Soft tissue profile changes after bilateral sagittal split osteotomy for mandibular advancement: a systematic review

PURPOSE: The purpose of the present systematic review was to evaluate the soft tissue/hard tissue ratio in bilateral sagittal split advancement osteotomy (BSSO) with rigid internal fixation (RIF) or wire fixation (WF). MATERIALS AND METHODS: The databases PubMed, Medline, CINAHL, Web of Science, Cochrane Library, and Google Scholar Beta were searched. From the original 711 articles identified, 12 were finally included. Only 3 studies were prospective and 9 were retrospective. The postoperative follow-up ranged from 3 months to 12.7 years for RIF and 6 months to 5 years for WF. RESULTS: The short- and long-term ratios for the lower lip to lower incisor for BSSO with RIF or WF were 50%. No difference between the short- and long-term ratios for the mentolabial-fold to point B and soft tissue pogonion to pogonion could be observed. It was a 1:1 ratio. One exception was seen for the long-term results of the soft tissue pogonion to pogonion in BSSO with RIF; they tended to be greater than a 1:1 ratio. The upper lip mainly showed retrusion but with high variability. CONCLUSIONS: Despite a large number of studies on the short- and long-term effects of mandibular advancement by BSSO, the results of the present systematic review have shown that evidence-based conclusions on soft tissue changes are still unknown. This is mostly because of the inherent problems of retrospective studies, inferior study designs, and the lack of standardized outcome measures. Well-designed prospective studies with sufficient sample sizes that have excluded patients undergoing additional surgery (ie, genioplasty or maxillary surgery) are needed.

Toward clinical X-ray phase-contrast CT: demonstration of enhanced soft-tissue contrast in human specimen

X-ray computed tomography (CT) using phase contrast can provide images with greatly enhanced soft-tissue contrast in comparison to conventional attenuation-based CT. We report on the first scan of a human specimen recorded with a phase-contrast CT system based on an x-ray grating interferometer and a conventional x-ray tube source. Feasibility and potential applications of preclinical and clinical phase-contrast CT are discussed.

Soft-Tissue Simulation for Cranio-Maxillofacial Surgery: Clinical Needs and Technical Aspects

Computerized soft-tissue simulation can provide unprecedented means for predicting facial outlook pre-operatively. Surgeons can virtually perform several surgical plans to have the best surgical results for their patients while considering corresponding soft-tissue outcome. It could be used as an interactive communication tool with their patients as well. There has been comprehensive amount of works for simulating soft-tissue for cranio-maxillofacial surgery. Although some of them have been realized as commercial products, none of them has been fully integrated into clinical practice due to the lack of accuracy and excessive amount of processing time. In this chapter, state-of-the-art and general workflow in facial soft-tissue simulation will be presented, along with an example of patient-specific facial soft-tissue simulation method.

A navigation system for percutaneous needle interventions based on PET/CT images: design, workflow and error analysis of soft tissue and bone punctures

Percutaneous needle intervention based on PET/CT images is effective, but exposes the patient to unnecessary radiation due to the increased number of CT scans required. Computer assisted intervention can reduce the number of scans, but requires handling, matching and visualization of two different datasets. While one dataset is used for target definition according to metabolism, the other is used for instrument guidance according to anatomical structures. No navigation systems capable of handling such data and performing PET/CT image-based procedures while following clinically approved protocols for oncologic percutaneous interventions are available. The need for such systems is emphasized in scenarios where the target can be located in different types of tissue such as bone and soft tissue. These two tissues require different clinical protocols for puncturing and may therefore give rise to different problems during the navigated intervention. Studies comparing the performance of navigated needle interventions targeting lesions located in these two types of tissue are not often found in the literature. Hence, this paper presents an optical navigation system for percutaneous needle interventions based on PET/CT images. The system provides viewers for guiding the physician to the target with real-time visualization of PET/CT datasets, and is able to handle targets located in both bone and soft tissue. The navigation system and the required clinical workflow were designed taking into consideration clinical protocols and requirements, and the system is thus operable by a single person, even during transition to the sterile phase. Both the system and the workflow were evaluated in an initial set of experiments simulating 41 lesions (23 located in bone tissue and 18 in soft tissue) in swine cadavers. We also measured and decomposed the overall system error into distinct error sources, which allowed for the identification of particularities involved in the process as well as highlighting the differences between bone and soft tissue punctures. An overall average error of 4.23 mm and 3.07 mm for bone and soft tissue punctures, respectively, demonstrated the feasibility of using this system for such interventions. The proposed system workflow was shown to be effective in separating the preparation from the sterile phase, as well as in keeping the system manageable by a single operator. Among the distinct sources of error, the user error based on the system accuracy (defined as the distance from the planned target to the actual needle tip) appeared to be the most significant. Bone punctures showed higher user error, whereas soft tissue punctures showed higher tissue deformation error.

