Benthic Dissolved Silicon and Iron Cycling at Glaciated Patagonian Fjord Heads.

Glacier meltwater supplies silicon (Si) and iron (Fe) sourced from weathered bedrock to downstream ecosystems. However, the extent to which these nutrients reach the ocean is regulated by the nature of the benthic cycling of dissolved Si and Fe within fjord systems, given the rapid deposition of reactive particulate fractions at fjord heads. Here, we examine the benthic cycling of the two nutrients at four Patagonian fjord heads through geochemical analyses of sediment pore waters, including Si and Fe isotopes (δ30Si and δ56Fe), and reaction-transport modeling for Si. A high diffusive flux of dissolved Fe from the fjord sediments (up to 0.02 mmol m-2 day-1) compared to open ocean sediments (typically <0.001 mmol m-2 day-1) is supported by both reductive and non-reductive dissolution of glacially-sourced reactive Fe phases, as reflected by the range of pore water δ56Fe (-2.7 to +0.8‰). In contrast, the diffusive flux of dissolved Si from the fjord sediments (0.02-0.05 mmol m-2 day-1) is relatively low (typical ocean values are >0.1 mmol m-2 day-1). High pore water δ30Si (up to +3.3‰) observed near the Fe(II)-Fe(III) redox boundary is likely associated with the removal of dissolved Si by Fe(III) mineral phases, which, together with high sedimentation rates, contribute to the low diffusive flux of Si at the sampled sites. Our results suggest that early diagenesis promotes the release of dissolved Fe, yet suppresses the release of dissolved Si at glaciated fjord heads, which has significant implications for understanding the downstream transport of these nutrients along fjord systems.

Tungsten Ligand-Based Sulfur-Atom-Transfer Catalysts: Synthesis, Characterization, Sustained Anaerobic Catalysis, and Mode of Aerial Deactivation.

The synthesis, properties, X-ray structures, and catalytic sulfur-atom-transfer (SAT) reactions of W2(µ-S)(µ-S2)(dtc)2(dped)2 [1; dtc = S2CNR2-, where R = Me, Et, iBu, and Bn; dped = S2C2Ph22-] and W2(µ-S)2(dtc)2(dped)2 (2) are reported. These complexes represent the oxidized (1) and reduced (2) forms of anaerobic SAT catalysts operating through the bidirectional, ligand-based half-reaction (µ-S)(µ-S2) ↔ (µ-S)2 + S0. The catalysts are deactivated in air through the formation of catalytically inactive oxo complexes, (dtc)WO(µ-S)(µ-dped)W(dtc)(dped) (3), prompting us to recommend that group 6 SAT activity be assessed under strictly anaerobic conditions.

Wound Closure in Nonidiopathic Scoliosis: Does Closure Matter?

BACKGROUND: Postoperative wound complications after posterior spinal fusion are difficult to manage. The incidence in the nonidiopathic patient population is significantly higher than the adolescent idiopathic population. A comparison of wound complications after posterior spinal fusion for nonidiopathic scoliosis between the utilization of the orthopaedic surgical team at the time of closure performing a nonstandardized wound closure versus a plastic surgeon with a plastic multilayered closure technique and rotational flap coverage when needed had not previously been evaluated. The purpose of this study was to compare the complication rate between nonstandardized and plastic multilayered closure of the surgical incision in patients undergoing posterior spinal fusion for nonidiopathic scoliosis. METHODS: The charts of 76 patients with a primary diagnosis of scoliosis associated with a syndrome or neuromuscular disease and who underwent a posterior spinal fusion were reviewed. Forty-two patients had their incisions closed using the nonstandardized technique and 34 using the plastic multilayered technique. These 2 groups were compared for age, sex, primary diagnosis, number of levels fused, estimated blood loss, number of units transfused, operating room time, wound complication, and return to operating room. RESULTS: The wound complication rate in the nonstandardized closure group was 19% (8/42) compared with 0% (0/34) in the plastic multilayered closure group (P=0.007). The unanticipated return to the operating room rate was 11.9% (5/42) for the nonstandardized closure patients versus 0% (0/34) for the plastic multilayered closure patients (P=0.061). CONCLUSIONS: The use of the plastic multilayered closure technique in this patient population is important in an effort to decrease postoperative wound complications. The ability of the surgical team to decrease the infection rate of nonidiopathic scoliosis cannot be overstated. The method of wound closure plays a major role in lowering this incidence. LEVEL OF EVIDENCE: Level III-therapeutic.

