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Biomedical subjects

Ralf Schön

Publications and source records attributed to Ralf Schön.

At least 19 recordsLinked to original sources
PubMed2006

Case report: brain and liver abscesses caused by oral infection with Streptococcus intermedius.

Organ abscesses are a rare and life-threatening complication mostly of hematogenously disseminated infections. We report a case of brain and liver abscesses. Identification of the lesions was made by contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI), respectively. An oral examination comprised an oral focus of infection. Streptococcus intermedius was isolated from oral smear, liver and ventricular drainage, and blood sample. After the commencement of antibiotic therapy, drainage of abscesses and oral rehabilitation, complete recovery was noted.

Adult↗
PubMed2006

Individual preformed titanium meshes for orbital fractures.

OBJECTIVES: The aim of this investigation was to develop and test the accuracy of a procedure for fabricating individual preformed titanium meshes for orbital fractures. STUDY DESIGN: Preoperative CT datasets from five patients with orbital fractures were used for 3D reconstruction by mirroring the unaffected side onto the defective one, resulting in a new sub-volume. A template for adaptation of the titanium mesh was produced by applying these sub-volumes. Navigation-aided procedures guaranteed the exact placement of the preformed mesh during the operation. RESULTS: The accuracy of the reconstructed orbital floor was determined to be approximately 1 mm, which lies within the technical limit of detection. CONCLUSION: These results indicate a further application or navigation-aided reconstruction, which will serve as a pilot project for further investigations. Clustered databases of patients will be used to produce various template sets, reflecting ideal skeletons, according to age, sex, and other patient variables. These could be used for manufacturing preformed osteosynthesis templates.

Databases, Factual↗
PubMed2006

Anatomical 3-dimensional pre-bent titanium implant for orbital floor fractures.

PURPOSE: This cadaver study evaluates the use of pre-bent 3-dimensional titanium mesh implants for orbital floor and medial wall reconstruction. DESIGN: Nonrandomized comparative study. PARTICIPANTS: Eight human cadaveric heads (n = 16 orbits). METHODS: Transcutaneous incisions were used to expose both orbital floors in each cadaveric head. Unilateral orbital floor and medial wall fractures were generated in each specimen. The contralateral orbit remained uninjured. The fractures then were repaired with pre-bent titanium mesh fan plates molded from aluminum templates presenting different sizes. The templates were generated from topographical computed tomography (CT) data previously obtained from normal subjects. The accuracy of orbital reconstruction was evaluated with postoperative CT scans. MAIN OUTCOME MEASURES: The mean value of the distances between the implant and the bony orbit was evaluated. RESULTS: The mean distance between all 16 plates and their respective orbital floors/medial walls was 0.81+/-0.74 mm. Mean values were 0.68+/-0.63 mm for the unfractured side and 0.93+/-0.82 mm for the fractured side. No significant differences were found between orbits when evaluated for side of injury, gender, or size of defect. CONCLUSION: Pre-bent 3-dimensional titanium mesh implants provide accurate reconstruction of orbital floor and medial orbital wall fractures. The mean implant error was <1 mm for all orbits studied.

Adult↗
PubMed2006

Cervicofacial necrotizing fasciitis.

Cervical necrotizing fasciitis is a fast spreading acute soft tissue inflammation. Death can occur within 12-24 h. Early identification and treatment is needed. We report the case of a 75 year old woman with diabetes and high cholesterol, adipositas who developed cervical necrotizing fasciitis of odotongenic origin with massive subcutaneous air collection and first sign of septicaemia. Surgical treatment with debridement and drainage in combination with intravenous broadbased antibiotics as well as daily irrigation of the wound with iodine solution (Betaisodona) and metronidazol (local antibiotic treatment) was performed. The patient recovered completely. Surgical debridement combined with broad-spectrum of antibiotics showed satisfying result for the management of cervical necrotizing fasciitis of dentogenous origin.

Aged↗
PubMed2006

Computer-assisted extracorporeal orbital reconstruction after optic nerve decompression by removal of sphenoid bone.

