Polyethylene Wear Particles Research Articles

Thigh mass associated with polyethylene wear-induced osteolysis after cementless total hip arthroplasty

Polyethylene wear-induced osteolysis is a common complication of total hip arthroplasty. We report a case of a patient who had an extensile osteolytic lesion that presented as a tumor-like thigh mass associated with a polyethylene wear debris-induced granuloma 18 years after cementless total hip arthroplasty. The patient received a proximally porous-coated stem that had not fully circumferentially coated surface, and, therefore, polyethylene wear particles could be transported to the distal stem tip area by fluid pressure generated from the hip joint during activity. Biologic reaction to polyethylene wear particles had then produced the extensile osteolytic lesion extending to the extramedullary diaphysis of the femur that presented as a solitary thigh mass mimicking a soft tissue tumor. To the authors' knowledge, no case of a thigh mass and osteolytic femoral lesion associated with polyethylene wear after total hip arthroplasty has previously been reported.

Exploration of the size, shape and abundance of UHMWPE wear particles using atomic force microscopy

Atomic force microscopy is proposed and explored as a technique for the characterisation of ultra-high molecular weight polyethylene (UHMWPE) wear particles from knee prostheses. This new approach may be an alternative to other techniques such as filtration and scanning electron microscopy. Atomic force microscopy can measure the size and geometry of polyethylene wear particles extracted from the joint lubricant with a precision on the nanometre-scale. This can further the understanding of wear processes at this length-scale. However, information about the absolute and the fractionated abundances of the particles in the lubricant is lost, since the particles precipitate non-uniformly on substrates suitable for atomic force microscopy. It is demonstrated that conventional filtration of polyethylene particles can cause similar non-uniform precipitation on a filter medium. This result gives support to the view that uniformity across a substrate or filter medium needs to be established in detail and quantitatively using an appropriate experimental protocol so that abundance distributions may be obtained reliably.

The induction of a catabolic phenotype in human primary osteoblasts and osteocytes by polyethylene particles

Polyethylene (PE) wear particles are associated with the osteolysis seen in aseptic loosening that leads to orthopaedic implant failure. While cells of the monocyte/macrophage lineage are implicated, evidence is now emerging that osteoblastic cells may also be affected by PE. In this study we investigated the effect of PE particles on osteoblasts, using a novel in vitro cell culture system that was developed to juxtapose cells and PE particles, replicating the 3-dimensional (3D) environment near implants. This system allowed normal human bone-derived cells (NHBC) to undergo differentiation into a mature osteocyte-like phenotype over a 21–28-day culture period. PE particles induced an increase in mRNA expression of the osteocyte markers E11, DMP-1 and SOST/sclerostin. NHBC responded to PE particles by increasing the mRNA expression of several genes associated with osteoclast formation and activity (RANKL, IL-8 and M-CSF) and decreased the expression of the osteoclast antagonist, OPG. PE also appeared to induce a switch in the RUNX2 control of gene expression from that of promoting matrix production (type I collagen) to inducing the expression of pro-osteoclastogenic genes. These results suggest that PE particles switch mature osteoblastic cells from an anabolic to a more catabolic phenotype. This concept was further supported by the finding that PE-induced expression of RANKL mRNA in the mouse osteocyte cell line, MLO-Y4. Overall, our results suggest that PE particles directly induce a change in the phenotype of mature osteoblasts and osteocytes, consistent with the net loss of bone near orthopaedic implants.

Influence of design and bearing material on polyethylene wear particle generation in total knee replacement

Periprosthetic osteolysis is one of the main reasons for revision of arthroplasty. The osteolytic reaction is influenced by the dose, size and shape of the wear particles. For arthroplasty, a low number and biologically less active particles are required. This is the first study which analyzes the impact of different knee designs, combined with crosslinked polyethylenes (sequentially irradiated and annealed as well as remelted techniques), on the amount, size and shape of particles. Overall, six material combinations, four of them with crosslinked polyethylene (XPE) and two of them with ultra-high molecular weight polyethylene (UHMWPE) inserts, including fixed and mobile bearings, were tested in a knee joint simulator. After isolation nearly 100,000 particles were analyzed in size, shape and number by scanning electron microscopy and image analysis. For all the designs, the wear was predominantly smooth and granular with few fibrillar particles. The Scorpio ® design with the X3™ insert, the Natural Knee ® II design with the Durasul™ insert and the LCS ® design, also combined with a crosslinked polyethylene insert, generated statistically significant ( P < 0.05) lower particle numbers. The particle size was independent of the radiation dose. The wear generated by the LCS ® knee design (XPE and UHMWPE) had a higher percentage fraction of particles >1 μm in size (equivalent circle diameter). The NexGen ® design, tested with the Prolong™ insert, showed a high number of particles in the biologically active size range compared with the other crosslinked designs, which could be a predictor for higher biological reactivity.

