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PubMed1995

Polyethylene particles stimulate monocyte chemotactic and activating factor production in synovial mononuclear cells in vivo. An immunohistochemical study in rabbits.

We report that polyethylene particles can activate mononuclear cells within the joint to produce the monocyte chemotactic and activating factor (MCAF) and to a lesser degree interleukin 8 (IL-8) as judged by immunohistological staining. Polyethylene particles suspended in hyaluronic acid were injected weekly for 12 weeks into the right knee joint of New Zealand white rabbits. The average size of the particles was 7 (3-12) microns in diameter. The left knee joint was injected with hyaluronic acid as the control. The animals were killed after 13 weeks. On the control side, the synovial membrane was histologically normal, without signs of inflammation. In the knees that were injected with polyethylene particles, histological analysis showed a weak inflammatory response, consisting of mononuclear cells, multi-nucleated giant cells and polyethylene particles. In the vicinity of the particles, the presence of mononuclear cells that were highly positive for MCAF was noted, whereas IL-8 was present in endothelial cells and in the lining layer, but not in cells in the vicinity of polyethylene particles, suggesting that polyethylene particles are able to activate cytokine metabolism in a differentiated way in the synovial monocytes.

Animals↗

PubMed1997

[Polyethylene wear in periprosthetic tissue of failed cemented total hip arthroplasties].

To elucidate the relationship between polyethylene wear and loosening of total hip arthroplasty, we observed grossly the periprosthetic tissues, polyethylene wear debris and polyethylene acetabular liners retrieved from 6 failed cemented total hip arthroplasties during revisions by means of polar light miscroscope and scanning electron microscope. The production mechanism of polyethylene wear debris from acetabular liner was analyzed together with its role in periprosthetic fibrosis and prosthetic loosening. Results showed the abrasion of two bearing surfaces interposed with third-body particles as called three-body abrasion was the main model of polyethylene wear. All inner surfaces of the liners appeared clear abrasive scratches and big flat debris were found in most of the retrieved tissues. Histologically, the wear debris of various sizes embraced by 1 or several polynuclear giant cells that were found not only great in number but also active in function. The implication is that three body abrasion is the key factor of high rate wear of the polyethylene liner and that polynuclear giant cell is acting as an important cellular component leading to the prosthetic loosening.

Arthroplasty, Replacement, Hip↗

PubMed2005

Conventional ultra-high molecular weight polyethylene: a gold standard of sorts.

Data from a series of four recent studies showed that conventional polyethylene liners sterilized by gamma irradiation in air and coupled with second-generation acetabular components outperformed first-generation components with consistent average wear behavior below 0.1 mm/yr. It was found that liners sterilized by gamma irradiation in air outperformed liners sterilized by gas plasma, indicating that cross-linking induced by gamma irradiation sterilization, even if the component is radiated in an oxygen environment, is essential for keeping wear rates low. No negative clinical effects were found on wear for conventional polyethylene sterilized by gamma irradiation in air with a shelf life up to 3 years (r2 = 0.04, P = 0.60). Finally, 16-year temporal wear patterns for gamma irradiation in air sterilized components demonstrated no significant changes in wear rates over time, indicating that gamma irradiation sterilized liners with short shelf lives will not likely experience late increases in wear because of continued in vivo oxidation of the polyethylene. From these studies it was determined that standardized radiographic methods, optimal radiographs, serial measurements, and minimum 4-year follow-up are essential for reliable wear data. More specifically, it was concluded that a conventional ultra-high molecular weight polyethylene liner gamma irradiation sterilized in air with a shelf life less than 3 years, coupled with a second-generation cup, performs well in vivo and is unlikely to experience late increases in wear. Because no comparable in vivo data will be available for new cross-linked polyethylene materials for several years, conventional gamma irradiated polyethylene can be considered the industry's current gold standard for wear performance comparisons.

Hip Prosthesis↗

PubMed2005

Polyethylene fiber-reinforced composite inlay fixed partial dentures: two-year preliminary results.

