Continuous mandibular distraction osteogenesis: novel device and preliminary results in minipigs.

PURPOSE: To develop and test a novel, hydraulic, continuous, automated distraction device capable of 3D movements for treatment of mandibular deformities. MATERIALS AND METHODS: We used 2 cadaveric and 5 live female Yucatan minipigs to test the distractor. The 3 components (miniature buried distractor, external power and control box, and user interface on handheld computer) operate on a closed loop in which the hydraulic pulse strength correlates with the resistance of the bone and soft tissue. The system auto-adjusts to correct any discrepancy between the actual and desired position of mandibular fragments. The distraction protocol included 0-day latency, 1 mm (divided into 94 increments) per day, and 24 days' fixation. Clinical examination was performed and lateral and anteroposterior cephalometric radiographs were obtained preoperatively and postoperatively, at mid distraction osteogenesis (DO), end DO, and end fixation. Position information was obtained through the user interface. RESULTS: Both cadaveric trials resulted in the desired distraction gap (11 to 12 mm), with all components functioning as designed. In 4 of the 5 live animals, distraction averaged 7.29 mm (range, 5 to 11 mm) over 12 days of activation. In 3 of the 5 live animals, the osteotomy gap filled in with bone by 24 days of fixation. Two animals were sacrificed prematurely (1 at mid DO and 1 at end DO) because vital components malfunctioned. CONCLUSIONS: The device is capable of automated, continuous, hydraulically powered DO at a rate of 1 mm/d. Future work will be directed at fortifying the device components and testing it in larger numbers of animals at varying distraction rates.

Primary jaw tumors in children.

PURPOSE: To document tumor type, biological/clinical behavior, management, and outcomes in children with primary jaw tumors. MATERIALS AND METHODS: A retrospective analysis of children with primary benign jaw tumors evaluated at Massachusetts General Hospital and Children's Hospital Boston from 1991 to 2009 was conducted. Patients were included if they were aged 16 years or younger and had adequate records and follow-up. Patient charts, radiographs, and pathology reports were reviewed. Demographic data; clinical, radiographic, and histopathologic findings; treatment; and outcomes were recorded. Predictor variables were tumor type, clinical behavior (nonaggressive/aggressive), and treatment. Outcome variables included presence or absence of recurrence and complications. Descriptive statistics were computed. RESULTS: There were 102 patients (44 male and 58 female patients) with a mean age of 8.3 years (range, 6 months to 16 years). Tumors were grouped by tumor type: mesenchymal (n=96), neurogenic (n=5), vascular (n=5), or hematopoietic (n=3); in addition, when appropriate, they were classified as nonaggressive (n=54) or aggressive (n=27). Treatment was based on the tumor's clinical/biological behavior and radiographic features and whether it was solitary or multifocal. Patients with nonaggressive tumors were treated by enucleation, debulking/contouring, or observation, and the recurrence rate was 0%. Aggressive tumors underwent en bloc resection or enucleation with systemic adjuvant therapy, and the recurrence rate was 7.1%. Mean follow-up was 2.4 years. CONCLUSIONS: The results of this study indicate that primary jaw tumors in children exhibit variable biological/clinical behavior, often not predicted by descriptive histologic findings. Management of these tumors should therefore be guided by clinical/biological behavior.

Automated continuous mandibular distraction osteogenesis: review of the literature.

PURPOSE: Current devices for mandibular distraction osteogenesis (DO) are complex and require significant patient or family skill during active distraction. Successful development of an automated, continuous distraction device would eliminate the need for patient participation in this process. The purpose of this study was to comprehensively review devices currently in development for continuous DO and to identify and evaluate the achieved successes and remaining problems. MATERIALS AND METHODS: A PubMed search of the English language literature in October 2008 using the keywords automatic or automated or continuous or hydraulic or motor or magnetic or spring and distraction osteogenesis was performed. The search included all technical notes, animal studies, and human studies describing the use of any automated continuous distraction device for the mandible. Excluded were studies using distraction devices employing hydraulics, motors, or springs that did not distract automatically and continuously and devices used for bones other than the mandible. RESULTS: The search returned 97 matches. Of these, 12 articles were selected as relevant to this review based on the inclusion and exclusion criteria detailed above. Eight distinct devices for automated, continuous DO were described in these reports and evaluated in this review. These included motor-driven, spring-mediated, and hydraulically powered distractors. CONCLUSIONS: The abundance of research currently underway to develop a continuous distractor highlights the clinical demand for, and usefulness, of such a device. Despite many advances and promising results, significant problems remain to be overcome before any of these devices gain widespread clinical acceptance.

Risk factor assessment for the development of osteoradionecrosis.

PURPOSE: Osteoradionecrosis (ORN) of the jaws has been extensively studied. However, controversy still exists regarding its etiology, risk factors, and the underlying mechanism of disease. The purpose of this study was to identify and evaluate significant risk factors for the development of ORN. PATIENTS AND METHODS: This was a retrospective cohort study of 82 Massachusetts General Hospital patients radiated for head and neck cancer between 1984 and 2005. Patient records were reviewed to collect demographic information, medical and dental history (including dental intervention or trauma), tumor specific data, treatment details, and follow-up. Biologic variables (ie, age and gender) of potential significance were also evaluated. The major outcome variable was the development of ORN or lack of development of ORN. The time from radiation to ORN, or for non-ORN patients, time to last follow-up visit, was computed. Univariate analyses identified candidate variables associated with ORN (P < .15). Cox proportional hazards regression was used to evaluate these candidate variables as well as biologically relevant variables. Significant prognostic factors for the development of ORN (P < .05) were identified. RESULTS: Multivariate regression identified the following variables as significantly associated with decreased ORN risk: higher body mass index (P = .02) and use of steroids (P = .02). Radiation dose greater than 66 Gray (P = .03) was associated with an increased ORN risk. CONCLUSIONS: Optimization of nutritional status, use of steroids, and limitation of total radiation dose may minimize the risk of ORN.