Mandibular Reconstruction with Fibula Free Flap in a Patient with Severe Peripheral Vascular Disease
A 62-year-old man with a T3N1M0 squamous cell carcinoma of the left tonsil is scheduled for composite resection including segmental mandibulectomy from the angle to the parasymphysis. His comorbidities include insulin-dependent diabetes mellitus (HbA1c 9.2%), hypertension, and severe peripheral arterial disease with an ankle-brachial index (ABI) of 0.45 on the right and 0.50 on the left. He has a history of smoking (60 pack-years, quit 2 years ago) and a prior coronary artery bypass graft using the left internal mammary artery. Physical examination reveals absent dorsalis pedis and posterior tibial pulses bilaterally, but the skin of the feet is intact with no ulcers. CT angiography of the lower extremities shows severe calcific atherosclerosis of the superficial femoral and popliteal arteries bilaterally, with reconstitution of the peroneal artery via collaterals but no direct continuity from the popliteal to the peroneal artery on either side. The anterior tibial and posterior tibial arteries are occluded bilaterally. The plastic surgery team is consulted for mandibular reconstruction.
1. What are the options for mandibular reconstruction in this patient, and what is the most appropriate choice given his vascular status? Justify your answer with anatomical and physiological reasoning.
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Options for mandibular reconstruction include: (1) vascularized free flap (fibular, iliac crest, scapular, or radial forearm), (2) non-vascularized bone graft (e.g., rib, iliac crest) with or without a titanium reconstruction plate, (3) reconstruction plate alone (with or without soft tissue coverage), and (4) pedicled flaps (e.g., pectoralis major myocutaneous flap, submental island flap) for soft tissue only, not bone.
Given the patient's severe peripheral arterial disease with ABI <0.5 bilaterally and CT angiography showing occlusion of the anterior and posterior tibial arteries and only collateral reconstitution of the peroneal artery, a fibula free flap is at high risk of ischemia. The peroneal artery is the sole supply to the fibula, and its dependence on collaterals indicates inadequate inflow for a free flap. Although the peroneal artery is often spared in PAD, the severe calcific disease and absence of direct continuity from the popliteal artery suggest that the flap would likely fail due to inadequate perfusion. Therefore, a fibula free flap is contraindicated.
The next best option is a non-vascularized bone graft, but this requires a well-vascularized recipient bed and is associated with higher rates of resorption and non-union, especially in a previously irradiated or contaminated field (not the case here, but the patient has diabetes and smoking history, which impair healing). A reconstruction plate alone provides immediate stability but has a high rate of plate exposure and fracture, particularly in the mandible, and does not restore bone continuity for osseointegrated implants.
Another alternative is a scapular free flap, which can provide bone and soft tissue. However, the scapular blood supply (circumflex scapular artery) may also be affected by atherosclerosis, though less commonly than the lower extremities. Preoperative assessment with CT angiography of the upper extremity would be necessary. If the upper extremity vessels are adequate, a scapular free flap could be considered. However, the patient's severe systemic atherosclerosis may also affect the subscapular system.
A reasonable choice is a reconstruction plate combined with a pedicled pectoralis major myocutaneous flap for soft tissue coverage, accepting the risks of plate exposure and the need for future revision. Alternatively, a non-vascularized bone graft (e.g., iliac crest) with rigid fixation and soft tissue coverage could be used, but the patient's diabetes and smoking history increase the risk of non-union.
Ultimately, the decision should be individualized. The most appropriate choice is likely a reconstruction plate with pedicled soft tissue coverage, because it avoids the high risk of free flap failure and provides reliable soft tissue coverage. However, if the patient is motivated and the upper extremity vessels are suitable, a scapular free flap could be attempted after careful preoperative planning. The key is to avoid the fibula free flap due to inadequate peroneal artery inflow.
2. If the patient were to undergo a fibula free flap despite the vascular findings, what technical modifications could improve the chance of success? Discuss the role of preoperative vascular mapping and intraoperative decision-making.
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If a fibula free flap is attempted despite the poor vascularity, several technical modifications could be considered:
Preoperative vascular mapping: CT angiography is essential to assess the peroneal artery and its collaterals. If the peroneal artery is reconstituted via collaterals but has adequate caliber and flow, it might still be usable. However, the absence of direct continuity from the popliteal artery is a poor prognostic sign. Magnetic resonance angiography (MRA) or digital subtraction angiography (DSA) could provide more detailed information about the collateral network and the quality of the peroneal artery. If the peroneal artery is of good caliber and has a strong pulse, it may be suitable.
Intraoperative assessment: Before committing to the flap, the surgeon should assess the peroneal artery directly. A handheld Doppler can be used to locate the peroneal artery preoperatively. Intraoperatively, after exposing the peroneal vessels, the surgeon should assess the quality of the artery (palpation, Doppler, and possibly a milrinone or papaverine infusion to relieve spasm). If the artery is severely calcified or has poor flow, the flap should be abandoned.
Alternative recipient vessels: If the peroneal artery is inadequate, the surgeon could consider using the contralateral fibula if it is less affected, or another flap. However, the patient has bilateral disease.
Technical modifications for the fibula flap: The fibula flap can be harvested with a skin paddle that is monitored for perfusion. If the skin paddle shows signs of ischemia, the flap can be revised or abandoned. The surgeon should be prepared to convert to a reconstruction plate and soft tissue flap.
Postoperative monitoring: Close monitoring with clinical assessment and possibly implantable Doppler or near-infrared spectroscopy can detect early ischemia.
Consideration of endovascular intervention: In selected cases, preoperative angioplasty or stenting of the peroneal artery could improve inflow, but this is not standard and carries risks.
Ultimately, the high risk of flap failure should prompt consideration of alternative reconstructive methods. The decision to proceed with a fibula free flap in this patient would be fraught with danger and should only be undertaken after thorough informed consent and with a clear backup plan.