A retrospective analysis of patients referred for implant placement to a specialty clinic: indications, surgical procedures, and early failures

Purpose: This retrospective study analyzed the pool of patients referred for treatment with dental implants over a 3-year period in a referral specialty clinic. Materials and Methods: All patients receiving dental implants between 2002 and 2004 in the Department of Oral Surgery and Stomatology, University of Bern, were included in this retrospective study. Patients were analyzed according to age, gender, indications for implant therapy, location of implants, and type and length of implants placed. A cumulative logistic regression analysis was performed to identify and analyze potential risk factors for complications or failures. Results: A total of 1,206 patients received 1,817 dental implants. The group comprised 573 men and 633 women with a mean age of 55.2 years. Almost 60% of patients were age 50 or older. The most frequent indication for implant therapy was single-tooth replacement in the maxilla (522 implants or 28.7%). A total of 726 implants (40%) were inserted in the esthetically demanding region of the anterior maxilla. For 939 implants (51.7%), additional bone-augmentation procedures were required. Of these, ridge augmentation with guided bone regeneration was performed more frequently than sinus grafting. Thirteen complications leading to early failures were recorded, resulting in an early failure rate of 0.7%. The regression analysis failed to identify statistically significant failure etiologies for the variables assessed. Conclusions: From this study it can be concluded that patients referred to a specialty clinic for implant placement were more likely to be partially edentulous and over 50 years old. Single-tooth replacement was the most frequent indication (> 50%). Similarly, additional bone augmentation was indicated in more than 50% of cases. Adhering to strict patient selection criteria and a standardized surgical protocol, an early failure rate of 0.7% was experienced in this study population

Effect of mesh distortion on the accuracy of high order vorticity-velocity CFD approaches

The numerical solution of the incompressible Navier-Stokes equations offers an alternative to experimental analysis of fluid-structure interaction (FSI). We would save a lot of time and effort and help cut back on costs, if we are able to accurately model systems by these numerical solutions. These advantages are even more obvious when considering huge structures like bridges, high rise buildings or even wind turbine blades with diameters as large as 200 meters. The modeling of such processes, however, involves complex multiphysics problems along with complex geometries. This thesis focuses on a novel vorticity-velocity formulation called the Kinematic Laplacian Equation (KLE) to solve the incompressible Navier-stokes equations for such FSI problems. This scheme allows for the implementation of robust adaptive ordinary differential equations (ODE) time integration schemes, allowing us to tackle each problem as a separate module. The current algortihm for the KLE uses an unstructured quadrilateral mesh, formed by dividing each triangle of an unstructured triangular mesh into three quadrilaterals for spatial discretization. This research deals with determining a suitable measure of mesh quality based on the physics of the problems being tackled. This is followed by exploring methods to improve the quality of quadrilateral elements obtained from the triangles and thereby improving the overall mesh quality. A series of numerical experiments were designed and conducted for this purpose and the results obtained were tested on different geometries with varying degrees of mesh density.

Active surgical positioning device for a cochlear implant electrode array

Cochlear implants have been of great benefit in restoring auditory function to individuals with profound bilateral sensorineural deafness. The implants are used to directly stimulate auditory nerves and send a signal to the brain that is then interpreted as sound. This project focuses on the development of a surgical positioning tool to accurately and effectively place an array of stimulating electrodes deep within the cochlea. This will lead to improved efficiency and performance of the stimulating electrodes, reduced surgical trauma to the cochlea, and as a result, improved overall performance to the implant recipient. The positioning tool reported here consists of multiple fluidic chambers providing localized curvature control along the length of the attached silicon electrode array. The chambers consist of 200μm inner diameter PET (polyethylene therephthalate) tubes with 4μm wall thickness. The chambers are molded in a tapered helical configuration to correspond to the cochlear shape upon relaxation of the actuators. This ensures that the optimal electrode placement within the cochlea is retained after the positioning tool becomes dormant (for chronic implants). Actuation is achieved by injecting fluid into the PET chambers and regulating the fluidic pressure. The chambers are arranged in a stacked, overlapping design to provide fluid connectivity with the non-implantable pressure controller and allow for local curvature control of the device. The stacked tube configuration allows for localized curvature control of various areas along the length of the electrode and additional stiffening and actuating power towards the base. Curvature is affected along the entire length of a chamber and the result is cumulative in sections of multiple chambers. The actuating chambers are bonded to the back of a silicon electrode array.