The removal of sphenoid bone parts was performed by the admitting neurosurgeons on a patient who presented an optic nerve compression syndrome. Beside the orbital trauma, an extensive midfacial trauma was sustained with dislocated multifractures of the zygomatic complex. In a secondary procedure, the orbital cavity was reconstructed successfully using 3 different methods of computer-assisted surgery. First, the reconstruction of the zygomatic complex was controlled intraoperatively by a virtual model obtained by mirroring the unaffected side to the affected side. Second, extracorporeal bone parts were virtually preoperatively relocated and orientated. The reconstruction of the orbital cavity by the insertion of these bony fragments was performed intraoperatively as planned after the zygomatic complex reconstruction. Third, the virtual reconstruction of the orbital floor was performed using preoperatively individually bent and preformed orbital titanium mesh. Combinations of these methods demonstrate the practical and high value of computer-assisted surgery in complex reconstructive craniofacial surgery.

Adult↗
PubMed2005

Navigational maxillofacial surgery using virtual models.

Ablative tumor surgery and orbital and midface reconstruction, as much as orthognathic surgery, requires detailed planning using computed tomography (CT) or magnetic resonance imaging (MRI). These techniques also allow simulation of complex surgeries preoperatively. Proper reconstruction depends on reliable information to choose the correct type of grafts and to predict the outcome. This study evaluates the benefit and indications of computer-assisted surgery in the treatment of 107 patients who underwent craniomaxillofacial surgery. Based on a CT or MRI data set, an optical navigation system was used for preoperative planning, intraoperative navigation, and postoperative control. Surgery could be preoperatively planned and intraoperatively navigated. Preoperatively, it required that soft and hard tissues were measured using the mirrored data set of the unaffected side; the size and location of the graft were chosen virtually. Intraoperatively contours of transplanted tissues were navigated to the preoperatively simulated reconstructive result. Computer-assisted treatment was successfully completed in all 107 cases. Preoperatively outlined safety margins could be exactly controlled during tumor resection. Reconstruction was designed and performed precisely as virtually planned. Image-guided treatment improves preoperative planning by visualizing the individual anatomy, outlining the intended reconstructive outcome, and by objectifying the effect of adjuvant therapy. Intraoperative navigation makes tumor and reconstructive surgery more reliable by showing the safety margins, saving vital structures, and leading the reconstruction to preoperatively planned objectives.

Adolescent↗
PubMed2005

Five-year experience with the transoral endoscopically assisted treatment of displaced condylar mandible fractures.

BACKGROUND: From April of 1998 to May of 2003, the minimally invasive transoral approach for endoscopically assisted reduction and osteosynthesis of 62 displaced condylar mandible fractures was performed in 58 patients. METHODS: By means of limited transoral incision, the endoscopically assisted reduction and fixation of condylar fractures was performed using 30- and 45-degree angled endoscopes. Twenty-five fractures were condylar and 37 were subcondylar. The condylar neck of the proximal fragment was displaced medially in 17 fractures and laterally in 45 fractures. Four patients presented bilateral condylar mandible fractures. Using angled endoscopes, good visibility of the fracture site was obtained, which allowed for precise anatomical reduction in all patients. An angulated drill and screwdriver facilitated miniplate fixation by means of the transoral approach. The mean operating time was measured in the last 30 consecutive cases: 1 hour 5 minutes. RESULTS: Postoperatively, all patients showed quick recovery to preinjury occlusion. Normal temporomandibular joint function was noted 6 months after surgery in all patients. CONCLUSIONS: The transoral endoscopically assisted treatment using an angulated drill and screwdriver is the method of choice for surgical management of displaced condylar fractures, even in fractures with medial override. Facial nerve injury and visible scars are avoided by using the transoral approach.

Adult↗
PubMed2004

Comparative study of locking plates in mandibular reconstruction after ablative tumor surgery: THORP versus UniLOCK system.

