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PubMed1999

Carpal tunnel syndrome after epiphysiolysis of the distal radius in a 5-year-old child. Case report.

Carpal tunnel syndrome after fracture of the distal radius is a well known complication in adults, but in small children carpal tunnel syndrome is extremely rare. A case of carpal tunnel syndrome in a 5-year-old girl is presented. She had a distal epiphysiolysis of the radius, which was treated conservatively. Eight weeks after removal of the plaster of Paris she had clinical signs of carpal tunnel syndrome after exercise but without new injuries. Conservative treatment with a dorsal splint was effective, and all her symptoms disappeared. So conservative treatment seems worth considering before operation in similar cases.

Carpal Tunnel Syndrome↗
PubMedDate not supplied

Preliminary study of potential for rapid prototype and surface scanned radiotherapy facemask production technique.

Preliminary investigations into the potential of an elegant technique to create a rudimentary facemask for patient immobilization during radiotherapy treatment are presented. This method combines modern technology to cause the patientfar less discomfort compared with current plaster of Paris (POP) face mould procedures. Near instantaneous patient face scanning is accomplished with charge-coupled devices for imaging in an optical surface scanning system. The surface generated data is input to a rapid prototype (RP) system that creates a life-size model of the patient's face topology. As proof of principle a basic prototype facemask was successfully constructed using this technique and some qualitative comparison measurements for position and surface dose were made. These initial results confirm the validity of this technique and justify the need for further quantitative studies to fully investigate the potential of RP facemasks over POP based methods for mask production.

Acrylic Resins↗
PubMed2003

CIR sand casting system for trans-tibial socket.

The authors have developed a trans-tibial socket fabrication system based on the "dilatancy" principle, a process that has been commonly used in forming wheelchair Seating. The CIR Sand Casting System replaces plaster of Paris with sand for forming both a negative sand mould and a positive sand model, which can be modified for either thermoplastic socket formation or resin lamination. Initial clinical trials suggest that fabrication times are approximately 90 minutes from patient evaluation and casting to dynamic alignment. Compatibility with all existing prosthetic components is retained. It is believed the CIR socket fabrication system may be a competitive alternative for prosthetic service providers in developing countries.

Amputation, Surgical↗
PubMed2005

Sand-casting technique for trans-tibial prostheses.

A sand-casting technique for trans-tibial sockets was applied to 28 amputees, and the prosthetic fit observed through transparent check sockets. The results were better than historical reports of fittings with plaster of Paris casting by qualified prosthetists. The fit was consistently and evenly larger than the stump, but total contact could be achieved by applying three (two to five) stump socks. This would normally be considered on the high side of a good fit.

Adult↗
PubMed2000

Contamination of in vivo bone-lead measurements.

This paper addresses one aspect of the calibration of a 109Cd based K-shell x-ray fluorescence measurement system, namely the treatment of the calibration line intercept. Under circumstances of contamination, the intercept may warrant statistical treatment different from that currently performed. This paper proposes refinements to the existing method of subtracting the phantom calibration line intercept from in vivo responses in the calculation of in vivo concentrations. These refinements are recommended because the existing method can underestimate in vivo concentrations by a small amount under normal operating conditions. Contamination of the calibration standard matrix of plaster of Paris by both lead and non-lead contaminants is addressed.

Bone and Bones↗
PubMed2004

An investigation of the 109Cd gamma-ray induced K-x-ray fluorescence (XRF) bone-lead measurement calibration procedure.

Two sets of phantoms have been used to calibrate a 109Cd y-ray induced K-XRF bone-lead measurement system. Both sets of phantoms are made of plaster of Paris, but the calibration lines are significantly different. This results in a significant difference for the derived concentrations of bone lead for the same person using these two sets of phantoms. This study shows that the different calibration lines are due to the different compositions of the phantoms, which can then be accounted for by adjusting the parameters related to the phantom composition in spectral analysis. Bone-lead concentrations for ten lead-exposed smelter workers were computed before and after analysis modification, and the results show that the bone-lead concentrations for the same person calculated from two sets of phantoms are not significantly different, only after the modifications are incorporated. Through these investigations, it was discovered that a common practice of setting the ratio of the calcium edge amplitude to the coherent scatter amplitude as a constant is only valid when all spectra are acquired at the same system resolution. When there is a change in the resolution between spectra, it has been determined that the ratio of the calcium edge amplitude to the coherent area should instead be used as the constant factor in the analysis program.

Bone Substitutes↗
PubMed1995

Experimental validation of a novel reconstruction algorithm for electrical impedance tomography based on backprojection of Lagrange multipliers.

