Distal Head Research Articles

Indication of pancreatoduodenectomy following severe acute pancreatitis in patients with distal bile duct or pancreas head cancer

Indication of pancreatoduodenectomy following severe acute pancreatitis in patients with distal bile duct or pancreas head cancer

Light microscope observations on the epididymis of paca (Agouti paca).

The features of paca epididymis, based on its appearance in light microscope, is described in this paper. The cellular population of the epithelial lining comprises principal cells, basal cells, apical cells, narrows cells, and hallo cells. The epididymis is divided in five distinct and continuous regions, Zone I, or initial segment, and zone II, are both localized into the head. Zone III comprises the distal head and all the body. Zones IV and V are restricted to the tail, in the proximal and distal cauda epididymis respectively. Each zone can be readily distinguished on the basis of morphological characteristics. The height of epididymal epithelium is greater in zone I. There is a progressive increase in the diameter of the tubular lumen through the different areas, with the maximum in the zone V. The presence of a high epithelium, and the virtual absence of sperm in zone I suggest fast transit of spermatozoa in this region. Zone V comprises the distal tail, has smaller epithelial lining, greater luminal diameter, shorter stereocilia than the other zones, and contains spermatozoa packed inside the lumen, that characterizes this zone as a place of sperm storage. The findings are compared with other reports in rodents and other domestic animals, to contribute to the understanding of epididymal morphophysiology.

AB0441 Bone geometry, density and microarchitecture: Relationship between peripheral and periarticular skeletal site assessed by high resolution peripheral quantitative computed tomography in patients with rheumatoid arthritis

BackgroundPatients with rheumatoid arthritis (RA) are associated with an increased risk of periarticular and generalized bone loss. A 3D high resolution peripheral quantitative computed tomography (HR-pQCT) system has been developed...

Treatment of a femoral fracture with a titanium locking compression plate distal femur (LCP-DF) in a young donkey

A closed complete mid-diaphyseal spiral fracture of the left femur in a one-year-old donkey was treated with a 4.5 mm titanium locking compression plate distal femur (LCP-DF)1. This plate was originally manufactured for human orthopaedics, primarily for femoral osteosynthesis. The LCP-DF1 has a distal head plate that was advantageous in this case because the distal fragment was smaller. Post operative radiographs showed optimal femoral reconstruction and a callus was present 3 weeks after surgery. The donkey was sound at the walk and trot 2 months after surgery. Radiographs taken 5 months after surgery showed stable implants and complete healing without complications.

Traumatic Elbow Injuries: What the Orthopedic Surgeon Wants to Know

Traumatic elbow injuries are commonly encountered in the emergency department setting, but their complexity and clinical significance often go unrecognized at the initial evaluation. Initial imaging in patients with elbow trauma should not only help identify major injuries that require immediate intervention but also allow detection of other, often more subtle injuries that may lead to instability or poor functional outcomes if appropriate treatment is delayed. Awareness and detection of these injuries may be improved by a better-developed and more intuitive understanding of the mechanisms that underlie the most common injury patterns. Ideally, such understanding should prompt appropriate early use of advanced imaging techniques. Traumatic elbow injuries should be described in the radiology report within the context of their clinical significance and their implications for management, information that is often best captured by the injury grading and classification systems used by the orthopedic surgery community. This article reviews the relevant anatomy and functional stability of the elbow and discusses common traumatic elbow injury patterns, including elbow dislocations as well as fractures of the distal humerus, radial head and neck, coronoid process, and olecranon. Less commonly encountered injury constellations that are clinically significant are also described. Injury patterns are explained in the context of the responsible force mechanism by using three-dimensional modeling and animation, with emphasis on the functional impact of associated secondary bone and soft-tissue injuries. The utility of cross-sectional imaging modalities such as computed tomography and magnetic resonance imaging in the acute care setting is discussed, and specific imaging guidelines are provided. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.333125176/-/DC1.