Symptomatic failure of snap-on bipolar radial head prosthesis

As the design of prosthetic radial head components improves, and the understanding of the necessity for early restoration of elbow and forearm stability in complex elbow trauma increases, prosthetic radial head replacement is becoming more common. In fact, open reduction and internal fixation of complex radial head fractures has been shown to have relatively poor results and is susceptible to early failure, nonunion, and poor forearm rotation. Few long-term results of radial head replacements have been published, and the current reports are in small series with a low level of evidence. Some of the largest series are with the Judet bipolar radial head prosthesis (Tornier SAS, Saint-Ismier, France), which uses a bipolar metal/polyethylene component that articulates with a monoblock metal head and stem. The Judet prosthesis has a snap-on mechanism to prevent disengagement. As with polyethylene bipolar inserts in hip replacement surgery, concerns exist with respect to polyethylene wear, especially in younger patients. We have used the Judet bipolar radial head prosthesis for revision radial head replacement surgery because it has the benefit of a longer radial stem. However, of the 14 inserted by the senior author in the last 6 years (between February 2001 and February 2007), we have noted 2 cases of failure of the snap-on mechanism, permitting axial slippage of the bipolar component off and on the head/stem. Both patients presented to us with a new lateral elbow pain that was constant and aching in nature and different from any pain they had had before. We believe the pain was caused by polyethylene wear particles. This condition has not been reported in the literature

Biotribological behavior of ultra high molecular weight polyethylene composites containing bovine bone hydroxyapatite

Abstract Wear particles of ultrahigh molecular weight polyethylene (UHMWPE) are the main cause of long-term failure of total joint replacements. Therefore, increasing its wear resistance or bioactivity will be very useful in order to obtain high quality artificial joints. In our study, UHMWPE composites filled with the bovine bone hydroxyapatite (BHA) were prepared by the method of compression moulding. A ball-on-disc wear test was carried out with a Universal Micro-Tribometer to investigate the friction and wear behavior of a Si3N4 ceramic ball, cross-sliding against the UHMWPE/BHA composites with human plasma lubrication. At the same time, the profiles of the worn grooves on the UHMWPE/BHA surface were scanned. The experimental results indicate that the addition of BHA to UHMWPE had a significant effect on the biotribological behavior of UHMWPE cross-sliding against the Si3N4 ceramic ball. The addition of BHA powder enhanced the hardness and modulus of elasticity of these composites and decreased the friction coefficients and wear rates under conditions of human plasma lubrication. When the added amount of BHA powders was up to 20%∼30%, UHMWPE/BHA composites demonstrated the designed performance of the mechanical properties and biotribological behavior.

Identification of nanometre-sized ultra-high molecular weight polyethylene wear particles in samples retrieved in vivo

Nanometre-sized particles of ultra-high molecular weight polyethylene have been identified in the lubricants retrieved from hip simulators. Tissue samples were taken from seven failed Charnley total hip replacements, digested using strong alkali and analysed using high-resolution field emission gun-scanning electron microscopy to determine whether nanometre-sized particles of polyethylene debris were generated in vivo. A randomised method of analysis was used to quantify and characterise all the polyethylene particles isolated. We isolated nanometre-sized particles from the retrieved tissue samples. The smallest identified was 30 nm and the majority were in the 0.1 microm to 0.99 microm size range. Particles in the 1.0 microm to 9.99 microm size range represented the highest proportion of the wear volume of the tissue samples, with 35% to 98% of the total wear volume comprised of particles of this size. The number of nanometre-sized particles isolated from the tissues accounted for only a small proportion of the total wear volume. Further work is required to assess the biological response to nanometre-sized polyethylene particles.

Can centrifugation affect the morphology of polyethylene wear debris?

