Search results for "CAD"
showing 10 items of 5323 documents
The "critical zones" of entrapment of the nerves of the lower limb.
1991
The author has studied, in a group of 40 dissections on cadavers of individuals of different ages, the main “critical zones” of entrapment of some terminal branches of the lumbo-sacral plexus, which include canals (fibrous, osteo-fibrous, fibro-muscular), intervals (intermuscular, fibro-muscular, musculo-ligamentous), rings (fibrous or fibro-muscular) and foramina. They provide the topographical anatomical basis for possible compressive phenomena of the nerves of the lower limb.
A Locked Intraosseous Nail for Transverse Patellar Fractures: A Biomechanical Comparison with Tension Band Wiring Through Cannulated Screws.
2018
Background Displaced transverse patellar fractures require open reduction and internal fixation. State-of-the-art stabilization techniques are tension band wiring (TBW) using Kirschner wires or cannulated screws. These techniques are associated with high rates of secondary fracture displacement, implant migration, implant prominence, wound-healing disturbances, and the need for implant removal. Recently, a locked intraosseous patellar nail prototype was developed. The aim of the present study was to investigate the biomechanical performance of this nail compared with TBW using cannulated screws. Methods Seven paired fresh-frozen human cadaveric knees were stripped of all soft tissues except…
Vergleich radiologischer Verfahren zur präoperativen Beurteilung der Verankerungsfestigkeit von Wirbelsäulenimplantaten
1997
PURPOSE To compare three techniques with regards to their ability to estimate pull out strength of spinal fusion hardware. MATERIAL AND METHODS VDS-screw fixation strength in 50 human cadaveric vertebral bodies was approximated by means of pull out force measurement. Bone quality was assessed by Dual X-ray Absorptiometry (DXA). Quantitative Computed Tomography (QCT) and T2*-relaxation time. For each of these techniques, correlation with axial pull out force strength was investigated. RESULTS Highest correlation was found for cancellous bone density measured by QCT (r = 0.72; p < 0.001). Immediately followed by DXA (r = 0.70; p < 0.001), which involves all bone components. Inverted T2*-relax…
Influence of the Screw Positioning on the Stability of Locking Plate for Proximal Tibial Fractures: A Numerical Approach
2020
Tibial fractures are common injuries in people. The proper treatment of these fractures is important in order to recover complete mobility. The aim of this work was to investigate if screw positioning in plates for proximal tibial fractures can affect the stability of the system, and if it can consequently influence the patient healing time. In fact, a more stable construct could allow the reduction of the non-weight-bearing period and consequently speed up the healing process. For that purpose, virtual models of fractured bone/plate assemblies were created, and numerical simulations were performed to evaluate the reaction forces and the maximum value of the contact pressure at the screw/bo…
The radial artery is larger than the ulnar.
2003
The radial artery is presently widely used as a bypass graft for coronary artery reconstruction. However, the traditional opinion that the ulnar artery is the larger forearm artery has been questioned.The internal diameters of the radial and ulnar arteries were measured at the wrist in postmortem angiograms of 24 cadavers. Differences in mean values of variables between ulnar and radial arteries were analyzed using the Wilcoxon test.The mean diameter of the radial artery was 28% larger than that of the ulnar artery in the right arm (p0.001) and 26% larger in the left arm (p0.001). In the right arm the radial artery was dominant in 20 of 24 cadavers (83%), the ulnar artery in 3 of 24 (13%), …
Biomechanical Analysis of a New Elbow Prosthesis
2019
Total elbow arthroplasty (TEA) is an effective and frequently used treatment for patients with debilitating elbow pathology. Total elbow prostheses have lagged behind those of the knee, hip and shoulder for different reasons, such as the high failure rate of the early designs. Concern remains regarding the longevity of TEA implants, especially in younger patients. The main cause of revision of the implant is usually related to the phenomenon of aseptic loosening mainly due to the cement-bone interface failure. Aim of this work is the biomechanical analysis of a new elbow prosthesis to investigate the mechanical behaviour at the cement-bone interface. For this reason, a musculoskeletal model…
Kinematics of the ulna during pronation and supination in a cadaver study: implications for elbow arthroplasty
2003
Objective. Aim of this study was to exactly describe and quantify kinematics of the ulna during pro- and supination. Design. Biomechanical study in fresh frozen cadavers. Background. A previous MRI study revealed a varus/valgus motion of the ulna averaging 7.1° during pro-/supination. Axial rotation, however, could not be quantified. Methods. Sixteen arms were examined in a new apparatus that fixed the humerus on a template and allowed forearm rotation. Motion of a Kirschner wire placed in the ulna was recorded in steps of 30° by two perpendicularly arranged charge coupled device cameras during pro- and supination. Results. From supination to pronation the ulna showed a semi-lunar evasive m…
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…
Morphomechanics of the humero-ulnar joint: I. Joint space width and contact areas as a function of load and flexion angle
1995
BACKGROUND Previous studies have shown that the trochlear notch is deeper than necessary for an exact fit with the humerus. However, humero-ulnar joint space width and contact areas have so far not been quantified for variations in the load and angle of flexion. METHODS Six fresh cadaveric specimens were investigated at 30 degrees, 60 degrees, 90 degrees, and 120 degrees of flexion and at loads of 25 and 500 N, simulating resisted elbow extension. The joint space width and contact were determined, using polyether casting material. RESULTS At 25 N all joints made contact in the ventral and dorsal aspects of the articular surfaces, whereas in the depth of the trochlear notch the joint space w…
Waterjet dissection in pediatric cranioplasty
2010
Object Waterjet dissection has been shown to separate tissues of different resistance, with preservation of blood vessels. In cranioplasty, separation of subcutaneous tissue and dura mater is often difficult to achieve because the various tissue layers strongly adhere to each other after decompressive craniotomy. In the present study, the potential advantages and drawbacks of the waterjet technique in cranioplasty after craniectomy and duraplasty are addressed. Methods The waterjet effect on fresh human cadaveric dura mater specimens as well as on several dural repair patches was tested in vitro under standardized conditions, with waterjet pressures up to 80 bar. Subsequently, 8 pediatric …