Heterotopic Ossification After Surgery for Fractures and Fracture-Dislocations Involving the Proximal Aspect of the Radius or Ulna

The objectives of this study were to (1) determine the prevalence of heterotopic ossification after surgery for fractures and fracture-dislocations involving the proximal aspect of the radius or ulna, (2) identify risk factors associated with the development of heterotopic ossification in these injuries, and (3) characterize the severity and location of the heterotopic ossification and the associated range of elbow motion. From 2004 to 2008, 142 elbow fractures and fracture-dislocations involving the proximal aspect of the radius or ulna were treated surgically at our institution. Records and radiographs of 130 elbows with adequate follow-up were retrospectively reviewed to identify cases of heterotopic ossification, characterize the ectopic bone, and analyze associated risk factors. The most frequent injuries included olecranon fractures, Monteggia fracture-dislocations, and various combinations of fractures of the radial head and coronoid with or without dislocation or subluxation. Heterotopic bone was identified on the radiographs of forty-eight elbows (37%). Heterotopic ossification interfered with motion in twenty-six elbows (20%), and thirteen elbows (10%) underwent additional surgery to remove heterotopic bone with the goal of improving motion. Risk factors associated with the development of heterotopic ossification included elbow subluxation or dislocation at the time of presentation, an open fracture, a severe chest injury, and a delay in definitive surgical treatment. Ectopic bone was preferentially located at the origin of torn soft-tissue structures or around fracture sites, and it was particularly common around the posterior aspect of the ulna and the neck of the radius. Heterotopic ossification was classified on radiographs as hazy immature in twenty-two elbows, limited mature in eighteen, extensive mature in five, and a complete bone bridge in three. Heterotopic ossification was more common in patients with an associated distal humeral fracture, radial head and coronoid fractures with an associated elbow dislocation (terrible triad injury), and a transolecranon fracture-dislocation. Thirty-seven percent of elbows treated surgically for fractures involving the proximal aspect of the radius and/or ulna developed heterotopic ossification. In twenty percent of elbows, heterotopic ossification was associated with clinically relevant motion deficits. More severe heterotopic ossification was encountered in patients presenting with an associated distal humeral fracture, terrible triad injury, transolecranon fracture-dislocation, or Monteggia fracture-dislocation. Patients with an open injury, instability, severe chest trauma, or delay in definitive surgical treatment had a higher prevalence of heterotopic ossification.

Platelet-Rich Plasma Added to the Patellar Tendon Harvest Site During Anterior Cruciate Ligament Reconstruction Enhanced Healing

Background: The objectives of this study were to (1) determine the prevalence of heterotopic ossification after surgery for fractures and fracture-dislocations involving the proximal aspect of the radius or ulna, (2) identify risk factors associated with the development of heterotopic ossification in these injuries, and (3) characterize the severity and location of the heterotopic ossification and the associated range of elbow motion. Methods: From 2004 to 2008, 142 elbow fractures and fracture-dislocations involving the proximal aspect of the radius or ulna were treated surgically at our institution. Records and radiographs of 130 elbows with adequate follow-up were retrospectively reviewed to identify cases of heterotopic ossification, characterize the ectopic bone, and analyze associated risk factors. The most frequent injuries included olecranon fractures, Monteggia fracture-dislocations, and various combinations of fractures of the radial head and coronoid with or without dislocation or subluxation. Results: Heterotopic bone was identified on the radiographs of forty-eight elbows (37%). Heterotopic ossification interfered with motion in twenty-six elbows (20%), and thirteen elbows (10%) underwent additional surgery to remove heterotopic bone with the goal of improving motion. Risk factors associated with the development of heterotopic ossification included elbow subluxation or dislocation at the time of presentation, an open fracture, a severe chest injury, and a delay in definitive surgical treatment. Ectopic bone was preferentially located at the origin of torn soft-tissue structures or around fracture sites, and it was particularly common around the posterior aspect of the ulna and the neck of the radius. Heterotopic ossification was classified on radiographs as hazy immature in twenty-two elbows, limited mature in eighteen, extensive mature in five, and a complete bone bridge in three. Heterotopic ossification was more common in patients with an associated distal humeral fracture, radial head and coronoid fractures with an associated elbow dislocation (terrible triad injury), and a transolecranon fracture-dislocation. Conclusions: Thirty-seven percent of elbows treated surgically for fractures involving the proximal aspect of the radius and/or ulna developed heterotopic ossification. In twenty percent of elbows, heterotopic ossification was associated with clinically relevant motion deficits. More severe heterotopic ossification was encountered in patients presenting with an associated distal humeral fracture, terrible triad injury, transolecranon fracture-dislocation, or Monteggia fracture-dislocation. Patients with an open injury, instability, severe chest trauma, or delay in definitive surgical treatment had a higher prevalence of heterotopic ossification. Level of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Structure of the trypanosome haptoglobin-hemoglobin receptor and implications for nutrient uptake and innate immunity.

