Metal Fixation Research Articles

Potential risk factors for undifferentiated connective tissue disease among women: implanted medical devices.

A case-control study was conducted among 205 women in Michigan and Ohio who were diagnosed with undifferentiated connective tissue disease (UCTD) to investigate the significance of self-reported past exposures to implanted silicone-containing or non-silicone-containing medical devices. The 205 UCTD cases were compared with 2,095 controls who were sampled by random digit dialing. When silicone-containing devices, including shunts and catheters, were analyzed collectively, a significant association was observed (odds ratio (OR) = 2.81, 95% confidence interval (CI): 1.34, 5.89). The odds ratio for exposure to breast implants was increased, but not significantly (OR = 2.22, 95% CI: 0.65, 7.57). Among the non-silicone-containing devices, artificial joints (OR = 5.01, 95% CI: 1.60, 15.71) and orthopedic metallic fixation devices (OR = 1.95, 95% CI: 1.05, 3.60) were associated with UCTD. The estimations of risk associated with implanted medical devices in UCTD cases were explored in a comparison with 660 scleroderma patients who were ascertained concurrently in Michigan and Ohio. In general, the associations that were observed with non-silicone-containing devices, and more specifically with the fixation devices, persisted in the comparison of UCTD cases with scleroderma patients. The studies conducted among populations in Michigan and Ohio are intended to stimulate new hypotheses, innovative approaches, and the fostering of understanding of the environmental determinants of autoimmune disease.

Resorbable plate fixation in pediatric craniofacial surgery: long-term outcome.

To determine the long-term efficacy of resorbable plate fixation in pediatric patients undergoing craniofacial surgery for congenital anomalies, traumatic deformities, or skull base tumors. Retrospective case review. Medical records of 57 consecutive cases using resorbable plates and screws for craniofacial fixation in patients younger than 18 years were analyzed. The status of bone healing postoperatively (anatomical union, malunion, delayed union, or nonunion) and any complications or adverse effects (hardware visibility or palpability, plate extrusion, or infection) were noted. In midfacial and upper face procedures (54 patients) anatomical union and uncomplicated bone healing occurred in 52 (96%) of the patients. In this same group, complications (plate extrusion) occurred in 2 patients (3.7%) and were resolved using conservative treatment without untoward sequelae. These outcomes are comparable to results using metal osteosynthesis in similar situations. Costs of resorbable hardware are similar to existing metal fixation systems. Our data support the use of bioresorbable plate fixation in pediatric craniofacial surgery as a means of avoiding the potential and well-documented problems with rigid metal fixation. Indications include fractures and segmental repositioning in low-stress non-load-bearing areas of the middle and upper craniofacial skeleton. Although there is an initial learning curve in using this technology, we believe the benefits are well worth the effort and represent a major advance in pediatric craniofacial surgery.

Fixation of bimaxillary osteotomies with resorbable plates and screws: Experience in 20 consecutive cases

Purpose: This study evaluated the potential effectiveness of resorbable plate and screw fixation for skeletal stabilization of simultaneously performed maxillary and mandibular osteotomies. Patients and Methods: Twenty consecutive patients underwent simultaneous maxillary and mandibular osteotomies that were fixed using copolymeric poly L-lactic acid/polyglycolic acid (PLLA/PGA) plates and screws. Prefabricated acrylic intermediate and final splints were used as guides and then removed at completion of the surgery. Guidance elastics were applied at 2 weeks postoperatively. Results: The LeFort I osteotomies included segmentalizations with and without bone grafts (7/20), impactions (4/20), advancements (8/20), and unilateral downgrafting with a bone graft (2/20)—one of which was segmental. The mandibular sagittal split osteotomies involved advancements (11/20), setbacks (5/20), and asymmetric rotation (4/20). Three patients had simultaneous genioplasties, which were also stabilized with resorbable fixation. All maxillae were fixed with four 2.0-mm L-shaped plates and screws. The mandibular rami were maintained with three 2.5-mm bicortical screws per side. The mandibular symphyseal segments were held in position with two or three 2.5 mm bicortical screws. All surgeries were accomplished uneventfully, and no problems in the immediate postoperative stability of the occlusion were encountered. Follow-up ranged from 12 to 25 months. Conclusions: The initial clinical findings suggest that this form of bone fixation is a viable alternative to standard metallic fixation techniques for certain maxillomandibular deformities in which excessive bony movements are not performed. Differences exist in both intraoperative application and postoperative management of masticatory function. This is partially a US government work. There are no restrictions on its use.

