MICROVASCULAR ANASTOMOSIS THROUGH THE TIBIAL TUNNEL:A NEW TECHNIQUE IN FREE-TISSUE TRANSFER TO THE LEG

KEIICHI MURAMATSU, M.D.,* MITSUNORI SHIGETOMI, M.D., KOICHIRO IHARA, M.D., and SHINYA KAWAI, M.D.

Free-tissue transfer to a severely traumatized leg has a high rate of vascular complications. We present three successful cases using a newtechnique of microvascular anastomosis through the tibial tunnel. Because of the unavailability of anterior tibial artery due to posttraumaticvascular disease, donor vascular pedicles were passed posterior to the tibia through the tibial tunnel and anastomosed to the posterior tibialartery or its branch in an end-to-end fashion. The flaps survived perfectly, without any vascular complication. This technique represents a saferoute, and the shortest route, to an expected anastomosis point. Our technique is indicated especially in cases with a single-vessel leg.ª 2004 Wiley-Liss, Inc.

Reconstruction of the lower extremity using free-tissuetransfer has been accepted as a standard procedure sincethe 1980s.1�4 However, recent reviews of a series of largenumber of patients revealed an incidence of free-flapfailure varying from 15�20%. There was concern in theliterature that a free-tissue transfer to a lower limb mayhave a higher incidence of vascular complications, re-sulting in flap necrosis.5�7 This was mainly due to thefact that directing recipient vessels away from the site ofa reconstructed defect could be difficult in the lowerlimb, especially in the proximal third, where they are notwell-protected from high-energy injuries. Adequate re-cipient vessels are often very difficult to find in the widezone of trauma caused by high-energy injuries, whichcommonly occur in the lower limb. The superficial veinsare often damaged due to injury, and the deep veinsaccompanying the major arteries are sometimes affectedwith varicosis, inducing insufficiency of venous return.Widespread changes could occur in the vessel walls andperivascular tissues following trauma or operations, e.g.,the so-called ‘‘posttraumatic vascular disease’’ (PTVD)suggested by Acland.8 Thus, avoidance of the use ofrecipient vessels affected by PTVD has become a rele-vant issue.

It was shown that the proper selection of recipientvessels is one of the most important factors for a suc-cessful free-tissue transfer to a lower extremity.9�13

Godina et al.14 suggested that the recipient vesselsshould be easily accessible and located outside the areaof injury without stigmata of trauma, should be closeenough to the defect, and should have a good ortho-

grade flow and large caliber. Godina et al.,14 Bowen andManktelow,6 and Chen et al.13 suggested that the pos-terior tibial artery is much less vulnerable than the an-terior tibial artery to damage in most cases of injury,and thus is more reliable as a recipient artery. However,until now, a reliable and accessible route from an injuredanterior to posterior site was controversial. Here, wedescribe three successful cases using a new technique ofmicrovascular anastomosis through the tibial tunnel,and discuss its indications and advantages.

PATIENTS

Case 1

A 23-year-old man (all patients are summarized inTable 1) sustained an open fracture (grade IIIb of Gu-stilo and Anderson15) of the right tibia and fibula in atraffic accident. The anterior compartment and anteriortibial artery were injured at time of trauma, but theposterior side of the tibia was intact, resulting in a so-called ‘‘single-vessel leg.’’ On the day of injury, severelycrushed muscles were debrided, and the open wound wasthoroughly irrigated. One week later, Pseudomonas ae-ruginosa was detected in the wound, and continuous ir-rigation was performed every day thereafter. Sevenweeks later, the patient underwent internal fixation of thetibia and a functional latissimus dorsi myocutaneous flaptransfer for reconstruction of the lost anterior compart-ment. A preoperative angiogram revealed that the ante-rior tibial artery was ruptured at the division of thepopliteal artery and could not be used for a recipientvessel. A microvascular anastomosis at the poplitealfossa was planned before surgery. Using a cannulatedflexible reamer, a bony tunnel with a diameter of 13 mmwas made from the lateral aspect of the proximal tibia tothe popliteal fossa. The subscapular artery and vein werepassed through the tibial tunnel and microsurgicallyanastomosed to the medial sural artery that was thenutrient vessel of the gastrocnemius muscle, with inter-

Department of Orthopedic Surgery, Yamaguchi University School of Medi-cine, Ube, Yamaguchi, Japan

*Correspondence to: Dr. Keiichi Muramatsu, Department of OrthopedicSurgery, Yamaguchi University School of Medicine, 1-1-1 Minami-Kogushi,Ube, Yamaguchi 755-8505, Japan. E-mail: muramatu@po.cc.yamaguchi-u.ac.jp

Received 3 September 2003; Accepted 22 December 2003

Published online 20 May 2004 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/micr.20023

ª 2004 Wiley-Liss, Inc.

position of 10-cm-long lesser saphenous vein grafts. Thethoracodorsal nerve was coapted directly to the peronealnerve. Postoperatively, the flap survived totally, withoutany vascular complications (Fig. 1A). Viability of themedial gastrocnemius muscle was not disturbed aftervascular anastomosis to the medial sural artery. At 2-year follow-up, the transferred latissimus dorsi musclewas found to be successfully reinnervated. Radiographsrevealed a narrowed but open tibial tunnel (Fig. 1B).