African trypanosomes are protected by a densely packed surface monolayer of variant surface glycoprotein (VSG). A haptoglobin-hemoglobin receptor (HpHbR) within this VSG coat mediates heme acquisition. HpHbR is also exploited by the human host to mediate endocytosis of trypanolytic factor (TLF)1 from serum, contributing to innate immunity. Here, the crystal structure of HpHbR from Trypanosoma congolense has been solved, revealing an elongated three α-helical bundle with a small membrane distal head. To understand the receptor in the context of the VSG layer, the dimensions of Trypanosoma brucei HpHbR and VSG have been determined by small-angle X-ray scattering, revealing the receptor to be more elongated than VSG. It is, therefore, likely that the receptor protrudes above the VSG layer and unlikely that the VSG coat can prevent immunoglobulin binding to the receptor. The HpHb-binding site has been mapped by single-residue mutagenesis and surface plasmon resonance. This site is located where it is readily accessible above the VSG layer. A single HbHpR polymorphism unique to human infective T. brucei gambiense has been shown to be sufficient to reduce binding of both HpHb and TLF1, modulating ligand affinity in a delicate balancing act that allows nutrient acquisition but avoids TLF1 uptake.

A Novel Human Membrane Protein Interacting with the Short Fiber of Enteric Adenovirus

Human enteric adenoviruses of species F, HAdV-40 and HAdV-41 (Ad40 and Ad41), are associated with gastroenteritis in children. Ad attachment to the primary receptor on the cell surface is mediated by the distal head domain of the fiber protein, an antenna-like component of the adenovirus capsid. Differently from the majority of human Ads that possess one type of fiber on their capsid, the Ad40 and 41 have two distinct fibers. The long fiber recognizes the host membrane protein CAR, which permits virus attachment, but nothing is known about the role of the short fiber. Using the head domain of the Ad41 short fiber, we fished out a putative membrane protein that has never been previously described. This partner of the short fiber of enteric Ad41 (ParAd41) is a small, hydrophobic protein with three putative trans membrane domains, which interacts with the Ad41 short fiber but not with the Ad41 long fiber or with the fiber of respiratory Ad2 serotype. ParAd41 is localized in intracellular membranes including the nuclear membrane. Saturation of the short fiber with ParAd41 inhibits virus infectivity, which substantiates the putative role of ParAd41 in enteric Ads tropism. It is conceivable that the interaction of the short fiber with ParAd41 mediates virus postattachment endocytosis step as well as interaction with the nuclear membrane prior to the injection of viral DNA into the nucleus, thus enabling enteric adenovirus infection. This study is the first one to probe the molecular nature of enteric Ad41 tropism.

