Oliver Ploder

Osteoporosis and bisphosphonates-related osteonecrosis of the jaw: Not just a sporadic coincidence – a multi-centre study

INTRODUCTION Bisphosphonates (BPs) are powerful drugs that inhibit bone metabolism. Adverse side effects are rare but potentially severe such as bisphosphonate-related osteonecrosis of the jaw (BRONJ). To date, research has primarily focused on the development and progression of BRONJ in cancer patients with bone metastasis, who have received high dosages of BPs intravenously. However, a potential dilemma may arise from a far larger cohort, namely the millions of osteoporosis patients on long-term oral BP therapy. PATIENTS AND METHODS This current study assessed 470 cases of BRONJ diagnosed between 2004 and 2008 at eleven different European clinical centres and has resulted in the identification of a considerable cohort of osteoporosis patients suffering from BRONJ. Each patient was clinically examined and a detailed medical history was raised. RESULTS In total, 37/470 cases (7.8%) were associated with oral BP therapy due to osteoporosis. The majority (57%) of affected individuals did not have any risk factors for BRONJ as defined by the American Association of Oral and Maxillofacial Surgery. The average duration of BP intake of patients without risk factors was longer and the respective patients were older compared to patients with risk factors, but no statistical significant difference was found. In 78% of patients the duration of oral BP therapy exceeded 3 years prior to BRONJ diagnosis. DISCUSSION The results from this study suggest that the relative frequency of osteoporosis patients on oral BPs suffering from BRONJ is higher than previously reported. There is an urgent need to substantiate epidemiological characteristics of BRONJ in large cohorts of individuals.

Virtual image guided navigation in tumor surgery — technical innovation

We present a new visualization system for image-guided stereotactic navigation in tumor surgery. The combination of frameless stereotactic localization technology with real-time video processing permits the visualization of medical imaging data as a video overlay during the actual surgical procedure. Virtual computer-generated anatomical structures are displayed intraoperatively in a semi-immersive head-up display. This results in surgical navigation assistance without limiting the judgement of the physician based on the continuous observation of the operating field. The case presented documents the potential of augmented reality visualization concepts in tumor surgery of the head.

Image-guided surgery

Interventional video tomography (IVT), a new imaging modality, achieves virtual visualization of anatomic structures in three dimensions for intraoperative stereotactic navigation. Partial immersion into a virtual data space, which is orthotopically coregistered to the surgical field, enhances, by means of a see-through head-mounted display (HMD), the surgeons visual perception and technique by providing visual access to nonvisual data of anatomy, physiology, and function. The presented cases document the potential of augmented reality environments in maxillofacial surgery.

Computed intraoperative navigation guidance-a preliminary report on a new technique

OBJECTIVE To assess the value of a computer-assisted three-dimensional guidance system (Virtual Patient System) in maxillofacial operations. DESIGN Laboratory and open clinical study. SETTING Teaching Hospital, Austria. SUBJECTS 6 patients undergoing various procedures including removal of foreign body (n=3) and biopsy, maxillary advancement, and insertion of implants (n=1 each). INTERVENTIONS Storage of computed tomographic (CT) pictures on an optical disc, and imposition of intraoperative video images on to these. The resulting display is shown to the surgeon on a micromonitor in his head-up display for guidance during the operations. MAIN OUTCOME MEASURES To improve orientation during complex or minimally invasive maxillofacial procedures and to make such operations easier and less traumatic. RESULTS Successful transferral of computed navigation technology into an operation room environment and positive evaluation of the method by the surgeons involved. CONCLUSIONS Computer-assisted three-dimensional guidance systems have the potential for making complex or minimally invasive procedures easier to do, thereby reducing postoperative morbidity.

Can dual-energy CT improve the assessment of tumor margins in oral cancer?

