Application specific adaption of a numerical based surgical process

Postoperative pain and functional limitations after an Anterior Cruciate Ligament reconstruction is usually inaccurate placement of the femoral and tibial tunnel. This paper presents a technology workflow including a software pipeline for patient-specific preoperative planning and analysis of the knee joint including functional-mechanical properties

Accuracy of KinectOne to quantify kinematics of the upper body

Motion analysis systems deliver quantitative information, e.g. on the progress of rehabilitation programs aimed at improving range of motion. Markerless systems are of interest for clinical application because they are low-cost and easy to use. The first generation of the Kinect™ sensor showed promising results in validity assessment compared to an established marker-based system. However, no literature is available on the validity of the new 'Kinect™ for Xbox one' (KinectOne) in tracking upper body motion. Consequently, this study was conducted to analyze the accuracy and reliability of the KinectOne in tracking upper body motion. Twenty subjects performed shoulder abduction in frontal and scapula plane, flexion, external rotation and horizontal flexion in two conditions (sitting and standing). Arm and trunk motion were analyzed using the KinectOne and compared to a marker-based system. Comparisons were made using Bland Altman statistics and Coefficient of Multiple Correlation. On average, differences between systems of 3.9±4.0° and 0.1±3.8° were found for arm and trunk motion, respectively. Correlation was higher for the arm than for the trunk motion. Based on the observed bias, the accuracy of the KinectOne was found to be adequate to measure arm motion in a clinical setting. Although trunk motion showed a very low absolute bias between the two systems, the KinectOne was not able to track small changes over time. Before the KinectOne can find clinical application, further research is required analyzing whether validity can be improved using a customized tracking algorithm or other sensor placement, and to analyze test-retest reliability

Towards the development of a novel experimental shoulder simulator with rotating scapula and individually controlled muscle forces simulating the rotator cuff

A preclinical analysis of novel implants used in shoulder surgery requires biomechanical testing conditions close to physiology. Existing shoulder experiments may only partially apply multiple cycles to simulate postoperative, repetitive loading tasks. The aim of the present study was therefore the development of an experimental shoulder simulator with rotating scapula able to perform multiple humeral movement cycles by simulating individual muscles attached to the rotator cuff. A free-hanging, metallic humerus pivoted in a polyethylene glenoid is activated by tension forces of linear electroactuators to simulate muscles of the deltoideus (DELT), supraspinatus (SSP), infraspinatus/teres minor and subscapularis. The abductors DELT and SSP apply forces with a ratio of 3:1 up to an abduction angle of 85°. The rotating scapular part driven by a rotative electro actuator provides one-third to the overall arm abduction. Resulting joint forces and moments are measured by a 6-axis load cell. A linear increase in the DELT and SSP motors is shown up to a maximum of 150 and 50N for the DELT and SSP, respectively. The force vector in the glenoid resulted in 253N at the maximum abduction. The present investigation shows the contribution of individual muscle forces attached to the moving humerus to perform active abduction in order to reproducibly test shoulder implants

Development of an instrumented knee endoprosthesis for measuring loads in vivo

Die Knieendoprothetik kann heutzutage hervorragende Resultate aufweisen. Die wichtigsten Ziele sind hierbei die Schmerzbeseitigung und die Wiederherstellung oder Aufrechterhaltung der Gelenkbeweglichkeit. Damit kann eine weitgehende Unabhängigkeit und Selbständigkeit der Patienten erzielt werden. Bei der Entwicklung einer Knieendoprothese wird eine Vielzahl präklinischer Untersuchungen durchgeführt, bei denen die mechanische Funktionalität des Implantates untersucht wird. Hierzu ist es notwendig, die auf das natürliche oder prothetisch versorgte Kniegelenk wirkenden Belastungen zu kennen. Diese konnten bisher in vivo messtechnisch nur unzureichend ermittelt werden. Deshalb sind bis heute viele nur theoretisch ermittelte, aber nicht verifizierte, Belastungswerte vorhanden. Aus diesem Grund wurde eine Knieendoprothese entwickelt, die in vivo Belastungsmessungen erlaubt. Nach der Implantation dieser Prothese bei zwei Patienten konnte die Belastung während des Gehens und Treppensteigens ermittelt werden. Es wurden Belastungen bis zum 3,5-fachen Körpergewicht gemessen. Die ermittelten Daten geben einen bisher nicht da gewesenen Einblick in die Belastungen des Kniegelenkes und helfen Ärzten, Physiotherapeuten und Herstellern bei der Weiterentwicklung der Knieendoprothetik.Total knee replacement has an excellent success rate and is a widely used surgical procedure to relieve pain from arthritic joints and to restore their range of motion. Various pre-clinical tests are undertaken to prove the mechanical functionality and integrity of the prostheses. The prostheses are subject to high loads in vivo, which are not accessible to the most technical measurement devices. Therefore, load data is nowadays mostly derived from theoretical models and is not fully validated. To overcome this lack of information, an instrumented knee prosthesis was designed to measure in vivo loading. The prosthesis was implanted in two subjects and measurements were performed during level walking and stair climbing. The measured loads were up to 3.5 times bodyweight. The availability of measured in vivo loads will increase the knowledge of orthopedic surgeons, physiotherapists, scientific researchers and manufacturers and help to further improve total knee replacement

Der virtuelle Körper als 3-D-Simulationsmodell

Patientenspezische 3-D-Simulationen ermöglichen präzise, wirtschaftliche und effiziente Eingriffe in der Medizin. Während heute vornehmlich Visualisierungen des menschlichen Körpers möglich sind, fehlt die Einbindung der funktionellen-mechanischen Eigenschaften der biologischen Materialien. An der ZHAW School of Engineering entwickelt ein interdisziplinäres Forschungsteam basierend auf den bisherigen Möglichkeiten eine Erweiterung der Operationsplanung mittels der Finite- Elemente-Methode (FEM) zur strukturmechanischen Analyse.

Validity of the new Kinect-sensor in measuring upper body kinematics

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