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At least 271 records · Page 15Linked to original sources

PubMed1997

Shapes and dimensional characteristics of polyethylene wear particles generated in vivo by total knee replacements compared to total hip replacements.

Periprosthetic tissue was obtained at revision surgery from 10 posterior cruciate retaining total knee replacement cases (five different manufacturers). The tissues were hydrolyzed and polyethylene particles were isolated from each case. Individual particles were analyzed by scanning electron microscopy combined with computerized image analysis. For comparison, periprosthetic tissues from 10 total hip replacement cases (six different manufacturers) were processed and analyzed simultaneously with identical methods. The morphologies of the isolated polyethylene particles from total knee specimens were distinctly different. There was more variety of size, shape, and texture in the total knee particles. Submicron granules were less prevalent than in hip specimens. Larger flake-shaped particles, some measuring several microns in length and width, were commonly seen in knee specimens but not hip specimens. The overall average area of particles from the total knees (1.2 microns2) was twice that of total hips (0.61 micron2) (p = 0.049). The average perimeter (p = 0.026) and length (p = 0.026) of total knee particles was also greater than the total hip particles. The proportion of the smallest polyethylene particles (those averaging 0.2 micron2) in the total knee specimens was significantly less than that in total hip specimens (p < 0.0001). Although the large flake-shaped particles were visually striking, it is important to note that the majority of the wear particles from the total knee cases were also submicron. These differences in wear particle morphology and size are due to differences in the wear mechanisms of total knees and total hips. Size is only one parameter in wear particle bioreactivity. Other factors include particle shape, surface area, and possibly size/shape variability, as well as surface chemistry and particle concentration. Polyethylene wear particles are not unidimensional; they have complex and variable shapes. The combination of morphologic description and quantitative image analysis used in this study defines several differences in polyethylene wear particles from different sources.

Adult↗

PubMed1998

Polyethylene failure in New Jersey low-contact stress total knee arthroplasty.

From January 1985 to December 1990, 598 consecutive New Jersey low-contact stress (LCS) total knee arthroplasties (TKAs) were performed for gonarthrosis. Among these 598 operations, 322 were with rotating platform elements and 276 were with meniscal bearing elements. During 5 to 8 years of follow-up, eight knees had severe symptomatic polyethylene failure that required revision surgery; all eight cases were meniscal bearing types. The failed polyethylene inserts were retrieved and studied. It was observed that there were four probable failure mechanisms associated with the catastrophic polyethylene wear. First, insufficient thickness of the meniscal bearing was the major reason for wear. Second, the malpositioning of the metal tibial tray in the transverse plane resulted in the breaking of the meniscal bearing. Third, the inability of the patellar to rotate due to tissue ingrowth made the polyethylene break. Last, yellowing of the subsurface of the meniscal bearing was a sign of polyethylene failure. These four possible failure mechanisms are all associated with the design of the meniscal bearing type of LCS knee prostheses. Therefore, it is suggested that the design of the LCS knee prosthesis should be modified.

Aged↗

PubMed1998

Macrophage phagocytosis of polyethylene particulate in vitro.

In this study, an in vitro model has been developed to examine the interactions of macrophages with ultrahigh molecular-weight polyethylene (UHMWPE) and high-density polyethylene (HDPE) particles. Polyethylene particles are the major constituent of the material debris formed as a result of orthopedic implant wear. However, the study of polyethylene particle interactions with cells has been limited. UHMWPE (18-20 microns) and HDPE (4-10 microns) were suspended in soluble collagen type I and subsequently solidified on glass coverslips. The particle chemistry was characterized by Fourier transform infra-red spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Mouse cell line macrophages (IC-21) were established on the collagen-particle substrata and maintained for up to 24 h. The response of the cells to the particles was examined by light and transmission electron microscopy (LM and TEM), as well as by scanning electron microscopy (SEM), and compared to cells on control collagen surfaces without particles. Histological analysis of the samples revealed that the macrophages surrounded larger particles (18-20 microns) and the cells appeared to be attached to the surface of the particles, and the smaller particles (4-10 microns) had been phagocytosed within 2 h. Inflammatory cytokines (TNF-alpha, IL-1 alpha, IL-1 beta, and IL-6), lysosomal enzymes (beta-galactosidase and hexosaminidase), and prostaglandin E2 were released into the medium, and IL-1 alpha, IL-1 beta, PGE2, beta-galactosidase, and hexosaminidase levels were significantly increased over collagen control values. The results demonstrate active phagochemotaxis by macrophages for wear particulates and validate this model as a means of studying the specific in vitro interactions of polyethylene with cells.

