Subtrochanteric femur fractures: current review of management.

Subtrochanteric (ST) femur fractures are proximal femur fractures, which are often difficult to manage effectively because of their deforming anatomical forces.Operative management of ST fractures is the mainstay of treatment, with the two primary surgical implant options being intramedullary (IM) nails and extramedullary plates.Of these, IM nails have a biologic and biomechanical superiority, and have become the gold standard for ST femur fractures.The orthopaedic surgeon should become familiar and facile with several reduction techniques to create anatomical alignment in all unique ST fracture patterns.This article presents a comprehensive and current review of the epidemiology, anatomy, biomechanics, clinical presentation, diagnosis, and management of subtrochanteric femur fractures. Cite this article: EFORT Open Rev 2021;6:145-151. DOI: 10.1302/2058-5241.6.200048.

Pediatric tibial eminence fracture treatment: A case series using a bioabsorbable screw.

BACKGROUND: Pediatric tibial eminence fractures constitute a complex injury with multiple treatment options. We have described a technique that combines direct visualization through an open approach and stable fixation using a bioabsorbable screw. The purpose of this study is to describe our surgical technique for tibial eminence fractures and to compare the radiographic and functional outcomes to previous open or arthroscopic methods. METHODS: We retrospectively reviewed a series of five pediatric patients who underwent open reduction and internal fixation of a tibial eminence fracture with a headless, bioabsorbable poly-L lactic acid (PLLA) screw (Bio-Compression screw, Arthrex Inc, Naples, FL) from 2016 to 2017. The surgical technique involves an open approach, direct fracture reduction, and fixation with a PLLA screw without violating the epiphyseal plate. Postoperative assessment was quantified using the Lysholm knee score (LKS), knee arc of motion (AOM), presence of a pivot shift or Lachman, and knee radiographs with an average of 18.4 months of follow-up. RESULTS: Five patients (average age of 11.3 years) were treated with a biobsorbable screw and followed for an average of 18.4 months. Average LKS was 99.6, AOM was 98.4%, all patients had negative pivot shift and Lachman exams, and all patients went on to radiographic union. No patients required re-operation or implant removal. CONCLUSIONS: The goals of tibial eminence fracture management are fracture union, restoring knee stability, and regaining normal knee motion and kinematics. Our study demonstrates that open treatment with a bioabsorbable screw is an excellent alternative surgical method as it reliably results in rigid fixation, fracture union, excellent knee function scores, and it mitigates the possible need for hardware removal. LEVEL OF EVIDENCE: Therapeutic Level IV - Case series.

Pediatric Tenosynovial Giant Cell Tumor of the Flexor Hallucis Longus Tendon Sheath: A Case Report.

CASE: An otherwise healthy 13-year-old girl presented with a firm nodule on the plantar right forefoot that was tender after cheerleading. Initial workup was unremarkable, but magnetic resonance imaging revealed a multilobulated mass surrounding the flexor hallucis longus tendon. Surgical resection revealed a tenosynovial mass without tendon infiltration. Pathologic examination was consistent with tenosynovial giant cell tumor. The patient resumed cheerleading and remained asymptomatic after 1 year. CONCLUSION: As far as we know, this is the first report of a tenosynovial giant cell tumor of the flexor hallucis longus in a pediatric patient; it illustrates the importance of considering this lesion when diagnosing a pediatric plantar mass.

Effect of a Dynamic Fixation Construct on Syndesmosis Reduction: A Cadaveric Study.