Reverse engineering the antigenic architecture of the haemagglutinin from influenza H5N1 clade 1 and 2.2 viruses with fine epitope mapping using monoclonal antibodies

The induction of neutralising antibodies to the viral surface glycoprotein, haemagglutinin (HA) is considered the cornerstone of current seasonal and pandemic influenza vaccines. Mapping of neutralising epitopes using monoclonal antibodies (mAbs) helps define mechanisms of antigenic drift, neutralising escape and facilitates pre-pandemic vaccine design. In the present study we reverse engineered the antigenic structure of the HAs of two highly pathogenic H5N1 vaccine strains representative of currently circulating clade 1 and 2.2 H5N1 viruses. The HA sequence of the A/Vietnam/1194/04 clade 1 virus was progressively mutated into the HA sequence of the clade 2.2 virus, A/Bar-headed Goose/Qinghai/1A/05. Fine mapping of clade-specific neutralising epitopes was performed by examining the cross-reactivity of mAbs raised against the native HA of each parent virus. The reactivity across all clade specific mAbs centred around a constellation of mutations at positions 140, 145, 171 and 172, all of which are proximal to the receptor binding site on the membrane distal globular head of the HA. Overlapping cross-reactivity of these antigenic sites suggests that these amino acid positions relate to the antigenic evolution of the H5 clade 1 and 2.2 viruses. This finding may prove useful for the design of vaccines with broader neutralising cross-reactivity against the different H5 HA sublineages currently in circulation. These findings provide important information about the amino acid changes involved in the cross-clade evolution of H5N1 viruses and their potential for human to human transmission; and facilitates a greater understanding of the pandemic potential of H5N1 isolates.

Computer-Assisted Corrective Osteotomy for Malunited Diaphyseal Forearm Fractures

Corrective osteotomy for malunited diaphyseal forearm fractures remains a challenging procedure. We developed a computer-assisted system for corrective surgery, including a three-dimensional simulation program and a custom-made osteotomy template, and investigated the results of corrective surgery for malunited diaphyseal forearm fractures with use of this technology. Twenty patients (fifteen male patients and five female patients) with malunited diaphyseal forearm fractures were managed with three-dimensional corrective osteotomy with a custom-made osteotomy template based on computer simulation. We performed osteotomy of both radius and ulna in fourteen patients and osteotomy of the radius alone in six patients. The median age at the time of surgery was eighteen years (range, eleven to forty-three years). The median duration between the time of injury and the time of surgery was thirty-three months (range, five to 384 months). The minimum duration of follow-up was twenty-four months (median, twenty-nine months; range, twenty-four to forty-eight months). To evaluate the results, we compared preoperative and postoperative data from radiographs, forearm motion, grip strength, and pain. The average radiographic deformity angle preoperatively was 21° (range, 12° to 35°) compared with the normal arm; the radiographic deformity angle was improved to 1° (range, 0° to 4°) postoperatively. The distal radioulnar joints of both sides were symmetric on postoperative radiographs regarding the relative lengths of the radius and ulna. In eighteen patients who had a restricted range of forearm motion preoperatively, the mean arc of forearm motion improved from 76° (range, 25° to 160°) preoperatively to 152° (range, 80° to 180°) postoperatively (p < 0.01). However, forearm supination was still restricted by ≥ 70° in three patients who had been younger than ten years old at the time of the initial injury and who had long-standing malunion for ninety-six months or longer. Painful recurrent dislocation of the distal ulna or radial head resolved or decreased in five patients. Average grip strength improved from 82% to 94% compared with that of the contralateral, normal side. Computer-assisted osteotomy can provide excellent radiographic and clinical outcome for the treatment of malunited diaphyseal forearm fractures. Satisfactory restoration of forearm motion can be achieved even in relatively long-standing cases in adults.

Distal Ulna Hook Plate Fixation for Unstable Distal Ulna Fracture Associated With Distal Radius Fracture