PURPOSE: Polyethylene fiber-reinforced composite inlay fixed partial dentures (FPDs) have been under development for some time. There is a lack of data on the clinical performance of such prostheses. This prospective clinical study evaluated the clinical performance of polyethylene fiber-reinforced composite FPDs over two years. MATERIALS AND METHODS: Twenty-eight polyethylene fiber-reinforced composite inlay FPDs were fabricated for 19 patients. The treatment plan included removal of the existing restorations, placement of an ultrahigh molecular weight polyethylene (UHMWP) fiber ribbon, and final restoration with a light-curing hybrid resin. The 28 polyethylene fiber-reinforced composite inlay FPDs were examined clinically after 2 years. RESULTS: All 28 FPDs were intact at the 2-year examination. There were no signs of fracture, debonding, or discoloration. CONCLUSION: Based on the results of this descriptive study, the polyethylene fiber-reinforced composite inlay FPDs were considered clinically successful at the 2-year examination.

Adult↗

PubMed1991

Aseptic loosening in total hip implants: the role of polyethylene wear debris.

Radiologic and routine histologic examinations, transmission electron microscopy and scanning electron microscopy were carried out on membranes retrieved from the following hip implant prostheses: loose cemented metal-on-polyethylene, resorptive cysts around fixed cemented metal-on-polyethylene, cemented without polyethylene (Thompson), noncemented without polyethylene (Moore), loose ceramic-on-ceramic and loose noncemented metal-on-polyethylene. From histologic analysis the most common factor in the membranes reviewed, in terms of production of multinucleated giant cells, is the presence of polyethylene wear debris. Neither loosening of the implant nor the presence or absence of bone cement produces such cells within the membrane.

Acetabulum↗

PubMed1991

All-polyethylene patellar components are not the answer.

Recent reports of the high incidence of polyethylene failure of metal-backed patellar components have rekindled the interest in cemented, all-polyethylene designs. One hundred four retrieved patellar components of metal-backed and all-polyethylene designs were analyzed for wear. Additionally, patellofemoral contact stress as a function of flexion angle was measured for unused components using pressure-sensitive Fuji film. Significant wear (2+ on a 0-3 scale) was seen in 65% of metal-backed designs and in 78% of all-polyethylene components. Severe wear (3) was seen in 44% of all-polyethylene components and in 39% of metal-backed devices. The incidence of severe wear (3) of congruent designs was statistically significantly lower than that of the noncongruent designs. Contact stress analysis confirmed that dome-type geometries typically resulted in stresses that exceed the yield strength of the polyethylene, whereas the more congruent geometries generated significantly reduced stress levels.

Biomechanical Phenomena↗

PubMed1980

Influence of polyethylene glycols on the kinetics of rat liver phosphofructokinase.

The influence of polyethylene glycols on the kinetics of purified rat liver phosphofructokinase was examined because polyethylene glycol often has an associative influence on proteins without specifically interacting with them. Polyethylene glycol was found to prevent or slow the spontaneous inactivation, due to subunit dissociation, of rat liver phosphofructokinase which occurs at low protein concentration (10 microgram/ml) in an isotonic, pH 7 buffer in the absence of substrates. This protection is favored by increasing size and concentration of polyethylene glycol. Inclusion of polyethylene glycol in kinetic assays of rat liver phosphofructokinase had little effect on maximal velocity determined under optimal conditions at pH 8. However, the Km value for fructose 6-phosphate measured at pH 7 and 3 mM MgATP was dramatically lowered with increasing polyethylene glycol concentration. The results support the proposal that more aggregated forms of rat liver phosphofructokinase have a decreased Km value for fructose 6-phosphate when assayed with inhibiting concentrations of MgATP.

Animals↗

PubMed1983

Failure of polyethylene acetabular cups. Two case reports.

Fatigue fracture involving the metallic femoral stem is well recognized after total hip arthroplasty. Two cases of Charnley-Mueller polyethylene acetabular cup failure, in a 54-year-old-woman and a 77-year-old woman with abnormal wear patterns, were diagnosed prior to operation. The fracture of the acetabular cup was recognized by the fragmented, crushed appearance of the cup. The arthrogram clearly showed the radiographic contrast agent passing through the substance of the cup. The wear of the cups was measured by micrometer calipers which have an accuracy of 0.001 mm. The polyethylene acetabular cup was analyzed in four zones formed by three circumferential grooves. Markedly increased wear of the components occurred in the superolateral dome area. This wear rate was as high as 0.8 mm/year, which is four times the average wear of 0.2 mm/year. This marked wear associated with repetitive cyclic fatigue or static load resulted in fracture of the polyethylene acetabular cup. Improper machining of the cup using low- rather than high-density polyethylene in the manufacturing process and the heavy weight of these patients may have been factors in the marked fissures and crack lines revealed by microscopic study of the fractured area after sputter coating with gold palladium. Fracture of the polyethylene acetabular component, although rare, may be encountered more often in longer follow-up studies of patients who have undergone total hip arthroplasty. Proper selection of patients, acetabular spacers, and pressure injection techniques may prevent early loosening of the acetabular polyethylene components.

