Validation of statistical shape model based reconstruction of the proximal femur - A morphology study

Seventeen bones (sixteen cadaveric bones and one plastic bone) were used to validate a method for reconstructing a surface model of the proximal femur from 2D X-ray radiographs and a statistical shape model that was constructed from thirty training surface models. Unlike previously introduced validation studies, where surface-based distance errors were used to evaluate the reconstruction accuracy, here we propose to use errors measured based on clinically relevant morphometric parameters. For this purpose, a program was developed to robustly extract those morphometric parameters from the thirty training surface models (training population), from the seventeen surface models reconstructed from X-ray radiographs, and from the seventeen ground truth surface models obtained either by a CT-scan reconstruction method or by a laser-scan reconstruction method. A statistical analysis was then performed to classify the seventeen test bones into two categories: normal cases and outliers. This classification step depends on the measured parameters of the particular test bone. In case all parameters of a test bone were covered by the training population's parameter ranges, this bone is classified as normal bone, otherwise as outlier bone. Our experimental results showed that statistically there was no significant difference between the morphometric parameters extracted from the reconstructed surface models of the normal cases and those extracted from the reconstructed surface models of the outliers. Therefore, our statistical shape model based reconstruction technique can be used to reconstruct not only the surface model of a normal bone but also that of an outlier bone.

[Intramedullary claw for stabilization of proximal humerus fractures: a comparison with other semirigid techniques]

Proximal humerus fractures (pHF) are common. In this retrospective study intra-operative and postoperative data and complications of patients stabilized with conventional semirigid techniques (pins, n=30; helix wire, n=19) or a novel semirigid technique, the intramedullary claw (IMC, n=82) were compared. The type and frequency of postoperative complications differed between the groups (p<0.001). The IMC is a novel semirigid technique to stabilize pHF and seems to result in fewer complications than pins or helix wire. The frequency and relevance of a loss of repositioning in patients after IMC implantation need to be elucidated in long-term studies.

Sirolimus and everolimus reduce albumin endocytosis in proximal tubule cells via an angiotensin II-dependent pathway

The proliferation signal inhibitors (PSIs) sirolimus (SRL) and everolimus (ERL) often induce proteinuria due to glomerular but also tubular dysfunction in transplant patients. The beneficial effect of angiotensin converting enzyme inhibitors (ACE-I) and angiotensin II (Ang II) type 1 receptor blockers (ARB) has been reported.

Acute Regulation of Renal Na+/H+ Exchanger NHE3 by Dopamine: Role of Protein Phosphatase 2A

Nephrogenic dopamine is a potent natriuretic paracrine/autocrine hormone that is central for mammalian sodium homeostasis. In the renal proximal tubule, dopamine induces natriuresis partly via inhibition of the sodium/proton exchanger NHE3. The signal transduction pathways and mechanisms by which dopamine inhibits NHE3 are complex and incompletely understood. This manuscript describes the role of the serine/threonine protein phosphatase 2A (PP2A) in the regulation of NHE3 by dopamine. The PP2A regulatory subunit B56 delta (coded by the Ppp2r5d gene) directly associates with more than one region of the carboxy-terminal hydrophilic putative cytoplasmic domain of NHE3 (NHE3-cyto), as demonstrated by yeast-two-hybrid, co-immunoprecipitation, blot overlay and in vitro pull-down assays. Phosphorylated NHE3-cyto is a substrate for purified PP2A in an in vitro dephosphorylation reaction. In cultured renal cells, inhibition of PP2A by either okadaic acid or by overexpression of the simian virus 40 (SV40) small t antigen blocks the ability of dopamine to inhibit NHE3 activity and to reduce surface NHE3 protein. Dopamine-induced NHE3 redistribution is also blocked by okadaic acid ex vivo in rat kidney cortical slices. These studies demonstrate that PP2A is an integral and critical participant in the signal transduction pathway between dopamine receptor activation and NHE3 inhibition. Key words: Natriuresis, Sodium transport, Signal transduction.

