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Biomedical subjects

Ralf Gutwald

Publications and source records attributed to Ralf Gutwald.

12 recordsLinked to original sources
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

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↗
PubMed2006

Clinical application of tissue-engineered transplants. Part I: mucosa.

OBJECTIVES: The study series aims at testing the feasibility of the clinical application of tissue-engineered oral mucosa. The preliminary results were gathered over a period varying from 6 months to 12 years depending on the surgical method. METHODS: Tissue-engineered oral mucosa was used to cover defects in various surgical procedures like vestibuloplasty (n=42), freeing of the tongue (n=10), prelaminating the radial flap (n=5) and reconstruction of the urethra (n=16). In all interventions small samples of oral mucosa were harvested, cut into small pieces, resuspended in culture medium and seeded into a culture flask. Cultured keratinocytes were transferred onto membranes which then were used to cover mucosal defects in the oral cavity. RESULTS: To gain a graft of 15 cm(2) size a mucosa biopsy of 4-8 mm(2) and 40 ml autologous patients serum is needed. Tissue-engineered oral mucosa was applied successfully in all four surgical methods. Six months after transplantation a regular epithelial layering with a histological delimitation of the stratum, epithelial crest and a strong basal membrane appeared. According to the reception site the tissue engineered oral mucosa differentiated in several ways. CONCLUSION: Tissue-engineered oral mucosa fulfils the requirements for clinical routine. With view to healing time and outcome it does not appear to be superior to regular harvested oral mucosa transplants. Because of a smaller harvesting defect and primary wound closure at the actual operation site the patients' convenience is increased. Thus this method reduces morbidity and advances the quality of life.

Aged↗
PubMed2005

Anterior approach to implant the Jarvik 2000 with retroauricular power supply.

The retroauricular power supply of the Jarvik 2000 (Jarvik Heart Inc, New York, NY) left ventricular assist device is suitable for permanent support, as it is associated with fewer infections than conventional drivelines. Implantation through a left-lateral thoracotomy limits the performance of additional cardiac procedures. We describe a technique that used a sternotomy for the implantation of the Jarvik 2000 with retroauricular power supply in two patients. The retroauricular power supply of the Jarvik 2000 can be provided with an anterior approach, allowing full surgical access to the heart. If the outflow graft to the ascending aorta indeed reduces aortic stasis and thromboembolic events, the anterior approach with retroauricular power delivery might evolve into a standard procedure.

Aged↗
PubMed2005

Implantation of the Jarvik 2000 left-ventricular-assist-device: role of the maxillofacial surgeon.

The Jarvik 2000 system of axial-flow LVAD-is implanted for permanent mechanical circularly support in patients with end-stage heart failure waiting to undergo heart transplantation. The battery is connected with a power plug to the percutaneous skull-mounted footplate, which is monocortically fixated to the retro auricular bone. Patient selection should be highly specific, including careful preoperative evaluation. No device failures have been published so far, but complications can occur due to heparinisation. We describe the procedure from the perspective of the maxillofacial surgeon and give suggestions to prevent surgical complications.

Cardiac Output, Low↗
PubMed2004

Navigation-aided reconstruction of medial orbital wall and floor contour in cranio-maxillofacial reconstruction.

The reconstruction of the anterio-posterior inclination of the medial aspect of the orbital floor, despite a wide 360 degrees exposure, including coronal and conjunctival incisions, is a challenging task in severe injuries of the orbit with massive comminution and complete displacement of the medial orbital wall and orbital floor. Out of a total of 20 patients with orbital fractures, five underwent a surgical intervention of repositioning the medial aspect of the orbital floor and especially the transition area between the orbital floor and medial orbital wall, using navigation-aided procedures. Using the mirroring tool of the Stryker-Leibinger STN-system, post-operative CTs indicated an average difference of the globe position of -4.9% between the operated side and the unaffected side, depending on the position of the medial aspect of the orbital floor. Navigation-aided procedures proved to be an essential precondition for achieving precise and predictable results in orbital reconstruction. In such cases, unlike those with an intact medial orbital wall remnant as a surgical target, bone grafts for reconstruction of the orbital floor cannot be implanted as onlay grafts.

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

Maxillary sinus floor augmention with autogenous bone grafts to enable placement of SLA-surfaced implants: preliminary results after 15-40 months.