The significance of distal ulna fractures is often undermined, which can result in inadequate treatment compared with fractures of the radius, the ulna's larger counterpart. However, little guidance exists in the current literature on how to manage distal ulna head or neck fractures and intra-articular ulna head fractures. Therefore, the purpose of this retrospective study was to evaluate the outcomes of distal ulna hook plate fixation for the treatment of an unstable distal ulna fracture associated with a distal radius fracture. Twenty-five patients with unstable distal ulna fractures who underwent stable fixation for an associated distal radius fracture were included in the study. All patients achieved satisfactory reduction and bony union. Average final motion was as follows: wrist flexion, 72° (range, 60°-85°); extension, 69° (range, 65°-80°); pronation, 77° (range, 55°-95°); supination, 82° (range, 65°-90°); ulnar deviation, 35° (range, 15°-50°); and radial deviation, 24° (range, 10°-40°). Average postoperative grip strength was 28 kg (range, 22-30 kg) and was 91% (range, 71%-100%) in the cases in which the dominant hand was injured and 80% (range, 65%-100%) in the cases in which the nondominant hand was injured. Average postoperative modified Mayo wrist score and Disabilities of the Arm, Shoulder and Hand score was 87 points (range, 65-100 points) and 14 points (range, 0-54 points), respectively. Chronic instability of the distal radioulnar joint was not encountered in any patient. Thus, the study demonstrated that distal ulna hook plate fixation for the treatment of unstable distal ulna fractures can achieve healing with good alignment, satisfactory function, and minimal transient morbidity.

Effect of a Metatarsal Pad on the Forefoot During Gait

Metatarsal pads are frequently prescribed for patients with metatarsalgia to reduce pain under the distal metatarsal heads. Several studies showed reduced pain and reduced plantar pressure just distal to the metatarsal pad. However, only part of the pain reduction could be explained by the decrease in plantar pressure under the forefoot. Therefore, an alternative hypothesis is proposed that pain relief is related to a widening of the foot and the creation of extra space between the metatarsal heads. This study focused on the effect of a metatarsal pad on the geometry of the forefoot by studying forefoot width and the height of the second metatarsal head. Using a motion analysis system, 16 primary metatarsalgia feet and 12 control feet were measured when walking with and without a metatarsal pad. A significant mean increase of 0.60 mm in forefoot width during the stance phase was found when a metatarsal pad was worn. During midstance, the mean increase in forefoot width was 0.74 mm. In addition, walking with a metatarsal pad revealed an increase in the height of the second metatarsal head (mean, 0.62 mm). No differences were found between patients and controls. The combination of increased forefoot width and the height of the second metatarsal head produced by the metatarsal pad results in an increase in space between the metatarsal heads. This extra space could play a role in pain reduction produced by a metatarsal pad.

Forearm Bones and Sexual Variation in Turkish Population

Forensic anthropologists are aware that there are considerable differences between human populations and therefore develop study models for each skeletal population. The purpose of this study was to analyze forearm bones obtained from forensic settings in Turkey. The sample consists of 42 males and 38 females with an average age of 40 and 36 years, respectively. Numerous measurements were taken from the radius and ulna including lengths (in millimeters), midshaft diameters, and epiphyseal breadths (0.01 mm). Individuals with any anomaly and pathology were not included in the investigation. A stepwise analysis, when applied to individual bones, selected only length and midshaft transverse dimension in the radius and length only in the ulna. When the length was excluded from the statistic, head diameter and distal breadth of the radius and distal minimum head and midshaft anteroposterior diameters of the ulna provided the best predicting functions. Classification results were 92% for the radius and 91% for the ulna. For the incomplete bones, the accuracy rates were about 92% and 83%, respectively. In conclusion, a sex determination was made, in different rates of accuracy, in the human skeleton. Correct assessment can vary among populations. Dimorphism in our region forearm bones is greater than American whites. This supported the hypothesis that human variation is diverse, and population difference should be taken into account when osteometric standards are applied to others. Further studies are needed to understand why the forearm is more dimorphic in Turks.