It was suggested that centrifugation may affect the morphology of ultra high molecular weight polyethylene wear particles isolated from periprosthetic tissues. In order to investigate this problem, several sets of in vivo polyethylene wear particles were isolated in the same way, using four different centrifugation speeds in the final isolation step. The first set of particles was separated only by flotation, the second set was centrifuged at 500 × g, the third at 16,000 × g and the fourth at 105,000 × g. The morphology of the wear particles was assessed by image analysis of SEM micrographs. Centrifugation speeds up to 105,000 × g had no effect on the morphology: quantitative image analysis parameters, such as equivalent diameter, circularity and elongation, remained the same as for particles obtained by spontaneous flotation.

Unterschiede des Polyäthylenabriebs bei Hüftgelenkendoprothesen mit Keramik-und Metall-Polyäthylenpaarung der Gleitflächen

Pseudocapsules of artificial hip joints with ceramic- and metal on polyethylene combination of the articulating surfaces from 126 revision arthroplasties and 41 autopsies were studied histologically with semiquantitative evaluation of the polyethylene wear. The results were compared with reports of laboratory tests in the literature. We found in the autopsy specimens as well as in the biopsies from revision arthroplasties of prostheses implanted for 4 to 8 years three times less polyethylene wear particles released from the ceramic on polyethylene prostheses. The newly established synovium surrounding prostheses with ceramic heads appeared 20% reduced in thickness with minor villous transformation. Different types of metal on polyethylene prostheses revealed no differences in wear behaviour with the exception of the bipolar prostheses which showed a markedly increased polyethylene wear.

Ergebnisse der experimentellen Prüfung einer einschraubbaren Hüftgelenkspfanne aus Polyäthylen beim Schaf

In 12 sheep 21 total hip endoprosthesis were implanted, using a polyethylene acetabulum, which was provided with a continuous conique thread for implantation without cement. Out of 14 non luxated hips only 2 acetabula were loosened. After an implantation between 1 week and 18 months the remaining 12 sockets were macroscopically stable and were examined radiologically and histologically. After 3 months of increased osteogenesis a layer of collagenous tissue developed between implant and bone. In the loadbearing area this layer is from 50-80 microns thick and often the ridges of the thread are stabilised by a thin layer of fiber-cartilage, expanding around the implant with longer implantation. Bore-holes in the thread are filled with partially lamellous bone after 6 months. Though sometimes a considerable amount of polyethylene wear particles caused by the disadvantageous and small shape of the sheeparthroplasty was observed, none of the examined acetabula showed any signs of loosening.

The use of structural periacetabular allografts in acetabular revision surgery: 2.5–5 years follow-up

"Acetabular bone loss" presents a major reconstructive challenge in total hip arthroplasty. Loss of acetabular bone stock is a consequence of removal of bone during the original procedure, subsequent prosthetic failure and osteolysis resulting from wear particles of cement and polyethylene. In case of severe bone loss treatment options are rather limited, as fixation requires either biological (cancellous allograft with cage or structural allograft) or non-biological (trabecular metal, triflange implant, etc.) scaffolds. Fourteen acetabular revisions with a cemented cup, supported by a deep frozen structural periacetabular allograft without using a reinforcement ring or an antiprotrusio cage were performed. Clinical assessment was done using a Harris hip score. Graft resorption was radiographically quantified using a digital measurement program. Kaplan-Meier survivorship was 67.1% at 42 months. After a mean follow-up of 3.6 years, 9 out of 14 patients had good clinical results. Mean resorption of 17.1% in six out of ten patients was observed. No sound evidence for union was found in nine out of ten patients. In the four re-revised patients, no bone stock restoration was found. The bicortical allograft without protective device seems to function as a passive biocompatible dead scaffold, which has a less intrinsic strength at intermediate term follow-up, compared to the by ring or cage protected structural allografts.

Wear particle analysis of highly crosslinked polyethylene isolated from a failed total hip arthroplasty

Polyethylene wear particles are one of the most important factors affecting the results of total hip arthroplasty (THA). To reduce wear generation and to achieve better long-term results of THA, highly crosslinked polyethylene (HXPE) has recently been introduced and come into wide use. Thus far, however, there have been no reports on in vivo analysis of HXPE wear particles. We isolated HXPE wear particles from periprosthetic tissue of a failed THA and analyzed using scanning electron microscope. The number of particles was 5.33 x 10(7) g(-1). Particle size (equivalent circle diameter) was 0.66 +/- 0.40 microm (mean +/- standard error). Aspect ratio and roundness were 1.37 +/- 0.26 and 1.44 +/- 0.67, respectively. All the particles were round shaped, and "fibrils" or "shreds" were not detected. Thus far, this was the first report on in vivo wear particle analysis of HXPE. HXPE generated less, smaller, and rounder particles, compared with the corresponding reported values for particles generated from conventional polyethylene. These characteristics might affect macrophage response, osteolysis, and long-term results of THA with HXPE.