Total Hip Arthroplasty After Proximal Femoral Osteotomy: A Technique That Can Be Used to Address Presence of a Retained Intracortical Plate.

Total hip arthroplasty (THA) can be challenging in the setting of internal fixation devices previously placed in the proximal femur. When these devices are used in adolescent patients, endosteal hypertrophy can lead to significant bony overgrowth. Removal of these implants can result in significant cortical defects that may compromise the results of THA. This article describes a technique that can be used when a plate applied to the lateral femoral cortex has become "intracortical" as a result of extensive bony overgrowth. In using this technique to avoid plate removal, the surgeon eliminates the need for more extensive procedures aimed at compensating for deficiency of the femoral cortex in the area of plate removal.

Ruptures of the distal biceps tendon.

Distal biceps ruptures occur most commonly in middle-aged males and result from eccentric contraction of the biceps tendon. The injury typically presents with pain and a tearing sensation in the antecubital fossa with resultant weakness in flexion and supination strength. Physical exam maneuvers and diagnostic imaging aid in determining the diagnosis. Nonoperative management is reserved for elderly, low demand patients, while operative intervention is generally pursued for younger patients and can consist of nonanatomic repair to the brachialis or anatomic repair to the radial tuberosity. Anatomic repair through a one-incision or two-incision approach is commonplace, while the nonanatomic repairs are rarely performed. No clear advantage exists in operative management with a one-incision versus two-incision techniques. Chronic ruptures present a more difficult situation, and allograft augmentation is often necessary. Common complications after repair include transient nerve palsy, which often resolves, and heterotopic ossification. Despite these possible complications, most studies suggest that better patient outcomes are obtained with operative, anatomic reattachment of the distal biceps tendon.

Is prophylactic surgery for femoroacetabular impingement indicated? A systematic review.

BACKGROUND: This is a systematic review to determine if prophylactic surgical intervention for asymptomatic patients with radiographic evidence of femoroacetabular impingement (FAI) is warranted to prevent early degenerative joint disease of the hip. METHODS: A systematic search was performed from 1965 to 2013 in PubMed and EMBASE. Inclusion criteria were prospective or retrospective studies comparing skeletally mature asymptomatic patients with radiographic evidence of FAI treated with prophylactic hip arthroscopic surgery versus nonoperative management. A total of 840 references were identified from the searches. After detailed eligibility screening, none of the references met the eligibility criteria. RESULTS: No trials were identified that met the criteria for inclusion in the review. CONCLUSION: There is a lack of available evidence to support surgical intervention for the treatment of FAI in asymptomatic patients. This article attempts to address this dilemma by reviewing the available literature to answer several questions that would indirectly address the topic. First, what is the prevalence of FAI in the asymptomatic population? Second, what is the natural history of FAI if left untreated? Upon reviewing these issues, the authors' conclusion parallels that of the systematic review: Current evidence does not support prophylactic surgery for asymptomatic FAI in the vast majority of cases. However, limited evidence suggests that asymptomatic patients who have previously undergone total hip arthroplasty for FAI-induced osteoarthritis of the contralateral hip are at a significantly increased risk for early degenerative joint disease. Further research is needed to better clarify surgical indications.

Injury to the superior gluteal artery during intramedullary fixation of an atypical subtrochanteric stress fracture - a case report.

Iatrogenic vascular injury during hip fracture surgery is a rare complication, with infrequent reports of injury during the procedure of cepahalomedullary nailing. We describe a case report of injury to the superior gluteal artery which occurred during insertion of a nail for prophylactic fixation of an incomplete femur fracture secondary to alendronate use. We describe the anatomy of the arterial branches, the postoperative course, and the management strategy and hope this will increase awareness of these rare injuries.

Decision making in the in-season athlete with shoulder instability.

