Mayo Clinic otolaryngologist Eric J. Moore, M.D. demonstrates a fibular free flap reconstruction of a mandibular defect following an oncologic resection for oral cavity cancer.
Eric Moore, I'm a head and neck surgeon at the Mayo Clinic. This uh video discusses fibula free flap reconstruction for osteocutaneous reconstruction of a defect of the mandible. It will include uh sections on fibula free flap design, harvest templating, how to use cutting guides, how to use models in setting the flap and microvascular Anestis. The mandible use of cutting guides is not absolutely necessary but for more complex defects of the mandible. The ability to 3D model the defect, the ability to use cutting guides to plan the reconstruction, the ability to use models to uh perfect the reconstruction are highly valuable. In this situation. We have a patient with a lateral mandible defect in several segments that's gonna be reconstructed to design the fibula free flap. We mark out the fibular head and the lateral Melius down by the ankle and then plan for preservation of 4 to 5 centimeters of bone, both proximately and distally to help protect the stability of the joint. The skin paddle. If one is necessary is designed off the inferior half of the fibular free flap as this is where the majority of the perforators occur. Any size skin paddle along a line drawn between those two points can be designed. The leg is then exsanguinated by elevating it, wrapping it tightly with an S mark to squeeze out venous um blood in the leg and then inflating the tourniquet to 350 millimeters. For an adult patient, the incision is started and the anterior portion of the incision, the interior portion of the incision is designed to elevate skin over the entire length of the file that's going to be harvest. And the first step in this incision is to identify the peras longest. The pers longus is most easily identified by identifying the long uh white stripe of the pers longest tendon inferiorly of the leg. This is uh found by cutting through the skin and the subcutaneous fat and then identifying the fash overlying the perenne longest, then in size in it and elevating it. After this, the skin and subfascial dissection is elevated post yearly to identify the septum between the anterior and posterior compartment musculature. The majority of the perforators to the skin coming off the perennial artery lie within the septum. The perforators are identified in the septum marked both over the fascia and then also in the skin for easy uh identification. Later after the flap has been elevated. And if the skin pedal is going to be contoured, if the perforators are not seen coming through the septum, then that means there must be their perforators coming through the flexor house as long as muscle. After identifying the perter and market them, we then elevate the interior musculature, the per longest unus brevis off of the fibula. This is done by cutting through the muscle and leaving a thin cuff of muscle just over the periosteum of the anterior fibula. But elevating the rest of the musculature anteriorly, there will be small perforators coming into this muscle which have to be either cauterized bipolared or e clipped. It's important to stay just over the periosteum of the fibula and to leave very little soft tissue onto it. This makes contra easier. After coming across the anterior portion of the fibula, dissection continues on through the anterior compartment, elevating the muscle elevating the anterior tibial artery and vein and identifying the in interosseous membrane between the fibula and the tibia. The interosseous membrane is then in size, the entire length of the interosseous membrane all the way up to the proximal bone cut and all the way down to the distal bone cut. This should be performed several millimeters away from the fibulas. So as to protect uh inadvertent injury to the perennial vessels which lie deep to the muscle there. After incising the interosseous membrane, we is in the skin paddle by making a post ear incision through the skin. The skin elevation continues post yearly back to a level uh of uh at the saphenous vein and um s nerve and then dissection car is carried forth the entire length of the fibula to elevate the poster musculature off the fibula. At this point, the skin paddle becomes is landed just on the perforators and the septum again, if there are no inner, inner septal perforators, that means they're coming through the muscle and a small cuff of flexor haus. As long as muscle should be harvested. This portion of the procedure is identifying, taking the gastrocnemius and the soleus loose from the fibula. This is done with careful dissection along the posterior fibular border. There are large perforating vessels that come off the paranal uh vessels to this gastrocnemius uh that may need to be divided and clipped. These are usually proximal and the proximal half of the fibular dissection, elevating this muscle loose from the fibula at this point allows easy identification uh of the uh perennial vessels at this point of the dissection. Everything has been isolated off of the fibula except for the vascular pedicle and uh its surrounding muscle of poster tibialis anteriorly and flexor haus. As long as post yearly. Again, the perforators to the skin are coming up through the septum and can be seen both anteriorly and post yearly on both sides of the skin. The muscle has been divided uh partially off the fibula and the remainder of the muscle is now gonna be divided off the fibula to carefully identify the perennial vessels which can be seen at this point. Again, care should be taken to divide perras with either uh harmonic scalpel or eclipse or division in this area as the perf can be quite large and bleed. Here is one of the perforators coming to the gastrocnemius muscle which is going to be divided with clamps and tied secondary to its diameter. These vessels should be divided several millimeters away from the uh fibula again. So as not to injure their takeoff from the perennial artery and vein, the fascia overlying the flexor house, as long as muscle is cut at this point, doing this allows it uh an easier elevation and more mobility on the fibula. Once the bone cuts are