Prevention of motor ascending branch of the rectus femoris injuries in Bernese periacetabular osteotomy: a cadaveric study.

The Bernese periacetabular osteotomy (PAO) is a surgical procedure used to treat hip dysplasia in young adults, but it carries the risk of neurological complications, including injury to the motor ascending branch of the rectus femoris (MABRF). This study aimed to describe anatomical considerations to prevent MABRF injuries during PAO. A cadaveric study was conducted on seven specimens. The original and modified PAO approaches were used, with and without disinsertion of the rectus femoris muscle origin. The femoral nerve was dissected in all specimens from the endopelvic position to the MABRF origin (T-point). The average distance from the anterosuperior iliac spine to the T-point was 10.2 ± 0.4 cm. To protect the MABRF, a safety zone was identified for the osteotome placement during the ischial cut. The osteotome was slid over the joint capsule, deflecting the iliocapsularis muscle medially and distally. This manoeuvre shields the MABRF with the iliocapsularis muscle, reducing the risk of neurological injury. Both the original and modified PAO approaches were considered safe techniques with low risk to the rectus femoris innervation. These findings offer valuable insights for surgeons performing PAO, emphasizing the significance of understanding anatomical relationships and implementing protective measures to enhance patient outcomes and minimize complications. In conclusion, implementing these anatomical considerations can help prevent MABRF injuries during PAO, contributing to safer and more successful surgical interventions for hip dysplasia in young adults.

Human occupations of upland and cold environments in inland Spain during the Last Glacial Maximum and Heinrich Stadial 1: The new Magdalenian sequence of Charco Verde II.

The settlement of cold and arid environments by Pleistocene hunter-gatherers has been a heated topic in Paleolithic Archaeology and the Quaternary Sciences for years. In the Iberian Peninsula, a key area for studying human adaptations to such environments is composed by the large interior and upland regions of the northern and southern plateaus (Mesetas) and bordering areas. As, traditionally, these regions have been relatively under-investigated compared to the ecologically more favored coastal areas of the peninsula, our knowledge of the human settlement of the whole Iberian hinterland remains scarce for the Last Glacial. In this paper we present the discovery and first geoarcheological, paleoenvironmental and chronometric evidence obtained at Charco Verde II, a new site close to the southwestern foothills of the Iberian system range (Guadalajara province, Spain), bearing a sequence of Magdalenian human occupations starting at least at 20.8-21.4 ka cal BP during the Last Glacial Maximum, and covering Greenland Stadial 2 until ∼15.1-16.6 ka cal BP, including Heinrich stadial 1. As this site is located in an upland region which today faces one of the harshest climates in Iberia, such occupation sequence, occurred during some of the coldest and most arid phases of the Last Glacial, has relevant implications for our understanding of human-environment-climate interactions and population dynamics in Iberia and Western Europe. These findings support the hypothesis that the Iberian hinterland was not avoided by Upper Paleolithic hunter-gatherers due to ecological constraints, but it hosted a complex and relatively dense settlement at least in some areas, even during cold periods. This suggest, one more time, that the historical scarcity of Upper Paleolithic sites in inland Iberia is, to a significant extent, an artifact of research bias.

Charge Engineering of the Nucleic Acid Binding Cleft of a Thermostable HIV-1 Reverse Transcriptase Reveals Key Interactions and a Novel Mechanism of RNase H Inactivation.

Coupled with PCR, reverse transcriptases (RTs) have been widely used for RNA detection and gene expression analysis. Increased thermostability and nucleic acid binding affinity are desirable RT properties to improve yields and sensitivity of these applications. The effects of amino acid substitutions in the RT RNase H domain were tested in an engineered HIV-1 group O RT, containing mutations K358R/A359G/S360A and devoid of RNase H activity due to the presence of E478Q (O3MQ RT). Twenty mutant RTs with Lys or Arg at positions interacting with the template-primer (i.e., at positions 473-477, 499-502 and 505) were obtained and characterized. Most of them produced significant amounts of cDNA at 37, 50 and 65 °C, as determined in RT-PCR reactions. However, a big loss of activity was observed with mutants A477K/R, S499K/R, V502K/R and Y505K/R, particularly at 65 °C. Binding affinity experiments confirmed that residues 477, 502 and 505 were less tolerant to mutations. Amino acid substitutions Q500K and Q500R produced a slight increase of cDNA synthesis efficiency at 50 and 65 °C, without altering the KD for model DNA/DNA and RNA/DNA heteroduplexes. Interestingly, molecular dynamics simulations predicted that those mutations inactivate the RNase H activity by altering the geometry of the catalytic site. Proof of this unexpected effect was obtained after introducing Q500K or Q500R in the wild-type HIV-1BH10 RT and mutant K358R/A359G/S360A RT. Our results reveal a novel mechanism of RNase H inactivation that preserves RT DNA binding and polymerization efficiency without substituting RNase H active site residues.