Shoulder instability in the in-season athlete can generally be managed nonoperatively during the season, except when specific contraindications are present, such as bone loss or involvement of the dominant limb in an overhead athlete. Brace wear, although advocated by many investigators, has no proven efficacy in reducing the number or frequency of in-season instability events. Arthroscopic approaches are used for both anterior and posterior instability, with rates of success similar to open approaches but with the advantage of improved postoperative range of motion. Return to play may be considered 6 month postoperatively for the nonthrowing athlete and 9 months postoperatively for the overhead-throwing athlete.

Platelet rich placebo? Evidence for platelet rich plasma in the treatment of tendinopathy and augmentation of tendon repair.

Platelet rich plasma (PRP), an autologous sample of blood with a platelet concentration above baseline values, is hypothesized to augment soft tissue healing. Its use in sports medicine has risen dramatically, with common applications including the treatment of refractory tendinopathy and augmenting tendon repair. Many commercial preparation systems are available, but the optimal preparation remains unknown. Increasing numbers of clinical studies evaluating PRP have been reported and have provided both positive and negative evidence for its effectiveness. Well-designed, controlled studies are still lacking, but PRP may have a benefit for patients with tendinopathy that is refractory to other non-surgical treatments. Its use in tendon repair is currently not supported. Randomized, controlled studies with documentation of platelet, white blood cell, and growth factor concentration in the PRP preparation are necessary for future comparative research. Use of PRP should be approached judiciously until further evidence is available.

Extensor indicis proprius and extensor digitorum communis rupture after volar locked plating of the distal radius--a case report.

Distal radius fractures are among the most commonly encountered fractures in the extremities. Volar plating of distal radius fracture has gained popularity in recent years with the introduction of the locked plating system. Complications of volar plating include extensor and flexor tendon rupture. Here we present a case report of an extensor indicis proprius and extensor digitorum communis to index finger tendon rupture after open reduction and internal fixation of distal radius fracture with locked plate.

Failed hip arthroscopy: causes and treatment options.

Indications for arthroscopic surgery of the hip have increased over the past several years, along with the number of procedures performed annually. In addition, the number of unsuccessful procedures and subsequent revision surgeries have also increased. Recent literature has defined several common causes for failed hip arthroscopy. Severe osteoarthritis and osteonecrosis are associated with poor outcomes. Findings during revision hip arthroscopy consistently demonstrate untreated femoroacetabular impingement, chondral defects, labral tears, and postoperative adhesions. The treating surgeon must be diligent in his or her indications for surgery, as well as in addressing all pathology at the initial surgery.

Aneurysmal bone cyst.

Aneurysmal bone cysts are rare skeletal tumors that most commonly occur in the first two decades of life. They primarily develop about the knee but may arise in any portion of the axial or appendicular skeleton. Pathogenesis of these tumors remains controversial and may be vascular, traumatic, or genetic. Radiographic features include a dilated, radiolucent lesion typically located within the metaphyseal portion of the bone, with fluid-fluid levels visible on MRI. Histologic features include blood-filled lakes interposed between fibrous stromata. Differential diagnosis includes conditions such as telangiectatic osteosarcoma and giant cell tumor. The mainstay of treatment is curettage and bone graft, with or without adjuvant treatment. Other management options include cryotherapy, sclerotherapy, radionuclide ablation, and en bloc resection. The recurrence rate is low after appropriate treatment; however, more than one procedure may be required to completely eradicate the lesion.

Are femoral nerve blocks effective for early postoperative pain management after hip arthroscopy?

PURPOSE: To evaluate the utility of femoral nerve blocks in postoperative pain control after hip arthroscopy. METHODS: Forty consecutive patients scheduled for hip arthroscopy were randomized into 2 groups for postoperative pain control. Half were to receive routine intravenous narcotics for pain scores of 7 or above in the postanesthesia care unit (PACU), and the other half were to receive a femoral nerve block in the PACU for the same pain scores. Data were compared with respect to patient sex, patient age, traction times, type of procedure, nausea, overall patient satisfaction with analgesia, and duration of time in the PACU. RESULTS: Thirty-six patients had initial pain scores of 7 of 10 or greater on a visual analog scale. Of these patients, 16 were randomized to receive postoperative morphine and 20 to receive a femoral nerve block. There were no significant differences between the 2 groups with respect to sex, age, traction times, or type of procedure performed. Patients who received morphine had a significantly longer time to discharge from the PACU (216 minutes) than the femoral nerve block group (177 minutes). The morphine group was also significantly more likely to report postoperative nausea (75%) than the femoral nerve block group (10%). Patients receiving femoral nerve blocks were significantly more likely to be satisfied with their postoperative pain control (90%) than those who had received morphine (25%). All of the patients receiving a femoral nerve block stated that they would undergo the block again if they needed another hip arthroscopy. CONCLUSIONS: On the basis of all criteria studied (quality of pain relief, length of stay in the PACU, side effects, and patient satisfaction), a femoral nerve block is an excellent alternative to routine narcotic pain medication in patients undergoing hip arthroscopy. LEVEL OF EVIDENCE: Level II, randomized controlled trial.

