Vitamin E-Enhanced Liners in Primary Total Hip Arthroplasty: A Systematic Review and Meta-Analysis.

OBJECTIVE: Adding vitamin E to highly cross-linked polyethylene liners is frequently performed in clinical practice, aiming at reducing liner wear, increasing liner survival, and delaying revision surgery. This study is aimed at evaluating the revision rate, total femoral head penetration, and postoperative clinical function of highly cross-linked polyethylene liners with and without vitamin E in total hip arthroplasty. METHODS: We conducted a systematic literature search to identify the use of highly cross-linked vitamin E liners compared to other liners in patients who received total hip arthroplasty (THA) before April 2021. The study quality assessment and data collection were conducted by two independent reviewers. Studies were artificially grouped, and vitamin E-enhanced liners (VE-PE) were compared with vitamin E-free liners (non-VE-PE). Analyses were executed using Review Manager version 5.4.1. RESULTS: From the preliminary screening of 568 studies, fourteen studies met the research criteria. Compared to non-VE-PE, using VE-PE reduced the all-cause revision rate (odds ratio = 0.54; 95% confidence interval (CI) 0.40, 0.73; P < 0.0001). The total femoral head penetration of the VE-PE was lower than that of the non-VE-PE (mean difference = -0.10; 95% CI -0.17, -0.03; P = 0.007). However, there was no difference in clinical function, including the Harris Hip Score and EuroQol Five-Dimension Questionnaire scores. CONCLUSION: Compared to the liners without vitamin E, the addition of vitamin E to liners could reduce the all-cause revision rate by approximately 46% in the short-term follow-up. In addition, even though addition of vitamin E could also slow down femoral head penetration, there is no contribution to clinical function.

Polyethylene eye-cover versus artificial teardrops in the prevention of ocular surface diseases in comatose patients: A prospective multicenter randomized triple-blinded three-arm clinical trial.

BACKGROUND: Polyethylene covers are claimed to be useful in preventing ocular surface diseases (OSD); however, evidence of their clinical efficacy is limited. This clinical trial aimed to compare the use of polyethylene eye covers and artificial teardrops versus normal saline on the incidence and severity of OSD in comatose patients. METHODS: Of 90 eligible patients randomly assigned to three treatment groups, 79 patients completed the study, In group A, patients (n = 25) received artificial teardrops for left and normal saline for right eyes, in group B (n = 29) polyethylene covers for left and normal saline for right eyes, and in group C (n = 25) polyethylene covers for left and artificial teardrops for right eyes. As the patients were comatose, their blinding did not applicable, and a blinded observer evaluated the patients' eyes based on the Corneal Fluorescein Staining Pattern. The blinded analyzer analyzed collected data by SPSS-16 software at a 95% confidential level. RESULTS: The OSDs were observed in 65 (41.14%) out of 158 eyes examined. The artificial teardrop was more effective than the normal saline in group A, polyethylene eye cover was more useful than the normal saline in group B, and polyethylene eye cover was more effective than the artificial teardrop in group C in reducing the incidence of OSD (p< 0.01). Polyethylene eye covers had the most impact on reducing the severity of the OSD compared to the other interventions (p< .001). CONCLUSIONS: Polyethylene eye covers significantly reduced the incidence and severity of OSD. Using polyethylene cover is suggested as a safe, effective, and accessible eye care intervention for preventing OSD in comatose patients. TRIAL REGISTRATION: (IRCT201609129014N115), Iranian Registry of Clinical Trials.

Comparison of a vitamin E-infused highly crosslinked polyethylene insert and a conventional polyethylene insert for primary total knee arthroplasty at two years postoperatively.