Aged↗

PubMed1995

The susceptibility of smooth implant surfaces to periimplant fibrosis and migration of polyethylene wear debris.

The purpose of this investigation was to establish whether the tissue response and migration of polyethylene debris differed at noncemented smooth and porous implant surfaces. This was accomplished through 3 separate but closely related studies: (1) a canine cylindrical implant model with smooth and porous surfaces exposed to polyethylene debris; (2) a canine total hip arthroplasty model analyzing the interface between bone and femoral implants with various porous-coating configurations; and (3) a histologic analysis of autopsy-retrieved, human, noncemented hip prostheses with noncircumferential porous coating. The cylindrical implant model involved the placement of split cylinders, 1/2 porous and 1/2 smooth, into the distal femur and proximal tibia of 4 dogs. Four control implants and 10 test implants (chronically exposed to simulated polyethylene debris with a mean size of 4.7 microns) were examined histologically as long as 30 weeks after surgery. The canine hip study involved the study of 54 noncemented hip prostheses at periods of 1, 6, and 24 months. The prostheses possessed 4 different porous surface configurations: 1 with circumferential porous coating, 2 with noncircumferential coating, and 1 without porous coating. The human retrieval analysis involved the study of 7 cadaveric femora (age, 6 months-5 years) implanted with a straight titanium-alloy prosthesis possessing proximal pads of titanium fiber metal on the anterior, posterior, and medial aspects. With all implants in all 3 studies, there was the common finding of bone ingrowth at the porous implant surface and a fibrous interface or periprosthetic cavity around the portion of the implant that was smooth surfaced. The periprosthetic cavity typically was encapsulated by a thin continuous shell of trabecular bone. In addition, polyethylene debris was found to have preferentially migrated along the smooth implant surfaces. In the longer-term canine and human hip retrievals, polyethylene particles in the micron size range were present within histiocytes, whereas larger particles as much as 100 microns were found within foreign-body giant cells. Of importance for the implants from all 3 studies, with the exception of some pronounced cavities on the lateral aspect of the human hip prostheses, the periimplant cavities around the smooth surfaces were not detectable radiographically. This study clearly established a fundamental principle of relative barriers to particulate debris migration. Smooth implant surfaces are more susceptible than porous surfaces to the development of a fibrous tissue filled periimplant cavity and the subsequent migration of polyethylene wear debris.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1994

Wear patterns on retrieved polyethylene tibial inserts and their relationship to technical considerations during total knee arthroplasty.

Fifty-five unconstrained polyethylene tibial inserts were retrieved at revision total knee arthroplasty and examined for evidence of wear after a mean implantation time of 34.2 months (2.5-80 months). Twenty inserts were ultra-high molecular weight polyethylene (UHMWPE) and 35 were carbon-reinforced polyethylene. Topographic maps of the articular and metal-backed surfaces of each component were constructed to characterize the extent and location of polyethylene degradation, identified visually by mode. In 32 of the retrieved inserts, pre- and postarthroplasty or prerevision radiographs were analyzed for component positioning, sizing, and extremity alignment. These factors then were compared with the patterns and severity of polyethylene wear on the inserts to establish correlations. Severe generalized articular wear was seen in inserts with third body wear from patellar metal-backed failure and cement debris. Severe localized delamination wear was seen in inserts with rotational-subluxation patterns of wear (p = 0.05). The external rotation subluxation wear pattern was strongly associated with knees that had lateral subluxation of the patella (p = 0.0002). Articular wear and cold flow into screw holes tended to be greater in the tightest prearthroplasty compartment (medial in the varus knee [p = 0.0157]; lateral in the valgus knees [p = 0.0226]). Fourteen of 16 knees with a preoperative varus deformities--even when corrected to a normal postarthroplasty anatomic axis--still had greater medial compartment articular wear (p = 0.001). Twelve of these knees did not have a medial release at the time of initial arthroplasty. Preoperative varus also was found to be related to the occurrence of posteromedial cold flow of polyethylene into tibial tray screw holes (p = 0.007). Increasing tibial insert posterior slope was associated with increasingly posterior articular wear track location (p = 0.03). This study indicates that unconstrained tibial component wear patterns and severity may be associated with clinical and mechanical factors under the surgeon's control, including component size and position, and knee alignment and ligament balance.