A novel approach to image reconstruction for electrical impedance tomography (EIT) has been developed. It is based on a constrained optimization technique for the reconstruction of difference resistivity images without finite-element modelling. It solves the inverse problem by optimizing a cost function under constraints, in the form of normalized boundary potentials. Its application to the neighboring data collection method is presented here. Mathematical models are developed according to specified criteria. These express the reconstructed image in terms of one-dimensional Lagrange multiplier functions. The reconstruction problem becomes one of estimating these functions from normalized boundary potentials. This model is based on a cost criterion of the minimization of the variance between the reconstructed and the true resistivity distributions. The algorithm was tested on data collected in a cylindrical saline-filled tank. A polyacrylamide rod was placed in various positions with or without a peripheral plaster of Paris ring in place. This was intended to resemble the conditions during EIT of epileptic seizures recorded with scalp or cortical electrodes in the human head. One advantage of this approach is that compensation for non-uniform initial conditions may be made, as this is a significant problem in imaging cerebral activity through the skull.

Algorithms↗
PubMed2004

The effect of layers in imaging brain function using electrical impedance tomograghy.

Electrical impedance tomography (EIT) has promise for imaging brain function with rings of scalp electrodes, but hitherto human images have been collected and reconstructed using a simple algorithm in which the head was modelled as a homogeneous sphere. The purpose of this work was to assess the improvement in image quality which could be achieved by adding layers to represent the cerebro-spinal fluid (CSF), skull and scalp in the forward model employed by the reconstruction algorithm. Solutions to the forward model were produced analytically and using the linear finite element method (FEM). This was undertaken for computer simulated data when a spherical conductivity change of 10%, radius 5 mm, was moved through 29 positions within a head modelled as four concentric spheres of radius 80-92 mm in order to verify the accuracy of the linear FEM by comparison with the analytical method. Test data were also recorded in a 93.5 mm, spherical, saline-filled tank in which the skull was simulated by a hollow sphere of plaster of Paris, 5 mm thick and a 20 x 20 mm right-cylindrical Perspex object, a 100% conductivity decrease, was moved through 39 positions. The best images were achieved by reconstruction with a four- or three-shell analytical model, giving a spatial accuracy of 5.8 +/- 2.2 mm for computer simulated or 14.0 +/- 5.8 mm for tank data. Mean FWHM was 57 mm and 91 mm in the XY-plane and along the z-axis, respectively. Reconstruction with a homogeneous analytical model gave localization errors greater by about 50-300%, but a reduction in FWHM of about 5% of the image diameter. Unexpectedly, reconstruction with FEM models gave poorer results similar to the analytical homogeneous case. This confirms that addition of shells to the forward model improves image quality as expected with an analytical model for reconstruction, but that the FEM method employed, which used a medium mesh and a linear element computation, requires improvement in order to yield the expected benefits.

Algorithms↗
PubMed2001

Efficiency and efficacy of different intracorporeal ultrasonic lithotripsy units on a synthetic stone model.

PURPOSE: The efficiency and efficacy of the available intracorporeal ultrasonic lithotripters were compared in a stone model experiment. MATERIALS AND METHODS: Plaster of Paris (POP) stone phantoms having ratios of 1:1, 1.5:1, and 2:1 with water were fabricated into cubes of various hardnesses weighing an average of 24.6 g. The stones were immersed in water in a plastic container, and continuous irrigation through a rigid nephroscope was used. Ultrasonic lithotripters from ACMI, Olympus, Storz, and Wolf manufacturers were evaluated for efficacy in breaking up the three POP concentrations. Time to complete stone fragmentation, occurrence of probe or tubing occlusion, and probe overheating were evaluated. RESULTS: Efficiency of fragmentation and time to fragmentation of the Storz lithotripter were significantly different from those of the Wolf (p = 0.01 and p = 0.02, respectively) and ACMI (p = 0.001 and p = 0.02, respectively) lithotripters. Comparison of the efficiency of fragmentation and time to fragmentation of the ACMI and Wolf lithotripters showed significant differences (p = 0.005 and p = 0.03, respectively) in favor of the Wolf device. The Olympus lithotriptor resulted in incomplete fragmentation of phantoms of all POP concentrations. CONCLUSION: The Storz ultrasonic lithotriptor was found to have the lowest fragmentation time and highest efficiency in the fragmentation of phantom stones.

Calcium Sulfate↗
PubMed2003

In vitro analysis of stone fragmentation ability of the FREDDY laser.

