Revision of reversed shoulder arthroplasty : is a reoperation possible?

Introduction. As the number of reversed shoulder arthroplasty (RSA) procedures increases, the revision rate will also increase. In case of severe bone insufficiency, instability or infection of the primary RSA, revision to another RSA is preferable but not always possible. Hemiarthroplasty (HA), spacers and resection arthroplasty (RA) have been described in this indication. Materials and methods. Between 2004 and 2016, 20 shoulders in 19 patientswere treated at Ghent University Hospital for failed revision of RSA. Nine received a megahead prosthesis, a spacerwas implanted in 6, and 5 underwent RA. Results. Indications for implantation of a megahead prosthesis were loosening RSA (n = 5), infection (n = 4), dislocation (n = 1) and nerve irritation (n = 1). Improvement of range ofmotionwas observed. Anterosuperior migration of the prosthesis was noted in 2 patients. Another 2 patients were ultimately revised to RSA. Seven permanent spacerswere implanted for infection, of which 2 remain in place till today. The other 5 were revised to RSA. Of the 5 patients treated with RA, 3 were revised further on to RSA, resulting in pain relief and regain of function. Discussion. Our study shows that amegahead prosthesis has better functional results than RA, but is inferior to RSA. Due to increasing surgical experience and improving technique, 9 patients could ultimately be reconverted to another RSA. A review of current literature is presented. In HA and RA, the functional results are poor, and pain relief is uncertain. Results of spacers are variable and can be satisfactory. Arthrodesis is a last resort. Conclusion. In our case series study, a hemiarthroplasty can be performed in case of failure of RSA. However, the results are inferior to another RSA

Relationship of the medial clavicular head to the manubrium in normal and symptomatic degenerated sternoclavicular joints

Background: Clavicular prominence is common in patients with symptomatic degenerative sternoclavicular arthritis. It is unclear if this is caused by enlargement or subluxation of the clavicle. The aim of this report is to describe a reproducible measurement technique to evaluate the relationship of the medial clavicular head to the manubrium. Methods: One hundred normal sternoclavicular joints, twenty-five sternoclavicular joints with symptomatic degenerative arthritis, and twenty-five non-symptomatic sternoclavicular joints on the contralateral side were studied with three-dimensional (3D) reconstruction with use of computer modeling. The greatest width (anterior-posterior distance) and height (superior-inferior distance) of the clavicle in the sagittal plane were measured, and the positions of the anterior and superior borders of the medial clavicle and their distances to the frontal and axial planes, respectively, were evaluated. The ratio of the anterior-posterior distance to the anterior-frontal plane distance was measured to evaluate the anterior-posterior position of the clavicle and the ratio of the superior-inferior distance to the superior-axial plane distance was measured to evaluate its superoinferior position. If the ratio was not in the 95% normal range, the clavicle was defined as subluxated. The reproducibility of this technique was evaluated on the basis of the interobserver and intraobserver reliability. Results: This technique showed good interobserver and intraobserver reliability. The mean anterior-posterior and superior-inferior distances were significantly larger in association with symptomatic sternoclavicular arthritis than in the normal sternoclavicular joints (p < 0001). The clavicle was subluxated anteriorly in twenty-two of the twenty-five cases of symptomatic sternoclavicular arthritis, but it was not subluxated superiorly. Conclusions: The medial clavicular head in patients with degenerative sternoclavicular arthritis is significantly larger than it is in the normal population, and it is usually subluxated anteriorly

Improving the surface properties of an UHMWPE shoulder implant with an atmospheric pressure plasma jet

Insufficient glenoid fixation is one of the main reasons for failure in total shoulder arthroplasty. This is predominantly caused by the inert nature of the ultra-high molecular weight polyethylene (UHMWPE) used in the glenoid component of the implant, which makes it difficult to adhesively bind to bone cement or bone. Previous studies have shown that this adhesion can be ameliorated by changing the surface chemistry using plasma technology. An atmospheric pressure plasma jet is used to treat UHMWPE substrates and to modify their surface chemistry. The modifications are investigated using several surface analysis techniques. The adhesion with bone cement is assessed using pull-out tests while osteoblast adhesion and proliferation is also tested making use of several cell viability assays. Additionally, the treated samples are put in simulated body fluid and the resulting calcium phosphate (CaP) deposition is evaluated as a measure of the in vitro bioactivity of the samples. The results show that the plasma modifications result in incorporation of oxygen in the surface, which leads to a significant improved adhesion to bone cement, an enhanced osteoblast proliferation and a more pronounced CaP deposition. The plasma-treated surfaces are therefore promising to act as a shoulder implant

Can an extracorporeal glenoid aiming device be used to optimize the position of the glenoid component in total shoulder arthroplasty?

