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Radiation therapy is often a critical component in the management of advanced head and neck malignancies, however, this potentially lifesaving treatment carries the risk of osteoradionecrosis (ORN). The classic presentation of this complication is late onset bone exposure through oral mucosa or skin which does not heal for at least 3 months. The mandible is the most common site of ORN due to a number of factors including bone density, adjacent and often compromised dentition and higher radiation dose given its proximity to oropharyngeal tumors. Other areas affected with relative frequency include the maxilla (in the case of facial and maxillary tumors) and the anterior spine (in the case of nasopharyngeal tumors).
Various theories of ORN pathophysiology include infection, hypocellularity of bone, and radiation-induced free radicals as contributing factors. However, there appears to be consensus that tissue hypovascularity and ischemia plays a major role.1,2 As a result, current accepted management strategies for moderate mandibular ORN involve debridement of necrotic bone, antibiotics and implementation of hyperbaric oxygen (HBO) therapy to improve oxygen delivery to affected tissues. This treatment pathway, however, remains controversial, as randomized controlled studies have not demonstrated clear advantage of HBO over placebo.3 Despite this uncertainty, no routinely employed and effective alternatives have been described.
The success of free tissue transfer in managing advanced stage mandibular ORN (i.e., requiring segmental bone resection and replacement) has been well-established. However, the morbidity, complexity and cost of these free osteocutaneous flap reconstructions has restricted their use to end-stage disease, when all other options have been exhausted. Unfortunately, at this point of the disease process, often after years of recurrent inflammation and scarring has set in, patients are commonly left with persistent trismus, pain and oromotor dysfunction, despite successful reconstruction.
New techniques in free tissue transfer, many of which have been developed and promoted by the Cleveland Clinic Head & Neck Institute, have dramatically reduced patient morbidity and have shortened both operative times and postoperative hospital stays. We have described minimal access approaches to isolate vessels for microvascular perfusion, advances in free anterolateral thigh (ALT) fascia perforator flaps for mucosal reconstruction, and maintenance of high flap success rates with abbreviated hospital stays.4-7 These advances have decreased overall treatment-related costs and patient morbidity. As a result, the indications for these “minor” free flap surgeries have continued to expand.
Using the novel methods described above, we first employed debridement of mandibular ORN and reconstruction with free vascularized fascia in a patient who experienced retinal detachment during HBO treatment (further HBO was contraindicated). Critically, radiographic imaging demonstrated sufficient unaffected bone to maintain mandibular stability following debridement and extraction of dentition within the affected area. (See Case 1 below.) Following hospital discharge on postoperative day No. 1 and an uneventful recovery, he has remained symptom-free for the past six years. His follow-up imaging has demonstrated full retention of remaining bone.
Since this time, we have successfully employed this method on 21 of 22 patients with mandibular, maxillary and skull base ORN, with one patient progressing to segmental mandibular resection and reconstruction due to persistent debilitating pain (despite full bone coverage and no evidence of infection). Critically, this minimal access rescue procedure does not preclude or impair larger resection and reconstruction if needed.
This patient was a 58-year-old male with moderate to severe ORN who developed retinal detachment while undergoing hyperbaric oxygen therapy, precluding further treatment. The steps of his procedure are outlined below.
Several strategies were employed to optimize outcomes in the setting of moderate ORN. First, debridement was performed to thoroughly remove all devitalized bone and mucosa via a transoral technique. Mandibular periosteum was otherwise maintained undisturbed to minimize further disruption of vascularity of remaining bone. Next, a robustly vascularized and thin ALT fascia lata perforator flap was harvested, critically avoiding any muscle bulk on the vascular pedicle to allow passage through a tunnel created between the vessel access point and the oral defect. A minimal access incision was employed to isolate superficial temporal, angular or facial vessels, with care taken to avoid areas severely affected by post-radiation fibrosis and induration. Vascularized fascia was then folded into the defect, secured to the surrounding mucosa and either allowed to mucosalize or capped with a full thickness skin graft obtained from the same thigh harvest site.