This study presents preliminary results of placing SLA(R) surfaced ITI(R) implants in conjunction with maxillary sinus floor augmentations using autogenous bone. One hundred and eighty three ITI implants (SLA(R) surface) were inserted after 66 sinus floor elevation procedures in 41 consecutive patients. Forty-eight implants were placed simultaneously and 135 implants in a staged procedure with an average healing time of 4.9 months (148 days) after sinus grafting. Loading of the implants was allowed following an average time of 4.1 months (122 days). The follow-up time was 15-40 months after implant placement. Clinical follow-up consisted of single tooth and panoramic X-rays, and determination of Bleeding On Probing (BOP) and Plaque Index. One implant failed. One hundred and eleven of the inserted implants were used for fixed dentures, 20 for bar constructions, 41 for single crowns, and 11 were loaded provisionally until today. The total 2-year implant survival rate was 99.5%. Keeping the short follow-up period in mind, the encouraging results compared with previous studies, further support the findings of a positive influence of rough surfaces in grafted bone.

Adult↗
PubMed2003

Marginal flap versus paramarginal flap in impacted third molar surgery: a prospective study.

OBJECTIVE: A clinical prospective study was carried out to compare 2 flap designs-marginal and paramarginal-that are used during impacted third molar surgery. MATERIALS AND METHODS: Twenty-seven healthy patients (ages 17 to 31 years) who underwent surgical removal of 4 impacted third molars, including 54 lower and 54 upper, were included. A marginal flap was used in 1 randomly chosen half of the jaw, and a paramarginal flap was used in the other half. The influence of these flaps on wound healing, periodontal pocket depth of the adjacent second molar, pain, trismus, and swelling was studied. RESULTS: Wound dehiscences developed in 8 paramarginal flap cases, whereas none occurred with the use of a marginal flap. The buccal and distal probing depths of the adjacent second molar were significantly bigger in marginal flaps at 5 and 10 days after surgery. However, the probing depth was similar with the use of both techniques at 3 months. Pain, trismus, and swelling were similar with both techniques. CONCLUSIONS: We found no advantages to the use of a paramarginal flap instead of a traditional marginal flap for removing impacted third molars.

Adolescent↗
PubMed2003

Principle and stability of locking plates.

A new internal Mini-Locking-System was tested compared with conventional 2.0 mm Miniplates. Standardised osteotomies in the angular region of 16 human cadaver mandibles were fixed with a 6-hole-plate at the oblique line. Osteosynthesis and stability of fixation was proofed in a three-dimensional in-vitro-model in which functional load was simulated. Comparison of the different osteosynthesis techniques showed that in the case of Miniplate fixation torsion and gapping of the bone fragments occurred following plate application and screw tightening when the plates were pressed onto the bone, so last incongruences between bone surface and plate were transferred to the mobile bone fragments resulting in more extended gaps and torsion. This was only observed to a much lesser extent with the Mini-Locking-System due to the fixation principle avoiding pressure to the bone. During functional loading the Mini-Locking-System showed also a significant higher stability in comparison to conventional Miniplates. Due to the fixation method imitating the principles of a fixateur the screws form together with the plate and the cortical bone a frame construction. Loading forces are transmitted without the need of plate friction directly from bone over the screws to the plate resulting in higher stability.

Bone Plates↗
PubMedDate not supplied

Immediate loading of 2 interforaminal dental implants supporting an overdenture: clinical and radiographic results after 24 months.

PURPOSE: In this study, preliminary results of immediate loading of ITI sandblasted, large-grit, acid-etched (SLA) implants with a bar-connected overdenture in the edentulous mandible are presented. MATERIALS AND METHODS: Ten edentulous patients between 48 and 74 years old were included in this study. All patients received 2 SLA-surfaced ITI solid-screw dental implants in the interforaminal region, which were loaded with a bar connector and an overdenture 1 day after implant placement. Marginal bone resorption was evaluated using periapical radiographs. Gingival health (ie, Bleeding Index) and patient satisfaction (measured using a visual analog scale) were evaluated. Follow-up time was 24 to 36 months (mean time 29.8 months) after implant loading. RESULTS: Twenty-four months after placement, none of the 20 implants had failed. Marginal bone resorption around all implants after 12 months averaged 0.71 mm, and 92% of the sites had a Bleeding Index of 0. Between 12 and 24 months, average bone resorption was an additional 0.08 mm. All patients demonstrated an improved quality of life. DISCUSSION: The amount of bone resorption was comparable to amounts reported in studies with standard loading times. The low rate of inflammation of the peri-implant soft tissue and the high level of patient satisfaction in this study demonstrate encouraging short-term results. CONCLUSION: The results suggest that immediate loading of 2 dental implants can be successful and further support the use of a rough implant surface in residual bone.

Aged↗