Ossifying Fibromyxoid Tumor of Soft Parts

Ossifying fibromyxoid tumor (OFMTs) of soft parts is a rare soft tissue and bone tumor of borderline malignancy displaying an uncertain line of differentiation. The existence of fully malignant OFMT is controversial. To better understand the natural history and line of differentiation taken by OFMT, we studied 46 cases by light microscopic, immunohistochemical (IHC), genomic, proteomic, and fluorescence in situ hybridization (FISH) methods. Cases were classified according to the 2003 Folpe and Weiss system. Clinical and follow-up information was obtained. IHC for S-100 protein, desmin, epithelial membrane antigen (EMA), cytokeratins, smooth muscle actin (SMA), INI-1, neurofilament protein (NFP), CD56d excitatory amino acid transporter-4 (EAAT4), and MUC4 was performed on formalin-fixed, paraffin-embedded (FFPE) tissues. Gene expression profiling and proteomic studies were conducted on FFPE tissues from 13 and 5 cases, respectively. FISH for INI-1 was performed on 10 cases. The 46 tumors arose in 29 men and 17 women (median age, 52 y; range 39 to 63 y) and involved the proximal (N=17) and distal extremities (N=13), head and neck (N=9), and trunk (N=5). Median tumor size was 5.4 cm (range, 1.0 to 21.0 cm). Cases were classified as typical OFMT (26 of 46, 57%), atypical OFMT (5 of 46, 11%), and malignant OFMT (15 of 46 cases, 32%). Clinical follow-up (27 cases, median 55 months' duration) showed all patients with typical and atypical OFMT to be alive without disease. Adverse events, including 3 local recurrences, 3 metastases, and 3 deaths, were seen only in malignant OFMT. IHC results were as follows: S-100 protein (30 of 41, 73%), desmin (15 of 39, 38%), cytokeratin (4 of 35, 11%), EMA (5 of 32, 16%), SMA (2 of 34, 6%), INI-1 (lost in mosaic pattern in 14 of 19, 74%), EAAT4 (31 of 39, 80%), MUC4 (3 of 14, 21%), NFP (8 of 10, 80%) and CD56 (6 of 14, 43%). Gene expression profiling showed typical and malignant OFMTs to cluster together, distinct from schwannian tumors. Proteomic study showed expression of various collagens, S-100 protein, and neuron-related proteins. FISH showed INI-1 deletion in 5 of 7 (71%) cases. We conclude that malignant OFMTs exist and may be recognized by the previously proposed criteria of Folpe and Weiss. Expression of neuron-related markers, in addition to Schwann cell and cartilage-associated markers, suggests a "scrambled" phenotype in OFMTs. Loss of INI-1 or other genes on 22q is likely important in the pathogenesis of these rare tumors.

A new large caseid (Synapsida, Caseasauria) from the Permian of Rodez (France), including a reappraisal of “Casea”rutenaSigogneau-Russell &amp; Russell, 1974

ABSTRACT The description of a new large caseid, Ruthenosaurus russelbrum n. gen., n. sp. from the Early Permian (upper Cisuralian to lower Lopingian) of the Rodez Basin, France, is based on a partial postcranial skeleton that was initially collected at the same time as the holotype of “Casea” rutena Sigogneau-Russell & Russell, 1974. Despite its distinctly larger size than “C.” rutena, the holotype of Ruthenosaurus n. gen. clearly represents an immature individual, as shown most clearly by the lack of fusion of the neural arches to their respective vertebral centra and incomplete ossification of the ends of the limb elements, including the absence of an ossified olecranon on the ulna. Nonetheless, Ruthenosaurus n. gen. is diagnosed by several autapomorphic characters, including dorsal vertebrae with anteriorly tilting neural spines and a diamond-shaped outline in transverse section, a first sacral rib with a dorsoventrally expanded distal head, and a low iliac blade with a poorly developed anterior proces...

Can Achilles tendon moment arm be predicted from anthropometric measures in pre-pubescent children?

