0000000000390276
AUTHOR
Lorenzo Nalbone
A new method to evaluate the influence of the glenosphere positioning on stability and range of motion of a reverse shoulder prosthesis
Abstract Purpose Shoulder instability and reduced range of motion are two common complications of a total reverse shoulder arthroplasty. In this work, a new approach is proposed to estimate how the glenoid component positioning can influence the stability and the range of motion of a reverse shoulder prosthesis. Materials and methods A standard reverse shoulder prosthesis has been analysed. To perform virtual simulation of the shoulder-prosthesis assembly, all the components of the prosthesis have been acquired via a 3D laser scanner and the solid models of the shoulder bones have been reconstructed through CT images. Loads on the shoulder joint have been estimated using anatomical models d…
Optimal positioning of the humeral component in the reverse shoulder prosthesis.
Total reverse shoulder arthroplasty is becoming more and more the standard therapeutic practice for glenohumeral arthropathy with massive lesions of the rotator cuff. The biomechanical principle of this prosthesis is represented by the reversion of the normal anatomy of the shoulder joint. This non-anatomical prosthesis leads to a medialization of the rotation centre of the glenohumeral joint and also to a distalization of the humeral head. All that causes a deltoid tension increasing so allowing a larger abduction of the arm. Main complications of the reverse shoulder prosthesis are due to the joint instability, the scapular notching and the wear of the polyethylene insert. The main goal o…
Influence of sutures configuration on the strength of tendon-patch joints for rotator cuff tears treatment
Abstract Purpose Massive rotator cuff tears are common in the aging population. The incidence of failed rotator cuff repairs is still quite high, especially in the treatment of full-thickness tears or revision repairs. In this context, natural and synthetic meshes can be used as augmentation scaffolds or as devices to close the gap between a retracted tendon and the bone. The purpose of this work is to evaluate the ultimate tensile strength of different tendon-patch joints in order to consider their use in the treatment of massive cuff tears. Materials and methods Porcine tendons and a synthetic low-density polypropylene mesh have been used. A preliminary study on the tensile strength of te…
Biomechanical Analysis of a New Elbow Prosthesis
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…
Emergent and delayed hybrid external fixation management of tibial pilon fractures: A multicentric retrospective analysis of 80 patients
Objective: To report our experience with the hybrid external fixator in emergency. Methods: We assessed 80 cases of pilon fracture treated with the external fixator during the period of January 2009 and December 2016:55 men (69%) and 30 women (33%) with a mean age of 40 years (range between 16 and 70). About 45 occurred as isolated trauma, 35 instead were politrauma. Each patient underwent standard radiographic examination and a CT examination. There were 28 open fractures (35%), (Gustilo type 1, 2 and 3) while closed fractures showed soft tissue involvement of various grade (2-3 Tscherne classification). In all cases, the external fixation, sometimes associated with other reduction and syn…
Microsurgery and external fixation in orthoplastic reconstruction of tibial injuries.
"Orthoplastics" is a relatively new approach to lower limb reconstruction, where an integration of both plastic and orthopedic expertise is required, together with the availability of well-equipped facilities. Acute shortening and long-term frames for lengthening are generally considered alternatives to length preservation and soft tissue microsurgical reconstruction, but an integration of external fixation and reconstructive microsurgery is gaining an increasing role with refinements of joint approaches.Data on sixteen patients who underwent microsurgical lower limb reconstruction and external fixation with an orthoplastic approach, following acute or chronic tibial injury, were retrospect…
Influence of the metaphysis positioning in a new reverse shoulder prosthesis
Aim of this work is to investigate the behaviour of a new reverse shoulder prosthesis, characterized by a humeral metaphysis with a variable offset, designed to increase the range of movements and to reduce the impingement. In particular, by means of virtual prototypes of the prosthesis, different offset values of the humeral metaphysis have been analysed in order to find the best positioning able to maximize the range of movements of the shoulder joint. The abduction force of the deltoid, at different offset values, has been also estimated. The study has been organized as follows. In the first step, the point clouds of the surfaces of the different components of the prosthesis have been ac…
Finite element analysis of two total knee joint prostheses
Aim of this work is to compare two different total knee prostheses that differ mainly in the shape of the polyethylene (PE) component inserted between the femoral and tibial plates. The best solution between them has been originally reshaped in order to reduce stress peaks. The study procedure has been divided into the following steps. First step is the digitalisation of the shape of the prostheses by means of a 3D laser scanner. The morphology of two prototypes of the prostheses has been acquired by elaborating multiple Moire fringe patterns projected on their surfaces. Second step consisted on the manipulation of these data in a CAD module, that is the interpolation of raw data into NURBS…
Study of a constrained finite element elbow prosthesis: the influence of the implant placement
Abstract Background The functional results of total elbow arthroplasty (TEA) are controversial and the medium- to long-term revision rates are relatively high. The aim of the present study was to analyze the stresses of TEA in its classic configuration, identify the areas of greatest stress in the prosthesis–bone–cement interface, and evaluate the most wearing working conditions. Materials and methods By means of a reverse engineering process and using a 3D laser scanner, CAD (computer-aided drafting) models of a constrained elbow prosthesis were acquired. These CAD models were developed and their elastic properties, resistance, and stresses were studied through finite element analysis (fin…
Biomechanical analysis of the humeral tray positioning in reverse shoulder arthroplasty design
Despite the widespread use of reverse total shoulder arthroplasty, the fundamental effects of implant configuration on certain biomechanical outcomes have not been completely elucidated especially for the most innovative prostheses. Aim of this work is to investigate the behaviour of a new reverse shoulder prosthesis, characterized by a humeral tray with a variable offset, designed to increase the range of motion and to reduce the impingement. The purposes of this study were to evaluate the effect of reverse shoulder implant design parameters on the deltoid muscle forces, required to produce abduction, and on the shoulder range of motion, in order to provide a more systematic understanding …