Adult↗

PubMed1994

Progressive subluxation and polyethylene wear in total knee replacements with flat articular surfaces.

One hundred eighty-six Microloc tricompartmental, cruciate-sparing, primary total knee replacements in 136 patients were performed between 1983 and 1987. Femoral components were made of cobalt-chrome-molybdenum alloy. The tibial component baseplates were made of titanium-aluminum-vanadium alloy. The baseplates were made with three small porous-coated pegs for fixation with or without cement, or with a central stem for fixation with cement. The polyethylene was affixed to the baseplate by a mechanical locking mechanism that was nonmodular. The articular surfaces of both components were flat mediolaterally and anteroposteriorly. The patellar components were dome shaped and metal backed with titanium-aluminum alloy. Seventy-three percent of the femoral components, 26% of the tibial components, and 48% of the patellar components were inserted without bone cement. The average time to maximum follow-up examination was 6.1 years (range, four to nine years). Of implants that had not been revised, 84.4% had good or excellent results (using the Hospital for Special Surgery scoring system) at final follow-up examination. The average range of motion of functioning implants at final follow-up examination was 108 degrees. Revisions for failure only of the metal-backed patellar component were performed in 22 knees (11.8%). Forty knees (21.5%) required revision for failure of the femoral-tibial articulation. Reasons for failure in this group included: polyethylene wear (57.5%); loosening (15.0%); tibial tray fracture (10.0%); sepsis (12.5%); and dislocation or ligament laxity (5.0%). An additional 15 functioning knees (8.1%) have radiographic evidence of progressive femoral-tibial subluxation. Future failure of these devices is considered likely. Polyethylene wear requiring revision was not statistically associated with patient age, gender, preoperative diagnosis, height, weight, or component size. Polyethylene failure leading to revision was related to the radiographic appearance of femoral-tibial component subluxation. This subluxation was most likely to occur after five years of component implantation. The development of progressive femoral-tibial subluxation was statistically associated with postoperative extremity malalignment, excessive varus positioning of the tibial component, bone grafting of the tibial plateau, the use of the small-pegged tibial component, and the use of this component without cement. Polyethylene wear associated with progressive femoral-tibial subluxation occurred at the periphery of the tibial plateau and along the raised portion of the tibial spine. The metal baseplate at the edge of the plateau was frequently exposed and worn. Bone lysis associated with the presence of polyethylene, metal, and cement debris was frequently observed.

Adult↗

PubMed1993

Biocompatibility of polyethylene and host response to loosening of cementless total hip replacement.

A human lymphocyte culture protocol was used to identify the biocompatibility pattern of fine particulate ultra-high molecular weight polyethylene. Polyethylene did not cause an increase in lymphocyte DNA synthesis as assessed by the 3H-thymidine incorporation method on culture Days 1, 3, nor 5. As analyzed with monoclonal activation markers, the polyethylene dependent expression of major histocompatibility complex (MHC) class II antigen as well as interleukin-2 receptor (CD25) was virtually nonexistent. An apparent increase in the amount of CD11b positive monocytes/macrophages from 7% +/- 2% to 22% +/- 6% was recorded. Samples of pseudocapsules of the totally replaced hips (THR) obtained at revision operations for aseptic loosening of cementless prostheses with polyethylene lining of the acetabular component, were obtained from ten patients for immunopathologic studies. In seven cases the prostheses consisted of chromium-cobalt-molybdenum steel alloy and in three cases of titanium. Revisions were performed on average 4.6 years (range, 2.5-7) after insertion of the prostheses. The predominant cell in the lining cell layer of the periprosthetic cavity was in each case the CD11b, CD68, and nonspecific esterase positive but endogenous peroxidase-negative macrophage. Proline 4-hydroxylase positive fibroblasts dominated the stroma that was also inhabited by usually perivascular mononuclear cell infiltrations of mainly CD11b/CD68 phenotype with occasional CD4-positive cells. Only few mononuclear cells were activated CD25 positive T cells or CD19-positive B-lymphocytes. In titanium-based THRs, the cytoplasm of the macrophages contained a large number of small metallic particles, although this phenomenon was not seen in chromium-cobalt-molybdenum steel-based THRs. Fine particulate ultra-high molecular weight polyethylene is immunologically relatively insert. Nevertheless, it causes a clear foreign body type of phenomenon in vitro. The loosening of cementless acetabular components was associated with CD11b- and CD68-positive macrophage reaction in the pseudocapsular tissue. In any case, there is no clinical or experimental evidence to suggest that the use of cementless THR prostheses with polyethylene sockets would prevent an adverse biologic host response.