The evans osteotomy: Technique and fixation with cortical bone pin

The use of a lamina spreader over converging pins facilitates opening of an Evans calcaneal osteotomy and allows for precise measurement of the recipient site. The technique of cortical bone pin insertion has been utilized when indicated by the authors a limited number of times (N = 10) and as such this will be the subject of a future scientific investigation. The authors feel the advantages of the cortical bone pins include ease of use, good resultant stability of the capital fragment, utilization of a material identical to that of the correcting graft, a more biologic form of absorbable internal fixation, and the avoidance of complications associated with percutaneous metallic fixation (Fig. 5).

Bioresorbable Fixation for Congenital Pediatric Craniofacial Surgery: A 2-Year Follow-Up

We describe our experience with the use of a polymeric biodegradable system for the correction of congenital pediatric craniofacial malformations. These fixation methods present several advantages over conventional metallic fixation systems. Our series consists of 51 patients that underwent craniofacial surgery, 46 for craniosysostosis, and 5 for encephalocele. The mean age of the patients was 3 years (median age 9 months). Patients with coronal or metopic craniosynostosis underwent a bifrontal craniotomy and anterior cranial vault and orbital reconstruction. Three patients with late sagittal synostosis underwent cranial vault reconstruction in two stages. Encephalocele defects were repaired with osteotomies, and/or onlay bone graft. Lactosorb (Lorenz Biomet, Warsaw, Ind.) plates (cut from a prefabricated mesh) and screws were employed using established fixation techniques. Cranial bone was the source of all bone graft when required. Pre- and postoperative clinical, radiographic and photographic examinations were performed on all patients. At 2 years follow-up, no evidence of infection, erythema, extrusion, instability of the bony fragments or relapse has been noted. The plates themselves were universally impalpable by the one year follow-up examination. The results in this series support the use of resorbable fixation systems in the correction of congenital craniofacial deformities.

Hydrothermal Solidification of Wastes withFormation of Zeolites

In order to use waste materials effectively, a possibility of simultaneous solidification of inorganic waste materials and fixation of alkaline ions and heavy metal through formation of zeolite by using hydrothermal processing, was investigated. Fly ash, cinder of sewage sludge, and cinder of rubbish were used as the starting materials. Ca/Si and 2Na/Si molar ratios of the specimens were changed by the addition of CaO and Na\d2CO\d3. These mixtures were formed and hydrothermally processed at 200 C. Various zeolites, such as analcime, Linde B\d1 zeolite, cancrinite, zeolite P-C, and hauyne, were formed at Ca/Si = 0.3 or 0.5 and 2Na/Si = 0.1–1.0. In the case of the fly ash system, although only the zeolite minerals were formed, the flexural strength reached up to 17 MPa when Ca/Si = 0.3 and 2Na/Si = 0.1, and the fixing ratio of Na\u+ ion reached a maximum value of 85% by the formation of zeolites. When cinder of rubbish was used, dissolution of heavy metals from the solidified specimen was scarcely observed. The microstructure and the variation of pore size distribution were also discussed.

Robotic System Based on X-Ray Navigation for Assistance in Orthopaedic Surgery

The treatment of femoral shaft fractures typically involves the surgical insertion of a metallic fixation device (intramedullary nail) into the marrow cavity of the femur. Depending upon the severity of the fracture, interlocking screws may then be inserted through the lower (distal) end of the nail/femur. Unfortunately, the pilot holes for these distal interlocking screws can only be drilled under fluoroscopic guidance. As a consequence, distal interlocking is a technically demanding process, which inevitably leads to irradiation of the surgeon. A custom-built robotic-assisted surgery system has therefore been developed with a view to providing a “remote” surgical drilling capability. This paper describes the digital X-ray photogrammetry based registration and trajectory planning techniques employed by the robotic system.

Principles of development and use of absorbable internal fixation.

Absorbable internal fixation implants, by virtue of their temporary in situ residence and variable load sharing with the healing tissues, have the potential to yield a clinical outcome that approaches the native state. Despite the growing availability and acceptance of absorbable fixation, however, many surgeons continue to rely upon metal fixation for their patients, due, in part, to unfamiliarity with the technology. Although many of the principles of metallic internal fixation also apply to absorbable internal fixation, significant differences exist as well. This paper presents basic background in absorbable technology and proposes a set of principles that may help govern the development and use of absorbable fixation devices in clinical practice.

Critical concepts of absorbable internal fixation.