Animals↗

PubMed2000

Effect of size and dose on bone resorption activity of macrophages by in vitro clinically relevant ultra high molecular weight polyethylene particles.

Polyethylene wear debris generated at the bearing surfaces of total artificial hip joints is thought to play an important role in the periprosthetic osteolysis and ultimately the aseptic loosening of these prostheses. The macrophage is believed to be central to this process by releasing various cytokines and other mediators of osteolysis upon phagocytosis of the polyethylene wear debris. This study evaluated the in vitro bone resorption response of C3H murine peritoneal macrophages to clinically relevant GUR 1120 polyethylene particles. Macrophages were co-cultured in vitro with GUR 1120 particles with a mean size of 0.24, 0.45, 1.71, and 7.62, and GUR 1120 polyethylene resin with a mean size of 88 microm at various particle volume (microm)(3): macrophage ratios (0.1:1; 1:1; 10:1; and 100:1). The conditioned supernatants were incubated with (45)calcium radio-labeled mouse calvariae, and bone resorption was measured as (45)calcium release. The results showed that the 0.24 microm particles stimulated the macrophages to generate bone resorbing activity at a ratio of 10(microm)(3) per macrophage. The 0.45 and 1.71 microm particles were active at a ratio of 100( microm)(3) per macrophage, and the 7.62 and 88 microm particles were inactive at all the doses tested. The co-culture supernatants were also assayed for TNF-alpha, IL-1beta, IL-6, and PGE(2). The results followed the same trend for particle size and volume dose to that observed for the bone resorbing activity. This study has demonstrated, for the first time, the importance of size and dose of clinically relevant polyethylene particles on the osteolytic response of macrophages in vitro.

Animals↗

PubMed2001

Osteoclast induction from bone marrow cells is due to pro-inflammatory mediators from macrophages exposed to polyethylene particles: a possible mechanism of osteolysis in failed THA.

Polyethylene debris from joint replacements may be transported in synovial fluid and be phagocytosed by macrophages. The activation and migration of macrophages may play important roles in osteolysis and implant loosening. Tissues from the bone-implant interface do not always contain wear debris, which may mean that osteolysis may not require direct contact with wear debris. We hypothesized that the release of polyethylene debris from the implants induces macrophage activation in the joint space. Then the activated macrophages release humoral factors, such as inflammatory cytokines, into the joint fluid. These cytokines may be transported to the bone marrow tissues around the implants where they stimulate the differentiation of the bone marrow cells into osteoclasts. Finally, the activated osteoclasts resorb the surrounding bone. To test this hypothesis, macrophages were stimulated by polyethylene particles. The levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were determined by enzyme-linked immunosorbent assay and were increased significantly. To test humoral interaction between macrophages and bone-marrow cells, a co-culture system was used in an in vitro model. With this system, two kinds of cells can be cultured together with humoral contact without the two cell types having to contact each other. We stimulated the macrophages with 5 microm of polyethylene particles and observed whether the bone marrow cells differentiated into the osteoclasts without contact with the macrophages. The numbers of osteoclasts were assessed using tartrate-resistant acid phosphatase (TRAP) staining. The numbers of TRAP-positive cells in the polyethylene particle-stimulated group were higher than in the control group. The ability of the TRAP-positive cells to resorb bone was confirmed by dentine pit formation assay. The results of this study support our hypothesis and suggest that one mechanism of osteolysis in failed joint arthroplasty is the more distant effects of pro-inflammatory cytokine release on osteoclast differentiation and/or activity.

Acid Phosphatase↗

PubMed1997

Tolerance and efficacy of polyethylene glycol 3350/electrolyte solution versus lactulose in relieving opiate induced constipation: a double-blinded placebo-controlled trial.