Case 2

A 39-year-old man sustained an open fracture (gradeIIIa of Gustilo and Anderson15) of the left proximaltibia. On the day of injury, the wound was thoroughlyirrigated, and the patient underwent open reduction andinternal fixation using a buttress plate. However, 6weeks later, osteomyelitis occurred in the proximal tibia.Eight weeks after injury, the patient underwent removalof the plate and extensive debridement. Fourteen weeksafter injury, the defect of the infected tibia and the an-terior compartment were reconstructed with a combi-nation of vascularized scapula and latissimus dorsimyocutaneous flap. Preoperatively, we planned to per-form a microvascular anastomosis in the popliteal fossa,anticipating the anterior tibial artery to be severelydamaged with PTVD. Using a cannulated flexiblereamer, a bony tunnel with a diameter of 13 mm wasmade from the lateral side of the proximal tibia (Fig.2A). The subscapular artery and vein were passedthrough the tibial tunnel and microsurgically anasto-mosed to the medial sural artery in end-to-end fashion.No vein graft was used for this patient. The graft sur-vived perfectly, without any vascular complications. Themedial gastrocnemius muscle had no complications aftersurgery. Six months after the vascularized bone graft,another debridement was performed due to residualinfection. There was no evidence of osteomyelitis at 2-year follow-up. Radiographs revealed the patency of thetibial tunnel (Fig. 2B).

Case 3

A 56-year-old woman with a history of chronic os-teomyelitis of the right tibia presented at our clinic dueto recurrent infection. The patient underwent thoroughdebridement of infected tibia and removal of the im-plant. A pathological fracture of the tibia occurred 1week after the operation. Three months later, we plan-ned a reconstruction with a vascularized fibula graft andperoneal flap. A preoperative angiogram revealed thatthe anterior tibial artery was patent, but the arterial wallwas irregular. The anterior tibial vessels were not suit-able for vascular anastomosis due to repeated exposuresand PTVD, and so the posterior tibial vessels were usedfor the recipient. After the tibia was fixed using an ex-ternal fixator, a tibial tunnel with a diameter of 12 mmwas made at the posterior side of the proximal shaft,using a surgical air drill. A 14-cm-long vascularizedfibula graft and 10 · 3 cm of peroneal flap were har-vested from the left leg, and the fibula graft was fixed tothe tibia as an inlay graft (Fig. 3A). The peroneal arteryand veins were passed through the tibial tunnel andanastomosed microsurgically to the posterior tibial ar-tery and veins in an end-to-end fashion. The peronealflap survived perfectly, without any vascular complica-tions. At 2-year follow-up, bony union was achieved,and signs of residual osteomyelitis were absent. Radio-graphs revealed a narrowed but open tibial tunnel(Fig. 3B).

DISCUSSION

Many microsurgeons suggest that in the lower limb,considerable difficulty could arise in locating adequaterecipient vessels well away from the site of previoustrauma.9�13 In the upper and middle thirds of the lowerleg, the major arteries are inaccessible from the ante-rior aspect, and they may themselves be damaged.Vein grafts to the femoral artery above the knee anas-

Table 1. Patients’ Data*

Case Age Gender Diagnosis Donor RecipientVeingraft

Operatingtime (hrs) Bleeding (ml) Results Complications

1 22 Male Open fracture,proximal third,Gustilo IIIB

L.D. Branch of G.M. 10 cm 12 2,000 Total survival None

2 39 Male Open fracture,proximal third,Gustilo IIIa

L.D. +scapula

Branch of G.M. None 12 900 Total survival Residualinfection

3 56 Female Chronicosteomyelitis,middle

Fibula + flap P.T. None 10 1,300 Total survival None

*L.D., latissimus dorsi myocutaneous flap; G.M., gastrocnemius muscle. Gustilo, grading system of Gustilo and Anderson.15

P.T., posterior tibal artery and vein.

294 Muramatsu et al.

tomosed in an end-to-side fashion can overcome thisdifficulty, but they prolong the procedure and introducethe added intrinsic problems of vein grafts. An alter-native method is to create a vascular loop by anasto-mosing a great saphenous vein graft proximally to theside of the femoral artery above the knee, and runningthe graft distally to the proximal limit of the defect

where it is then looped back and anastomosed in an end-to-end fashion to the great saphenous vein. Postopera-tive vascular complications, however, frequently occurbecause very long saphenous vein grafts get kinkedeasily.

Vessels located in the anterior compartment aremore vulnerable at the time of traffic accidents. Themedial sural artery, posterior tibial artery, and their

Figure 1. Case 1. Pedicles of latissimus dorsi myocutaneous flap

were passed through tibial tunnel with a diameter of 13 mm and

anastomosed microsurgically to vascular pedicle of gastrocnemius

muscle. A: Flap survived totally, without any vascular complications.