Following surgery, patients are extubated, as the folded fascia flap incurs minimal bulk and limited surgical exposure for both debridement and vascular access minimizes postoperative edema. Patients typically begin a liquid diet immediately postoperatively and remain on a mechanical soft diet (to minimize trauma to the reconstruction) for 3-4 weeks. Once ambulating without issues and able to perform wound and drain care (thigh drain remains for one week), they are discharged home, with most patients leaving on postoperative day 2 or 3.
Importantly, this “minor” free flap reconstruction has several criteria which dictate a successful outcome. First, sufficient viable bone must be present following debridement to maintain mandibular stability. Computed tomography and panorex imaging is performed preoperatively to assess this likelihood, with candidates needing at least 1 cm of unaffected bone at the inferior mandible to be considered for this technique. If a patient appears borderline in terms of viable bone stock, the addition of iliac crest bone grafting is also discussed. This supplemental procedure provides the potential to add healthy bone progenitor material to re-enforce remaining mandible. Second, significant complications related to longstanding ORN such as severe trismus or chronic neuropathic pain may undermine outcomes, as these conditions do not appear to improve following revascularization. In these cases, segmental mandibular resection and reconstruction appears to be a better option.
We recently reviewed our early experience with the mandibular rescue flap technique, with eight patients having at least three years of post-surgical follow-up. In all of these patients, debridement of ORN and free ALT fascia flap reconstruction was performed as described. Six of eight patients had failed previous debridement and HBO therapy. In the postoperative period, one patient experienced free flap compromise (vessels utilized were isolated from a heavily irradiated tissue bed), which was addressed with a successful re-do ALT flap. Another patient was readmitted for aspiration pneumonia related to baseline dysphagia exacerbated by intubation. Otherwise, there were no perioperative complications.
On follow-up, all patients retained fully mucosalized bone, with elimination of recurrent pain, edema and infection. Serial radiographic imaging has demonstrated maintenance of bone viability, and in some instances, increased bone density over time. One patient, a poor candidate for more extensive procedures due to medical comorbidities, had minimal viable bone after debridement and despite oral healing, demonstrated a fracture on postoperative panorex. In this instance however, the fracture healed without further intervention and minor bite adjustment was performed in an office setting. Critically, in all patients, there has been no evidence of recurrent ORN and no need for further surgery or hospital admission related to this disease process.
As previously discussed, standard management for moderate ORN involves bone debridement and HBO therapy, with typically 40 sessions (aka dives) required. Not only does this therapy involve a significant financial cost, but the social implications of several weeks of treatment lasting 2-3 hours each are not insignificant. We compared the costs of surgery and hospital stays for the last five patients in our study to standard costs for our patients undergoing 40 dives of hyperbaric oxygen therapy. On average, surgical management incurred 26.2 percent of the cost of HBO. Furthermore, patients typically returned to normal activity within a week of surgery.
As this technique appears to be effective over time, we have begun to offer this option routinely to patients with moderate ORN that has failed previous HBO therapy. We also consider this technique in patients who have more severe ORN and are unlikely to respond to HBO yet appear to possess adequate unaffected bone to maintain stability. Patients who will have significant defects following debridement are also offered supplemental iliac crest cancellous bone grafts. Importantly, those patients with severe chronic neuropathic pain (in the absence of infection) and those with profound trismus are not considered for this operation.
Given early success, we feel the anterolateral thigh fascia lata rescue flap merits strong consideration as an intervention for moderate ORN. It has the potential to arrest ORN and prevent long-term sequelae of pain, trismus and oral motor dysfunction commonly seen in late stage patients, even after successful treatment and reconstruction. Rapid recoveries and consistent positive outcomes have underscored the value of this operation. Importantly, this technique does not impair further resection and reconstructive surgery should this be required.
A 62-year-old male patient suffered from widespread moderate ORN persistent after previous debridement and hyperbaric oxygen therapy. He also had many devitalized and fractured teeth in need of extraction with several foci of exposed bone bilaterally necessitating aggressive mandibular debridement from angle to angle. The steps of his procedure are delineated in this slideshow. He remains symptom-free over five years following the rescue flap procedure.
Dr. Fritz is a staff surgeon with the Section Facial Plastic and Microvascular Surgery in the Head & Neck Institute and Associate Professor of Surgery for the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University.
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