Chronicity and high therapeutic cost prompted this study to determine a cost-effective and efficacious regimen in treating narcotic-induced constipation. The efficacy of lactulose was compared with polyethylene glycol 3350/electrolyte solution for relief of methadone-induced constipation. This was a randomized, triple cross-over after control run-in (no treatment) study conducted at a methadone maintenance program in Baltimore, Maryland in 57 patients who are affected by opiate-induced constipation. The study was measured by self-reported frequencies, consistency, and ease of defecation during a 1 week run-in control period, followed by 3 treatment phases of 2 weeks each. Polyethylene glycol 3350/electrolyte solution and lactulose produced more "nonhard" stools than the placebo (P < 0.01) and control (P < 0.003). Polyethylene glycol 3350/electrolyte solution produced the loosest stool (P < 0.0001) compared with the control, whereas lactulose had the most adverse effects. There were no significant differences in reducing hard stool formation in either experimental group, but both were better than having nothing or just the placebo. Polyethylene glycol/electrolyte solution resulted in the loosest (diarrheal) stool. It is also likely that polyethylene glycol/electrolyte solution is the most cost effective.

Adult↗

PubMed1995

Migration of polyethylene wear debris in hip arthroplasties: a canine model.

The distal migration of polyethylene wear debris appears to be a major cause of loosening and osteolysis of cementless total hip arthroplasties. The use of modern cementing techniques, circumferential porous or hydroxyapatite (HA) coating has been advocated as a means of preventing access of the particles to the bone-implant interface. The purpose of this study was to compare the ability of different methods of implant fixation to prevent wear debris migration. Three each of smooth, porous-coated, HA-coated, and cemented hemiarthroplasties were implanted in the right hip of 12 dogs. Polyethylene particles were injected into the hip once a month for 4 months and then the femurs were sectioned. The percentage bone ingrowth was 8% for the smooth, 38% for the porous, and 83% for the HA-coated sections. Infiltration of the interface membrane by histiocytes containing polyethylene particles, and endosteal scalloping or osteolysis were found on all sections of the smooth prostheses. No particles or osteolysis were found on any sections of the other three types of prostheses. Capsular and lymph node sections from all dogs revealed histiocytic infiltration with numerous polyethylene particles present. It is concluded that the use of cement, porous, or HA coating prevents or delays access of the polyethylene wear debris to the bone-implant interface. No one of these methods of fixation proved more advantageous in the 5-month limit of this study.

Animals↗

PubMed2002

Interaction of oxidation and crosslinking in gamma-irradiated ultrahigh molecular-weight polyethylene.

The interaction between oxidation and crosslinking in gamma-irradiated ultrahigh molecular-weight polyethylene with and without artificial aging was studied. The effect of the atmosphere during irradiation (air vs. low oxygen) occurred primarily within about 0.5 mm of the surface, that is, the depth to which oxygen had diffused when the polyethylene specimen was machined and when it was irradiated. Irradiation in the presence of oxygen induced oxidation instead of crosslinking, so that the level of crosslinking achieved was lower than that which normally would occur at the same dose in the absence of oxygen. Subsequent artificial aging reduced the gel content (crosslinking) and had a maximal effect on the surface and subsurface regions for the gamma-air and gamma-low oxygen polyethylenes, respectively. Thus the storage environments and durations prior to irradiation and prior to artificial aging must be taken into account when attempting to duplicate the oxidation-crosslinking profiles that occur with actual implants in clinical use. In addition, the oxidation mechanisms initiated by the artificial aging method used in this study (i.e., heating in air to 80 degrees C) initiated somewhat different oxidative reactions from those that occur during prolonged shelf life at room temperature or in vivo. In particular, the formation of a peak of oxidation below the free surface of the polyethylene is due to the combined effects of the distribution of residual free radicals and the diffusion gradient of the oxygen. The interactive relationship between oxidation and crosslinking characterized in the present study provides a fundamental basis for understanding the wear behavior of gamma-sterilized components in past clinical use. It also provides guidelines for the development of polyethylenes with improved resistance to oxidation and wear, with particular relevance to estimation of the amount of crosslinking need- ed to potentially eliminate the clinical problem of osteolysis.

Biocompatible Materials↗

PubMed2002

Wear of conventional and cross-linked ultra-high-molecular-weight polyethylene acetabular cups against polished and roughened CoCr femoral heads in a biaxial hip simulator.