B: Radiographs at 2-year follow-up revealed narrowed but open tibial

tunnel (arrow).

Figure 2. Case 2. Using a cannulated flexible reamer, a bony tunnel

with a diameter of 13 mm was made from lateral side of proximal tibia

(arrow). A: Latissimus dorsi myocutaneous flap survived perfectly,

without any vascular complications. B: Radiograph at 2-year follow-

up revealed patency of tibial tunnel (arrow).

Anastomosis Through Tibial Tunnel 295

concomitant veins are protected by abundant soft tissueand bone located anterior to them. The force of traumausually comes from the front, especially in a motorcycleaccident, but is rarely large enough to break the pro-tective shield of the posterior tibial artery. A posteriorapproach to the vessels of the lower leg with a particularemphasis to the posterior tibial artery is presented as themethod of choice for microvascular free-tissue transferto this region.9 As O’Brien and Morrison16 and otherauthors10,13 suggested, the flap pedicle may be passedthrough the interosseous membrane for anastomosis tothe recipient vessels in the popliteal fossa, but in thiscase, the distance to the anastomosis point is unex-pectedly long, and the vascular pedicle may get kinkedat the edge of the fibula head. The tibial tunnel is thebest route to access the popliteal fossa and the posteriortibial vessels. To the best of our knowledge, there wereno previous papers relating to microvascular anasto-mosis through the tibial tunnel. A donor vascular

pedicle can be pulled out at the shortest expected dis-tance. This technique may be best indicated in a casewith a ‘‘single-vessel leg’’ or a case with PTVD of theanterior tibial artery. Preoperative angiographies andcareful planning of the operation are essential in thesepatients.

A microvascular anastomosis through the tibialtunnel has several problems. First among them isweakening of the mechanical strength of the tibia.Holes of any size significantly weaken bone strength.Brooks et al.17 investigated the effect of a drill hole onthe strength of long bones and on the fracture resultingfrom rapidly applied tensional loads. Paired caninefemora were tested, and it was concluded that changesin the ratio of drill-hole area to bone area from12�28% are not accompanied by significant changes inbone strength or in the stress concentration factor.Burstein et al.18 also demonstrated that a fresh scre-whole weakened bone in bending and tensional load-

Figure 3. Case 3. A 14-mm-long vascularized fibula graft was transfered to tibia as inlay graft. A: Pedicles were passed through tibial tunnel

and anastomosed microsurgically to posterior tibial artery and veins in end-to-end fashion (right) anteroposterior view, (left) lateral view. B:

Radiograph at 2-year follow-up revealed a narrowed but open tibial tunnel (arrow).

296 Muramatsu et al.

ing, whereas Bechtol and Lepper19 found a value of20% to be the critical level. Burstein et al.18 determinedthat the size of the hole had no effect on breakingstrength until it exceeded 30% of the diameter of thebone. Laurence et al.20 found that the bending momentrequired to fracture an intact canine tibia varied from59�226 Nm (mean, 137 Nm). However, when a 3-mmdrill hole was made through the tibia, the moment re-quired was reduced from 29�147 Nm (mean, 98 Nm).There was no mechanical weakness of the tibia in cases1 and 2, as the tunnels through which the vascularpedicles passed were 13 mm in diameter and less than20% of the proximal tibia. In case 3, the tibial shaftfracture was reconstructed with a vascularized fibulagraft, and the total mechanical strength of the recon-structed tibia was found to be enough for weight-bearing.

The second problem is external pedicle compressionand obstructive kinking inside or at the edge of the bonetunnel. This leads to vascular stasis, thrombosis, andeventual tissue necrosis. O’Brien and Morrison16 sug-gested that tight wound closure, soft-tissue swelling,wound hematoma, and vascular angulations over abony fracture or internal fixation device are the mostcommon causes of external vascular compression.Inside the bony tunnel, formation of hematoma seemsto be difficult to control due to a loss of adequatehemostasis. However, in our cases, there was no vas-cular complication, and the flaps survived completely.Careful preoperative planning including the location,direction, length, and diameter of the tibial tunnel iskey in avoiding obstructive kinking of the pedicle.The shortest possible tunnel should be made to theexpected anastomosis point, and abnormal angulationsshould be avoided. The tibial tunnel may protect ex-ternal compression to the vascular pedicle from post-operative soft-tissue swelling exacerbated by woundhematoma.

The third problem is narrowing of the tibial tunnelwith the passage of time. After removal of an internalfixator and screws, the drilled holes remained evident onradiographs for a long period, but gradually closed.Histological examination showed that the defect wasfilled with woven bone in 6�8 weeks.21 In our threecases, the tibial tunnels narrowed gradually but neverclosed completely, even after 2 years. Dissimilar to re-moval of a screw, the tibial tunnel may remain open fora long time due to the existence of a pulsing vascularpedicle.

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