Absorbable internal fixation implants, by virtue of their temporary in situ residence and variable load sharing with the healing tissues, have the potential to yield a clinical outcome that approaches the native state. Despite the growing availability and acceptance of absorbable fixation, however, many surgeons continue to rely on metal fixation for their patients, because, in part, of unfamiliarity with the technology. Although many of the principles of metallic internal fixation also apply to absorbable internal fixation, significant differences exist as well. This article presents basic background in absorbable technology and proposes a set of principles that may help govern the development and use of absorbable fixation devices in clinical practice.

Intrathoracic migration of Kirschner pins

We report two cases of intrathoracic migration of Kirschner pins used for the treatment of sternoclavicular joint dislocation. The migration was asymptomatic in both cases. Treatment involved median sternotomy in one patient and video-assisted thoracoscopy in the other. A favorable outcome was observed in both patients. The reports confirm the potential dangers related to management of sternoclavicular joint dislocation with metallic fixation devices.

A Critical Study of the Use of Hydrogen Peroxide to Determine Trace Metals Bound to Soil Organic Matter

The risk due to the presence of large amounts of trace metals in soils is related strongly to their speciation, which is usually estimated by sequential extraction procedures. However, this approach is now very controversial. As one of the soil compartments responsible for the trace metal fixation is the organic matter, the aim of this work was to study the reliability of the use of a chemical reagents such as hydrogen peroxide in determining the trace metal quantities bound to the soil organic matter. A comparison of the quantities of trace metals extracted by H+ or H+ + H2O2 for different values of the final pH, has shown that an optimal pH is required in order to provide the best estimate of trace metals bound to soil organic matter, when using for this goal the hydrogen peroxide. Using this approach, we found for example that more than 60% of copper is truly bound to organic matter.

Musculoskeletal infections: US manifestations.

One of the most important prognostic factors in patients with musculoskeletal infections is the delay in establishing therapy. Early diagnosis of septic arthritis requires analysis of joint fluid. Ultrasonography (US) is a rapid, portable, sensitive technique for confirming the presence of joint effusions. The study can be easily repeated for follow-up of lesions. US allows real-time guidance of fluid aspiration and can reduce the risk of contaminating other anatomic compartments, especially in the hands, wrists, and feet. Radiography provides complementary information and should be performed in conjunction with US. US is the imaging modality of choice for diagnosis of superficial abscesses. Dynamic compression with the US probe and color Doppler imaging can facilitate detection of superficial abscesses. US may help in the early diagnosis of osteomyelitis by demonstrating subperiosteal or juxtacortical fluid collections and by providing guidance for aspiration of these collections. Evaluation of osseous involvement requires additional imaging; a US examination with normal results does not allow exclusion of bone infection. US is not degraded by metallic artifact and may be useful in cases of osteomyelitis complicating metallic fixation in an extremity. After initial radiography, US can play an important role in the management of musculoskeletal infections.

Stabilization of Oxidic Tailings and Contaminated Soils by Calcium Oxyphosphate Addition: The Case of Montevecchio (Sardinia, Italy)

The effectiveness of an in situ heavy metals fixation technique aimed at converting contaminants to low solubility and low bioavail-ability forms, eliminating the risk posed by oxidic tailings and contaminated soils, was investigated. Calcium oxyphosphate salt (Ca(H2PO4)2·H2O) was used as a stabilizing agent for oxidic tailings and contaminated soils originating from Montevecchio, Sardinia, Italy. Stabilization was effected by mixing the contaminated soil or oxidic tailing sample with calcium oxyphosphate salt at various doses. The effectiveness of stabilization was evaluated by USEPA TCLP standard toxicity testing. Complementary EDTA extraction tests and biological tests using beans Phaseolous vulgaris as plant indicator were carried out. The toxicity of Pb and Cd was reduced below TCLP regulatory limits at calcium oxyphosphate doses higher than 0.7 and 0.2% w/w for soils and tailings, respectively. Lead solubility according to the EDTA test decreased with phosphate dose for both materials tested. Lead uptake by plant leaves and roots from the soil sample decreased with the phosphate addition, while Cd uptake remained almost constant. An adverse effect on plant growth and Zn uptake was observed for calcium oxyphosphate dose up to 1.1% w/w. Based on the results, a remediation scheme for oxidic tailings and contaminated soils is proposed.

Osseointegration of preformed polymethylmethacrylate craniofacial prostheses coated with bone marrow-impregnated poly (DL-lactic-co-glycolic acid) foam.

