Computational Modeling to Predict Mechanical Function of Joints: Validations and Applications of Lower Leg Simulations

Computational models of musculoskeletal joints and limbs can provide useful information about joint mechanics. Validated models can be used as a predictive device for understanding joint function and serve as a clinical tool for predicting the outcome of surgical procedures. A new computational modeling approach was developed for simulating joint kinematics that are dictated by bone/joint anatomy, ligamentous constraints, and applied loading.Three-dimensional computational models of the lower leg were created. Model development involved generating three-dimensional surfaces from CT images, followed by importing these surfaces into SolidWorks and COSMOSMotion. ThroughSolidWorks and COSMOSMotion, each bone surface was created into a solid object and positioned, necessary components added, and simulations executed. Three dimensional contacts inhibited intersection of the bones during motion. Ligaments were represented as linear springs. Model predictions were then validated by comparison to three different previously performed cadaver studies (syndesmotic injury study, inversion stability study, and mechanical laxity study) and one simultaneously performed cadaver study (anterior drawer test).In the syndesmotic injury study, the relative motion between the tibia and fibula in intact, transected, and repaired states was measured under the application of an external rotation of the ankle. The inversion stability study focused on the elongation behavior of lateral ankle ligaments and inversion range of motion during the application of an applied load. The mechanical laxity study focused on differences in anterior/posterior and inversion/eversion movement in intact and transected states. Each computational simulation was placed under the same conditions as its respective cadaver study and revealed a capability to predict behaviors in each case. The syndesmotic injury model was able to predict tibia1 rotation, fibular rotation, and anterior/posterior displacement. In the inversion simulation, calcaneofibular ligament extension and angles of inversion compared well. The laxity study showed increases in anteroposter motion after the transactions of the ATFL and CFL; and diffenences in inversion after the transaction of the CFL. The Anterior Drawer simulation produced similar ligament elongations and loads when compared to cadaver studies.Overall, the computational models were able to predict joint kinematics of the lower leg with particular focus on the ankle complex. Additional parameters can be calculated through such models that are not easily obtained experimentally such as ligament forces, force transmission across joints, and three-dimensional movement of all bones

Radiological Society of North America (RSNA) 3D printing Special Interest Group (SIG): guidelines for medical 3D printing and appropriateness for clinical scenarios

Abstract Medical three-dimensional (3D) printing has expanded dramatically over the past three decades with growth in both facility adoption and the variety of medical applications. Consideration for each step required to create accurate 3D printed models from medical imaging data impacts patient care and management. In this paper, a writing group representing the Radiological Society of North America Special Interest Group on 3D Printing (SIG) provides recommendations that have been vetted and voted on by the SIG active membership. This body of work includes appropriate clinical use of anatomic models 3D printed for diagnostic use in the care of patients with specific medical conditions. The recommendations provide guidance for approaches and tools in medical 3D printing, from image acquisition, segmentation of the desired anatomy intended for 3D printing, creation of a 3D-printable model, and post-processing of 3D printed anatomic models for patient care.https://deepblue.lib.umich.edu/bitstream/2027.42/146524/1/41205_2018_Article_30.pd

Eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an atopic condition of the esophagus that has become increasingly recognized over the last decade. Diagnosis of the disorder is dependent on the patient’s clinical manifestations and histologic findings on esophageal mucosal biopsies. Patients with eosinophilic esophagitis should be referred to both an allergist and gastroenterologist for optimal management, which may include dietary modifications, pharmacologic agents such as corticosteroids, leukotriene modifiers and biologics as well as mechanical dilatation of the esophagus. The epidemiology, pathophysiology, diagnosis, treatment, and prognosis of EoE are discussed in this review

Esomeprazole for the treatment of erosive esophagitis in children: an international, multicenter, randomized, parallel-group, double-blind (for dose) study

<p>Abstract</p> <p>Background</p> <p>Acid suppression with a proton pump inhibitor is standard treatment for gastroesophageal reflux disease and erosive esophagitis in adults and increasingly is becoming first-line therapy for children aged 1-17 years. We evaluated endoscopic healing of erosive esophagitis with esomeprazole in young children with gastroesophageal reflux disease and described esophageal histology.</p> <p>Methods</p> <p>Children aged 1-11 years with endoscopically or histologically confirmed gastroesophageal reflux disease were randomized to esomeprazole 5 or 10 mg daily (< 20 kg) or 10 or 20 mg daily (≥ 20 kg) for 8 weeks. Patients with erosive esophagitis underwent an endoscopy after 8 weeks to assess healing of erosions.</p> <p>Results</p> <p>Of 109 patients, 49% had erosive esophagitis and 51% had histologic evidence of reflux esophagitis without erosive esophagitis. Of the 45 patients who had erosive esophagitis and underwent follow-up endoscopy, 89% experienced erosion resolution. Dilation of intercellular space was reported in 24% of patients with histologic examination.</p> <p>Conclusions</p> <p>Esomeprazole (0.2-1.0 mg/kg) effectively heals macroscopic and microscopic erosive esophagitis in this pediatric population with gastroesophageal reflux disease. Dilation of intercellular space may be an important histologic marker of erosive esophagitis in children.</p> <p>Trial Registration</p> <p>D9614C00097; ClinicalTrials.gov identifier NCT00228527.</p