, because of the significantamount of soft tissue necrosis that had occurred, a high likelihood offailure was explained to the patient. Initially, the patient wanted topursue limb salvage measures but then decided to proceed withbelow-the-knee amputation. The patient was doing well since theamputation. She was fitted for a prosthesis and participated inphysical therapy once she was cleared by her vascular surgeon. At

approximately 18 months after her below-the-knee amputation, shewas living at home with her family and able to complete her activitiesof daily living in an independent manner.

Discussion

Angiosomes

Throughout the preoperative and perioperative workup, nophysical examination findings were present indicating the possibility

Fig. 2. The posterior malleolus was stabilized with a posterior malleoli plate and 3.5-mmlocking and nonlocking screws. The fibula was stabilized with an anatomic fibular plate,and the medial malleolus was fixated with 2 partially threaded cannulated screws.

P.A. Bellezza et al. / The Journal of Foot & Ankle Surgery xxx (2016) 1–64

of vascular insult leading to critical limb ischemia. The patient hadpulses at the location of the PT and DP arteries that were identifiableon ultrasound examinationwith a handheld Doppler probe. The pedalpulses were faintly identifiable on the day of her below-the-kneeamputation. It is difficult to understand how this could occur whenboth the AT and PR arteries were traumatically occluded. Angiosomesof the foot and ankle have been well described by previous in-vestigators (21–23). In the presence of popliteal variants, the angio-somal vascular distribution to the foot and ankle can be significantlyaltered.

Arterial connections around the ankle are complex and difficult toevaluate. Normally, the PT, AT, and PR arteries of the leg communicatewith each other at the level of the ankle joint. In the presence of apopliteal variant, this predictable distribution becomes more convo-luted. In the normal anatomy, the AT and PR arteries are directly

Fig. 3. (A and B) Traumatic occlusion of the distal aspect of the right anterior tibial (AT) artery. Tthat was reconstituted approximately 5 cm distally. (C) No trifurcation of the popliteal artery wathe anterior tibial and peroneal (PR) arteries were present.

connected through the anterior perforating branch of the PR arteryand the lateral malleolar branch of the AT artery. The flow of the PRartery can be retrograde from the AT artery by way of the lateralmalleolar artery. The flow can also be antegrade, to provide a collat-eral support to the AT artery. Within the foot, the AT and PT arteriescommunicate directly by way of the anastomosis of the DP with thelateral 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 anatomicpopliteal variant. Because the patient had a type IIIA popliteal variant,the PRwas dominant to replace the aplastic PT artery. This became theprimary vascular supply to the plantar aspect of the foot. If pulseswere identifiable on ultrasound examination with the handheldDoppler probe, even on the day of the patient’s below-the-kneeamputation, it is quite possible that antegrade arterial inflow wasoccurring from the perforating branch of the PR, which was nottraumatically occluded. The anastomosis with the lateral malleolarartery failed to supply antegrade or retrograde support owing to thetraumatic disruption to the AT artery.

Antegrade flow from the remaining aspect of AT artery then mostlikely traveled through the anastomosis of the first dorsal metatarsalartery between the DP and the lateral plantar artery. Retrograde flowat this anastomosis most likely explains the pulses identifiable onultrasound examination with a handheld Doppler probe at the otherend of the traumatically severed PR.

Angiographic Imaging

No guidelines are available to justify the routine use of invasiveangiographic imaging after foot and ankle trauma. Intuitively, patientswith known peripheral arterial disease, claudication, or other meta-bolic conditions contributing to vascular disease require invasiveangiographic imaging before any surgical intervention. Patients withan ischemic foot or a Gustillo IIIb/IIIc fracture should be considered

raumatic segmental occlusion of the peroneal artery approximately 10 cm above the ankles present. The branch of the posterior tibial artery was congenitally absent. The branches of

Fig. 3. (continued).

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

Fig. 5. If the signal is absent at the first interspace, pressure on the dorsalis pedis shouldbe released. Return of the signal indicates adequate inflow at the dorsalis pedis artery.

P.A. Bellezza et al. / The Journal of Foot & Ankle Surgery xxx (2016) 1–6 5

high-risk patients necessitating angiographic imaging to assess theblood flow to the lower extremity.

On the surface, our casewas a straightforward trimalleolar fracturedislocation in an otherwise healthy elderly patient. Obviously, anangiogram or CTA would have been helpful in identifying the varia-tion in the vascular anatomy. However, no physical examinationfindings or patient risk factors were present to warrant the use ofinvasive angiographic imaging.

Lower Extremity Allen Test

Several methods are available to evaluate the vascular status of thelower extremity. These range from physical examination to invasivetests, such as angiography. Other common tests include ankle/brachialindexes, directional Doppler flow studies, toe pressure determination,and magnetic resonance angiography (24–29). Each of these testshelps define the anatomy and aid in the evaluation of healingpotential. However, these tests could fall short in addressing specificfunctional changes in the lower extremity circulation (30).

In the presence of foot and ankle trauma, performing a manualvascular examination at the bedside can be difficult owing to thelocalized soft tissue edema. An ultrasound examination using ahandheld Doppler probe is a quick method to assess the blood flow tothe foot at the AT, PT, and PR arteries. Haddock et al (30) described thelower extremity Allen test (LEAT) as an adjunct examination to theangiographic data available when determining the appropriaterecipient vessel during the planning for free tissue transfer. This test isperformed by placing a handheld Doppler probe at the first dorsalmetatarsal artery in the first web space. Initially, both the DP and PTarteries are compressed (Fig. 4). A persistent signal indicates collateralflow through the PR. Haddock et al (30) did not describe the exactmechanism by which a signal remains but did note this would behighly unusual, because the PR artery usually reconstitutes at the DPpulse, which has already been initially compressed.

If the signal is not heard at the first interspace, pressure on the DPartery should be released (Fig. 5). A return of the signal would indicateadequate inflowat the DP artery. If releasing pressure on the DP arterydoes not result in a return of the signal, the PT artery should bereleased (Fig. 6). If the signal returns under these conditions, the distalfoot is dependent on the PT artery for perfusion.

The discussion of the LEAT demonstrates that simple digital pulseexamination can be potentially misleading, because retrograde flowcan yield palpable vessels in an otherwise healthy patient. This is the

Fig. 6. If releasing pressure on the dorsalis pedis pulse does not result in a return of thesignal, the posterior tibial is released. If the signal returns under these conditions, thedistal foot is dependent on the posterior tibial artery for perfusion.

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basis of our theorized blood flow mechanism discussed above andcould explain why our patient’s pulses were identifiable on ultrasoundexamination with a handheld Doppler probe even on the day of ourpatient’s below-the-knee amputation. Haddock et al (30) described theLEAT as an easy test to perform that can detect cases in which a singlevessel might be responsible for distal perfusion of the foot. The LEATcan be of service to the foot and ankle surgeon. The ability to identifyabnormal distal perfusion to the foot could provide enough insight towarrant evaluating the patient with angiography or CTA.

In conclusion, to the best of our knowledge, this is the first casereport describing popliteal variants that ultimately resulted in criticallimb ischemia and below-the-knee amputation after foot and ankletrauma. This was an unfortunate case inwhich the anatomic variationaltered the expected outcome from a relatively straightforward sur-gical case. Although the incidence of popliteal variants is rare (1), it ispossible the LEAT could have been helpful in initially identifying theobvious anatomic variation in the vascular supply to our patient’s foot.The LEAT is extremely easy to perform at the bedside, and we proposeit should be a part of any initial physical examination to ensureaccurate identification of possible abnormalities in the vascular sup-ply to the foot in the presence of foot and ankle trauma.

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