Osseointegration of bone marrow-PLGA-coated, preformed polymethylmethacrylate cranioplasties offers the possibility of reducing: operative time, periimplant seroma and infection, metallic fixation, and periprosthetic resorption following surgical skull remodeling. These alloplastic materials are FDA-approved but previously have not been used together to promote cranioplasty incorporation. The objective of this study was to determine whether the use of PLGA foam coating improves host osseointegration of preformed, textured, polymethylmethacrylate prosthetic cranioplasties. A critical-sized cranial defect was created in two groups of 10 and one group of three rabbits. The defect was filled with either a textured, preformed polymethylmethacrylate disc or a textured, preformed polymethylmethacrylate disc coated with poly (DL-lactic-co-glycolic acid). Both implants were immersed in autologous bone marrow for 20 minutes before implantation. Half of each group of 10 were killed at 3 weeks, and the remainder at 6 weeks. A third group of three rabbits with excised periosteum was evaluated at 6 weeks. Histologic analysis of the discs determined relative amounts of cancellous bone formation adjacent to the prostheses. Woven trabecular bone was present at each host bone to implant perimeter interface at 3 weeks, with fine fibrous capsular formation around the implants. Thicker, lamellar trabeculae were present at 6 weeks with an increased fibrous layer surrounding both types of implants. Bone formed on the superficial and deep implant surfaces in a noncontiguous fashion. Two of five measures showed that total bone formation was significantly greater in the PLGA-coated implants. Polymethylmethacrylate discs coated with bone marrow-impregnated PLGA foam demonstrate increased bone formation at 3 and 6 weeks as compared with non-coated preformed polymethylmethacrylate discs. Only implants with preserved periosteum showed bone formation away from the host-implant interface (centrally) on the superficial surface at 6 weeks.

A New Method for Arthroscopic Treatment of Tibial Eminence Fractures With Eyed Steinmann Pins

Summary: This report describes a new and simple method to treat tibial eminence fractures. We treated these fractures arthroscopically by using eyed Steinmann pins and pullout sutures of 1-0 polydioxane or 1-0 polypropylene monofilament under local anesthesia. From March 1993 to February 1997, we treated 16 patients with tibial eminence fractures. There were 12 cases of type II and 4 cases of type III fractures, according to the classification of Meyers and McKeever. All of the patients had good results according to the International Knee Documentation Committee and Müller's knee scoring systems, and had good stability by anterior stress radiographs compared with the uninjured side. Advantages of this method are minimal arthrotomy, simple technique, short operation and hospitalization times, early rehabilitation, no need for metal fixation removal, and, this procedure can be done under local anesthesia.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 15, No 6 (July), 1999: pp 672–675

Clay Formation and Metal Fixation during Weathering of Coal Fly Ash

The enormous and worldwide production of coal fly ash cannot be durably isolated from the weathering cycle, and the weathering characteristics of fly ash must be known to understand the long-term environmental impact. We studied the weathering of two coal fly ashes and compared them with published data from weathered volcanic ash, it's closest natural analogue. Both types of ash contain abundant aluminosilicate glass, which alters to noncrystalline clay. However, this study reveals that the kinetics of coal fly ash weathering are more rapid than those of volcanic ash because the higher pH of fresh coal fly ash promotes rapid dissolution of the glass. After about 10 years of weathering, the noncrystalline clay content of coal fly ash is higher than that of 250-year-old volcanic ash. The observed rapid clay formation together with heavy metal fixation imply that the long-term environmental impact of coal fly ash disposal may be less severe and the benefits more pronounced than predicted from previous studie...

Biodegradable semirigid plate and miniscrew fixation compared with rigid titanium fixation in experimental calvarial osteotomy.

To determine the biocompatibility and suitability of resorbable plates and miniscrews, consolidation of symmetrical, bilateral frontal bone craniotomies that had been closed using various methods was studied in 20 growing lambs. Bone fixation with a flexible, punched polylactide plate and four slowly degradable, self-reinforced poly-levolactide (SR-PLLA) or rapidly degradable, self-reinforced polyglycolide (SR-PGA) miniscrews (10 animals in each group) was compared intraindividually with rigid fixation by using a titanium miniplate and four miniscrews. Plain x-ray films, magnetic resonance images, histological studies, and histomorphometric studies were obtained at 4 to 104 weeks. No dislocation, instability, clinical foreign body reactions, infections, or loss of fixation were observed. Bone consolidation of the 2.35-mm-wide craniotomy lines was incomplete; connective tissue-filled defects through the bone were observed in 13 of 28 lines at 26 to 52 weeks. Statistical analyses based on histomorphometric studies showed no difference in consolidation with SR-PLLA miniscrew and titanium plate/screw fixation or between the two resorbable fixation methods. Fixation with rapidly degradable SR-PGA miniscrews resulted in less effective consolidation than on the contralateral titanium-treated side (p<0.05), but the bone segment was thicker (p<0.005). The SR-PGA miniscrews had disappeared by 6 weeks, the polyactide plate by 104 weeks, and the SR-PLLA miniscrews had been mostly resorbed at 104 weeks. Passive translocation of the titanium plates and screws into the bone tissue was seen at 52 and 104 weeks. In rapidly growing lamb frontal bone, comparable consolidation results, without complications, can be achieved with semi-rigid resorbable fixation compared with rigid metallic fixation.