Comparative study on the impact of equally stressful environmental sporulation conditions on thermal inactivation kinetics of B. subtilis spores.

Control of bacterial spores continues to be one of the main challenges for the food industry due to their wide dissemination and extremely high resistance to processing methods. Furthermore, the large variability in heat resistance in spores that contaminate foods makes it difficult to establish general processing conditions. Such heterogeneity not only derives from inherent differences among species and strains, but also from differences in sporulation environments that are generally ignored in spores encountered in foods. We evaluated heat inactivation kinetics and the thermodependency of resistance parameters in B. subtilis 168 spores sporulated at adverse temperatures, water activity (aw), and pH, applying an experimental approach that allowed us to quantitatively compare the impact of each condition. Reduction of incubation temperature from the optimal temperature dramatically reduced thermal resistance, and it was the most influential factor, especially at the highest treatment temperatures. These spores were also more sensitive to chemicals presumably acting in the inner membrane. Reducing sporulation aw increased heat resistance, although the magnitude of that effect depended on the solute and the treatment temperature. Thus, changes in sporulation environments varied 3D100°C values up to 10.4-fold and z values up to 1.7-fold, highlighting the relevance of taking such a source of variability into account when setting heat processing conditions. UV-C treatment and sodium hypochlorite efficiently inactivated all spore populations, including heat-resistant ones produced at low aw.

IL-15/IL-15Rα in SJS/TEN: Relevant Expression of IL15 and IL15RA in Affected Skin.

Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) is a life-threatening hypersensitivity reaction to medications characterized by keratinocyte apoptosis and skin detachment. IL-15 serum levels have been associated with severity and prognosis of SJS/TEN. We have measured IL-15 concentrations in serum and blister fluid (BF) from patients with SJS/TEN by ELISA and used quantitative RT-PCR to analyze the expression of IL15 and IL15RA (encoding for IL-15 Receptor-α chain) genes in peripheral blood and BF cells, including isolated monocytes, and in affected skin. A positive correlation was found between IL-15 serum levels and a percent of detached skin. BF concentrations were higher, but no correlation was found. Higher IL15 and IL15RA gene expression levels were found in skin-infiltrating blister fluid cells compared to peripheral mononuclear cells. Moreover, IL15RA transcripts were barely detected in healthy skin, being the highest expression levels found in samples from two SJS/TEN patients who did not survive. The cutaneous expression of IL-15Rα in SJS/TEN may provide an explanation to the tissue-specific immune cytotoxic response in this clinical entity, and the results suggest that the effects of IL-15 in SJS/TEN patients may be dependent on the expression of its private receptor IL-15Rα in affected skin.

Impact of a Home Telehealth Program After a Hospitalized COPD Exacerbation: A Propensity Score Analysis

Introduction: Currently there is lack of data regarding the impact of a home telehealth program on readmissions and mortality rate after a COPD exacerbation-related hospitalization. Objective: To demonstrate if a tele-monitoring system after a COPD exacerbation admission could have a favorable effect in 1-year readmissions and mortality in a real-world setting. Methods: This is an observational study where we compared an intervention group of COPD patients treated after hospitalization that conveyed a telehealth program with a followance period of 1 year with a control group of patients evaluated during one year before the intervention began. A propensity-score analyses was developed to control for confounders. The main clinical outcome was 1-year all-cause mortality or COPD-related readmission. Results: The analysis comprised 351 telemonitoring patients and 495 patients in the control group. The intervention resulted in less mortality or readmission after 12 months (35.2% vs. 45.2%; hazard ratio [HR] 0.71 [95% CI=0.56–0.91]; p=0.007). This benefit was maintained after the propensity score analysis (HR=0.66 [95% CI=0.51–0.84]). This benefit, which was seen from the first month of the study and during its whole duration, is maintained when mortality (HR=0.54; 95% CI=[0.36–0.82]) or readmission (subdistribution hazard ratio [SHR] 0.66; 95% CI=[0.50–0.86]) are analyzed separately. Conclusion: Telemonitoring after a severe COPD exacerbation is associated with less mortality or readmissions at 12 months in a real world clinical setting. (AU)

Novel RNase H Inhibitors Blocking RNA-directed Strand Displacement DNA Synthesis by HIV-1 Reverse Transcriptase.