Differences across health care systems in outcome and cost-utility of surgical and conservative treatment of chronic low back pain: a study protocol

BACKGROUND: There is little evidence on differences across health care systems in choice and outcome of the treatment of chronic low back pain (CLBP) with spinal surgery and conservative treatment as the main options. At least six randomised controlled trials comparing these two options have been performed; they show conflicting results without clear-cut evidence for superior effectiveness of any of the evaluated interventions and could not address whether treatment effect varied across patient subgroups. Cost-utility analyses display inconsistent results when comparing surgical and conservative treatment of CLBP. Due to its higher feasibility, we chose to conduct a prospective observational cohort study. METHODS: This study aims to examine if1. Differences across health care systems result in different treatment outcomes of surgical and conservative treatment of CLBP2. Patient characteristics (work-related, psychological factors, etc.) and co-interventions (physiotherapy, cognitive behavioural therapy, return-to-work programs, etc.) modify the outcome of treatment for CLBP3. Cost-utility in terms of quality-adjusted life years differs between surgical and conservative treatment of CLBP.This study will recruit 1000 patients from orthopaedic spine units, rehabilitation centres, and pain clinics in Switzerland and New Zealand. Effectiveness will be measured by the Oswestry Disability Index (ODI) at baseline and after six months. The change in ODI will be the primary endpoint of this study.Multiple linear regression models will be used, with the change in ODI from baseline to six months as the dependent variable and the type of health care system, type of treatment, patient characteristics, and co-interventions as independent variables. Interactions will be incorporated between type of treatment and different co-interventions and patient characteristics. Cost-utility will be measured with an index based on EQol-5D in combination with cost data. CONCLUSION: This study will provide evidence if differences across health care systems in the outcome of treatment of CLBP exist. It will classify patients with CLBP into different clinical subgroups and help to identify specific target groups who might benefit from specific surgical or conservative interventions. Furthermore, cost-utility differences will be identified for different groups of patients with CLBP. Main results of this study should be replicated in future studies on CLBP.

Differentiating normal hyaline cartilage from post-surgical repair tissue using fast gradient echo imaging in delayed gadolinium-enhanced MRI (dGEMRIC) at 3 Tesla

The purpose was to evaluate the relative glycosaminoglycan (GAG) content of repair tissue in patients after microfracturing (MFX) and matrix-associated autologous chondrocyte transplantation (MACT) of the knee joint with a dGEMRIC technique based on a newly developed short 3D-GRE sequence with two flip angle excitation pulses. Twenty patients treated with MFX or MACT (ten in each group) were enrolled. For comparability, patients from each group were matched by age (MFX: 37.1 +/- 16.3 years; MACT: 37.4 +/- 8.2 years) and postoperative interval (MFX: 33.0 +/- 17.3 months; MACT: 32.0 +/- 17.2 months). The Delta relaxation rate (DeltaR1) for repair tissue and normal hyaline cartilage and the relative DeltaR1 were calculated, and mean values were compared between both groups using an analysis of variance. The mean DeltaR1 for MFX was 1.07 +/- 0.34 versus 0.32 +/- 0.20 at the intact control site, and for MACT, 1.90 +/- 0.49 compared to 0.87 +/- 0.44, which resulted in a relative DeltaR1 of 3.39 for MFX and 2.18 for MACT. The difference between the cartilage repair groups was statistically significant. The new dGEMRIC technique based on dual flip angle excitation pulses showed higher GAG content in patients after MACT compared to MFX at the same postoperative interval and allowed reducing the data acquisition time to 4 min.

Lateral external fixation: a new surgical technique for displaced unreducible supracondylar humeral fractures in children

BACKGROUND: Percutaneous Kirschner wire fixation represents the classic treatment for displaced supracondylar humeral fractures in childhood. This type of treatment first requires satisfactory reduction of the fracture. Failure to achieve a satisfactory reduction or inadequate stabilization can result in instability of the fracture fragments, which can result in either an unsatisfactory cosmetic or functional outcome. In our experience, these problems can be overcome with the use of a small lateral external fixator. METHODS: Between 1999 and 2005, thirty-one of 170 Gartland type-III supracondylar humeral fractures were treated with a lateral external fixator. The outcome of treatment was analyzed with regard to limb alignment, elbow movement, cosmetic appearance, and patient satisfaction. RESULTS: In twenty-eight of the thirty-one patients, a satisfactory reduction was achieved with closed methods. All children except one had a normal or good range of movement. The cosmetic result was excellent in all cases. All of the children and their parents stated that they would choose this treatment again. CONCLUSIONS: The use of a small lateral external fixator seems to be a safe alternative for the treatment of displaced supracondylar fractures of the humerus when a closed reduction appears to be unattainable by means of manipulation alone or when sufficient stability is not achieved with standard methods of Kirschner wire fixation.