99/01249 Drying of mock spent nuclear fuel elements : Crepeau, J. C. et al. Drying Technology, 1998, 16, (3–5), 545–560

This work investigated the feasibility and effectiveness of MSWI fly ash-based Friedel matrices on stabilizing/solidifying industrial chromium-bearing electroplating sludge using MSWI fly ash as the main raw material with a small addition of active aluminum. The compressive strength, leaching behavior and chemical speciation of heavy metals and hydration phases of matrices were characterized by TCLP, XRD, FTIR and other experimental methods. The results revealed that MSWI fly ash-based Friedel matrices could effectively stabilize chromium-bearing electroplating sludge, the formed ettringite and Friedel phases played a significant role in the fixation of heavy metals in electroplating sludge. The co-disposal of chromium-bearing electroplating sludge and MSWI fly ash-based Friedel matrices with a small addition of active aluminum is promising to be an effective way of stabilizing chromium-bearing electroplating sludge.

Correlation between the Limiting pH of Metal Ion Solubility and Total Metal Concentration

As an alternative to species distribution diagrams (pM vs pH curves in aqueous solution) drawn for a fixed total metal concentration, this work has developed simple linear models for correlating the limiting pH of metal ion solubility—in equilibrium with the least soluble amorphous metal hydroxide solid phase—to the total metal concentration. Thus adsorptive metal removal processes in complex systems can be better designed once the limiting pH of heavy metal solubility (i.e., pH*) in such a complex environment can be envisaged by simple linear equations. pH* vs pMt (Mt = total metal concentration that can exist in aqueous solution in equilibrium with M(OH)2(s)) linear curves for uranyl–hydroxide, uranyl–carbonate–hydroxide, and mercuric–chloride–hydroxide simple and mixed-ligand systems and cupric–carbonate–hydroxide complexes in equilibrium with mixed hydroxide solid phases may enable the experimental chemist to distinguish true adsorption (e.g., onto hydrous oxide sorbents) from bulk precipitation removal of the metal and to interpret some anomalous metal fixation data—usually attributed to pure adsorption in the literature—with precipitation if the pMt at the studied pH is lower than that tolerated by pH* vs pMt curves. This easily predictable pH* corresponding to a given pMt may aid the design of desorptive mobilization experiments for certain metals as well as their adsorptive removal with the purpose of simulating metal adsorption and desorption cycles in real complex environments with changing groundwater pH.

Treatment of Used Diesel Invert Drilling Mud to Remove Hydrocarbons, Fix Lead, and Leach Brine

A sample of used, highly saline diesel invert drilling mud (DIDM), artificially contaminated with lead, was tested for remediation using ICPET/ NRC's Solvent Extraction Soil Remediation (SESR) process. The work comprised investigation of the concurrent solvent extraction of diesel oil and fixation of lead by co-agglomeration of metal binding agents. Peat, soluble and insoluble phosphates, coal combustion fly ashes, and flue gas desulfurization scrubber sludge were tested as lead fixation agents. Virtually complete extraction of diesel oil was achieved in a five-step extraction process using toluene, trichloroethylene, or hexane as solvents. The effect of the metal fixation agents on solvent extraction efficiency was also investigated. After remediation to remove hydrocarbons and fix heavy metals, the DIDM sample remained saline. Successful leaching of brine from the dried agglomerates was accomplished by water percolation through a fixed bed of the dried, agglomerated soil. The cleaned DIDM was evaluated for resistance to acid leaching of lead using the U.S.-EPA's toxicity test method 1310A and Toxicity Characteristics Leaching Procedure method 1311. Long-term stability of the treated solids to acid leaching was tested using the U.S.EPA's multiple extraction procedure method 1320. Bioavailability of fixed lead to barley plants grown on synthetic soils prepared from remediated DIDM was determined by analyzing the roots and shoots for lead content. Acid phosphatase, peroxidase, and protein levels were determined in plant roots and soil leachates by biochemical analysis methods. These results were used to assess the effect of enzymes produced by plant root systems, or soil associated microorganisms, on the stability of fixed lead. The presence of fixation agents reduced the bioavailability of lead to the plants.