Combined bone and soft-tissue augmentation surgery in temporo-orbital contour reconstruction

Temporal hollowing due to temporal muscle atrophy after standard skull base surgery is common. Various techniques have been previously described to correct the disfiguring defect. Most often reconstruction is performed using freehand molded polymethylmethacrylate cement. This method and material are insufficient in terms of aesthetic results and implant characteristics. We herein propose reconstruction of such defects with a polyetheretherketone (PEEK)-based patient-specific implant (PSI) including soft-tissue augmentation to preserve normal facial topography. We describe a patient who presented with a large temporo-orbital hemangioma that had been repaired with polymethylmethacrylate 25 years earlier. Because of a toxic skin atrophy fistula, followed by infection and meningitis, this initial implant had to be removed. The large, disfiguring temporo-orbital defect was reconstructed with a PEEK-based PSI. The lateral orbital wall and the temporal muscle atrophy were augmented with computer-aided design and surface modeling techniques. The operative procedure to implant and adopt the reconstructed PEEK-based PSI was simple, and an excellent cosmetic outcome was achieved. The postoperative clinical course was uneventful over a 5-year follow-up period. Polyetheretherketone-based combined bony and soft contour remodeling is a feasible and effective method for cranioplasty including combined bone and soft-tissue reconstruction of temporo-orbital defects. Manual reconstruction of this cosmetically delicate area carries an exceptional risk of disfiguring results. Augmentation surgery in this anatomic location needs accurate PSIs to achieve satisfactory cosmetic results. The cosmetic outcome achieved in this case is superior compared with previously reported techniques.

Treatment of soft tissue recessions at titanium implants using a resorbable collagen matrix: a pilot study

OBJECTIVES: To histologically assess the effectiveness of a porcine-derived collagen matrix (CM) and a subepithelial connective tissue graft (CTG) for the coverage of single mucosal recessions at osseointegrated dental implants. MATERIALS AND METHODS: Chronic-type mucosal Miller Class I-like recessions (mean clinical defect height: 0.67 ± 0.33-1.16 ± 0.19 mm) were established at the buccal aspect of titanium implants with platform switch in six beagle dogs. The defects were randomly allocated to either (1) coronally advanced flap surgery (CAF) + CM, (2) CAF + CTG or (3) CAF alone. At 12 weeks, histomorphometrical measurements were made (e.g.) between the implant shoulder (IS) and the mucosal margin (PM) and IS and the outer contour of the adjacent soft tissue (mucosal thickness [MT]). RESULTS: All treatment procedures investigated were associated with an almost complete soft tissue coverage of the defect area (i.e. coronal positioning of PM relative to IS). Mean IS-PM and MT values tended to be increased in both CAF + CM (1.04 ± 0.74 mm/0.71 ± 0.55 mm) and CAF + CTG (0.88 ± 1.23 mm/0.62 ± 0.66 mm) groups when compared with CAF (0.16 ± 0.28 mm/0.34 ± 0.23 mm) alone. These differences, however, did not reach statistical significance. CONCLUSIONS: Within the limits of this pilot study, it was concluded that all treatment procedures investigated were effective in covering soft tissue recessions at titanium implants.