Adult↗

PubMed1996

Overview of polyethylene as a bearing material: comparison of sterilization methods.

Polyethylene has been used for more than 30 years as an orthopaedic bearing material; however, there has been recent concern regarding the early failure of a small percentage of the polyethylene bearings. The damage seen in some retrieved polyethylene components has been linked to gamma radiation sterilization in air, which was widely used by the industry for years. Gamma radiation in air has been documented to cause an increase in oxidation and degradation of mechanical properties with time. The degradation of polyethylene initiated by gamma sterilization in air has led the orthopaedic industry toward alternative sterilization methods, including gamma radiation in an inert gas or vacuum environment, ethylene oxide gas sterilization, and gas plasma sterilization. For many of these alternative techniques, little clinical performance data exist. This study is a comparative evaluation of sterilization methods using the same analytic techniques that have been used to document the effects of gamma sterilization in air on polyethylene. Fourier transform infrared spectroscopy, electron spin resonance, and uniaxial tensile testing are used to compare, respectively, the oxidation levels, free radical concentration, and mechanical properties of material sterilized by each method. The polyethylene is evaluated before sterilization, poststerilization, and postartificial aging. All examined alternative sterilization methods, when compared with gamma sterilization in air, caused less material degradation during a component's preimplantation shelf life.

Electron Spin Resonance Spectroscopy↗

PubMed1997

Tibial insert undersurface as a contributing source of polyethylene wear debris.

Sixty-seven ultrahigh molecular weight polyethylene tibial inserts from cementless total knee arthroplasties were retrieved at autopsy and revision surgery and analyzed for evidence of articular and nonarticular surface wear after a mean implantation time of 62.8 months (range, 4-131 months). Polyethylene cold flow and abrasive wear on the nonarticular insert surface (undersurface) were assigned a wear severity score (Grade 0-4). The severity of articular wear was assessed quantitatively and graded. Corresponding prerevision radiographs were evaluated for evidence of tibial metaphyseal osteolysis and osteolysis around tibial fixation screws. Exact nonparametric conditional inference methods were used to establish correlations between different variables and the occurrence of tibial metaphyseal osteolysis. Severe Grade 4 wear of the tibial insert undersurface was associated with tibial metaphyseal osteolysis or osteolysis around fixation screws. Time in situ statistically was related to Grade 4 undersurface wear and tibial metaphyseal osteolysis. The occurrence of tibial osteolysis was not related statistically to articular wear severity, insert thickness, or implant type. The main articulation between the femoral implant and ultrahigh molecular weight polyethylene insert has been assumed to be the primary source of polyethylene debris contributing to osteolysis and total knee arthroplasty implant failure. The undersurface of the insert is an additional source of polyethylene debris contributing to tibial metaphyseal osteolysis. To lessen polyethylene debris produced at this modular interface, the tibial implant locking mechanism should fix the insert firmly to the metal backing to decrease relative micromotion. Because motion between the insert and metal backing may be inevitable, the wear characteristics of the inner tray surface should be optimized to minimize wear debris production at this other articulation.

Arthroplasty, Replacement, Knee↗

PubMed1993

Evaluation of wear in an all-polymer total knee replacement. Part 1: laboratory testing of polyethylene on polyacetal bearing surfaces.

The friction and wear characteristics of a prototype, all-polymer hip prosthesis were evaluated using a multi-station hip-joint simulator. The components consisted of 41 mm diameter polyacetal copolymer balls in combination with acetabular cups of UHMW polyethylene, and were compared to the conventional combination of cobalt-chromium alloy balls against UHMW polyethylene cups. The all-polymer combination exhibited about 20% lower friction and 39% lower wear of the polyethylene cups. The total volume of polymer wear from the all-polymer combination (i.e. including the wear of the polyacetal ball) was 23% less than the volume of polyethylene wear from the metal-polymer components. The appearance of the worn surfaces of the polyethylene cups in the scanning electron microscope were similar for the two combinations of materials, and the surfaces of the polyacetal balls showed only mild wear. Formaldehyde, a product of the degradation of polyacetal, was present in traces in some samples of lubricant from the test chambers with polyacetal balls. In this laboratory model, the friction and wear properties of a polyacetal copolymer ball in combination with an UHMW polyethylene demonstrated good potential for clinical application.