Primary reconstruction of open depressed skull fractures with titanium mesh

Open skull fractures have been traditionally managed in 2 stages: urgent craniotomy and elevation of the fracture with removal of contaminated bone, debridement, and delayed cranioplasty. Primary, single-stage repair of these injures has been said to entail risks such as infections. Recent experience, however, disproved these concerns.We used a primary single-stage reconstruction for patients presenting with open depressed skull fractures. All patients received antibiotic prophylaxis. The patients underwent elevation of the compound fracture and craniotomy if necessary. Debridement was performed, followed by skull reconstruction using a 0.6-mm titanium mesh.We present 5 consecutive male patients (age, 32.2 +/- 15.6 years) who underwent primary reconstruction of open depressed skull fractures. Clinical and radiologic follow-up was performed 2 months after surgery. The duration of the surgery was 2 +/- 1.6 hours. The size of the implanted mesh was 13 +/- 13.1 cm. No infection was detected in our series, with a follow-up period of 22 +/- 6.5 months (range, 16-29 months). The cosmetic result was defined in 4 patients as "excellent" and in 1 patient as "good."Primary reconstruction of open skull fractures with titanium mesh is feasible, safe, and cosmetically preferable than the conventional staged approach. The introduction into clinical practice can be warranted.

RISK OF SHUNT-DEPENDENT HYDROCEPHALUS AFTER OCCLUSION OF RUPTURED INTRACRANIAL ANEURYSMS BY SURGICAL CLIPPING OR ENDOVASCULAR COILING: A SINGLE-INSTITUTION SERIES AND META-ANALYSIS

OBJECTIVE: To compare the risk of shunt-dependent hydrocephalus after treatment of ruptured intracranial aneurysms by clipping versus coiling. METHODS: We analyzed 596 patients prospectively added to our database from July of 1999 to November of 2005 concerning the risk of shunt dependency after clipping versus coiling. Factors analyzed included age; sex; Hunt and Hess grade; Fisher grade; acute hydrocephalus; intraventricular hemorrhage; angiographic vasospasm; and number, size, and location of aneurysms. In addition, a meta-analysis of available data from the literature was performed identifying four studies with quantitative data on the frequency of clip, coil, and shunt dependency. RESULTS: The institutional series revealed Hunt and Hess grade, Fisher grade, acute hydrocephalus, intraventricular hemorrhage, and angiographic vasospasm as significant (P < 0.05) risk factors for shunt dependency after a univariate analysis. In a multivariate logistic regression analysis, we isolated intraventricular hemorrhage, acute hydrocephalus, and angiographic vasospasm as independent, significant risk factors for shunt dependency. The meta-analysis, including the current data, revealed a significantly higher risk for shunt dependency after coiling than after clipping (P = 0.01). CONCLUSION: Clipping of a ruptured aneurysm may be associated with a lower risk for developing shunt dependency, possibly by clot removal. This might influence long-term outcome and surgical decision making.

Staged surgical therapy of basal cell carcinoma of the head and neck region: an evaluation of 500 procedures

QUESTIONS UNDER STUDY / PRINCIPLES: The surgical therapy of basal cell carcinoma (BCC) is especially demanding in the facial area. This retrospective study was undertaken to evaluate the outcome of staged surgical therapy (SST) of BCC of the head and neck region performed on an interdisciplinary basis at our institution. METHODS: Patients treated for BCC in the head and neck area between 1/1/1997 and 31/12/2001 were included in the study. The lesions were histologically evaluated. Diameter of lesion, number of stages, defect coverage, operation time, and recurrence and infection rates were analysed using descriptive and inferential statistical procedures. RESULTS: 281 patients were included in the study. SST was performed in two stages in 43.7%, in three stages in 12.9% and in four or more stages in 2.7%, depending on the type of tumour and the patient's pretreatment status. The total operating time per lesion averaged one hour. Defect coverage was achieved by direct closure (37.7%), by full thickness skin graft (39.5%), by split skin graft (1.1%), by local flaps (20.3%) or by composite grafts (1.1%). Median follow-up time was 58.5 months. Low rates of recurrence (3.6%) and infection (2%) were observed with this technique. CONCLUSIONS: The staged surgical therapy of basal cell carcinoma evaluated here offers a series of advantages in respect of patient comfort and safety and economy, while allowing precise histological safety with low infection rates and reliable long-term results.