Analysis of 3D Soft Tissue Changes After 1- and 2-Jaw Orthognathic Surgery in Mandibular Prognathism Patients

Purpose Orthognathic surgery has the objective of altering facial balance to achieve esthetic results in patients who have severe disharmony of the jaws. The purpose was to quantify the soft tissue changes after orthognathic surgery, as well as to assess the differences in 3D soft tissue changes in the middle and lower third of the face between the 1- and 2-jaw surgery groups, in mandibular prognathism patients. Materials and Methods We assessed soft tissue changes of patients who have been diagnosed with mandibular prognathism and received either isolated mandibular surgery or bimaxillary surgery. The quantitative surface displacement was assessed by superimposing preoperative and postoperative volumetric images. An observer measured a surface-distance value that is shown as a contour line. Differences between the groups were determined by the Mann-Whitney U test. The Spearman correlation coefficient was used to evaluate a potential correlation between patients' surgical and cephalometric variables and soft tissue changes after orthognathic surgery in each group. Results There were significant differences in the middle third of the face between the 1- and 2-jaw surgery groups. Soft tissues in the lower third of the face changed in both surgery groups, but not significantly. The correlation patterns were more evident in the lower third of the face. Conclusion The overall soft tissue changes of the midfacial area were more evident in the 2-jaw surgery group. In 2-jaw surgery, significant changes would be expected in the midfacial area, but caution should be exercised in patients who have a wide alar base.

Microsurgery and liver research: Lumbricus terrestris, a reliable animal model for training?

Experiments using animal models are the most common way to learn microsurgery. This expertise is necessary for liver research, microsurgical reconstruction of the esophagus by free jejunum or reconstruction of the hepatic artery during reimplantation from living donors. The goal of this prospective study is to assess the reliability of an invertebrate model for microsurgical training.

A dedicated animal model for mechanical thrombectomy in acute stroke

BACKGROUND: Recent studies have focused on mechanical thrombectomy as a means to reduce the time required for revascularization and increase the revascularization rate in acute stroke. To date no systematic evaluation has been made of the different mechanical devices in this novel and fast-developing field of endovascular interventions. To facilitate such evaluations, we developed a specific in vivo model for mechanical thrombectomy that allows visualization of dislocation or fragmentation of the thrombus during angiographic manipulation. METHODS: Angiography and embolization with a preformed thrombus was performed in 8 swine. The thrombus was generated by mixing 25 IU bovine thrombin and 10 mL autologous blood. For visualization during angiography, 1 g barium sulfate was added. RESULTS: The preformed thrombus exhibited mechanical stability, reproducibility, and high radiographic absorption, providing excellent visibility during angiography. The setting allowed selective embolization of targeted vessels without thrombus fragmentation. Despite the application of barium sulfate no local or systemic reaction occurred. Histologic evaluation revealed no intimal damage caused by the thrombus or contrast agent washout. CONCLUSION: The model presented here allows selective and reliable thromboembolization of vessels that reproduce the anatomic and hemodynamic situation in acute cerebrovascular stroke. It permits visualization of the thrombus during angiography and intervention, providing unique insight into the behavior of both thrombus and device, which is potentially useful in the development and evaluation of mechanical clot retrieval in acute cerebrovascular stroke.

Treatment of advanced soft-tissue sarcomas using a combined strategy of high-dose ifosfamide, high-dose doxorubicin and salvage therapies

Having determined in a phase I study the maximum tolerated dose of high-dose ifosfamide combined with high-dose doxorubicin, we now report the long-term results of a phase II trial in advanced soft-tissue sarcomas. Forty-six patients with locally advanced or metastatic soft-tissue sarcomas were included, with age <60 years and all except one in good performance status (0 or 1). The chemotherapy treatment consisted of ifosfamide 10 g m(-2) (continuous infusion for 5 days), doxorubicin 30 mg m(-2) day(-1) x 3 (total dose 90 mg m(-2)), mesna and granulocyte-colony stimulating factor. Cycles were repeated every 21 days. A median of 4 (1-6) cycles per patient was administered. Twenty-two patients responded to therapy, including three complete responders and 19 partial responders for an overall response rate of 48% (95% CI: 33-63%). The response rate was not different between localised and metastatic diseases or between histological types, but was higher in grade 3 tumours. Median overall survival was 19 months. Salvage therapies (surgery and/or radiotherapy) were performed in 43% of patients and found to be the most significant predictor for favourable survival (exploratory multivariate analysis). Haematological toxicity was severe, including grade > or =3 neutropenia in 59%, thrombopenia in 39% and anaemia in 27% of cycles. Three patients experienced grade 3 neurotoxicity and one patient died of septic shock. This high-dose regimen is toxic but nonetheless feasible in multicentre settings in non elderly patients with good performance status. A high response rate was obtained. Prolonged survival was mainly a function of salvage therapies.