PURPOSE: This retrospective study compared 2 types of rigid locking plates (THORP and UniLOCK; Stratec Medical, Oberdorf, Switzerland) in 107 patients undergoing reconstruction for bridging mandibular defects following ablative tumor surgery. PATIENTS AND METHODS: From January 1993 to December 2000, 107 patients were reconstructed following ablative tumor surgery with 57 THORP plates and 50 UniLOCK plates. Study follow-up ranged from 18 to 87 months (average, 32 months). Complications were categorized into delayed wound healing, infection, plate exposure, and plate fracture, taking into account the type and timing of reconstruction. RESULTS: Overall type and number of complications show no statistically significant differences between THORP and UniLOCK groups. Infection was the most frequent type of complication (THORP, 30; UniLOCK, 32). Others included delayed wound healing (THORP, 13; UniLOCK, 12), plate exposure (THORP, 8; UniLOCK, 7), and plate fracture (THORP, 5; UniLOCK, 1). Plates were removed in 22 THORP and 11 UniLOCK plates. The most frequent reason for plate removal in both groups was infection. Other reasons for plate removal include tumor recurrence, plate fracture, plate exposure, or a combination of reasons. CONCLUSIONS: THORP and UniLOCK plates do not present statistically significant differences in the parameters studied. Nevertheless, the UniLOCK group had slightly better results. Considering that the THORP system is much bulkier and its screws bigger, our results lead to the conclusion that bridging osteosynthesis with a 2.4 UniLOCK system is adequate for plate reconstruction of mandibular defects.

Adult↗
PubMed2003

Color duplex sonography for the monitoring of vascularized free bone flaps.

OBJECTIVE: When vascular complications are suspected after the microsurgical transfer of free buried fibular bone flaps without a skin island, revision surgery often proves to be unnecessary. We sought to determine the efficacy of color duplex sonography in the close observation of bone graft patency postoperatively. Study design Twelve free fibular bone flaps without a skin island were postoperatively monitored through color duplex sonography with a 7.5-MHz scanner. RESULTS: With color duplex sonography, the rate of perfusion in the vascular pedicle could be visualized in all 12 fibular flaps. In 3 patients, vascular complications and flap failure were suspected. However, because adequate perfusion of the vascular pedicle was observed immediately after surgery and in the daily follow-up examinations, revision surgery was not necessary. CONCLUSIONS: Color duplex sonography is not time-consuming; in fact, it is a reliable, noninvasive, and inexpensive method for the postoperative monitoring of free bone flaps.

Bone Transplantation↗
PubMed2003

Frontiers in maxillofacial endoscopic surgery.

The use of endoscopically assisted techniques allows limited incisions for the open reduction of condylar process fractures. Intraoperative control after fracture reduction in areas of limited exposure and visibility is possible. In addition, the risk of facial nerve damage and extensive visible scars can be reduced by using minimally invasive endoscopic techniques. Although the use of endoscopically associated techniques in maxillofacial surgery offers many options and advantages, indications for open treatment of maxillofacial trauma have not changed. The repair of severely dislocated and comminuted fractures of the facial skeleton and major reconstruction of craniomaxillofacial structures still require extended exposure with traditional intraoral and extraoral approaches.

Endoscopy↗
PubMed2003

Follow-up of condylar fractures of the mandible in 8 patients at 18 months after transoral endoscopic-assisted open treatment.

PURPOSE: The results of endoscopic-assisted transoral approach for open reduction and miniplate fixation of condylar mandible fractures were evaluated 18 months after surgery. PATIENTS AND METHODS: The transoral endoscopic-assisted treatment of condylar fractures was performed in 8 consecutive patients from April 1998 to December 1999 at the University Hospital Freiburg. Four of 8 condylar fractures were dislocated, and 6 of the 8 patients had additional mandibular fractures. RESULTS: Anatomic reduction was achieved in all patients without facial nerve damage. There were no signs of bony resorption and good temporomandibular joint function 18 months after surgery. In 4 patients, the transoral management of condylar fractures was facilitated by angulated drills and screw drivers. Transbuccal stab incisions were not needed in these 4 patients. In all 8 patients, visible scars were avoided. CONCLUSIONS: The endoscopic-assisted transoral approach proved to be a reliable surgical method for condylar fractures when dislocation with lateral override was present.

Adult↗
PubMed2002

Navigation-guided resection of temporomandibular joint ankylosis promotes safety in skull base surgery.

PURPOSE: Computer-assisted surgery (CAS) has not been a routine part of craniomaxillofacial surgery to date. This report investigates the use of CAS to promote the safe removal of ankylosed temporomandibular joint bone in the skull base. PATIENTS AND METHODS: Out of a total pool of experience with 102 navigation-guided CAS procedures between January 1998 and December 2000, we report on 2 cases of navigation-aided resection of severe ankylosis of the mandibular condyle with a predetermined safety margin of the resection toward the middle cranial fossa, and identification of the foramen ovale. RESULT: The use of CAS with navigation resulted in the promotion of safe surgical excision of the ankylosed skull base tissue. CONCLUSIONS: We regard navigation-aided resection of an ankylosis fo the mandibular condyle as a valuable additional technique in this potentially complicated procedure.

