A numerical study towards shape memory alloys application in orthotic management of pediatric knee lateral deviations

Exerting a constant load would likely improve orthosis effectiveness in treating knee lateral deviations during childhood and early adolescence. Shape memory alloys are potential candidates for such applications due to their so called pseudoelastic effect. The present study aims to quantitatively define the applicable mechanical loads, in order to reduce treatment duration while avoiding tissular damage and patient discomfort. This is essential for performing a more efficient design of correction devices. We use a patient-specific finite elements model of a pediatric knee to determine safe loading levels. The achievable correction rates are estimated using a stochastic three-dimensional growth model. Results are compared against those obtained for a mechanical stimulus decreasing in proportion to the achieved correction, emulating the behavior of conventional orthoses. A constant flexor moment of 1.1 Nm is estimated to change femorotibial angle at a rate of (7.4 ± 4.6) deg/year (mean ± std). This rate is similar to the achieved by more invasive growth modulation methods, and represents an improvement in the order of 25% in the necessary time for reducing deformities of (10 ± 5) deg by half, as compared with conventional orthoses.

A tool for solving bone growth related problems using finite elements adaptive meshes

Long bones geometry changes in response to longitudinal growth in the epiphyseal plates and hydroxyapatite apposition in the periosteum. Due to its relevance for growth modulation and orthotics performance, researchers have extensively modeled these phenomena, using the finite elements method for it almost since the introduction of modern computers. This is a rather complex task that, besides the inherent difficulty of solving the models equations, requires considering a moving boundary. Here, the development of a new computational tool for its resolution is described. A generalized formulation of these problems is established based on the most common approaches taken in the literature and a novel finite elements algorithm is proposed for its resolution. The later allows a significant reduction of the spatial discretization requirements, the computational cost and the numerical errors associated with more classical approaches. The potentiality of the method is demonstrated by its application to three cases of practical interest, namely, hemiepiphysiodesis treatment, growth in the distal femur and bone remodeling around hip prosthesis. Eight relevant cases of study and an open source implementation of the proposed algorithm are also provided as supplementary material.

Phase II trial of cabazitaxel in patients with advanced or metastatic transitional cell carcinoma of the urothelial tract who have progressed within less than 12 months after cisplatin-based chemotherapy: A Spanish Oncology Genitourinary Group (SOGUG) study

TPS4672

Background: Advanced transitional cell carcinoma of the urothelium (TCCU) on progression after previous cisplatin-based combination is generally an incurable disease. The appropriate management of these patients is still an unmet need. Many drugs have shown modest or no activity in previous phase 2 trials. Population heterogeneity in these studies emerges as one of the key determinants that could explain the variable outcomes. Recently, in a phase III study in this setting, prognostic factors (PF) for overall survival were identified (Bellmunt J et al, JCO 2010). Taxanes are active drugs in 2nd-line metastatic TCCU. Cabazitaxel (C) is a semi-synthetic taxane that is a poor substrate for the multidrug resistance system. C could be a valid alternative in this patient population. Methods: This is an open label phase II study of C in patients (pts) with advanced or metastatic TCCU who have progressed within 12 months after receiving a 1st-line platinum based chemotherapy. There are three treatment arms as patients will be assigned to one of three groups previously defined based on the presence of 0, 1 or 2-3 PFs as defined by Bellmunt et al. The activity of C will be assessed separately in each group and overall. The primary endpoint is response rate (RR) evaluated according to RECIST 1.1, a maximum of 35 pts are needed in each subgroup (maximum number of pts required: 105). Secondary objectives are RR in the whole population, toxicity, progression-free survival and overall survival. In addition, an external validation of the prognostic model proposed by Bellmunt will be conducted, as well as a pharmacogenomic study in order to better define the toxicity profile of the drug and the potential responders.

Use of the Gamma nail in the treatment of fractures of the proximal femur

Fractures of the proximal femur are, more than ever, an important challenge in the field of traumatology. The Gamma nail, a combination of advantages of the sliding screw with the intramedullary nail, represents an efficient technique in the management of these fractures. A series of 224 fractures of the proximal femur in which this nail was used is reported. The average age of the patients was 79.2 years. The mean healing time was 68.2 days in 99.4% of the cases. The incidence of perioperative complications was 10.3% showing that, in most of the cases, the complications occurred because of poor technique. Postoperative complications occurred with an incidence of 14.1%. Seven cases of migration of a proximal screw, six shaft fractures, and one broken nail were the most important complications. The device allowed for early mobilization and full weightbearing of the affected hip regardless of the type of fracture. With adequate surgical technique and experience, the advantages of the Gamma nail increases as the complication rate diminishes.