BACKGROUND AND PURPOSE: The Frequency-Doubled Double-Pulse Nd:Yag) (FREDDY) laser (World of Medicine, Berlin Germany) is a short-pulsed, double-frequency solid-state laser with wavelengths of 532 and 1064 nm. This low-power, low-cost laser was developed for intracorporeal lithotripsy. We designed an experimental set-up to test its fragmentation efficiency at different energy and frequency settings. MATERIALS AND METHODS: Forty previously weighed plaster-of-Paris stone phantoms were divided into four groups in order to test fragmentation at 5 and 10 Hz for 2 and 4 minutes. A hands-off underwater laboratory set-up including a holder to keep the stone phantom in contact with the quartz laser fiber was utilized. The 280-microm laser fiber was cleaved and stripped between runs to ensure optimal energy delivery. After fragmentation was completed, all of the stone fragments remaining within the holder were allowed to desiccate for 48 hours and reweighed. Fragmentation was measured as the percentage weight loss. RESULTS: Stone phantoms fragmented at 5 Hz for 2 minutes sustained a mean 24% loss of weight, whereas the 4-minute treatment at 5 Hz reduced stone weight by 54%. Treatment at 10 Hz for 2 minutes demonstrated results similar to those of stones treated for 4 minutes at 5 Hz, reducing stone weight by 51%. Fragmentation at 10 Hz for 4 minutes revealed a 64% loss of mass, less than expected for these power settings. Fiber deterioration observed at the higher energy settings may be the cause of the reduced stone-fragmentation efficiency. CONCLUSIONS: Fragmentation with the FREDDY laser in the 5 Hz, 4 minutes and 10 Hz, 2 minutes protocols is comparable, suggesting that stone fragmentation correlates well with the total energy delivered to the stone. The slight drop in fragmentation efficiency at 10 Hz, 4 minutes is most likely explained by fiber damage occurring consistently at these higher energy settings. The safety profile and low investment and running costs of this laser are advantages that suggest the laser warrants further clinical trials.

In Vitro Techniques↗
PubMed1998

Laboratory and clinical assessment of pneumatically driven intracorporeal lithotripsy.

A pneumatically driven intracorporeal lithotripter (the Swiss Lithoclast) has recently been approved for use in the United States. We compared its performance in vitro with ultrasonic, electrohydraulic and laser lithotripsy devices using a standard plaster-of-Paris stone phantom. The probe sizes and output settings were identical to those used during clinical treatment. The fragmentation efficiency index (measured as the lithotripsy time needed to reduce the stone phantom to particles <2 mm divided by the initial stone weight) ranged from 5.0 to 8.5 min/g of stone mass, with this value increasing from pneumatic to electrohydraulic to laser and to ultrasonic lithotripsy. We also performed an objective study in a swine model, which showed no adverse consequence of pneumatic lithotripsy. Finally, we evaluated our initial 41 patients who had undergone pneumatic stone fragmentation. We treated 8 patients having 11 renal calculi, 30 patients having 37 ureteral calculi, and 3 patients having 6 bladder calculi employing pneumatic probes ranging in size from 0.8 to 2.0 mm. Stone fragmentation was successful in a single session in 95% of the ureteral calculi and 100% of both renal and bladder calculi. Stone analysis in 23 patients revealed 17 (74%) calcium oxalate monohydrate and 1 (4%) cystine calculi. Our clinical and laboratory assessment of this newly developed pneumatic lithotripsy device further validates its efficacy in fragmenting stone of all compositions and its overall safety associated with clinical application.

Adolescent↗
PubMed1998

Impact of holmium laser settings and fiber diameter on stone fragmentation and endoscope deflection.