In retroviruses, strand displacement DNA-dependent DNA polymerization catalyzed by the viral reverse transcriptase (RT) is required to synthesize double-stranded proviral DNA. In addition, strand displacement during RNA-dependent DNA synthesis is critical to generate high-quality cDNA for use in molecular biology and biotechnology. In this work, we show that the loss of RNase H activity due to inactivating mutations in HIV-1 RT (e.g. D443N or E478Q) has no significant effect on strand displacement while copying DNA templates, but has a large impact on DNA polymerization in reactions carried out with RNA templates. Similar effects were observed with ß-thujaplicinol and other RNase H active site inhibitors, including compounds with dual activity (i.e., characterized also as inhibitors of HIV-1 integrase and/or the RT DNA polymerase). Among them, dual inhibitors of HIV-1 RT DNA polymerase/RNase H activities, containing a 7-hydroxy-6-nitro-2H-chromen-2-one pharmacophore were found to be very potent and effective strand displacement inhibitors in RNA-dependent DNA polymerization reactions. These findings might be helpful in the development of transcriptomics technologies to obtain more uniform read coverages when copying long RNAs and for the construction of more representative libraries avoiding biases towards 5' and 3' ends, while providing valuable information for the development of novel antiretroviral agents.

Impact of a Home Telehealth Program After a Hospitalized COPD Exacerbation: A Propensity Score Analysis.

INTRODUCTION: Currently there is lack of data regarding the impact of a home telehealth program on readmissions and mortality rate after a COPD exacerbation-related hospitalization. OBJECTIVE: To demonstrate if a tele-monitoring system after a COPD exacerbation admission could have a favorable effect in 1-year readmissions and mortality in a real-world setting. METHODS: This is an observational study where we compared an intervention group of COPD patients treated after hospitalization that conveyed a telehealth program with a followance period of 1 year with a control group of patients evaluated during one year before the intervention began. A propensity-score analyses was developed to control for confounders. The main clinical outcome was 1-year all-cause mortality or COPD-related readmission. RESULTS: The analysis comprised 351 telemonitoring patients and 495 patients in the control group. The intervention resulted in less mortality or readmission after 12 months (35.2% vs. 45.2%; hazard ratio [HR] 0.71 [95% CI=0.56-0.91]; p=0.007). This benefit was maintained after the propensity score analysis (HR=0.66 [95% CI=0.51-0.84]). This benefit, which was seen from the first month of the study and during its whole duration, is maintained when mortality (HR=0.54; 95% CI=[0.36-0.82]) or readmission (subdistribution hazard ratio [SHR] 0.66; 95% CI=[0.50-0.86]) are analyzed separately. CONCLUSION: Telemonitoring after a severe COPD exacerbation is associated with less mortality or readmissions at 12 months in a real world clinical setting.

Bernese Periacetabular Osteotomy: A Comparative Study of Four Types of Incisions.

Bernese periacetabular osteotomy has diverse complications associated with incisions, such as dehiscence, hypertrophy, depression, and hyperpigmentation on scars, which affect patient satisfaction. The objective was to evaluate aesthetics and satisfaction outcomes in four different incisions. We evaluated 176 incisions in 148 patients. The incisions performed were the original modified (16, group I), straight and shortened, (64, group II), "Z" shaped (16, group III), and oblique inguinal (48, group IV). The scars were evaluated for width and length, development of a hypertrophic scar, depression or hyperpigmentation, and dehiscence and resuture. A scale of satisfaction was applied (points ranging from 1 to 10). The Bartlett test and Kruskal-Wallis test were used. The mean width and length of the scars were 20.3 and 6.8 cm for group I, 6.5 and 8.1 for group II, 12.1 and 7.1 cm for group III, 13 and 1.4 cm for group IV, respectively. Hypertrophic scars were found in 18% in group I, 12.5% in group II, and 31.2% in group III. Depressed scars were found in 10.8% in group I and 7.1% in group II. Hyperpigmentation was found in 16% in groups I and II, 37% in group III, and 2% in group IV. Dehiscence was found in 8.1% in group I and 8.9% in group II. Satisfaction for group IV was nine points. The difference in length and width and satisfaction were statistically significant (P < 0.05). The oblique inguinal incision (group IV) showed a smaller percentage of complications, with an adequate aesthetic result, and a high grade of patient's satisfaction.