Adult↗
PubMed2002

Quantification of the neurodegenerative impact on the visual system following sudden retrobulbar expanding lesions - an experimental model.

INTRODUCTION: Afferent disorders of the visual system are a potential consequence following orbital trauma. The aim of this study was to investigate the tolerance of neurons in the retinal ganglion cell layer to acute expanding retrobulbar lesions. MATERIAL AND METHODS: In 42 male albino rats, intraorbital haemorrhage was simulated by transconjunctival insertion of a retrobulbar micro-balloon (filling volume 0.2-0.5 ml, duration of lesion 60 or 90 min). Neurodegeneration in the retinal ganglion cell layer was investigated by measuring the mean total neuron number and the mean neuron size. RESULTS: Increased retrobulbar volumes of 0.3 ml for 60 min led to a decrease in a number of neurons by 14.5% and in size of the neurons by 1.7%. Prolongation of the trauma to 90 min resulted in a decrease in number of neurons by 48.3% and in reduction of size of neurons by 22.1%. In contrast, a retrobulbar filling volume of 0.5 ml for 60 min resulted in a decrease in number of neurons by 11.4% and in size of neurons by 6.7%. CONCLUSION: The duration of a retrobulbar lesion leading to subsequent retinal ischaemia seems to be more important for neuron survival than the exerted pressure (once it is greater than a critical point for producing retinal ischaemia). The results strengthen the need for emergency treatment in cases of retrobulbar haemorrhage.

Animals↗
PubMed2002

Calcification of the branches of the external carotid artery detected by panoramic radiography: a case report.

Atherosclerosis, a progressive inflammatory disease, may lead to stroke, coronary artery disease, or peripheral artery disease. The prevalence of atherosclerosis associated with morbidity and mortality is very high in industrialized countries. This report describes the case of a 49-year-old male patient whose panoramic radiograph taken as part of a dental examination showed calcification in the branches of the external carotid artery. The right facial artery and left maxillary, facial, and lingual arteries were also calcified. The patient had a history of thrombosis in the right axillary and brachial veins with extension to half of the brachiocephalic trunk. In addition, selective lesions were found in the aorta and mitral valve. The patient's medical history also included hypertriglyceridemia, essential arterial hypertonia, terminal renal insufficiency, renal anemia, neurogen disturbance micturition, secondary hyperparathyroidism, hyperuricemia, lymphatic edema, polyneuropathy, tachyarrhythmia absoluta, and erysipelas. The case presented reports on the possibility of detecting signs of atherosclerosis in arteries of the maxillofacial region by use of panoramic radiography.

Angiography↗
PubMed2002

Endoscopic fracture treatment.

Experience from TMJ arthroscopy and endoscopic sinus and skull base surgery has enabled oral and maxillofacial surgeons to use endoscopic assisted treatment in other operative fields. The endoscopic assisted management of maxillofacial trauma has been described for the treatment of fractures of the mandibular condyle, the zygomatic complex, the orbit and the frontal sinus. The operative management for open reduction and fixation of fractures by miniplate osteosynthesis has not changed. Using endoscopic assisted techniques limited incisions can be used and intraoperative control after fracture reduction in areas of limited exposure and visibility is possible. The indications for open treatment of maxillofacial trauma have not changed because of these endoscopic approaches.

Bone Plates↗
PubMed2002

Computer-aided procedures in implantology, distraction and cranio-maxillofacial surgery.

Smaller implants and less invasive techniques for osteotomies using an endoscope assisted approach may facilitate the surgical procedures in cranio-maxillofacial distraction osteogenesis. Although sophisticated distraction devices are routinely used, there are still certain problems which need to be addressed. The preoperative planning, even of complex cases can be facilitated by using modern imaging techniques such as computer assisted surgery (CAS). The placement of the devices and the outline of complex osteotomies can be controlled intra-operatively. CAS allows for postoperative monitoring and for the long term follow up. The vector of distraction can be monitored and, depending on the device, a change of the vector of distraction may be possible during the activation period.

Cephalometry↗