OBJECTIVES The aim was to investigate the image quality of dual-energy computed-tomography (DECT) compared to single-energy images at 80 kV and 140 kV in oral tumors. MATERIALS AND METHODS Forty patients underwent a contrast-enhanced DECT scan on a definition flash-CT. Four reconstructions (80 kV, 140 kV, mixed (M), and optimum-contrast (OC)) were assessed by four blinded readers for subjective image quality (10-point scale/10=best). For objective quality assessment, linear attenuation measurements (line density profiles (LDP)) were positioned at the tumor margin, and the difference between minimum and maximum was calculated. Signal-to-noise ratios (SNR) were measured in the tongue. RESULTS The mean image quality for all readers was 5.1±0.3, 8.4±0.3, 8.1±0.2, and 8.3±0.2 for the 140 kV, 80 kV, M, and OC, respectively (P<001 between 140 kV and all others). The mean difference between the minimum and maximum within the LDP was 139.4±59.0, 65.7±29.5, 105.1±46.5, and 118.7±59.4 for the 80 kV, 140 kV, M, and OC, respectively (P<001). The SNR for the tongue was 3.8±2.1, 3.8±2.1, 4.2±2.4, and 4.1±2.3 for the 80 kV, 140 kV, M, and OC, respectively. DISCUSSION DECT of oral tumors offers high image quality, with subjectively rated image quality and attenuation contrast at the tumor margin similar to that of 80 kV; DECT, however, provides a significantly higher SNR compared to 80 kV.

Neoadjuvant radiochemotherapy of oral cavity and oropharyngeal cancer: evaluation of tumor response by CT differs from histopathologic response assessment in a significant fraction of patients.

Our aim was to compare and assess the predictive value of CT and histopathologic grading of tumor regression at primary tumor sites in patients with squamous cell carcinoma of the oral cavity and oropharynx after neoadjuvant (preoperative) radiochemotherapy (RCT).

High resolution magnetic resonance imaging with an orbital coil as an alternative to computed tomography scan as the primary imaging modality of pediatric orbital fractures.

PURPOSE The computed tomography (CT) scan is currently the gold standard in the imaging of orbital fractures. The weak points of this imaging modality, however, include restricted soft tissue depiction as well as the radiation. Both attributes are of particular importance in children because of the high rate of trapdoor fractures and the radiation to the lens. Although magnetic resonance imaging (MRI) is not associated with these drawbacks, it has not been established in the primary diagnosis of pediatric orbital fractures. The aim of our study was to establish the use of MRI with a special orbital coil for the primary diagnosis of pediatric orbital trauma. PATIENTS AND METHODS In our retrospective study, 14 pediatric patients presented to our department with a blunt orbital trauma from 2003 to 2007. Twelve of 14 patients with orbital floor fractures required surgical reconstruction. Until 2004, imaging was carried out by plain x-rays and CT scan for a decision regarding the necessity of surgery. Since introducing the MRI microscopy orbital coil in 2004, CT scans have been replaced by MRI for the primary fracture diagnosis in 8 pediatric cases. Kappa statistics have been applied to assess inter- and intraobserver reliability for CT scans and MRI. This study shows our experiences using MRI in combination with conventional x-rays to determine the operative approach in 2 of the 8 pediatric cases suffering from blunt orbital trauma. RESULTS The most common causes for pediatric orbital trauma in our collective were accidents. In 8 cases using MRI as the primary imaging modality, depiction of the fracture dislocation and differentiation of the adjacent fatty and muscle tissue was excellent and indication for surgery was distinct. MRI reached a high intra- and inter-rater agreement level (kappa=0.80). CONCLUSION MRI combined with a microscopy orbital coil is a valuable alternative to the CT scan in the primary diagnosis of pediatric orbital fractures. Floor fractures, and particularly muscle incarceration, should be diagnosed by high resolution MRI combined with a microscopy coil instead of CT to avoid radiation to the lens and to obtain a better soft tissue depiction.