We compared the impact of various energy settings, frequency, and fiber diameters on the stone fragmentation capabilities of the holmium laser. Stone phantoms, made from plaster of Paris and uniform in weight, were treated with one of two laser fiber sizes: small (200 and 365 microm) and large (550 and 1000 microm). Stones were immersed in water and fragmented for 3 minutes at 0.5, 1.0, or 2.0 J and 5, 10, or 15 Hz. The mean percentage decrease in weight in the two groups was compared using one-way ANOVA. The effect on flexible ureterorenoscope deflection of the small fibers was tested in two different ureterorenoscopes. Raising the energy level when using the small fibers resulted in more weight loss (P < 0.05). Increasing the frequency up to 10 Hz also resulted in a significant increase in weight loss (P < 0.05), yet above 10 Hz, there was no significant additional weight loss noted for either small fiber. There was no significant difference in the weight loss produced by the two fibers unless the energy setting was >1.0 J. Studies with the large fibers demonstrated similar results, with significant increments of weight loss occurring with increased energy (P < 0.05), while nonsignificant differences were seen for the two fiber diameters. Increasing laser frequency up to 15 Hz resulted in a significant increase in weight loss for the large fibers. Loss of ureterorenoscope deflection ranged from 7% to 16% and 18% to 37% for the 200-microm and 365-microm fibers, respectively. Small-diameter fibers, in combination with semirigid or flexible ureteroscopes, should be used to treat upper urinary tract stones. The 365-microm fiber should be utilized for the management of ureteral stones, as minimal endoscopic deflection is required to access these calculi. Because the 200-microm fibers are considerably more expensive, their use should be reserved for fragmentation of intrarenal calculi, where maximum deflection is required during flexible ureterorenoscopy. The ideal energy and frequency settings for the small fibers are <1.0 J and 5 to 10 Hz. Larger fibers can be used for managing bladder or renal calculi, as there is no need for significant fiber deflection. The 550-microm fiber is preferred, as it is comparable in efficacy to the 1000-microm fiber and is less expensive. Energy and frequency can be maximized to 2.0 J and 15 Hz without damage to the fiber, but visibility can be affected by high frequencies. Appropriate fiber selection and energy/frequency settings will allow access to most stones throughout the urinary tract, maximize fiber life, and minimize fiber expense.

Analysis of Variance↗
PubMed2000

Focal brain injury, FGF-2 and the adverse effects of excessive motor demand on cortical and nigral degeneration: marked protection by delayed intermittent exposure to halothane.

The neuroprotective potential of halothane anesthesia was investigated following unilateral electrolytic lesions to the forelimb representation area of the sensorimotor cortex (FL-SMC). Previously, it was found that the FL-SMC lesion increases substantially in size when the intact forelimb is immobilized with a plaster of paris cast for the first 7 days postlesion, which forces extreme overuse of the impaired forelimb during a time when nonlethally damaged tissue is vulnerable to behavioral demand. Initially, the purpose of this study was to investigate whether intracisternal infusion of basic fibroblast growth factor (bFGF or FGF-2), a potent neurotrophic factor that has been shown to have neuroprotective and plasticity promoting properties in focal stroke and other injury models, could prevent this use-dependent exaggeration of injury. Although intracisternal bFGF (starting 24 h after surgery, twice per week) was not found to produce significant neuroprotective or behavioral effects, the brief exposure to halothane anesthesia (15-20 min) during bFGF or vehicle administration was found to prevent expansion of the lesion size, and to reduce delayed loss of neurons in the substantia nigra pars reticulata (SNr). The data have implications for investigations of the effects of neurotrophic factor in vivo, and other investigations requiring brief, intermittent halothane anesthesia.

Animals↗
PubMed1985

Autologous corticocancellous bone paste for long bone discontinuity defects: an experimental approach.

A number of materials have been used in treating long bone discontinuity defects, some with rewarding results and some without. These materials vary from autologous, allogenic, and xenogenic grafts, to bone implants. Other inorganic implants, such as plaster of Paris and gold, have been used, most inducing a strong inflammatory reaction. In this experiment, a paste of autologous corticocancellous bone particles was used to reconstitute discontinuity defects in long bones. The defects were healed to a solidified state within six months. This finding confirms our previous work; in membranous bone discontinuity defects, autologous corticocancellous bone gave best overall results either when used alone or with a template carrier for contouring purposes.

Animals↗
PubMed2002

Closure of critical sized defects with allogenic and alloplastic bone substitutes.

PURPOSE: This study evaluates bone regeneration of critical sized cranial vault defects in New Zealand white rabbits using four commercially available bone substitutes: OsteoSet (calcium sulphate pellets), DynaGraft Putty (demineralized bone matrix delivered in a poloxmer excipient), Norian CRS, and Bone Source (two commercially available calcium phosphate cements). MATERIALS AND METHODS: Critical sized defects 15 mm in diameter were created bilaterally in the parietal bones of 30 adult male New Zealand White rabbits. They were divided into three groups with ten animals in each. Bone healing was assessed clinically, radiographically, and histomorphometrically. Group 1 had calcium sulfate bioimplant on one side of the calvarium and an unfilled defect on the contralateral side. Group 2 had DBM putty on one side and Poloxamer gel on the contralateral side. Group 3, the Calcium phosphate cements (CPC), had Norian CRS on one side and Bone Source on the contralateral side. Five animals in each group were killed at 6 weeks and 12 weeks post operatively. RESULTS: All unfilled defects healed with fibrous scar, as did the Plaster of Paris and the poloxamer gel defects. Defects reconstructed with the demineralized bone matrix putty healed with bone throughout the entire defect. This was obvious clinically and radiographically where the defects appeared completely filled with a dense radiopaque tissue. The six-week group displayed new bone formation (87.1%) surrounding the remaining allogeneic particles. Resorption was evidenced by the presence of osteoclastic activity and by the significant decrease in the size of the demineralized bone particles. By 12 weeks, the demineralized bone putty bioimplant was almost completely replaced by new bone (95.5%). Both calcium phosphate cement groups (Norian CRS and Bone Source) had identical patterns of healing. They clinically were visible and firm and uniformly radiopaque with little evidence of new bone formation. Histologically the cement remained unresorbed with little new bone with in the defect at 12 weeks. CONCLUSIONS: The utilization of a demineralized bone matrix putty appeared to allow for complete closure of critical sized calvarial defects in New Zealand white rabbits with viable new bone at 12 weeks.