Tratamiento quirúrgico de las fractura de pared posterior de acetábulo: resultados a corto y mediano plazo / Surgical treatment in acetabular posterior wall fractures: short and medium-term results

OBJETIVO: Evaluar los resultados radiológicos a corto y mediano plazo de pacientes operados de fractura de pared posterior de acetábulo, describir la morfología de la fractura, presencia de lesiones asociadas y la necesidad de artroplastia total de cadera (ATC) durante la evolución. MATERIAL Y MÉTODOS: Estudio retrospectivo-descriptivo de una serie consecutiva de 40 pacientes operados entre julio de 2012 y julio de 2017 por fractura de pared posterior de acetábulo. Treinta y siete hombres y tres mujeres con una edad promedio de 41 años fueron operados (mediana de seguimiento 17,7 meses). Se registró el mecanismo del accidente y presencia de lesiones asociadas. Se registraron el número de fragmentos que presentaba la fractura, presencia de impactación marginal, compromiso de la cabeza femoral, presencia de fragmentos intra-articulares y complicaciones postoperatorias. Para el análisis estadístico se utilizó el test de Wilcoxon. RESULTADOS: Todos los casos fueron secundarios a un accidente de alta energía. Un 70% de los pacientes presentó luxación posterior. La mayoría de los pacientes presentó una fractura entre 2 y 5 fragmentos (70%), 47,5% de los pacientes presentó impactación marginal, 37,5% compromiso de la cabeza femoral en zona de carga, 30% fragmentos intra-articulares. La complicación que más frecuente se observó fue la artrosis post-traumática la cual se presentó en un 22,5%. Cinco pacientes (12,5%) requirieron ATC. CONCLUSIÓN: Aunque se categorizan dentro de los patrones simples, las fracturas de pared posterior son lesiones complejas. La tomografía axial computada preoperatoria es esencial para determinar lesiones intra-articulares dada su alta frecuencia y también permite realizar un buen plan preoperatorio.

OBJECTIVE: Evaluate radiologic results in short and medium-term in surgically treated patients with acetabular posterior wall fracture. Describe fracture morphology, the presence of associated lesions and the necessity of total hip arthroplasty (THA) during the evolution. MATERIALS AND METHODS: A retrospective-descriptive study design of 40 patients treated during July 2012 and July 2017 for acetabular posterior wall fracture. 37 men and 3 women, 41 years old mean age. The mean follow-up was 17.7 months. Accident mechanism and presence of associated lesions were registered, as well as the number of fragments of the fracture, the presence of marginal impaction, femoral head compromise, intra-articular fragments and postoperatory complications. Wilcoxon test was used for the statistical analysis. RESULTS: Every case resulted due to a high energy accident. 70% of patients had posterior luxation of the hip. 70% of patients presented 2 to 5 fragments. 47.5% of patients presented marginal impaction, 37.5% compromised femoral head and 30% intra-articular fragments. The most frequent complication was post-traumatic arthrosis, which appeared in 22.5% of patients. Five patients required THA. CONCLUSION: Though it is categorized as simple fracture pattern, posterior wall fractures are complex. Preoperatory CT scan is essential to determine intra-articular lesions due to its high frequency and permits to plan an adequate intervention.