made, this fashion can be divided the entire length of the flexor house. As long as muscle proximal bone cut is then made by passing a uh curve clamp immediately deep to the fibula just uh super perio uh at the level where the bone cut is gonna be performed and then passed in a gig saw cutting from medial to lateral, prevents inadvertent injury to the perennial vessels which are deep to the fibula. At this point. The proper way to use the Gigli saw is to keep the saw handles very wide and to cut from side to side rather than up, up and down. This will keep the saw from locking out, be sure to protect the surrounding soft tissue. So it's not abraded by the gig we saw, this is a relatively a traumatic uh cut in the bone cuts are made approximately and distally. And at the time that the distal cut is made, the fibula that can be elevated slightly laterally to identify the distal perennial artery and venna comma. If these vessels are not seen, it means that they're just deep to the postal. In a small amount of muscle, it needs to be cut. Once these vessels are identified, they're clamped and tied distally. The perennial vessels maintain their width throughout the entire length of the fibula. And reports have been made of actually sewing distillate to the perennial vessels as a continuation flap to isolate the vessel divide the post ear tibialis muscle and tied to it and the flexor haus, as long as poste to it, there are perforators in this muscle. So this needs to be divided in a hemostatic method as well. This is son using ultrasonic shears, divide the muscle several millimeters medial to the fibula. Again, the vessel is up against the fibula at this point. And this will prevent inadvertent injury by dividing the post. Your in the flexor house was longest. Equally, the bone can be further and further mobilized and lateralized, which will give the surgeon more room for dissection at the termination of the flexor Haasis longest muscle, which is shown here, the perennial vessels start to diverge immediately away from the fibula to join the post tibial vessels. This is show this is showing the post tibial nerve and post tibial artery and vein immediately and the peral vessels up against the fibula laterally. The entire length of the poster tibialis muscle is divided up to the proximal bone cut. And at this point, the flap is only peta on its vasculature. Any perforating vessels coming off, the perennial immediately are divided and the fascia overlying the artery and vein is divided. So as to allow individual clamping and tying of these vessels, all of this has been done under tourniquet time. Tourniquet time should be kept under an hour and a half uh to prevent uh ischemic changes to, to the lower extremity. After isolating the vessels and dividing the fascia, then the turn it can be can be released and the flap can be allowed to rep perfuse. Typically, we allow the flap to rep perfuse for approximately 10 minutes. This allows several things. It allows them elimination of some of the ischemic uh metabolic products in the fibula to be cleared. And it also allows time for small vessels which are vasoconstricted to vasodilate at which point they can be recognized and controlled prior to cutting and insetting. The flat care should be assured uh that the post tibial vessels and anti tibial vessels are patented running at this point. The vessels can be divided and the flap can be taken to the back table or a contrary can be performed inside you. The advantage of performing contra inside you is that you can ensure that all the segments have adequate vascularization. While it's still in the leg to do this. We strip back the periosteum from the vessels to lengthen the pedicle. This is showing attachment of a cutting guide uh with um monocortical screws to the fibular segment. Once the cutting guide has been attached, then we do subperiosteal dissection around the segments that will be removed uh in the intervening segments that will be removed. In order to create the bony segments that we want. The periosteum should remain attached to the bony segments that are going to remain uh as part of the reconstruction and then stripped away from the intervening wedges that are gonna be taken to perform wedge osteotomies. And contrary to the fibula, an instrument is placed between the vasculature and the bone during cutting to prevent inadvertent injury to the saw. And the sale saw under irrigation is used to remove wedges uh that have been predetermined in their size and shape by previous planning and formation of the cutting guide, the osteotomy should be carried forth full thickness all the way through the bone so that these wedges can be completely removed, avoid the temptation to fracture the bone uh rather than completely removing the wedges as this will make contrary, more precise and even at the remaining segments, the proximal bone that's not gonna be incorporated into the flap is removed. And this allows lengthy in the peta, the more the proximal bone is removed, the longer the peta becomes after the flap is contoured inside you. Then the vessels are divided. We place two clips proximately and distally on each of the venom. We place pro two clips, proc uh excuse me distally on the perennial artery. And then we clamp and tie the proximal perennial artery in the patient. The two clips ensures that we know which vessels are gonna be used for anastomosis. Although this sounds obvious it can be confusing once the flap is detached and in inside into the patient, the flap is placed into a kidney basin with a wet salt and it can be taken to the back table. Use of a pre uh formed model to help bend the plate saves a lot of time. This is showing bending of the Titanium reconstruction plate to be contoured to the reconstruction model. After the plate is contoured to the reconstruction model, then we can ensure that it will fit precisely against the fibular segments that we've cut with the use of the cutting guide. The fibular segments are placed up against the model to ensure that we have the appropriate length and angles adjustments could be made at this point. If necessary. If the cutting guides were designed and used properly, then no adjustment should be necessary. And