Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_892_Библиотеки_им_академика_М_И_Перельмана

ap reconstruction as high as 25% in the mandible, with 70% occurring in the unre­sected, previously unaffected, proximal segment. This can present an additional echelon of complication if the continued ORN occurs in a bony segment that has already been dentally rehabilitated, as now the surgeon and dentist must address the potential loss and replacement of dental implants and a new prosthesis, adding not only the need for additional surgical procedures but also supplementary expense for the patient. Unfortunately, progression of necrosis and tissue damage is difcult to account for and predict. Preoperative assessment via clinical examination and imag­ing provides the best tool to assess the extent of disease and should be carefully evaluated to ensure adequate resection margins. Moreover, it is extremely crucial that recurrent malignant disease is ruled out preoperatively with biopsies if indi­cated, as it has been reported that up to as much as 3.4% of ORN resection speci­mens demonstrate the presence of malignancy upon postoperative histopathological examination [27]. Some surgeons may opt to minimize the extent of surgery by performing a more conservative resection, for example, to retain the proximal seg­ment (if uninvolved) to avoid a disarticulation mandibular defect to reconstruct and to maintain the patient’s natural joint articulation, given some studies that have shown increased rates of complications and patient morbidity after total condylec­tomy and reconstruction [28]. Others may choose to limit the amount of resection to maximize the dental rehabilitation for the patient by being conservative on the amount of dentate segment they resect. While these approaches can provide some benet, they must be weighed with the possibility of progression of the osteoradio­necrosis within those unresected nearby segments of the bone. Intraoperatively sur­geons will often resect to “bleeding bone,” which frequently indicates healthy tissue; however given the progressive nature of this disease process, this does not guarantee long-term success. Moreover, it is difcult to assess for bleeding from the proximal segment, in particular the condylar region, as this is dense cortical bone with little to no marrow space. Additionally, decreased blood supply to the proximal segment due to compromise of the inferior alveolar vessels and stripping of perios­teum during hardware xation can contribute to hypovascularity and necrotic changes in the future. Given these ndings, many surgeons have become more aggressive with their resection margins and have a lower threshold to resect the proximal segment of the mandible, especially if the ORN extends to the angle or into the ramus and have noted that postoperative function is grossly unaffected with a good composite free ap reconstruction. A recent study by Tang etal. [29] looked at 48 patients who underwent bula ap reconstruction of the mandibular condyle and assessed both changes in the neo-condylar position and function and concluded that despite slight changes in bula condyle positioning, patient’s postoperative function was intact. Additionally, the free osseous ap can be used in combination with a joint prosthesis in order to reconstruct the condylar segment (Fig.12.13). Moreover, with all the advances in dental implants and prosthetics, it is certainly acceptable to maintain at least a 1cm margin from obviously involved necrotic bone during resection and even be slightly more aggressive in resecting more of the ORN-adjacent dentate segments of the jaws if questionable. It is much easier deal­ing with a slightly larger defect on the front end, rather than having to navigate

being treated with radiation for malignancy often inherently have issues with mal­nutrition, whether from the cancer diagnosis itself causing weight loss or as a result of dysphagia and odynophagia from the radiation therapy itself. A plan for both preoperative nutritional assessment and optimization and the route of postoperative nourishment should be planned ahead of time. Not only can this have an effect on the overall health of the patient but also has been shown to affect rates of microvas­cular free tissue transfer success, as low prealbumin levels have been demonstrated as a risk factor for free ap failure [32]. Percutaneous endoscopic gastrostomy (PEG) tubes may be useful in these patients and can either be placed preoperatively for improvement of nutritional status before surgery or at time of surgery to opti­mize postoperative feeding. If patients have been on medical treatment for their ORN (i.e., pentoxifylline-tocopherol or PENTO protocol, as well as antibiotics), these should not be interrupted until the day of surgery and can be continued post­operatively if indicated.

Postoperative free ap healing with bony union also presents as a concern in patients with MRONJ, given that many of these patients are immunocompromised, either due to concomitant use of steroids, chemotherapy regimens, or simply by virtue of having advanced stage cancer in itself. Furthermore, some authors state that the risk of nonunion is higher in this cohort of patients given the systemic nature of delivery of anti-resorptive and anti-angiogenic medications such that both the recipient bone and the donor bone likely demonstrate generalized uptake of these agents and thus may have issues with adequate bone turnover and thus bony healing. However despite this claim, reports in the literature do not support this postulation, as the incidence of poor healing and nonunion of bony segments after osseous reconstruc­tion in MRONJ is only about 5–6.5%, with the rate of resultant stula formation only at about 10% [47]. The concept of a “drug holiday,” namely, stopping the offending anti-resorptive and anti-angiogenic medications about 6–9months prior to undergoing resection and free ap reconstruction, has been suggested; however denitive evidence that this helps in increasing the incidence of healing and decreas­ing complication rates is still not available and, as such, is not widely practiced. Additionally, given the higher risk of postoperative complications secondary to patients’ immunocompromised status, discussion with the patients’ oncologist regarding optimal chemotherapy and immunosuppressive regimens is encouraged, though the overall patient condition should always be taken into account and should not be compromised. The role of HBO in MRONJ has not yet been fully elucidated; however it has been studied in the context of more conservative treatment such as medical management and localized surgical interventions such as debridement and sequestrectomy. In a randomized control trial, Frieberger etal. [48] assessed the use of HBO as an adjunct to conservative surgical procedures and antibiotic therapy and concluded that HBO did play a role as part of multimodal therapy in severe cases. However no studies have yet been done to evaluate its role as an adjunct to more extensive surgical procedures such as large resections and free vascularized ap reconstruction. In addition to bony healing, the quality of the overlying and adjacent soft tissues should be taken into consideration, as bisphosphonates have been shown to have a negative effect on oral mucosal healing [49], which could precipitate wound breakdown, plate and bone exposure, and infection. As such, osteotomies should ideally be placed in areas where the vascular supply is robust, such as areas of muscle attachment, and they should be at least 1cm away from any tooth [50].