OBJECTIVES: To explore what effect a dynamic fixation construct would have on the final reduction of the syndesmosis. METHODS: Syndesmotic ligaments were sectioned in 10 cadaveric specimens. The syndesmosis was intentionally malreduced with a clamp, and the distance from the anterior edge of the fibula to the anterior incisura of the tibia was measured to quantify the sagittal syndesmotic displacement (SSD). A 3.5-mm quadricortical screw was then placed, the clamp was removed, and the SSD measured. The clamp was then replaced, and a suture-button construct (Knotless Tightrope; Arthrex Inc, Naples, FL) was then placed through the bone tunnel, the clamp was again removed, and the SSD was measured. RESULTS: In all cases, the fibula reduced to within 1 mm of its native anatomical position with the dynamic construct. The static screw construct, however, maintained an identical SSD measurement as the clamped malreduction. The dynamic suture-button construct reliably improved the SSD (P < 0.0001). CONCLUSIONS: Our study demonstrates that dynamic fixation constructs can help restore anatomical alignment in the case of syndesmotic malreduction. The size difference between the suture diameter and drill hole effectively allows the fibula to be pulled and seated into the tibial incisura fibularis. These findings should not be viewed as a justification to ignore the syndesmotic reduction; however, they do validate an important benefit of dynamic fixation that has been found in the recent clinical literature. LEVEL OF EVIDENCE: Therapeutic Level III.

The Chopart Variant Dislocation: Plantar Dislocation of the Cuboid and Navicular.

This case report demonstrates a unique variant of a Chopart dislocation resulting in a plantar cuboid and navicular dislocation without concomitant fracture in a 48-year-old man. The mechanism of injury involved a low-energy plantarflexion moment from stepping off a small embankment. This report reviews the pertinent midfoot anatomy, discusses the proposed mechanism of injury, and demonstrates an effective method of treating these complex injuries with open reduction and internal fixation. Final results with 20 months of follow-up were excellent. This unusual midfoot dislocation is a complex injury that required open treatment for anatomic restoration. In complex Chopart dislocations, early open reduction should be strongly considered as the initial treatment to properly restore anatomy and function. Level of Evidence: Level V, expert opinion.

Development of a metabolism factor for polycyclic aromatic hydrocarbons for use in multipathway risk assessments of hazardous waste combustion facilities.

As a state authorized to permit hazardous waste combustion facilities, the Texas Natural Resource Conservation Commission (TNRCC) has conducted several site-specific, multipathway risk assessments in support of permitting actions. These risk assessments were carried out in accordance with guidance provided in U.S. Environmental Protection Agency's Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities, Peer Review Draft (HHRAP). This protocol uses a prospective, screening-level, risk assessment paradigm and incorporates conservative default assumptions. In conducting such risk assessments, staff of the Toxicology and Risk Assessment Section have found that modeled emissions of polycyclic aromatic hydrocarbons (PAHs) at concentrations near or below detectable levels can produce unacceptable risk in the "farmer" exposure scenario. In accordance with recommendations in HHRAP, the TNRCC followed a tiered approach, whereby additional site-specific information is incorporated in place of standard default assumptions in cases where the initial screening-level risk assessment yielded unacceptable risk or hazard. Sensitivity analyses indicated that one of the key parameters affecting the risk estimates for PAHs in the farmer exposure scenario was the way in which PAHs were modeled up through the food chain. Therefore, refinement of the model focused on the development of a PAH-specific metabolism factor, as described in the article.

Assessment of the effectiveness of composting for the reduction of toxicity and mutagenicity of explosive-contaminated soil.

Composting is being developed as an economical method for remediating explosive-contaminated soils and has been found to reduce the concentrations of target contaminants such as 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). However, whether environmental safety is improved by composting can be determined only by assessing the effects of the treated material on living organisms. In this study two bioassays, the Mutatox assay and the earthworm acute toxicity test, were used to evaluate the effectiveness of a pilotscale composting demonstration in reducing environmental hazard. Explosive-contaminated soil was collected from a military installation and amended for composting in two adiabatic reactors. The unamended soil was lethal to all exposed earthworms, as were both amended replicates, prior to composting. Serial dilutions of the finished composts with artificial soil had earthworm 14-day LC50 values of 35.7 and 100% finished compost: artificial soil. Extracts of the initial materials were also toxic to bacteria in the Mutatox assay. Dilutions of those extracts to sublethal concentrations revealed a low level of mutagenicity. Extracts of the finished composts indicated reduced bacterial toxicity, but the mutagenicity was markedly increased by composting. The reduction in lethality reflected the attenuation of explosives caused by composting, as indicated by chemical analysis. However, the increased mutagenicity was a result that would not have been indicated by chemical analysis alone and is inferred to be the result of the formation of mutagenic metabolites of explosives during composting and their incomplete degradation.

