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Keywords:

  • Osteoradionecrosis;
  • fibular free flap;
  • osteoradionecrosis of mandible;
  • bilateral mandible osteoradionecrosis;
  • microvascular surgery

INTRODUCTION

  1. Top of page
  2. INTRODUCTION
  3. CASE REPORT
  4. DISCUSSION
  5. CONCLUSION
  6. BIBLIOGRAPHY

Osteoradionecrosis (ORN) of the mandible is reported to occur in approximately 5% of the patients who undergo external beam radiation therapy for a head and neck malignancy.1 The management of ORN is based on the clinical stage at presentation and response to initial management. We utilized the Marx staging system and treatment algorithm to guide our decision making.2, 3 In recent years, it has been our philosophy and that of others to perform a segmental mandibulectomy with an immediate reconstruction utilizing the transfer of vascularized bone for patients with Marx stage III disease.4–6 We feel that the placement of vascularized tissue into this unfavorable environment has greatly improved our outcomes in patients with advanced ORN.7

CASE REPORT

  1. Top of page
  2. INTRODUCTION
  3. CASE REPORT
  4. DISCUSSION
  5. CONCLUSION
  6. BIBLIOGRAPHY

A 72-year-old woman presented with a past medical history of cancer of the tonsil, 4 years prior, which had been treated with opposing fields of external beam radiation therapy. Although she had remained free of cancer, she developed exposure of the lingual surface of both bodies of her mandible. She was diagnosed with bilateral ORN and treated by an outside physician with hyperbaric oxygen, antibiotics, and local debridements with no improvement. For the 6 months prior to presentation to our head and neck cancer center she developed increasing pain, trismus, and anesthesia of the lower lip. The patient had advanced ORN of her mandible with the epicenter of the disease involving the full height of the mandible body, bilaterally. The central segment (symphysis) did not appear to be involved either clinically or radiologically, and the gingiva appeared healthy (Fig. 1). This patient was classified with Marx stage III ORN of the mandible body, bilaterally. We approached this situation with the intention of performing separate segmental mandibulectomies, with preservation of the native symphysis, and a reconstruction using a single fibular free flap to address both mandibular defects.

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Figure 1. Preoperative panorex.

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To accomplish this goal, we first performed a right segmental mandibulectomy and then harvested a fibular osteocutaneous flap with as much bone and pedicle length as we could safely recruit. We then performed a single osteotomy in the fibula creating a proximal segment of fibular bone that matched the right segmental defect. We inset the proximal segment of the fibula into the right segmental defect and then revascularized the flap. After revascularization, the entire length of fibula was robustly bleeding bright red blood from the marrow, periosteum and surrounding soft tissue. Because we were confident that the bone flap was healthy and well vascularized, we proceeded with the contralateral (left) segmental mandibulectomy. It was unclear if the central segment (symphysis) of the mandible would remain viable after removing both inferior alveolar arterial supplies to the bone. We had a contingency plan to resect the native symphysis if it was not viable and replace the entire mandible from angle to angle with our fibular free flap. Fortunately, this scenario did not materialize and the native symphysis remained viable.

We performed a subperiosteal dissection along the central segment of the fibula and removed 6 cm of fibular bone. This maneuver allowed us to establish two freely mobile segments of fibular bone connected by the peroneal artery, paired venae comitantes, and periosteum (Fig. 2). It was unclear if the distal segment of bone would remain viable, therefore, we were prepared to leave the left mandibulectomy defect without a bony reconstruction temporarily and to return at a later date to perform a second vascularized bone flap. Fortunately, both the distal and the proximal segments bled robustly from the marrow, periosteum and surrounding soft tissue allowing us to inset the distal segment into the left mandible defect with the connecting pedicle and periosteum draped across the submentum (Fig. 3). The patient had an uneventful postoperative course. To date, there appears to be bony union both clinically and radiologically, and there has been no evidence of ORN progression at the native symphysis (Fig. 4).

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Figure 2. (A) Illustration of fibular free flap with skin paddle and (B) central segment removed with a resulting periosteal sling. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

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Figure 3. Illustration of bilateral segmental defects reconstructed with a single fibular free flap. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

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Figure 4. Postoperative panorex.

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DISCUSSION

  1. Top of page
  2. INTRODUCTION
  3. CASE REPORT
  4. DISCUSSION
  5. CONCLUSION
  6. BIBLIOGRAPHY

After an extensive review of the literature we have concluded that this is the first publication reporting a reconstruction of bilateral segmental mandible body defects in a single stage with a single fibular free flap. There were a variety of different strategies that we could have used to approach this situation. Each segmental defect could have been reconstructed with a separate bony free flap in a single procedure or in a staged fashion. Either one or both of the segmental defects could have been reconstructed with an allograft rather than a vascularized bone flap. Additionally, the native symphysis could have been resected regardless of its viability, allowing for the much more common scenario of an angle-to-angle defect, which is traditionally reconstructed with a single fibular free flap.

It had been our intention from the outset to perform a single definitive procedure without the need for multiple free flaps or the need to perform a staged reconstruction. Additionally, we felt it was important to preserve the native symphysis, because this segment of the mandible serves as an anchor for both the tongue musculature and the larynx, and if this segment was removed the patient would have been at a much higher risk for speech and swallowing dysfunction as well as obstructive sleep apnea. By executing this approach we were able to significantly decrease the short- and long-term morbidity that this patient encountered and reduce the overall cost to the healthcare system by performing a faster and more efficient procedure.

The blood supply to the fibula is favorable to performing osteotomies that create multiple independent vascularized bone grafts, which are connected by a single pedicle. The fibula flap is based on the peroneal artery and two veins that run parallel to the bone. The peroneal artery provides a nutrient artery, which enters the fibula just proximal to the midpoint of the shaft. Periosteal vessels arise from the continuation of the artery and pass circumferentially around the fibula. It has been demonstrated that an osteotomy can be made distal to the entry of the nutrient artery to produce two separate struts, both of which remain vascularized.8 The proximal strut is vascularized by the nutrient artery, and the periosteal arteries provide both endosteal and periosteal circulation. The distal segment is vascularized by the periosteal vessels passing circumferentially around the fibula from the distal continuation of the peroneal artery and by perfusion through the connected periosteum. Hence, one can remove a central segment of fibula and preserve the periosteum and muscle, which had encased that segment allowing for the two remaining segments of bone to continue to be well vascularized (Fig. 2).

CONCLUSION

  1. Top of page
  2. INTRODUCTION
  3. CASE REPORT
  4. DISCUSSION
  5. CONCLUSION
  6. BIBLIOGRAPHY

To the best of our knowledge, this is the first publication reporting the treatment of bilateral segmental mandible body defects using a single fibular osteocutaneous free flap. We believe that this is an effective and reliable technique for dealing with bilateral segmental mandibulectomy defects.

BIBLIOGRAPHY

  1. Top of page
  2. INTRODUCTION
  3. CASE REPORT
  4. DISCUSSION
  5. CONCLUSION
  6. BIBLIOGRAPHY