Muscle–tendon moment arm magnitudes are essential variables for accurately calculating muscle forces from joint moments. Their measurement requires specialist knowledge and expensive resources. Research has shown that the patellar tendon moment arm length is related to leg anthropometry in children. Here, we asked whether the Achilles tendon moment arm (MA AT) can be accurately predicted in pre-pubescent children from surface anthropometry. Age, standing height, mass, foot length, inter-malleolar ankle width, antero-posterior ankle depth, tibial length, lower leg circumference, and distances from the calcaneus to the distal head of the 1st metatarsal and medial malleolus were determined in 49 pre-pubescent children. MA AT was calculated at three different ankle positions (neutral, 10° plantarflexion, and 10° dorsiflexion) by differentiating tendon excursion, measured via ultrasonography, with respect to ankle angle change using seven different differentiation techniques. Backwards stepwise regression analyses were performed to identify predictors of MA AT. When all variables were included, the regression analysis accounted for a maximum of 49% of MA AT variance at the neutral ankle angle when a third-order polynomial was used to differentiate tendon excursion with respect to ankle angle. For this condition, foot length and the distance between calcaneus and 1st metatarsal were the only significant predictors, accounting for 47% of the variance ( p<0.05). The absolute error associated with this regression model was 3.8±4.4 mm, which would result in significant error (mean=14.5%) when estimating muscle forces from joint moments. We conclude that MA AT cannot be accurately predicted from anthropometric measures in children.

REMODELING OF DISTAL ULNA AFTER EXCISION ARTHROPLASTY FOR ACUTE COMMINUTED DISTAL ULNAR FRACTURE: A CASE REPORT

Bone adaptation after excision arthroplasty of distal radioulnar joint in an acute traumatic distal ulna fracture has never been reported. A case of irreparable and comminuted distal ulnar head fracture was managed by excising the ulna head and repairing the fovea (deep ligament) attachments of distal radioulnar ligaments, and then an unexpected remodeling of the distal ulna with the shape of pole and seat was noted. The anatomy of deep fibers of distal radioulnar ligament is important not only in biomechanics about the stability of distal radioulnar joint but it is also possible in the morphology about the shape of the distal radioulnar joint.

A Step Forward in the Treatment of Advanced Biliary Tract Cancer

The term “biliary tract cancer” refers primarily to cancers that develop in the gallbladder and bile ducts, although periampullary tumors are often considered part of this group as well. Bile-duct tumors that develop within the liver and the distal biliary tree are referred to as intrahepatic and extrahepatic cholangiocarcinomas, respectively. Periampullary tumors originate at the ampulla of Vater, near the distal common bile duct, duodenum, and head of the pancreas; the precise anatomical origin of these cancers often cannot be determined before operative resection. Among the new cases of biliary tract cancer that are diagnosed every year in the United . . .

Biomechanical evaluation of the dynamic radioulnar convergence after ulnar head resection, two soft tissue stabilization methods of the distal ulna and ulnar head prosthesis implantation

The biomechanical performance of the Darrach procedure, its stabilizing methods and the effectiveness of an ulnar head prosthesis was evaluated in this experiment. The purpose of this study was to: (1) analyze the dynamic effects of the resection of the distal ulna on radioulnar convergence; and (2) evaluate the mechanical performance of two soft tissue stabilizing procedures (pronator quadratus advancement flap and ECU/FCU tenodesis) for the unstable distal ulnar stump and the implantation of an ulnar head prosthesis (uHead) following a distal ulnar resection (Darrach procedure) on radioulnar convergence. With a dynamic PC-controlled forearm simulator, cadaveric forearm rotation was actively and passively performed while simultaneously loading the relevant muscles. The resultant total forearm torque and the three-dimensional kinematics of the ulna, radius and third metacarpal were simultaneously recorded in seven fresh-frozen cadaver upper extremities. The resection of the distal ulna created an extreme instability of the forearm with movement of the radius toward the ulna (0.92-0.38 cm compared to the intact state) in each particular loading condition. The implantation of the ulnar head prosthesis effectively restored the stability of the DRUJ by simulating the geometry of the ulnar head. There were significantly better results after the implantation of the prosthesis compared with the Darrach and the soft tissue stabilization procedures. This study provides laboratory validity to the option of implanting an ulnar head endoprosthesis as an attempt to stabilize the distal forearm with instability after Darrach resection in lieu of performing soft tissue stabilization techniques.