Cytotoxicity and mutagenicity of 2,4,6-trinitrotoluene and its metabolites.

Composting has been advocated and is being used as an economical method for remediating 2,4,6-trinitrotoluene (TNT)-contaminated soils. However, evidence suggests that TNT is transformed into products of unknown toxicity during the process. This study was undertaken to examine the in vitro cytotoxicity and mutagenicity of TNT and several of its degradation products/metabolites. TNT was equally cytotoxic to H4IIE cells and Chinese hamster ovary-K1 (CHO) cells (LC50 of 4 g/ml vs 24 microg/ml, with overlapping 95% prediction intervals), indicating that TNT does not need to be metabolized to exhibit cytotoxicity. Four metabolites studied, 4-hydroxylamino-2,6-dinitrotoluene; 2-amino-4,6-dinitrotoluene; 4,4',6,6'-tetranitro-2,2'-azoxytoluene; and 2,2',6,6'-tetranitro-4, 4'-azoxytoluene, were equally cytotoxic to both H4IIE and CHO cells. The LC50s were in the 3- to 18-microg/ml range and were not significantly different from TNT cytotoxicity in both cell lines. 4-Amino-2,6-dinitrotoluene (4-A) was moderately less cytotoxic than TNT to H4IIE cells, but was noncytotoxic to CHO cells. This result indicates that 4-A is metabolized to a cytotoxic compound. Both TNT and its metabolites exhibited only slight mutagenicity at high doses in one or both of the mutagenicity assays. While composting may reduce the levels of TNT in composted material, the hazard associated with TNT-contaminated soils is probably lower, but still uncertain.

A comparison of the Ames assay and Mutatox in assessing the mutagenic potential of contaminated dredged sediment.

The ability of the Ames assay and of Mutatox to identify the genotoxic potential of dredged sediments was compared. The Ames assay has been used extensively in the testing of environmental contaminants, whereas Mutatox, a new bacterial bioluminescence test, has only recently been used for this purpose. Ten sediments with varying degrees of contamination were soxhlet extracted. Each of the 10 extracts was split with half remaining in a crude form and half cleaned using silica gel chromatography, resulting in 20 extract samples. Both the Ames assay (using Salmonella typhimurium strains TA98 and TA100) and Mutatox were conducted with and without S9 metabolic activation. When metabolically activated, TA98 and TA100 indicated a positive mutagenic response in 80 and 50%, respectively, of the sediment extracts. Without S9 activation, TA98 indicated a positive mutagenic response with half the extracts, whereas only 10% did so with TA100. Mutatox indicated a positive mutagenic response with S9 activation in 75% of the extracts and no mutagenic response in any of the sediment extracts without metabolic activation. In a side-by-side comparison of the Ames assay (TA98 with S9) and Mutatox, 80% of the sediment extracts had similar responses, both positive and negative. Fifty percent of the sediment extracts had similar responses when tested with TA100 and Mutatox in the presence of S9. Mutatox compared reasonably well with the Ames assay but was insensitive to the presence of direct-acting mutagens in the sediments tested. Although Mutatox demonstrates promise as a screening tool to assess sediment genotoxicity, the authors consider it appropriate to use the Ames assay as a confirmation for definitive investigations.

Cadmium disposition in the earthworm Eisenia fetida.

The disposition of cadmium was examined in the earthworm Eisenia fetida using two exposure media, filter paper, and artificial soil. Uptake and elimination rates were estimated to be 0.03039 and 0.00895 hr-1, respectively, for 1.25 micrograms Cd/cm2 filter paper exposure and 0.00512 and 0.00029 hr-1, respectively, for 10 micrograms Cd/g artificial soil exposure. The distribution of cadmium was examined using whole body autoradiography, tissue distribution, and subcellular localization. Cadmium tissue distribution was exposure-dependent, while cadmium subcellular localization apparently was not exposure-dependent. Acid-soluble thiol levels, examined as an index of cadmium exposure, were too variable in nonexposed earthworms to serve as an indicator of cadmium exposure.