Search results for "Orthodontics."

Posterior stability in posterior-stabilized vs medially congruent total knee replacement: A radiological comparison of two polyethylene designs in a …

2020

Objective:The purpose of this radiological study was to assess the posterior laxity of a single model of a total knee arthroplasty design (TKA) having a medially constrained (MC) or a Posterior-Stabilized (PS) polyethylene insert using a well-documented stress x-ray. To the authors knowledge, this is the first report evaluating MC TKA outcomes according to the “kneeling view.”Materials and Methods:Sixty patients with non-traumatic primary knee osteoarthritis undergoing TKA were first matched by age, sex, BMI and diagnosis and then divided in two groups: group A (37 knees) received a MC TKA and group B (23 knees) a PS implant made by the same manufacturer. In all cases the posterior cruciate…

In Silico Analysis of Bone Tension During Fixation of the Medial Malleolus Fracture After Ankle Joint Endoprosthesis

2020

Total ankle arthroplasty (TAR) is a procedure alternative to arthrodesis which enables the biomechanical stabilization of the ankle joint. The procedure is associated with a high risk of complications, including fractures of the medial malleolus. In this study, the finite element method (FEM), based on CT examinations, was used to model the ankle fracture fixation after TAR. Three types of fracture stabilization were considered: screw, Blount staple, and both screw and Blount staple. In the in silico model, the maximum stress tension was found at prosthetic junctions with the base, cone, and talar components of the tibial prosthesis. When the fracture was stabilized with the Blount staple, …

2019

Ultrasound tissue characterization (UTC) imaging has been previously used to describe the characteristics of patellar and Achilles tendons. UTC imaging compares and correlates successive ultrasonographic transverse tendon images to calculate the distribution of four color-coded echo-types that represent different tendon tissue types. However, UTC has not been used to describe the characteristics of patellar tendons after anterior cruciate ligament reconstruction (ACLR). The aim of this cross-sectional study was to assess the intra and inter-rater reliability of the UTC in unharvested and harvested patellar tendons of patients undergoing ACLR. Intra and inter-rater reliability of both UTC da…

(i) Comminuted patellar fractures

2006

Summary Purpose of review This article reviews current best practice for the diagnosis and treatment of comminuted patellar fractures. Recent findings Patellar fractures make up about 1% of all fractures. As a rule, fractures of the patella are caused by direct trauma to the knee. A transverse fracture is the most common fracture type. Open reduction and internal fixation is the treatment of choice for the majority of displaced patellar fractures. Treatment must achieve anatomic reduction of the articular surface and reestablish the continuity of the extensor mechanism. Tension-band wiring, interfragmentary screw fixation and a combination of cerclage wiring and screw fixation are the most …

Influence of Drilling Technique on the Radiographic, Thermographic, and Geomorphometric Effects of Dental Implant Drills and Osteotomy Site Preparati…

2020

The aim of this comparative study is to analyze the influence of drilling technique on the radiographic, thermographic, and geomorphometric effects of dental implant drills and osteotomy site preparations. One hundred and twenty osteotomy site preparations were performed on sixty epoxy resin samples using three unused dental implant drill systems and four drilling techniques performed with a random distribution into the following study groups: Group A: drilling technique performed at 800 rpm with irrigation (n = 30)

Breaststroke swimmer's knee

1980

The cause of the breaststroke swimmer's knee with medial pain of the knee joint has not been clearly identified. Breaststroke swimmers with knee pain were, therefore, examined arthros copically. None showed any other disorders of their knees than medial synovitis in seven of nine swimmers. Since structural abnormalities could be ruled out, biomechanical analyses utiliz ing cinematographic techniques were used to study patients swimming in a special flume with the speed set at 90% of their best competitive performance. The results indicate that the extension and flexion and also in some cases the hip abduction and adduction movements of the whip kick were performed with high peak angular ve…

Screw‐in‐screw fixation of fragility sacrum fractures provides high stability without loosening—biomechanical evaluation of a new concept

2020

Surgical treatment of fragility sacrum fractures with percutaneous sacroiliac (SI) screw fixation is associated with high failure rates. Turn-out is detected in up to 20% of the patients. The aim of this study was to evaluate a new screw-in-screw implant prototype for fragility sacrum fracture fixation. Twenty-seven artificial hemipelvises were assigned to three groups (n = 9) for instrumentation of an SI screw, the new screw-in-screw implant prototype, ora transsacral screw. Before implantation, a vertical osteotomy was set in zone 1 after Denis. All specimens were biomechanically tested to failure in upright position. Validated setup and test protocol were used for complex axial and torsi…

Improving the cementation of the tibial component in knee arthroplasty : a study of four techniques in the cadaver.

2021

Aims The main objective of this study is to analyze the penetration of bone cement in four different full cementation techniques of the tibial tray. Methods In order to determine the best tibial tray cementation technique, we applied cement to 40 cryopreserved donor tibiae by four different techniques: 1) double-layer cementation of the tibial component and tibial bone with bone restrictor; 2) metallic cementation of the tibial component without bone restrictor; 3) bone cementation of the tibia with bone restrictor; and 4) superficial bone cementation of the tibia and metallic keel cementation of the tibial component without bone restrictor. We performed CT exams of all 40 subjects, and mea…

In vitro comparative study on the friction of stainless steel wires with and without Orthospeed (JAL 90458) on an inclined plane

2016

Background: During the treatment of orthodontics, in the mechanics of slide, there takes place friction, which they reduce the slide of the arch across bracket. Therefore, clinical there takes place an increase of the time of treatment. There are different the technologies that try to reduce this friction, as the self-ligating braces. The purpose of this study was to research the in vitro behavior of JAL 90458 as a buffering agent which reduces friction between brackets and stainless steel arch wires of different cross sections and sizes. Material and Methods: Three types of stainless steel wires with different cross sections and three types of ligatures were used with and without JAL 90458…

Novel Digital Technique to Quantify the Area and Volume of Cement Remaining and Enamel Removed after Fixed Multibracket Appliance Therapy Debonding: …

2020

The aim of this study was to construct a novel, repeatable, reproducible, and accurate measurement protocol for the area and volume of the remaining cement after removal of fixed multibracket appliances, the area and volume of remaining cement after cement removal, the area and volume of enamel removed after cement removal, and the volume of cement used to adhere fixed multibracket appliances. A total of 30 brackets were cemented and removed with over 30 extracted teeth embedded into three experimental models of epoxy resin. The models were scanned before and after bracket placement, bracket debonding, and polishing the remaining cement. The brackets were submitted to micro-computed tomogra…