CC
A 67-year-old male is referred for evaluation of left perimandibular swelling, pain, and exposed intraoral bone.
HPI
The patient is a 67-year-old male with a history of cT2N1M0 SCC p16+ left base of tongue status after definitive concurrent chemoradiotherapy with weekly cisplatin 70 Gy to gross disease. He completed therapy with complete response. Unfortunately, he developed an area of osteoradionecrosis in his left mandible 1 year later and was treated with multiple rounds of superficial debridement by his dentist. Shortly thereafter, he developed a superinfection along the osteonecrotic left mandible with severe trismus requiring antibiotic therapy. Since then, he reports progressive inferior alveolar nerve numbness, including the left lower lip and chin distribution, left-sided persistent facial swelling, and severe trismus; he is unable to open his mouth more than 1 to 2 finger breadths.
Has been taking pentoxifylline and vitamin E for more than 1 month. He is also had 40 of 50 dives of hyperbaric oxygen therapy (HBOT). Unfortunately, his symptoms have worsened in the past several months. His main goals are to be able to eat, improve his facial function, be able to open his mouth, and improve his lower lip numbness.
PMHX/PDHX/medications/allergies/SH/FH
The patient has a history of hypertension and previous cutaneous squamous cell carcinoma (SCC) treated with Mohs surgery. As per his HPI, he was diagnosed with a stage I human papillomavirus–associated oropharynx SCC 2 years before this presentation and treated with definitive concurrent chemoradiation. He developed radiation-induced hypothyroidism and has been taking therapeutic levothyroxine for this.
In addition, he has been taking pentoxifylline and vitamin E for the past month. He is a never smoker and is a social alcohol drinker. He has no previous history of bleeding or clotting disorders, myocardial infarction, or cerebrovascular accidents.
He takes all his nutrition by mouth but requires liquids and purees since his cancer radiotherapy. In addition, his oral intake has reduced in the setting of new trismus, swelling, and pain with a 3- to 4-lb weight loss.
Examination
General. The patient is a thin male in no apparent distress. He has mild dysarthria.
Maxillofacial. There is left lower facial edema with overlying cutaneous erythema. The skin is thin and atrophic with superficial telangiectasias. The left upper neck is fibrotic, firm, and indurated, making lymph node examination difficult.
Intraoral. There is severe trismus with maximal incisal opening of 15 mm. Postradiation changes are noted. There is a 2-cm × 1-cm area of exposed bone on the lingual mandibular alveolus adjacent to the roots of teeth #18 and #19. This is painful to palpation with mild purulent discharge.
Nasal fiberoptic endoscopy. No obvious mass or lesion is identified. Postradiation changes are noted with lack of tonsillar and tongue base lymphoid tissue. He has smooth, desiccated mucosa with mild lymphedema. The vocal cords abduct and adduct symmetrically.
Extremities. Warm and atraumatic. No signs of edema, venous stasis, or arterial insufficiency. Normal male hair growth. Capillary refill is less than 2 seconds with 2+ palpable popliteal, dorsalis pedis, and posterior tibial pulses bilaterally.
Imaging
Orthopantomogram or cone-beam computed tomography (CBCT) of the maxillofacial skeleton is an excellent imaging modality to assess the osseous and dentoalveolar structures. When osteoradionecrosis is suspected, in-office CBCT is sufficient. When there is concern for deep abscess formation or neoplasia, a medical-grade CT scan with intravenous contrast is preferred. CBCT in this patient demonstrated a large area of “moth-eaten” bone in the left mandibular body and ramus. There is full-thickness involvement of the mandible from the buccal to the lingual cortex and the superior to inferior border. Although there does not appear to be fracture or displacement of the segments, there is almost certainly a pathologic fracture of the mandible, which is held in place by fibrosis and soft tissue ( Fig. 47.1 ).
There have been many proposed staging systems to help classify the severity of mandibular osteoradionecrosis, but one major common theme is the extent of bone destruction. Notani et al. described a commonly used staging system in 2003:
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Stage: 1: necrotic and exposed bone limited to the alveolus
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Stage 2: necrotic bone limited to the alveolus and mandible above the inferior alveolar canal
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Stage 3: necrotic bone extending below the inferior alveolar nerve canal, orocutaneous fistula, or pathologic fracture ( Fig. 47.2 ).
• Fig. 47.2 A, Stage III osteoradionecrosis of the left mandible of a different patient with a 3-cm area of exposed necrotic bone. Note the presence of failing anterior mandibular mini-implants. B, The same patient with a draining orocutaneous fistula from full-thickness mandibular osteoradionecrosis of the jaw (ORN) with pathologic fracture. C, Final reconstruction with an osteocutaneous free flap with externalized skin paddle to resurface the neck. In patients with orocutaneous fistula from mandibular ORN, it is nearly impossible to close the neck skin after resection. The radiation injury and fibrosis along with chronic inflammation from the fistula require the addition of imported vascularized tissue to close. In this case, the skin paddle from a fibula osteocutaneous free flap was used.