Chondrocyte acting as phagocyte to internalize polyethylene wear particles and leads to the elevations of osteoarthritis associated NO and PGE 2

It remains a mystery about the role of chondrocyte or cartilage on the co-existence of ultra-high molecular weight polyethylene (UHMWPE) wear particles from partial joint arthroplasty. An inverted co-culture system was performed to investigate the interactions between chondrocytes and UHMWPE wear particles. It was first time observed that chondrocytes can engulf UHMWPE particles and release osteoarthritis associated pro-inflammatory factors. TEM observation and flow cytometric analysis demonstrated the phagocytosis of particles by chondrocytes. It was found that polyethylene particles may reduce the viability of chondrocytes, and enhance the secretion of nitric oxide (NO) and PGE 2. In conclusion, all these phenomena may contribute to further cartilage degeneration after partial joint arthroplasty surgery. It is first identified in this study that the chondrocyte acts as phagocyte to internalize wear particles and leads to the elevations of precursor mediators of osteoarthritis.

Quantification of UHMWPE wear in periprosthetic tissues of hip arthroplasty: Description of a new method based on IR and comparison with radiographic appearance

Ultra-high molecular weight polyethylene (UHMWPE) has been used as a bearing material in total joint replacements (TJR) for more than three decades. Although UHMWPE is regarded as the gold standard in this field, microscopic wear particles are released from the polymer causing inflammatory response in the surrounding tissues. In this study, a new fast method for the quantification of polyethylene wear particles, called IRc, was introduced. The IRc method is based on infrared spectroscopy and determines the total volume of UHMWPE wear debris in particular zones around TJR. The IRc results correspond very well to the results obtained by an independent method, which estimates the numbers of wear particles by means of image analysis of scanning electron micrographs. The IRc results were also compared with radiographic images and with the reports from TJR revisions. Again, very good correlation was found, indicating that the extent of tissue damage in a particular zone around TJR is proportional to the volume of UHMWPE wear debris in the zone.

Characteristics of Hylamer polyethylene particles isolated from peri‐prosthetic tissues of failed cemented total hip arthroplasties

Polyethylene wear particles are one of the most important factors affecting the results of total hip arthroplasty. Hylamer, a highly crystalized ultra-high-molecular-weight polyethylene, has been used in total hip arthroplasty for wear reduction, but has exhibited high wear rate and excessive osteolysis. The aim of the present study was to examine Hylamer wear particles in peri-prosthetic tissues with osteolysis obtained from two cases of failed cemented total hip arthroplasty at 8 and 6 years after operation. Polyethylene particles were isolated, and examined using a scanning electron microscope and image analyzer. Total numbers of Hylamer polyethylene particles in the two cases were 5.6 x 10(9) and 8.0 x 10(9) g(-1). Particle sizes (in equivalent circle diameter) for the two cases were 1.07 +/- 0.06 microm and 1.16 +/- 0.05 microm, and particle shapes (roundness) were 3.05 +/- 0.22 and 3.76 +/- 0.28. The Hylamer polyethylene particles were larger in size and more elongated and their number was larger, compared with the corresponding reported values for particles generated from conventional polyethylene. This increase in particle number and elongation may lead to early osteolysis in total hip arthroplasty with Hylamer.

Inactivation of a subpopulation of human neutrophils by exposure to ultrahigh-molecular-weight polyethylene wear debris