Fractura de cuello femoral en trauma de alta energía: ¿podemos confiar en la tomografía computarizada multicorte? caso clínico / High energy femoral neck fracture: can we trust the computerized tomography scan? case report

Las fracturas asociadas de diáfisis y cuello femoral son lesiones infrecuentes. A pesar de ser una asociación conocida, es pasada por alto entre un 19-31% de las veces. A continuación presentamos un caso de una fractura de diáfisis femoral en la cual la tomografía computarizada inicial no evidenció ningún rasgo a nivel del cuello femoral; sin embargo, este rasgo se hizo presente en las imágenes de control. Existen diversos exámenes para reconocer las fracturas de cuello femoral asociadas a diáfisis femoral, como la radiografía y la tomografía computarizada. Sin embargo, a pesar de estas imágenes, pueden no ser diagnosticadas. Con este caso reafirmamos la necesidad del uso de imágenes preoperatorias e intraoperatorias en pacientes con fracturas de diáfisis femoral de alta energía y que la tomografía computarizada multicorte de ingreso puede no evidenciar fracturas mínimamente desplazadas del cuello femoral.

Simultaneous fractures of the neck and shaft of the femur are uncommon injuries. Despite it being a known combination, it is overlooked in between 19 and 31% of cases. This case report describes a femoral shaft fracture in which the initial computed tomography did not show the femoral neck fracture, although it was present in the follow-up images. There are different imaging techniques to recognise femoral neck fractures associated with femoral shaft fractures, such as radiography and computed tomography. However, despite these images, they cannot be diagnosed. This case re-affirms the need for using imaging techniques before and during the operation in patients presenting with high energy femoral shaft fractures, in order to look for an associated femoral neck fracture. Although the use of fine-cut computed tomography scan may improve the diagnostic accuracy of this test, some femoral neck fractures will still go under-diagnosed.

Effect of protein incorporation on the nanostructure of the bicontinuous microemulsion phase of Winsor-III systems: a small-angle neutron scattering study.

Small-angle neutron scattering (SANS) analysis using the Teubner-Strey model has been employed to evaluate the effect of protein incorporation into the middle, bicontinuous microemulsion (BµE) phase of Winsor-III (WIII) systems formed by an aerosol-OT (AOT)/alkyl ethoxylate mixed surfactant system to understand better the extraction of proteins into and out of BµEs and to study the effect of proteins on a system that serves as a biomimetic analog of cell membranes. Under conditions of high salinity, the incorporation of positively charged proteins cytochrome c, lysozyme, and α-chymotrypsin, near their solubilization limit in the BµEs promoted the release of water and oil from the BµEs, a decrease in the quasi-periodic repeat distance (d), an increase in ordering (a decrease in the amphiphilicity factor, fa) for the surfactant monolayers, and a decrease in the surface area per surfactant headgroup, suggesting that the proteins affected the self-assembly of components in the BµE phase and produced Debye shielding of AOT's sulfonate headgroup. For WIII systems possessing lower salinity, cytochrome c reduced the efficiency of surfactant in the BµE phase, noted by increases in d and fa, suggesting that the enzyme and AOT underwent ion pairing. The results of this study demonstrate the importance of ionic strength to modulate protein-surfactant interactions, which in turn will control the release of proteins encapsulated in the BµEs, relevant to WIII-based protein extraction and controlled release from BµE delivery systems, and demonstrate the utility of BµEs as a model system to understand the effect of proteins on biomembranes.

Protein extraction by Winsor-III microemulsion systems.

Proteins (bovine serum albumin (BSA), α-chymotrypsin, cytochrome c, and lysozyme) were extracted from 0.5 to 2.0 g L(-1) aqueous solution by adding an equal volume of isooctane solution that contained a surfactant mixture (Aerosol-OT, or AOT, and a 1,3-dioxolane (or cyclic ketal) alkyl ethoxylate, CK-2,13-E5.6), producing a three-phase (Winsor-III) microemulsion with a middle, bicontinuous microemulsion, phase highly concentrated in protein (5-13 g L(-1)) and small in volume (12-20% of entire volume). Greater than 90% forward extraction was achieved within a few minutes. Robust W-III microemulsion systems were formulated at 40°C, or at 25°C by including a surfactant with shorter ethoxylate length, CK-2,13-E3 , or 1.5% NaCl (aq). Successful forward extraction correlated with high partitioning of AOT in the middle phase (>95%). The driving force for forward extraction was mainly electrostatic attractions imposed by the anionic surfactant AOT, with the exception of BSA at high ionic strength, which interacted via hydrophobic interactions. Through use of aqueous stripping solutions of high ionic strength (5.0 wt %) and/or pH 12.0 (to negate the electrostatic attractive driving force), cytochrome c and α-chymotrypsin were back extracted from the middle phase at >75% by mass, with the specific activity of recovered α-chymotrypsin being >90% of its original value.