Purpose: Successful total shoulder arthroplasty (TSA) requires a correct position of the glenoid component. This study compares the accuracy of the positioning with a new developed glenoid aiming device and virtual three-dimensional computed tomography (3D-CT) scan positioning. Materials and Methods: On 39 scapulas from cadavers, a K-wire (KDev) was positioned using the glenoid aiming device. It consists of glenoid components connected to the aiming device, which cover 150 degrees of the inferior glenoid circle, has a fixed version and inclination and is available with several different radii. The aiming device is stabilized at the most medial scapular point. The K-wire is drilled from the center of the glenoid component to this most medial point. All scapulas were also scanned with CT and 3D reconstructed. A virtual K-wire (Kct) was positioned in the center of the glenoid and in the scapular plane. Several parameters were compared. Radius of the chosen glenoid component (rDev) and the virtual radius of the glenoid circle (rCT), spinal scapular length with the device (SSLdev) and virtual (SSLct), version and inclination between KDev and Kct, difference between entry point and exit point ("Matsen"-point). Results: Mean rDev: 14 mm +/- 1.7 mm and mean rCT: 13.5 mm +/- 1.6 mm. There was no significant difference between SSLdev (110.6 mm +/- 7.5 mm) and SSLct (108 mm +/- 7.5 mm). The version of KDev and Kct was -2.53 degrees and -2.17 degrees and the inclination 111.29 degrees and 111.66 degrees, respectively. The distance between the "Matsen-point" device and CT was 1.8 mm. Conclusion: This glenoid aiming device can position the K-wire on the glenoid with great accuracy and can, therefore, be helpful to position the glenoid component in TSA. The level of evidence: II

Efficient Quality Diversity Optimization of 3D Buildings through 2D Pre-optimization

Quality diversity algorithms can be used to efficiently create a diverse set of solutions to inform engineers' intuition. But quality diversity is not efficient in very expensive problems, needing 100.000s of evaluations. Even with the assistance of surrogate models, quality diversity needs 100s or even 1000s of evaluations, which can make it use infeasible. In this study we try to tackle this problem by using a pre-optimization strategy on a lower-dimensional optimization problem and then map the solutions to a higher-dimensional case. For a use case to design buildings that minimize wind nuisance, we show that we can predict flow features around 3D buildings from 2D flow features around building footprints. For a diverse set of building designs, by sampling the space of 2D footprints with a quality diversity algorithm, a predictive model can be trained that is more accurate than when trained on a set of footprints that were selected with a space-filling algorithm like the Sobol sequence. Simulating only 16 buildings in 3D, a set of 1024 building designs with low predicted wind nuisance is created. We show that we can produce better machine learning models by producing training data with quality diversity instead of using common sampling techniques. The method can bootstrap generative design in a computationally expensive 3D domain and allow engineers to sweep the design space, understanding wind nuisance in early design phases.Comment: This is the final version and has been accepted for publication in Evolutionary Computation (MIT Press

Formal symplectic groupoid of a deformation quantization

We give a self-contained algebraic description of a formal symplectic groupoid over a Poisson manifold M. To each natural star product on M we then associate a canonical formal symplectic groupoid over M. Finally, we construct a unique formal symplectic groupoid `with separation of variables' over an arbitrary Kaehler-Poisson manifold.Comment: 41 page, Lemma 13, several typos and notations correcte

Clinical and radiographic outcomes of an all-polyethylene fluted central peg glenoid component, implanted utilizing an off-label, uncemented technique, at a minimum 5-year follow-up

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