PATHOLOGICAL MANDIBULAR FRACTURES: A RETROSPECTIVE STUDY

Pathological mandibular fractures occur in regions with previously damaged bone structure due to different etiologies. The purpose of the study is to present a retrospective review of patients with pathological mandibular fractures who passed through the Clinic of Oral and Maxillo-facial Surgery of St. George University Hospital, Plovdiv, for the period 2005-2019 and to compare the results with published literature. Material and methods: The study includes1328 patients with pathological fractures of the mandible with different etiology. Data were collected on age, gender, pre-existing bone damage and lesions, history of any interventions of the lower jaw and treatment approach. Results: Patients with pathological mandibular fractures are 5,1% of all patients who passed through the clinic for this period. Two hundred of them are associated with benign or malignant bone tumors, 161 with osteomyelitis, 202 with other causes: third molar extraction, implant placement, osteonecrosis. Conclusion: Pathological mandibular fractures have different etiologies. Diagnosis and treatment of this condition are challenging, and the treatment plan should be decided individually, according to the underlying disease.


INTRODUCTION:
Pathological fractures of the lower jaw represent a very small percentage of all mandibular fractures. They occur in places where the integrity of the bone structure is damaged as a result of another primary process [1]. The most common reasons for this can be divided into: non-tumor and tumor causes. Various interventions in the area of the facial skull, such as extraction of the third molar, osteonecrosis in radiation therapy, osteomyelitis, etc., can lead to a violation of bone integrity. Tumor causes include both benign -most often bone cysts, and malignant, primary or metastatic tumors.
In this article, we will present our experience in pathology, diagnosis and treatment of patients over a 15-year period. The treatment of these patients is challenging and is judged depending on the etiology of occurrence [2,3,4,5].

MATERIALS AND METHODS:
The study includes 1328 patients with pathological fractures of the mandible, who passed through the Clinic of Oral and Maxillofacial Surgery of St. George University Hospital for the period 2005-2019 -5.1% of the total number of patients who passed through the clinic for this period. Of these, the most common are fractures as a result of tumor processes -200 patients, followed by osteomyelitis of the bone -161 patients.

Mandibular fractures associated with tumors
Pathological fractures of the lower jaw associated with benign bone tumors are extremely rare-25 for the fifteen-year period. In the group, we also include the only 5 patients with cystic findings. They are all men, mean age 52.6 years (range18-72 years), respectively with: residual cyst (2 patients), aneurysmal bone cyst (1 patient), odontogenic cyst (1 patient), follicular cyst (1 patient). Of the remaining benign tumors, hemangiomas and ossifying fibroids are the most common.
Pathological fractures based on a cystic lesion occur before surgical removal [6]. The sites of occurrence in these cases are mainly in the area of the mandibular angle and body and relatively less frequently in the area of the symphysis and condyles [7]. Surgical treatment of these patients is divided into two types: -in the presence of sufficient underlying healthy bone, open reduction and internal fixation is performed in combination with removal of the cystic formation; -in case of insufficient underlying healthy bone tissue or a large bone defect, resection of the involved areas and subsequent reconstruction [1].
Pathological fractures, as a result of malignant tumor formations, are mainly due to metastatic tumors in the mandible. Primary tumors originate as follows: thyroid gland (19%), breast (23%), squamous cell carcinoma (31%), lung cancer (19%) and others (8%). The affected anatomical areas are the mandibular angle, followed by the body and the condyles. The mean age of the patients was 62.14 years, range 18-87 years. Men are more often affected, and in malignant tumors, the frequency of involvement is approximately the same for both sexes (Table 1). https://doi.org/10.5272/jimab.2022281.4276 Surgical treatment of this group of patients depends on the underlying pathological process and is often limited due to the general condition of the patients, as metastases in the area of the madibula are the result of advanced primary neoplastic processes. Radical removal of the tumor formation by segmental resection of the mandible and selective or radial lymphatic cervical dissection is defined as the 'gold standard' for treatment if the tumor formation allows it [1]. Depending on the underlying pathological process and the TNM stage of the patient, reconstruction of the jaw is performed using the bone structure of the fibula and subsequent chemotherapy or radiation therapy. Very often, however, the general condition of the patients does not allow this (Fig.1, Fig.2)

Mandibular fractures associated with osteomyelitis
Osteomyelitis of the mandible can develop as a result of untreated or improperly treated primary infection [3,5]. This weakens the bone and leads to subsequent pathological fracture. Several predisposing conditions could lead to the development of osteomyelitis of the mandible -diabetes, immunodeficiency, osteogenesis imperfecta, and others [8].
The mean age of patients with pathological mandibular fracture based on osteomyelitis is 50.7 years, range 19-78 years; males are significantly more affected. The fracture sites are the mandibular angle and the body. (Table 2) The treatment plan begins with a course of antibiotics, if possible, after an antibiogram for a minimum of 6 weeks and preferably intravenous administration [1]. The restoration of the fractured area depends on the condition of the bone. If necessary, sequesterectomy or resection of the affected area is performed. The newly obtained bone defect can be filled with a 2.4 mm mandibular plate with subsequent reconstruction, simultaneously or in stages, depending on the general condition of the patient. According to Ogasawara and co-workers, closed replacement with intermaxillary fixation is recommended as a treatment for the pathological fracture associated with osteomyelitis to avoid future ischemic necrosis at the site of reconstruction [3].
Mandibular fracture, as a result of implant placement, is also rare. Females are more often affected, mean age 59.1 years. The reason for this is significant resorption of bone tissue, with a thickness of the anterior part of the mandible less than 12 mm, due to which the ratio between implant length and the distance to the occlusal plane is compromised resulting in unfavorable biomechanics [5]. The fractures are more often in the symphysis. In fact, a large proportion of mandibular fractures result from the placement of dental implants in the symphysis area due to bone depletion in this area to perform an overdenture prosthetic rehabilitation [5,11,12]. There is variability in the time of onset of the fracture: from 3-6 weeks to 3 months after implant placement, and one case of fracture at the time of placement. There are several ways to treat this type of fracture, the choice is individual and based on the history of a particular patient. Open reduction and internal fixation via an extraoral approach is the most frequently adopted treatment option [5], followed by conservative treatment and bone graft with fixation.
Mandibular fractures resulting from osteonecrosis -osteoradionecrosis (ORN) or bisphosphonate-related os-teonecrosis of the jaw (BROJN) are not uncommon. They are found in adult patients, mainly with progressive diseases, wallowing disorders, a result of previous surgery and/or radiation therapy. Treatment includes coverage of the main pathological problem requiring surgical intervention or radiotherapy, followed by the restoration of the function of the mandible and the ability to resume chewing, speech and facial proportions.
Oral bisphosphonates are the most commonly prescribed antiresorptive drugs for the treatment of osteoporosis. However, there are several adverse effects associated with oral bisphosphonates, including BRONJ. With a better understanding of this side effect, reported incidences for BRONJ in oral bisphosphonate users have in-creased in time. Several risk factors such as dentoalveolar surgery, therapy duration, and concomitant steroid usage have been linked to BRONJ [13]. These are mainly patients with proven osteoporosis or cancer (breast or prostate cancer), 16 female patients, 4 male, mean age 59.5 years, (42-78 years).

CONCLUSION:
Pathological mandibular fractures have different etiologies. Diagnosis and treatment of this condition are challenging, and the treatment plan should always be consistent with the concomitant disease to provide the best possible quality of life in such patients.