Proximal row carpectomy in emergency

Proximal row carpectomy (PRC) is a well-accepted procedure for the treatment of early post-traumatic degenerative disease of the wrist. Much less frequently, PRC has been advocated as an emergency procedure for irreparable fracture-dislocation of the wrist. Our objective was to compare the results of PRC in patients having undergone this procedure in the two contexts. We conducted a retrospective analysis of the clinical and radiographic results of six patients treated by emergency PRC as compared to six patients who underwent elective PRC. The mean follow-up was 36 months. Both the patient's satisfaction and the grasp of the wrist joint were significantly better in patients who underwent PRC emergency as compared to those having undergone elective PRC. Quick DASH score, radiographic results, and return to work were also more favourable in these patients, but the difference between the two groups was not significant. This study confirms that PRC is a valuable salvage technique indicated in early posttraumatic wrist collapse. Moreover, when performed in emergency, the procedure shows even better subjective and objective results, allowing a majority of patients to return to their previous job.

Sutureless proximal anastomosis using the PAS-Port system: six-month patency and five-year follow-up in "all-comers"

The PAS-Port system (Cardica, Inc, Redwood City, CA) was used routinely for patients undergoing coronary surgery with at least one venous graft. Graft patency and clinical results were evaluated, respectively, at 6 months and 5 years after surgery.

Vasculitides associated with IgG antineutrophil cytoplasmic autoantibodies in childhood

Immunoglobulin (Ig)G antineutrophil cytoplasmic autoantibodies are causally associated with necrotizing vasculitides that are characterized immunopathologically by little or no deposition of immunoreactants, such as Wegener granulomatosis, microscopic polyangiitis, Churg-Strauss angiitis, "renal-limited" vasculitis and a number of drug-induced vasculitides. Clinical routine testing targets the antigens myeloperoxidase and proteinase 3. However, in all of the conditions mentioned, the renal histopathologic findings are indistinguishable. Churg-Strauss angiitis (characterized by necrotizing vasculitis, granulomatous inflammation and tissue eosinophilia), Wegener granulomatosis (characterized by necrotizing vasculitis and granulomatous inflammation) and microscopic polyangiitis (characterized by necrotizing vasculitis) often present with fever, weight loss and a multisystem involvement (ear, nose, throat, lung, eyes, peripheral nerve and heart). Fifty years ago these conditions were very often fatal within 6 months of diagnosis. The introduction of corticosteroids and cyclophosphamide has resulted in a dramatic clinical benefit. Patients who develop treatment-related morbidity can be switched from cyclophosphamide to azathioprine after achieving remission. In patients with less severe disease, methotrexate achieves remission with a success rate similar to that of cyclophosphamide. Plasma exchange, in association with immunosuppression, is likely to be a beneficial therapy for patients with severe kidney disease or pulmonary hemorrhage.

Adult Proximal Humerus Locking Plate for the Treatment of a Pediatric Subtrochanteric Femoral Nonunion: A Case Report

Nonunions of pediatric subtrochanteric femur fractures are exceedingly rare and have to date not been reported in the literature. We present the case of an 11-year-old boy who developed such a nonunion after open reduction internal fixation using a pediatric locked proximal femur plate. Using an adult proximal humerus locking plate, adequate proximal fixation of the nonunion was obtained. Furthermore, previously placed distal screw holes were safely bridged and the biomechanical environment around the nonunion site improved. Uneventful healing was possible with the use of adjuvant bone grafting. No short- or midterm complications occurred. Although other implants can certainly be adapted to a use different than that of its original design, the present case suggests that adult proximal humerus locking plates may be a safe option for revision surgery of the proximal pediatric femur.

Personalized X-Ray Reconstruction of the Proximal Femur via Intensity-Based Non-rigid 2D-3D Registration

This paper presents a new approach for reconstructing a patient-specific shape model and internal relative intensity distribution of the proximal femur from a limited number (e.g., 2) of calibrated C-arm images or X-ray radiographs. Our approach uses independent shape and appearance models that are learned from a set of training data to encode the a priori information about the proximal femur. An intensity-based non-rigid 2D-3D registration algorithm is then proposed to deformably fit the learned models to the input images. The fitting is conducted iteratively by minimizing the dissimilarity between the input images and the associated digitally reconstructed radiographs of the learned models together with regularization terms encoding the strain energy of the forward deformation and the smoothness of the inverse deformation. Comprehensive experiments conducted on images of cadaveric femurs and on clinical datasets demonstrate the efficacy of the present approach.