AIMS: The use of vitamin E-infused highly crosslinked polyethylene (HXLPE) in total knee prostheses is controversial. In this paper we have compared the clinical and radiological results between conventional polyethylene and vitamin E-infused HXLPE inserts in total knee arthroplasty (TKA). PATIENTS AND METHODS: The study included 200 knees (175 patients) that underwent TKA using the same total knee prostheses. In all, 100 knees (77 patients) had a vitamin E-infused HXLPE insert (study group) and 100 knees (98 patients) had a conventional polyethylene insert (control group). There were no significant differences in age, sex, diagnosis, preoperative knee range of movement (ROM), and preoperative Knee Society Score (KSS) between the two groups. Clinical and radiological results were evaluated at two years postoperatively. RESULTS: Differences in postoperative ROM and KSS were not statistically significant between the study and control groups. No knee exhibited osteolysis, aseptic loosening, or polyethylene failure. Additionally, there was no significant difference in the incidence of a radiolucent line between the two groups. One patient from the study group required irrigation and debridement, due to deep infection, at six months postoperatively. CONCLUSION: Clinical results were comparable between vitamin E-infused HXLPE inserts and conventional polyethylene inserts at two years after TKA, without any significant clinical failure. Cite this article: Bone Joint J 2019;101-B:559-564.

Extent of Inflammation and Foreign Body Reaction to Porous Polyethylene In Vitro and In Vivo.

BACKGROUND/AIM: High-density porous polyethylene (PP) offers possibilities for reconstruction in craniofacial surgery. The purpose of this study was to evaluate the extent of inflammation and foreign body reactions to PP in vitro and in vivo. MATERIALS AND METHODS: Cell attachment, proliferation and expression of inflammatory cytokines were assessed using murine macrophages (RAW 264.7) on two different PP materials in vitro. In vivo, Balb/c mice received PP implants at their dorsum. After sacrifice, samples were analyzed histologically and real-time PCR was used to assess expression of inflammatory cytokines. RESULTS: Cells showed a significantly decreased proliferation (p<0.001) after 48 h and a significantly increased expression of TNF-α (p<0.05) at 24, 48 and 72 h. All animals showed foreign body cell reactions and signs of chronic inflammation. Expression of all but one of the investigated cytokines dropped to non-significant levels after an initial increase. CONCLUSION: Application of porous polyethylene can cause local chronic inflammatory reactions. Although clinical application seems to be immunologically safe, indication and risks should be evaluated carefully when using PP implants.

Suture wear particles cause a significant inflammatory response in a murine synovial airpouch model.

BACKGROUND: Commonly used contemporary orthopaedic sutures have been identified as a potential causative factor in the development of post-arthroscopic glenohumeral chondrolysis. Currently, little is known about the body's immune response to these materials. The aim of this study was to examine the biological response of synovial tissue to three commonly used orthopaedic sutures, using a murine airpouch model. METHODS: Fifty rats were used in this study (ten per group). An airpouch was created in each rat, and test materials were implanted. Test materials consisted of an intact polyethylene terephthalate suture with a polybutilate coating (suture A), an intact polyethylene suture braided around a central polydiaxannone core (suture B), an intact polyethylene/polyester cobraid suture with a silicone coating (suture C), and particles of suture C (particles C). Rats were sacrificed at 1 or 4 weeks following implantation. Histological (multinucleated giant cell count) and immunohistochemical (expression of matrix metalloproteinases MMP-1,-2,-3,-9,-13) markers of inflammation were examined. RESULTS: Multinucleated giant cells were present in all specimens containing suture material but not in the control specimens. No significant differences were found in the number of giant cells between the intact suture groups at either time point. Significantly higher numbers of giant cells were noted in the particles C group compared to the intact suture C group at both time points (p = 0.021 at 1 week, p = 0.003 at 4 weeks). Quantitative analysis of immunohistochemical staining expression at 4 weeks showed that significantly more MMP (-1,-2,-9,-13) was expressed in the particles C group than the intact suture C group (p = 0.024, p = 0.009, p = 0.002, and p = 0.007 for MMP-1, MMP-2, MMP-9, and MMP-13, respectively). No significant difference was seen in the expression of MMP-3 (p = 0.058). CONCLUSIONS: There were no differences observed between the biological reactivity of commonly used intact orthopaedic sutures A, B, and C. However, wear particles of suture C elicited a significantly greater inflammatory response than intact suture alone. This was confirmed by increased numbers of multinucleated giant cells as well as MMP ( -1,-2,-9,-13) expression. Further studies are needed to determine whether this inflammatory response may play a role in the development of post-arthroscopic glenohumeral chondrolysis or interfere with biological healing. These findings have important clinical implications relating to surgical technique and surgical implant design.