This patient’s ORN is classified as severe, or stage III, disease given the full-thickness mandibular involvement. It is also very common for patients to experience paresthesia of the inferior alveolar and mental nerves when this process encroaches on the canal. In most patients with stage III disease, the only treatment effective in eradication of this disease is surgical resection and vascularized flap reconstruction.
Labs
Routine preoperative laboratory examination includes a complete blood count, comprehensive metabolic panel, and coagulation studies. In patients with acute or chronic infection, inflammatory markers, including C-reactive protein or procalcitonin, can be used to trend and track response to therapy. In addition, patients who have received neck radiation or have documented hypothyroidism should have thyroid function tests to optimize levothyroxine dosage. Untreated hypothyroidism may lead to perioperative wound and cardiac complications. All laboratory study results in this patient were within normal ranges. Patients who have previously undergone chemotherapy may be less likely to develop leukocytosis in the setting of acute inflammation because of ongoing bone marrow suppression, making the white blood cell count a less useful marker.
Assessment
Stage III osteoradionecrosis of the left mandible with superimposed infection and worsening malnutrition.
Treatment
There has always been controversy in the optimal management of osteoradionecrosis. In the 1980s, HBOT was considered a backbone of therapy, though many clinical trials since then have failed to demonstrate efficacy. In addition, surgical debridement of ORN was used often to remove diseased bone in early-stage ORN, but this often led to further osseous insult and progression of disease. It is clear that stage III osteoradionecrosis will almost always progress to pathologic fracture or orocutaneous fistula, which can result in significant impairment in function and quality of life. There is a plethora of data supporting radical resection (segmental osseous resection) and immediate microvascular tissue transfer of stage III ORN with a 95% to 100% success rate in complete resolution of disease. It is important to note that in patients with ORN, there is significant soft tissue radiation injury, making postoperative wounds, infections, and dehiscence more common. The use of HBOT in the perioperative period may improve wound healing in these instances but is not effective in treating osteoradionecrosis.
In this patient, the treatment plan included left segmental hemimandibulectomy with immediate reconstruction with an osteocutaneous fibula free flap, immediate dental implant placement, and inferior alveolar nerve allograft. Because this patient had baseline dysphagia from oropharyngeal cancer treatment and worsening trismus, a gastrostomy tube was placed at the beginning of surgery.
As in most modern jaw resection and reconstructions, computer-aided surgery is used to improve accuracy and predictability. In this case, 1-cm osseous margins from radiographically necrotic bone were marked to ensure complete resection. The decision was made to preserve the mandibular condyle; if one can place two screws in this segment, it is preferable to preserve viable condyle to prevent postoperative open bite or lateral migration of the reconstructed mandible.
In cases of ORN, it is preferred to minimize soft tissue dissection because the tissue envelope is radiated and hypovascular. Rather than a large apron neck incision or lip split for access, transoral subperiosteal dissection with vestibular release is used to expose the majority of the mandible to be resected. A conservative neck incision is made over the planned recipient vessels for microvascular anastomosis; this is also used to make the posterior mandibular osteotomy if needed. This combined approach minimizes disruption of the cutaneous blood supply in an irradiated neck, thereby reducing the risk of neck wound dehiscence or fistula formation. The procedure used of cutting jigs with predictive holes and custom patient specific reconstruction plates allows inset of the osseous free flap with minimal access. It is important to design low-profile cutting jigs that can be adapted through transoral or small cervical access.
Often, fibrotic tissue and scar must be sharply excised from the wound bed after the mandibulectomy to make sufficient space for the flap inset. Unlike normal tissue, radiated tissue has little compliance and does not stretch to adapt the free flap. If the soft tissue envelope is too tight, compression of the flap and associated vasculature may lead to venous compromise and failure.
Although many patients with mandibular resection and reconstruction can commence oral intake 2 to 5 days after surgery, patients with ORN should maintain nothing by mouth status for 1 to 2 weeks postoperatively. As previously stated, wound dehiscence at the junction of radiated tissue is more common in this population and may result in salivary leak, infection, or fistula. In addition, patients who have been irradiated have some baseline oral or pharyngeal muscle fibrosis. Postsurgical edema and inflammation magnify this, resulting in significant dysphagia, at least transiently. If the oral cavity tissue appears sealed on clinical examination at 1 to 2 weeks after surgery, oral trials with the aid of a speech-language pathologist are initiated. The patient should remain on a nonchew diet for 8 weeks to allow adequate time for hard callous formation between the osseous flap and native jawbone ( Figs. 47.3 to 47.8 ).