then the segments are plated with monocortical screws to the reconstruction plate that we've already bent and the construct is ready to be inset into the patient, uses screw as few screws as necessary into the bone to prevent devascularization or excess foreign material being implanted into the patient. A final check against the cutting guide ensures that we have the flap in its proper orientation and size in this uh flap. The vessels are gonna be brought an cheer to the opposite side of the neck. The pentacle is shown here inferiorly, it could be brought to the ipsilateral side of the neck as well or we could have designed the flap to have the vessels come out more approximately the skin paddle on this side of the um on the in this patient is going to be brought out immediately and used intraorally. The preform flap attached to its plate is then inset into the patient with monocortical screws. Skin setting is done in setting is done with mattress, vital sutures and now we're ready to perform vascular aosis. The feb flap typically has a single perennial artery and two veno comma which are fairly large in diameter compared to most of the other micro vester free flaps of the neck. That can be a nasty mos when we have the option of a nasty most in two veins, we usually take that option to give us more venous outflow and potentially salvage of a flap. If one of the venous outflows could become compromised, it's more common to have compromise of the vein than the artery. If you are gonna have any postoperative arterial problems, an appropriate size artery in the neck is selected as a donor artery, it's clamped with a microvascular of a traumatic clamp cut irrigated with heiny saline dilated with a vessel dilator. And the aven tissue is trimmed back for several millimeters to prevent incorporating the aven tissue into the anastomosis. Care is taken to make sure that the donor artery and the and the uh flap artery can meet each other with no tension. And then a O nylon microvascular suture is placed for running anastomosis. In most circumstances, if applicable, the anastomosis is initiated by placing two sutures 100 and 80 degrees apart and tied with three simple knots. The needle is left on the suture. The other suture is placed approximately 100 and 80 degrees from this suture and the needle is left on and then those two ends are run towards the surgeon, you know, running anastomosis. The assistant can uh help with the procedure by providing suction, tinting out the vessel irrigating with heroized saline and making sure the tension is taken off the vessels during anastomosis. This is the anterior portion of the arterial anastomosis showing tying the second suture 100 and 80 degrees apart. The keys to this anastomosis again are to provide a 10 free anastomosis. The vessels should have reasonable size match. They should not be redundant with kinking and they should not be under excessive amount of tension. Once the anterior anastomosis is run and tied to the opposing free end, the vessel is then flipped over uh and to see the backside of the uh artery at this point, it's inspected irrigated with heper saline. And then the poster anastomosis can be done flipping the clamps over allows the vessel ends to open up. And so that the surgeon can see both the external surface and the intima of the vessel. And again, it's irrigated with Heper saline at this point to ensure that no back wall sues have been placed and that the um backside of the anastomosis looks appropriate. The sutures should be evenly spaced. They should not leave any gaps uh that could leak. Once the claps are released, minimal tension is placed on the sutures, uh and then they'll all be tightened uh prior to throwing the final knot. After the arterial anastomosis is performed. The Venus anastomosis is typically performed with the help of a Venus coupler. An appropriately sized Venus coupler is chosen, there should be minimal tension on the vein. So choosing a Venus coupler is slightly smaller than the diameter of the vein. Uh is usually effective. The vessel ends are pulled through the coupler and then pulled out over the uh coupler pins and draped over and impaled over these pins on each side. Since the external uh since the portions of the vessel lateral to the pins will remain external to the anastomosis, the inner edge of the vein can be grabbed at this point. As opposed to the technique used for the artery anastomosis is irrigated with Heery saline. The coupler is closed and then a mosquito is used to crimp the couple to make sure that it is tight. Make sure at this point that the vein has not been twisted. And then the venous clamps are removed by removing the proximal and distal clamps off of each vein and then the flap side, clamp off the artery prior to removing the patient's donor side artery clamp. Make sure that you have a stitch in your hand that could be used to place quickly over any anastomotic leak. This is demonstrating filling of the flap. Usually with release of the clamps, there'll be some bleeding immediately from the muscle and the fibular free flap. There's a small hole in the flap artery just distal to the anastomosis here where a branching point uh was not appreciated. And the suture is gonna be placed through this hole uh to provide hemostasis. Don't be alarmed if there's some rapid bleeding from the flap at this point. Usually, this will slow down after several minutes. The flap should be irrigated with warm saline and any obvious arterial sources of bleeding. Bleeding should be sought out and managed with either clips or sutures. Typically uh immediately upon releasing the clamps. There'll be some vas of constriction and so we place gel foam soaked in papain around the vessels and irrigate with warm saline to help with the basal constriction. It may be useful to, to get the patient's blood pressure elevated by con conversations with the anesthesiologist at this point, the fibular free flap has its advantage as a very reliable and broad skin paddle that can be placed either intraorally or externally or both as the needs may be. The arterial vessels are a very reasonable diameter to match vessels in the neck. And it's the workhorse flap from anti reconstruction.