Polymorphonuclear neutrophils, a first line of defence against invading microbial pathogens, may be attracted by inflammatory mediators triggered by ultrahigh-molecular-weight polyethylene (UHMWPE) wear particles released from orthopaedic prostheses. Phagocytosis of UHMWPE particles by neutrophils may indirectly compromise their phagocytic-bactericidal mechanisms, thus enhancing host susceptibility to microbial infections. In an in vitro assay, pre-exposure of purified human neutrophils to UHMWPE micrometre- and submicrometre-sized wear particles interfered with subsequent Staphylococcos aureus uptake in a heterogeneous way, as assessed by a dual label fluorescence microscopic assay that discriminated intracellular rhodamine-labelled UHMWPE particles from fluorescein isothiocyanate-labelled S. aureus. Indeed, a higher percentage (44%) of neutrophils having engulfed UHMWPE particles lost the ability to phagocytize S. aureus, compared with UHMWPE-free neutrophils (<3%). Pre-exposure of neutrophils to UHMWPE wear particles did not impair but rather stimulated their oxidative burst response in a chemoluminescence assay. The presence of UHMWPE wear particles did not lead to significant overall consumption of complement-mediated opsonic factors nor decreased surface membrane display of neutrophil complement receptors. In conclusion, engulfment of UHMWPE wear particles led to inactivation of S. aureus uptake in nearly half of the neutrophil population, which may potentially impair host clearance mechanisms against pyogenic infections.

Isolation, characterization and quantification of polyethylene wear debris from periprosthetic tissues around total joint replacements

Three basic methods of isolation of polyethylene wear particles from periprosthetic tissues (alkaline, acid and enzymatic) were compared. All the three methods had to be significantly modified to obtain pure polyethylene wear particles. For isolation of wear particles the acid method was found to be the most convenient. Purity of isolated wear debris was checked by: scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDS) and infrared spectroscopy (FTIR). SEM micrographs were used as an input for automated quantitative analysis, i.e. for determination of the total number of wear particles. The reliability of our automated quantification method (called SEMq) was verified on several sets of experiments; relative errors were less than 10%. The first results, obtained by the SEMq method, indicate that the distribution of UHWMPE particles around total joint replacements is quite non-homogenous.

Wear-Induced Osteolysis and Synovial Swelling in a Patient With a Metal–Polyethylene Wrist Prosthesis

We present a patient with a metal and polyethylene wrist prosthesis who had recurrent synovial swelling on the volar side of the wrist. Surgical exploration showed synovitis, a severely worn and broken polyethylene insert, polyethylene wear particles, and titanium debris from fretting corrosion. Pathological analysis showed macrophage-phagocytosing polyethylene wear particles and titanium oxide debris. This shows that polyethylene and titanium wear in wrist prosthesis might be a bigger problem than originally believed.

The Potential Role of Phagocytic Capacity in the Osteolytic Process Induced by Polyethylene Wear Particles

Osteolysis induced by ultra-high molecular weight polyethylene wear particles is the major cause of long-term failure of artificial joints. We examined the effects of wear particles on bioactivity by analysing the biophysical aspects of particle phagocytosis. We estimated the maximum number of internalized particles (the phagocytic capacity) for particles of various sizes and shapes. We demonstrated that elongated particles had a smaller phagocytic capacity than spherical particles of the same volume. A review of the literature showed that the ratio of particle concentration (number of particles/number of cells) to phagocytic capacity is critical for particle-induced biological responses. When this ratio was < 1, the biological response was approximately proportional to the ratio itself. When this ratio was > 1, limited changes in the biological response were observed. The saturation level of the phagocytic capacity for a particle population appears to reflect the degree of polyethylene particle-induced biological response.

Effects of local infusion of OP‐1 on particle‐induced and NSAID‐induced inhibition of bone ingrowth in vivo

Excessive polyethylene wear particles from joint replacements may lead to periprosthetic osteolysis and loosening. Nonsteroidal anti-inflammatory drugs (NSAIDs) decrease fracture healing and bone ingrowth. We hypothesized that continuous local infusion of OP-1 (BMP-7) would increase local bone formation in the presence of two different adverse stimuli, polyethylene particles, and an oral NSAID. The Drug Test Chamber (DTC) was implanted in the proximal tibia of mature rabbits. The tissue growing into the chamber was exposed to OP-1 solution (110 ng/day), which was infused via an osmotic pump. Infusion of OP-1 alone for 6 weeks enhanced local bone formation in the chamber by 80% (p < 0.05) over infusion of carrier alone. In the presence of polyethylene particles, infusion of OP-1 increased local bone formation by 38% (p < 0.05) over treatment with particles and carrier. Oral administration of NSAID reduced local bone formation by 58% (p < 0.05); this suppressive effect caused by NSAIDS was completely reversed by the infusion of OP-1 (p < 0.05). These findings underline a potential role for local treatment with OP-1 to increase bone formation in the presence of potentially adverse stimuli such as polyethylene wear particles or NSAID use.