Partitioning behavior of an acid-cleavable, 1,3-dioxolane alkyl ethoxylate, surfactant in single and binary surfactant mixtures for 2- and 3-phase microemulsion systems according to ethoxylate head group size.

Partition coefficients for a pH-degradable 1,3-dioxolane alkyl ethoxylate surfactant, 4-CH(3)O (CH(2)CH(2)O)(5.6)-CH(2), 2,2-(CH(2))(12)CH(3), 2-(CH(2)) CH(3), 1,3-dioxolane or "cyclic ketal" surfactant, CK-2,13-E(5.6,ave), between isooctane- and water-rich phases of 2- and 3-phase microemulsion systems (K(n)) were determined as functions of the ethoxylate size, n, and temperature for the neat surfactant and its binary surfactant mixtures, to understand the partitioning of alkyl ethoxylates possessing a broad distribution of ethoxylate size and to determine conditions required for formation of 3-phase microemulsion systems at an optimal temperature where phase separation occurs rapidly, important for protein purification via proteins' selective partitioning to the middle phase, driven by affinity to the second surfactant of the binary mixture. A semi-empirical thermodynamic mathematical model described the partitioning data well, provided optimal temperature values consistent with phase diagrams and theory, and demonstrated that the tail region of CK-2,13-E(5.6,ave) is more polar than the hydrophobes of fatty alcohol ethoxylates. The addition of Aerosol-OT (AOT) removed the temperature sensitivity of CK-2,13-E(5.6,ave)s partitioning, producing 3-phase microemulsion systems between 20 °C and 40 °C. Analysis of the bottom phases of the 2- and 3-phase microemulsion systems formed by CK-2,13-E(5.6,ave) via small-angle neutron scattering demonstrated the presence of spherical, monodisperse oil-in-water microemulsions.

Symptomatic medial exostosis of the great toe distal phalanx: a complication due to over-correction following akin osteotomy for hallux valgus repair.

UNLABELLED: The authors present the case of a 54-year-old female who developed a painful compression lesion localized to the medial aspect of the base of the distal phalanx of the great toe as a complication of hallux valgus surgery. Preoperative radiographic evaluation of the patient's foot revealed the first ray to be longer than the second, a 12 degrees first intermetatarsal angle, a 33 degrees hallux abductus angle, and an exostosis at the medial aspect of the base of the hallux that was not considered by the surgeon to be important. Correction of the hallux valgus deformity was performed with a combination of scarf and Akin osteotomies, and the intermetatarsal and hallux abductus angles reduced to 2 degrees and 8 degrees , respectively. By 2 months postoperative, the patient was complaining of pain at the medial aspect of the distal phalanx of the hallux associated with shoe pressure. The pain correlated both clinically and radiologically with the exostosis at the base of the distal phalanx, and had become symptomatic only after the hallux had been operatively realigned. At 6 months postoperative, percutaneous exostectomy was undertaken to remove the exostosis. Pain relief was complete, thereafter, and after 2 years of postoperative follow-up the patient remained pain free. The clinical importance of a medial exostosis localized to the base of the distal phalanx of the hallux must be taken into consideration whenever hallux valgus correction is undertaken, and this is particularly important whenever an Akin osteotomy is being considered. LEVEL OF CLINICAL EVIDENCE: 4.

Environmental performance and spillover effects on productivity: evidence from horticultural firms.

This study investigates the effect of environmental investment and related spillover effects on productivity in the agricultural sector by using a panel data of horticultural firms in Andalusia (Southern Spain). The results indicate a positive relationship between firm investment in environmental practices and productivity improvement, also showing the presence of positive environmental spillovers. In a second-stage of analysis, the incidence of environmental factors in firm specific individual technical efficiency is estimated. This analysis also shows the link between environmental knowledge diffusion and horticultural firms' performance.

Catastrophic wear in a metal-on-ceramic total hip arthroplasty.