The wear of acetabular cups made from conventional gamma-sterilized, and electron-beam cross-linked ultra-high-molecular-weight polyethylene was studied with a biaxial hip wear simulator. The femoral heads were either polished or roughened so that they represented the type of roughening and the value of surface roughness (R(a) = 0.14-0.18 micro m) observed in the roughest explanted femoral heads. The lubricant was diluted calf serum, and the test length 3 million cycles. The mean wear rate and standard deviation of conventional polyethylene cups against polished and against roughened heads was 11.6 +/- 0.07 and 64.4 +/- 10.1 mg per 1 million cycles, respectively. The latter value closely corresponds to that measured from explanted Charnley prostheses. Against polished heads, cross-linked polyethylene cups showed net weight gain, whereas against roughened heads, their mean wear rate was 2.4 +/- 0.3 mg per 1 million cycles. The mean equivalent circle diameters of polyethylene wear particles produced in the above four categories were: conventional/roughened 0.32 micro m, cross-linked/roughened 0.29 micro m, conventional/polished 0.28 micro m, cross-linked/polished 0.23 micro m. The size ranges and shapes were close to those seen in particles isolated from tissue samples. In conclusion, the tests indicated that electron-beam irradiation effectively reduces the harmful polyethylene wear particle production in total hip arthroplasty.

Biocompatible Materials↗

PubMed1990

The histological effects of the implantation of different sizes of polyethylene particles in the rabbit tibia.

This study examines the histological effects of different sizes of polyethylene particles implanted into the rabbit tibia. Seventeen mature New Zealand white female rabbits were allocated into three groups. Group 1 (5 rabbits) received polyethylene particles averaging approximately 16 microns in diameter, implanted into the right proximal tibia through a drill hole. Group 2 (5 animals) received particles averaging 26 microns, and Group 3 (7 rabbits) received particles averaging 67 microns. The left tibia was drilled but not implanted. Animals were sacrificed after 16 weeks. Histological analysis disclosed decreased hematopoietic activity within the left tibial drill hole. In all groups, the right tibia demonstrated positively birefringent polyethylene particles surrounded by, and within (smaller particles), histiocytes and giant cells in a fibrous tissue stroma. Statistical analysis disclosed more fibrocytes and less marrow cells at the interface of Group 3 (largest particles) compared to Group 1 and 2. Larger polyethylene particles, being less readily phagocytosed, appear to produce more fibrous encapsulation, compared to particles of a smaller size. The histological reaction stimulated by the different sizes of polyethylene particles resembled the membrane surrounding loose joint arthroplasties in humans.

Animals↗

PubMed2003

Bonding strength of the apatite layer formed on glass-ceramic apatite-wollastonite-polyethylene composites.

Bioactive glass-ceramic apatite-wollastonite (A-W) has been incorporated into polyethylene in particulate form to create new bioactive composites for potential maxillofacial applications. The effects of varying the volume fraction of glass-ceramic A-W filler and the glass-ceramic A-W particle size were investigated by measuring the bonding strength of the bonelike apatite layer formed on the surface of glass-ceramic A-W-polyethylene composites. The bonding strength was evaluated via a modified ASTM C-333 standard in which a tensile stress was applied to the substrate and the strength of the bioactive layer was compared with that formed on commercially available hydroxyapatite-polyethylene composite samples, HAPEX. The composites demonstrated greater bonding strength with increased filler content and reduced filler particle size (maximum 6.9 +/- 0.5 MPa) and a marginally greater bonding strength as compared with HAPEX (2.8 +/- 0.5 MPa), when glass-ceramic A-W-polyethylene composite samples with the same filler content were tested. The higher bonding strength of the apatite layer formed on the A-W-polyethylene composite samples suggests that, in addition to maxillofacial applications, these composites might also be utilized in applications involving higher levels of load bearing.

Adhesiveness↗

PubMed1996

Technique for generating submicrometer ultra high molecular weight polyethylene particles.

Ultra high molecular weight polyethylene wear debris is believed to have a major role in aseptic loosening of prosthetic joints. In order to study the cellular and host response to this and other such particulate debris, a source of fine ultra high molecular weight polyethylene debris is needed. We have described a technique to fracture the GUR 4150 primary ultra high molecular weight polyethylene grain, which reproducibly generated particles less than 1 micron in size. Furthermore, the particle morphology was similar to that of ultra high molecular weight polyethylene particles generated in vivo and retrieved from interfacial tissues. The fabricated polyethylene particles ranged from 0.1 to 33 microns in diameter, with a mean of 2.3 +/- 0.2 micron. Sixty percent of the particles were smaller than 1 micron and 90% were smaller than 7 microns. Using filtration and sedimentation, it is possible to acquire finer particle fractions. These particles are currently being used for biological response studies.