Preoperative radiochemotherapy in the treatment of advanced oral cancer: Outcome of 276 patients

INTRODUCTION The aim of this study was to review survival and locoregional control in patients with advanced oral and oropharyngeal squamous cell carcinoma treated by multimodal therapy with preoperative radiochemotherapy and radical surgery. MATERIAL Retrospective cohort study. METHODS Included in this analysis are 276 consecutive patients with UICC disease stages III and IV (T2: 13.0%; T3: 16.7%; T4: 70.3%; N0: 29.7%; N1: 20.3%; N2: 45.3%; N3: 4.7%; stage III: 16.3%; stage IV: 83.7%). All patients received preoperative radiochemotherapy (50Gy, Mitomycin and 5-Fluorouracil) and radical locoregional resection. RESULTS Median surveillance period was 101.4 months (24-202 months). 5-year overall survival probability was 53.9%. 5-year local control probability was 70.2%. CONCLUSION These results underline the reliability of preoperative treatment of patients with oral and oropharyngeal cancer.

Three-Dimensional Measurement of the Mandible After Mandibular Midline Distraction Using a Cemented and Screw-Fixated Tooth-Borne Appliance : A Clinical Study

PURPOSE The aim of this study was to analyze the 3-dimensional movement of the mandible segments after distraction of the mandibular midline by use of a cemented and screw-fixated tooth-borne appliance. PATIENTS AND METHODS Twenty patients with transverse deficiencies of the lower arch were included in a consecutive study. Before surgical intervention, a custom-made appliance was cemented to the teeth and also fixed with 2 screws between the teeth on each side. The distraction appliance was activated after 5 days at a rate of 0.6 mm/d. After a consolidation period of 6 weeks, the appliance was removed and an orthodontic retainer was applied. Radiographs and cast models were taken preoperatively and postoperatively, and direct linear measurements were performed at the same intervals. RESULTS Mean expansion (+/- SD) of the osteotomy line measured on the radiographs for the superior, middle, and inferior part of the mandible was 5.1+/-2.4, 5.9+/-2.8, and 5.7+/-2.9 mm, respectively. The mean overall expansion was 5.6+/-2.6 mm. The width increase of the models between the canines, first premolars, second premolars, first molars, and second molars was 4.2+/-1.8, 5.0+/-2.0, 4.7+/-2.0, 4.3+/-1.7, and 3.6+/-1.3, respectively, at the tooth level and 3.4+/-2.0, 3.6+/-1.8, 3.3+/-1.4, 3.2+/-1.5, and 2.2+/-1.8, respectively, at the bone level. CONCLUSIONS Expansion of the osteotomy line in the vertical dimension showed a uniform pattern. Lateral movements of the mandibular segments decreased from the symphysis to the gonial angles. The positional changes of the teeth and the bone segments were proportionate. Minimal dental movement was observed.

Three-dimensional histomorphometric analysis of distraction osteogenesis using an implanted device for mandibular lengthening in sheep.

The aim of this study was to lengthen the sheep mandible with a fully buried device and to quantitatively analyze the tissue regenerate in the distraction gap by means of two-dimensional and three-dimensional histomorphometry. A custom-made device for continuous distraction was used in five adult sheep and fixed with three bicortical screws on either side of an osteotomy, anterior to the premolar region of the mandible. A cable-connected power and control unit was implanted in the neck region. After a 5-day latency period, distraction was activated every 2 hours and advanced at a rate of 1.01 mm per day. The distraction period was planned for 14 days, but because of stability problems and cable breakage, the actual distraction period ranged from 2 to 17 days, resulting in gap distances from 1.7 to 17.1 mm (mean, 0.95 mm/day). Osteogenesis was followed by radiographic imaging, and after a 6-week consolidation period, the harvested mandibles were serially sectioned for histologic and two-dimensional histomorphometric analysis, with three-dimensional reconstruction. Histologic examination of the specimens demonstrated predominantly membranous bone formation with remodeling bridging the distraction gap mainly in the periosteal region of the lingual side. In addition, cartilaginous areas and chondral bone formation were observed where the bridging appeared incomplete. Because of device fixation on the buccal side of the mandible, the preservation of the lingual periosteum seemed to play the major role for sufficient bone repair in the distraction gap. Cartilage within the distraction gap suggests fixation instability in this animal model.