Galeazzi fracture with volar dislocation of the distal radioulnar joint.

Galeazzi fracture dislocations are fractures of the distal one-third of the radial diaphysis with traumatic disruption of the distal radioulnar joint (DRUJ). This injury results in subluxation or dislocation of the ulnar head. We present a case of a Galeazzi fracture with a volar dislocation of the DRUJ. Open reduction of the DRUJ with Kirschner wire fixation in pronation was necessary to reduce the joint and maintain anatomic alignment. Repair of the triangular fibrocartilage complex was also necessary to maintain stability of the DRUJ.

Anterior shoulder instability - a history of arthroscopic treatment.

The glenohumeral joint is the most commonly dislocated joint in the body. The prevalence of this condition and the instability that may result from it has been a focus of diagnosis and treatment since the original description of the Bankart lesion in 1923. Now, with the introduction of MRI, lesions causing anterior shoulder instability can be diagnosed more accurately. This has led to improved understanding of the pathoanatomy that must be addressed and corrected during surgical repair. Initial attempts at arthroscopic treatment, including staple repair, transosseus suture repair, rivets, and thermal capsulorraphy were fraught with complications and unacceptably high recurrence rates. The development of arthroscopic suture anchors have revolutionized the treatment of anterior shoulder instability, such that arthroscopic management is now the standard of care. In the hands of experienced surgeons, outcomes for arthroscopic treatment of shoulder instability now approaches the success of open treatment.

Interaction between Langmuir and Langmuir-Blodgett films of two calix[4]arenes with aqueous copper and lithium ions.

The binding interactions between aqueous copper (Cu(2+)) and lithium (Li(+)) ions and Langmuir monolayers and Langmuir-Blodgett (LB) multilayers have been investigated by studying surface pressure-area (Pi-A) isotherms and surface potential-area (DeltaV-A) behavior in order to find the effective dipole moment, mu(perpendicular), of the calixarene molecules in the uncomplexed and complexed states. The orientation of both calix[4]arenes, namely, 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarbonyl methyleneoxy-26,28-dihydroxycalix[4]arene and 5,17-(9H-fluoren-2-yl)methyleneamino)-11,23-di-tert-butyl-25,27-diethoxycarbonyl methyleneoxy-26,28-dihydroxycalix[4]arene, is such that the plane of the calix ring is parallel with the plane of the water surface regardless of the ion content of the subphase. The Gibbs equation was used to interpret the adsorption of ions with both calix[4]arenes as a function of the concentration. Effective dipole moments have been calculated from surface potential values using the Helmholtz equation. In this work, new LB films have been prepared employing two novel amphiphilic calix[4]arene derivatives bearing different upper rim substituents. Thus, the effect of modifiying the upper rim has been observed. The results have shown that these calixarenes may be useful components of ion sensors.

Using Search Time and Regression to Estimate Abundance of Territorial Spotted Owls.

Using conventional sampling methods, unbiased, precise estimates of the number of individuals in a population can be difficult to obtain for rare, secretive species. We used a Leslie regression model (ARM) to estimate the number (N0 ) and the variance of the number (V[N0 ]) of adult and subadult Northern Spotted Owls in a territorial population from direct counts within a 292 km2 study area. Estimates of N0 from day counts were more accurate and precise and more robust to fluctuations in survey effort than estimates from night counts. ARM estimates from day counts were not significantly different from two different maximum-likelihood estimates and required 30-64% less effort. These findings suggest a less costly method for statistically comparing Spotted Owl abundance between spatial or temporal units.