Analysis of Variance↗
PubMed1991

Orbital augmentation by hydroxylapatite-based composites. A rabbit study and comparative analysis.

Hydroxylapatite, a synthetic bone mineral, was implanted alone or as a composite with either calcium sulfate (plaster of Paris) or Avitene (microfibrillar collagen hemostatic agent) into the orbital bony defects and orbital soft tissues of 23 rabbits. Plain Avitene was also placed into these bony and soft tissue sites and bone defects with no additives served as controls. Additionally, each implant material was placed into subcutaneous tissues to determine its relative inflammatory potential. New bone formation was noted in bony defects as early as 10 days. Bone ingrowth was greatest when hydroxylapatite was in direct apposition to bone. Material implanted away from bone showed predominantly connective tissue ingrowth. Minimal inflammatory reaction was noted early on in the hydroxylapatite and hydroxylapatite/calcium sulfate samples and had resolved by 2 months when placed in both soft and bony tissues. Samples of Avitene and the hydroxylapatite/Avitene composite demonstrated an intense inflammatory response, and in several cases large granulomas were seen after 2 months.

Animals↗
PubMedDate not supplied

Septic arthritis of the hip in a hemophiliac. Report of a case.

Septic arthritis of the hip occurred in a 32-year-old hemophiliac with circulating Factor VIII antibodies. The clinical presentation suggested a soft tissue hematoma, but failure of early resolution with immobilization and Factor VIII replacement led to a correct diagnosis. A non-invasive method of management is essential if antibodies to Factor VIII are present. Compression and Plaster of Paris immobilization of the joint with adequate antibiotic therapy allows resolution of the infection and return to normal function. To avoid the serious complication of septic arthritis in hemophilia, expeditious treatment of all foci of infection is a necessity.

Adult↗
PubMed2000

A new anthropometric phantom for calibrating in vivo measurements of stable lead in the human leg using x-ray fluorescence.

A new anthropometric phantom has been developed for calibrating in vivo measurements of stable lead deposited in bone using x-ray fluorescence. The phantom reproduces the shape of the mid shaft of the adult human leg and is fabricated using polyurethanes and calcium carbonate to produce materials that exhibit the same density, energy transmission, and calcium content as cortical bone, bone marrow, and muscle. The phantom includes a removable tibia fabricated using simulants for cortical bone and bone marrow to which a precise amount of stable lead has been added to cortical bone. The formulations used in fabricating the new anthropometric phantom are much more uniform in density and composition than the conventional phantom made from Plexiglas cylinders filled with plaster-of-Paris. The energy spectrum from an x-ray fluorescence measurement of the phantom using a 109Cd source is indistinguishable from an in vivo x-ray fluorescence measurement of the human leg, demonstrating that the materials used in the phantom exhibit the same radiological properties as human tissue. Likewise, results from x-ray fluorescence measurements of the phantom exhibit the same positional dependency as the human leg and vary by approximately 36% when, for example, the phantom containing 54 ppm of stable lead in the tibia was rotated by only 15 degrees. The detection limit for a 30 min 109Cd K shell x-ray fluorescence in vivo measurement is approximately 20 ppm determined from a background measurement using the new phantom containing no added lead in the muscle, bone, or bone marrow. The new anthropometric phantom significantly improves in vivo x-ray fluorescence calibration measurements by (1) faithfully reproducing the anatomy of the human leg, (2) having components that exhibit radiological properties similar to that of human tissue, and (3) providing a realistic calibration standard that can be used for in vivo x-ray fluorescence intercomparison measurements.

Adult↗