Postoperative hypoesthesia and pain: qualitative assessment after open and laparoscopic inguinal hernia repair

BACKGROUND: Chronic pain is an important outcome variable after inguinal hernia repair that is generally not assessed by objective methods. The aim of this study was to objectively investigate chronic pain and hypoesthesia after inguinal hernia repair using three types of operation: open suture, open mesh, and laparoscopic. METHODS: A total of 96 patients were included in the study with a median follow-up of 4.7 years. Open suture repair was performed in 40 patients (group A), open mesh repair in 20 patients (group B), and laparoscopic repair in 36 patients (group C). Hypoesthesia and pain were assessed using von Frey monofilaments. Quality of life was investigated with Short Form 36. RESULTS: Pain occurring at least once a week was found in 7 (17.5%) patients of group A, in 5 (25%) patients of group B, and in 6 (16.6%) patients of group C. Area and intensity of hyposensibility were increased significantly after open nonmesh and mesh repair compared to those after laparoscopy (p = 0.01). Hyposensibility in patients who had laparoscopic hernia repair was significantly associated with postoperative pain (p = 0.03). Type of postoperative pain was somatic in 19 (61%), neuropathic in 9 (29%), and visceral in 3 (10%) patients without significant differences between the three groups. CONCLUSIONS: The incidence of hypoesthesia in patients who had laparoscopic hernia repair is significantly lower than in those who had open hernia repair. Hypoesthesia after laparoscopic but not after open repair is significantly associated with postoperative pain. Von Frey monofilaments are important tools for the assessment of inguinal hypoesthesia and pain in patients who had inguinal hernia repair allowing quantitative and qualitative comparison between various surgical techniques.

Granulocyte colony stimulating factor supports liver regeneration in a surgical small for size liver remnant mouse model

ntense liver regeneration and almost 100% survival follows partial hepatectomy of up to 70% of liver mass in rodents. More extensive resections of 70 to 80% have an increased mortality and partial hepatectomies of >80% constantly lead to acute hepatic failure and death in mice. The aim of the study was to determine the effect of systemically administered granulocyte colony stimulating factor (G-CSF) on animal survival and liver regeneration in a small for size liver remnant mouse model after 83% partial hepatectomy (liver weight <0.8% of mouse body weight). Methods: Male Balb C mice (n=80, 20-24g) were preconditioned daily for five days with 5μg G-CSF subcutaneously or sham injected (aqua ad inj). Subsequently 83% hepatic resection was performed and daily sham or G-CSF injection continued. Survival was determined in both groups (G-CSF n=35; Sham: n=33). In a second series BrdU was injected (50mg/kg Body weight) two hours prior to tissue harvest and animals euthanized 36 and 48 hours after 83% liver resection (n=3 each group). To measure hepatic regeneration the BrdU labeling index and Ki67 expression were determined by immunohistochemistry by two independent observers. Harvested liver tissue was dried to constant weight at 65 deg C for 48 hours. Results: Survival was 0% in the sham group on day 3 postoperatively and significantly better (26.2% on day 7 and thereafter) in the G-CSF group (Log rank test: p<0.0001). Dry liver weight was increased in the G-CSF group (T-test: p<0.05) 36 hours after 83% partial hepatectomy. Ki67 expression was elevated in the G-CSF group at 36 hours (2.8±2.6% (Standard deviation) vs 0.03±0.2%; Rank sum test: p<0.0001) and at 48 hours (45.1±34.6% vs 0.7±1.0%; Rank sum test: p<0.0001) after 83% liver resection. BrdU labeling at 48 hours was 0.1±0.3% in the sham and 35.2±34.2% in the G-CSF group (Rank sum test: p<0.0001) Conclusions: The surgical 83% resection mouse model is suitable to test hepatic supportive regimens in the setting of small for size liver remnants. Administration of G-CSF supports hepatic regeneration after microsurgical 83% partial hepatectomy and leads to improved long-term survival in the mouse. G-CSF might prove to be a clinically valuable supportive substance in small for size liver remnants in humans after major hepatic resections due to primary or secondary liver tumors or in the setting of living related liver donation.