A 51-year-old woman came to our clinic 6 months after a right total hip arthroplasty. She had noticed a slowly growing mass in the proximal thigh and referred progressive pain in the right groin. Plain radiography revealed premature acetabular cup aseptic loosening, and in the computed tomography study, a 14-cm-diameter mass was observed. Revision surgery was performed, showing a metal-on-ceramic bearing surface. The histologic analysis of surrounding tissues was reported as massive metallosis. Although occasionally chosen for primary or revision hip arthroplasty, there is little information available about the in vivo wear behavior of this combination. This important fact should be taken into account before considering such a surface alternative.

Metal levels in corrosion of spinal implants.

Corrosion affects spinal instrumentations and may cause local and systemic complications. Diagnosis of corrosion is difficult, and nowadays it is performed almost exclusively by the examination of retrieved instrumentations. We conducted this study to determine whether it is possible to detect corrosion by measuring metal levels on patients with posterior instrumented spinal fusion. Eleven asymptomatic patients, with radiological signs of corrosion of their stainless steel spinal instrumentations, were studied by performing determinations of nickel and chromium in serum and urine. Those levels were compared with the levels of 22 patients with the same kind of instrumentation but without evidence of corrosion and to a control group of 22 volunteers without any metallic implants. Statistical analysis of our results revealed that the patients with spinal implants without radiological signs of corrosion have increased levels of chromium in serum and urine (P < 0.001) compared to volunteers without implants. Corrosion significantly raised metal levels, including nickel and chromium in serum and urine when compared to patients with no radiological signs of corrosion and to volunteers without metallic implants (P < 0.001). Metal levels measured in serum have high sensibility and specificity (area under the ROC curve of 0.981). By combining the levels of nickel and chromium in serum we were able to identify all the cases of corrosion in our series of patients. The results of our study confirm that metal levels in serum and urine are useful in the diagnosis of corrosion of spinal implants and may be helpful in defining the role of corrosion in recently described clinical entities such as late operative site pain or late infection of spinal implants.

Corrosion and late infection causing delayed paraparesis after spinal instrumentation.

A 28-year-old female patient came to our hospital 14 years after surgical correction of adolescent idiopathic scoliosis with a 316L stainless-steel instrumentation. She presented progressive paraparesis during the last 2 months. Plain radiography, computed tomography scan and computed tomography-scan-guided needle biopsy revealed that a metallotic mass penetrated into the spinal canal, causing compression of the spinal cord at the T5-T6 level. The patient's symptoms were related to corrosion of the implant and infection by Propionibacterium acnes. Through a posterior approach, the instrumentation was retrieved and the metallotic mass and tissues were excised. Six months after the surgery, the patient is completely asymptomatic. Corrosion of stainless-steel implants is a finding more common than supposed. Biocorrosion--or microbially influenced corrosion--is a concept to be taken into account. It is possible that bacteria may modify the rate of corrosion of metals. Early diagnosis of corrosion is essential in order to prevent cases like the one we report, and perhaps, as suggested for total hip arthroplasties, metal levels could be useful to monitor spinal implants.

Retention of Cd, Zn and Co on hydroxyapatite filters.

This study qualifies and quantifies the immobilization of Cd, Zn and Co, (used as models of bivalent metal ions due to their relevant toxicity) in filters of synthetic hydroxyapatite (HAP) [Ca5(PO4)3OH]. They were flushed with solutions containing Cd (1 x 10(-5)M), Zn and Co (1 x 10(-4)M) at constant pH (8.6) and ionic strength (0.01 M). The concentration of these metal ions in the outlet was measured by ICP-OEM spectroscopy. The software PHREEQC (version 2.4.2) was used to model sorption process and the potential effect of salinity (KCl), pH, alkalinity (NaHCO3) and hardness (CaCl2) over the efficiency of the treatment. Results showed an excellent retention capacity of HAP for Cd, Zn and Co. Sorption data were successfully described considering a mix model of surface complexation onto phosphate surface groups, ionic exchange in surface calcium sites and the precipitation of ZnO. Co exchange and surface complexation constants (Kex and Kc) were taken from previous experiments, while KexCd=0.32 and KcCd=0.63 were estimated from our modeling results. Predictive values of metal ion sorption show that: (a) an increase in hardness does not play a significant role in the retention capacity of these metals on HAP; (b) an increase in alkalinity promotes the precipitation of MeCO3 which could alter the hydrodynamic of the column; (c) a decrease in pH and an increase in salinity inhibit ZnO precipitation enhancing Zn and Cd adsorption and decreasing Co retention on HAP.