Acetals↗

PubMed2006

[Microstructural characterization for pyrolysis hydrogenation fragments in polyethylene by pyrolysis hydrogenation gas chromatography/mass spectrometry].

The microstructural characterization of 47 samples, respectively of high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), copolymer of ethylene and alpha-olefins, was performed by pyrolysis hydrogenation gas chromatography/mass spectrometry (Py-H-GC/MS) with 10% Pt on 80-100 mesh Diasolid H as a hydrogenation catalyst. The samples were obtained from 12 domestic plants and 12 plants abroad as well. The sample sizes ranging from 30 to 80 microg were pyrolyzed at 770 degrees C in a flow of hydrogen carrier gas. It was found that short methyl branches as the characteristic isoalkanes of pyrolysis hydrogenation in polyethylene would be related closely to the different classes of polyethylene. The microstructural characterization has been carried out by means of Py-H-GC/MS, according to the relative amount of the four short methyl branches, 5-methyldodecane (5-MC12), 4-methyldodecane (4-MC12), 2-methyldodecane (2-MC12) and 3-methyldodecane (3-MC12) existed in C12-C13 isoalkanes. The Py-H-GC/MS technique will be providing further scientific evidences for the characterization of polyethylene plastics in forensic science.

English Abstract↗

PubMed1999

Senna vs polyethylene glycol for mechanical preparation the evening before elective colonic or rectal resection: a multicenter controlled trial. French Association for Surgical Research.

HYPOTHESIS: Senna is more efficient than polyethylene glycol as mechanical preparation before elective colorectal surgery. DESIGN: Prospective, randomized, single-blind study. SETTING: Multicenter study (18 centers). PATIENTS: Five hundred twenty-three consecutive patients with colonic or rectal carcinoma or sigmoid diverticular disease, undergoing elective colonic or rectal resection followed by immediate anastomosis. INTERVENTION: Two hundred sixty-two patients were randomly allotted to receive senna (1 package diluted in a glass of water) and 261 to receive polyethylene glycol (2 packages diluted in 2-3 L of water), administered the evening before surgery. All patients received 5% povidone iodine antiseptic enemas (2 L) the evening and the morning before surgery. Ceftriaxone sodium and metronidazole were given intravenously at anesthetic induction. MAIN OUTCOME MEASURES: Degree of colonic and rectal cleanliness. RESULTS: Colonic cleanliness was better (P=.006), fecal matter in the colonic lumen was less fluid (P=.001), and the risk for moderate or large intraoperative fecal soiling was lower (P=.11) with senna. Overall, clinical tolerance did not differ significantly between groups, but 20 patients receiving polyethylene glycol (vs 16 with senna) had to interrupt their preparation, and 15 patients (vs 8 with senna) complained of abdominal distension. Senna, however, was better tolerated (P = .03) in the presence of stenosis. There was no statistically significant difference found in the number of patients with postoperative infective complications (14.7% vs 17.7%) or anastomotic leakage (5.3% vs 5.7%) with senna and polyethylene glycol, respectively. CONCLUSION: Mechanical preparation before colonic or rectal resection with senna is better and easier than with polyethylene glycol and should be proposed in patients undergoing colonic or rectal resection, especially patients with stenosis.

Adult↗

PubMed1997

Analysis of polyethylene wear debris using micro-Raman spectroscopy: a report on the presence of beta-carotene.

This paper describes micro-Raman spectroscopy of ultra-high molecular weight polyethylene wear debris isolated from revised knee replacements. The novel application of micro-Raman spectroscopy to the analysis of in vivo-generated wear debris was used to evaluate the chemical nature of individual, retrieved polyethylene particles. The analysis revealed the presence of beta-carotene on particles from both synovial fluid and tissue samples. Raman analysis of retrieved polyethylene tibial inserts also revealed localized beta-carotene signals within the primary wear region. In this paper, a mechanism is suggested that may account for the coupling of beta-carotene and polyethylene wear debris. We also discuss the origin of beta-carotene within the implanted joint and the implications that beta-carotene, an anti-oxidant, has for the overall host response to polyethylene orthopedic components.

Adsorption↗