Microscopy, Electron, Scanning↗

PubMed1998

Residual stresses in ultra-high molecular weight polyethylene loaded cyclically by a rigid moving indenter in nonconforming geometries.

The characterization of stress and deformation fields that incorporate moving cyclic loads and nonlinear material response in ultra-high molecular weight polyethylene components for total knee replacements is required to quantify mechanisms of surface damage. A simulation of stresses in polyethylene components for total knee replacement subjected to cyclic moving loads was performed with use of nonlinear finite element analysis. Convergence to a steady-state cycle of stress and deformation was observed within five cycles of loading. Differential plastic deformation under the surface of the polyethylene led to horizontal residual stresses that were tensile at the surface and compressive in the subsurface. The magnitudes of the residual stresses indicate their importance in surface failure mechanisms. Horizontal residual tensile stresses at the surface are consistent with the initiation and propagation of surface cracks that could cause pitting in polyethylene. Horizontal residual compressive stresses under the surface could cause such cracks to arrest or turn and thus limit damage to a region just beneath the surface. The results emphasize the importance of incorporating nonlinear effects to simulate long-term stress fields associated with surface damage in polyethylene.

Arthroplasty, Replacement, Knee↗

PubMed1999

Ultrahigh molecular weight polyethylene particles have direct effects on proliferation, differentiation, and local factor production of MG63 osteoblast-like cells.

Small particles of ultrahigh molecular weight polyethylene stimulate formation of foreign-body granulomas and bone resorption. Bone formation may also be affected by wear debris. To determine if wear debris directly affects osteoblasts, we characterized a commercial preparation of ultrahigh molecular weight polyethylene (GUR4150) particles and examined their effect on MG63 osteoblast-like cells. In aliquots of the culture medium containing ultrahigh molecular weight polyethylene, 79% of the particles were less than 1 microm in diameter, indicating that the cells were exposed to particles of less than 1 microm. MG63 cell response to the particles was measured by assaying cell number, [3H]thymidine incorporation, alkaline phosphatase specific activity, osteocalcin production, [35S]sulfate incorporation, and production of prostaglandin E2 and transforming growth factor-beta. Cell number and [3H]thymidine incorporation were increased in a dose-dependent manner. Alkaline phosphatase specific activity, a marker of cell differentiation for the cultures, was significantly decreased, but osteocalcin production was not affected. [35S]sulfate incorporation, a measure of extracellular matrix production, was reduced. Prostaglandin E2 release was increased, but transforming growth factor-beta production was decreased in a dose-dependent manner. This shows that ultrahigh molecular weight polyethylene particles affect MG63 proliferation, differentiation, extracellular matrix synthesis, and local factor production. These effects were direct and dose dependent. The findings suggest that ultrahigh molecular weight polyethylene wear debris particles with an average size of approximately 1 microm may inhibit bone formation by inhibiting cell differentiation and reducing transforming growth factor-beta production and matrix synthesis. In addition, increases in prostaglandin E2 production may not only affect osteoblasts by an autocrine pathway but may also stimulate the proliferation and activation of cells in the monocytic lineage. These changes favor decreased bone formation and increased bone resorption as occur in osteolysis.

Alkaline Phosphatase↗

PubMed1980

Comparison of polyethylene glycol and polyoxyethylene stearate as excipients for solid dispersion systems of griseofulvin and tolbutamide II: dissolution and solubility studies.

The effects of joining a long-chain ester group with the polyethylene glycol molecule were studied in solid dispersion systems by comparing the dissolution and solution properties of such systems prepared from polyethylene glycol 2000 with those prepared from the nontoxic, water-soluble, solid excipient polyoxyethylene 40 stearate. Solid dispersion systems of griseofulvin and tolbutamide were prepared by physical mixing, fusion, or coprecipitation from ethanol. The compacted dispersion systems dissolved by progressive erosion, releasing floccules of microcrystals. The released microcrystals of tolbutamide (3--10 micrometer) were smaller than the original drug particles (approximately 20 micrometer), but those of griseofulvin were of similar size to the original particles. In general, the rate of and extent of release of each drug were greater from polyoxyethylene 40 stearate than from polyethylene glycol 2000 dispersions. The aqueous solubility and dissolution rate of nondisintegrating disks of each pure drug increased only slightly in the presence of polyethylene glycol 2000 but increased considerably with increasing concentration of polyoxyethylene 40 stearate due to micellar solubilization. Thus, polyoxyethylene 40 stearate generally is superior to polyethylene glycol 2000 in promoting the dispersion of the drugs in solids, disintegration of the compacted solids, and solubilization of the drug during dissolution.

Chemical Precipitation↗

PubMed1990

Comparison of clonazepam sorption to polyvinyl chloride-coated and polyethylene-coated tubings.

The sorption of clonazepam to polyvinyl chloride tubing, polyethylene-coated tubing and to a polyethylene syringe was determined. Pumping of clonazepam (5 mg/48 ml) through the polyvinyl chloride tubing with flow rates of 2 ml/h and 4 ml/h resulted in a reduction of the clonazepam concentration to about 40% and 55% of the original strength after 0.6 h, respectively. This value was 55% at a flow rate of 2 ml/h and a clonazepam concentration of 10 mg/48 ml. The effluent clonazepam concentration increased gradually after an infusion period of 1 h. Sorption of clonazepam to the polyethylene syringe and to the tubing coated on the inside with polyethylene does not occur. The use of polyethylene-coated administration sets is recommended for intravenous administration of clonazepam.

Adsorption↗

PubMed2000

Oral sodium phosphate solution is a superior colonoscopy preparation to polyethylene glycol with bisacodyl.

PURPOSE: The aim of this study was to compare the efficacy and patient tolerance of two bowel preparations for colonoscopy. METHODS: Three hundred twenty-three consecutive patients undergoing colonoscopy were randomly assigned to receive either oral sodium phosphate, or 2 liters of polyethylene glycol solution preceded by the stimulant laxative bisacodyl. Patients were asked to record the effects of the preparation, noting any vomiting, nausea, or abdominal pain, and to determine a discomfort rating on a scale of 1 to 5. One hundred sixty-nine patients were assigned to the oral sodium phosphate solution, and 154 to polyethylene glycol with bisacodyl. Surgeons were blinded to the preparation used and rated the quality of the bowel preparation on a scale of 1 to 5. RESULTS: Ninety-nine percent of patients in the sodium phosphate group drank all of the solution as opposed to 91 percent of patients in the polyethylene glycol with bisacodyl group. Patients in the sodium phosphate group reported significantly less discomfort (P = 0.002). No significant difference was reported for vomiting, nausea, or abdominal pain associated with the preparations. The quality of bowel cleansing was considered by the colonoscopists significantly better for the sodium phosphate group than the polyethylene glycol with bisacodyl group (P < 0.000001). CONCLUSIONS: Colonoscopy preparation with sodium phosphate solution is better tolerated and more effective than polyethylene glycol with bisacodyl.

Administration, Oral↗

PubMedDate not supplied

MR rectography evaluation of rectoceles with oral gadopentetate dimeglumine and polyethylene glycol solution.

BACKGROUND: We assessed the value of magnetic resonance (MR) rectography in diagnosing rectocele by using a combination of oral gadopentetate dimeglumine and polyethylene glycol solutions. METHODS: T1-weighted, breath-hold, fast low-angle shot sequences were made in 22 patients in resting and straining states in the supine position before and after administration of oral paramagnetic contrast. Twelve patients received polyethylene glycol solution in addition to contrast, and 10 received contrast only. The pubococcygeal line was the reference used for diagnostic measurements. The quality of each sequence was graded. Paired t test, chi-square test, and the Kolmogorov-Smirnov test were applied for statistical analysis. RESULTS: The results of noncontrast images were inconclusive. There was a statistically significant difference between MR imaging diagnosis of rectocele in patients in the straining position without and with contrast ( p < 0.05), and the difference was more prominent in patients using polyethylene glycol solution ( p < 0.001). Using oral contrast plus polyethylene glycol produced significantly better MR examinations in the resting and straining positions ( p < 0.05). CONCLUSION: The combination of oral contrast and polyethylene glycol solution improves the diagnostic value of MR rectography and is particularly useful when noncontrast examinations are inconclusive.

Administration, Oral↗