Fabrication of poly (butadiene-block-ethylene oxide) based amphiphilic polymersomes: An approach for improved oral pharmacokinetics of Sorafenib.

Sorafenib (SFN), a hydrophobic anticancer drug, has several limitations predominantly poor aqueous solubility and hepatic first-pass effect, limiting its oral delivery that results into several other complications. Present study aims to develop Sorafenib loaded polymersomes using poly butadiene block poly ethylene oxide (PB-b-PEO), an amphiphilic co-block polymer. Prior to drug loading, critical aggregate concentration (CAC) of polymer was calculated for stable formulation synthesis. The developed SFN loaded PB-b-PEO polymersomes (SFN-PB-b-PEO, test formulation) characterized by DLS and cryo-TEM showed particle size 282 nm, polydispersity (PDI) of less than 0.29 and membrane thickness of about 20 nm. SFN-PB-b-PEO polymersomes demonstrated encapsulation efficiency of 71% and showed sustained drug release up to 144 h. Formulation remained stable for 3 months in suspension form. In vitro cytotoxicity against HepG2 cells showed 1.7 folds improved toxicity compared to SFN suspension. In addition, oral administration of SFN-PB-b-PEO polymersomes in BALB/c mice showed increased Cmax and AUC0-96 by 1.7 and 2.77-fold respectively (p < 0.05) compared to those of SFN suspension (reference formulation). Findings suggest that the SFN-PB-b-PEO polymersomes can be a potential candidate for oral delivery of SFN.

The Role of Resorbable Plate and Artificial Bone Substitute in Reconstruction of Large Orbital Floor Defect.

It is essential to reduce and reconstruct bony defects adequately in large orbital floor fracture and defect. Among many reconstructive methods, alloplastic materials have attracted attention because of their safety and ease of use. We have used resorbable plates combined with artificial bone substitutes in large orbital floor defect reconstructions and have evaluated their long-term reliability compared with porous polyethylene plate. A total of 147 patients with traumatic orbital floor fracture were included in the study. Surgical results were evaluated by clinical evaluations, exophthalmometry, and computed tomography at least 12 months postoperatively. Both orbital floor height discrepancy and orbital volume change were calculated and compared with preoperative CT findings. The average volume discrepancy and vertical height discrepancies were not different between two groups. Also, exophthalmometric measurements were not significantly different between the two groups. No significant postoperative complication including permanent diplopia, proptosis, and enophthalmos was noted. Use of a resorbable plate with an artificial bone substitute to repair orbital floor defects larger than 2.5 cm(2) in size yielded long-lasting, effective reconstruction without significant complications. We therefore propose our approach as an effective alternative method for large orbital floor reconstructions.

An in vitro study comparing limited to full cementation of polyethylene glenoid components.

BACKGROUND: Glenoid component survival is critical to good long-term outcomes in total shoulder arthroplasty. Optimizing the fixation environment is paramount. The purpose of this study was to compare two glenoid cementing techniques for fixation in total shoulder arthroplasty. METHODS: Sixteen cadaveric specimens were randomized to receive peg-only cementation (CPEG) or full back-side cementation (CBACK). Physiological cyclic loading was performed and implant displacement was recorded using an optical tracking system. The cement mantle was examined with micro-computed tomography before and after cyclic loading. RESULTS: Significantly greater implant displacement away from the inferior portion of the glenoid was observed in the peg cementation group when compared to the fully cemented group during the physiological loading. The displacement was greatest at the beginning of the loading protocol and persisted at a diminished rate during the remainder of the loading protocol. Micro-CT scanning demonstrated that the cement mantle remained intact in both groups and that three specimens in the CBACK group demonstrated microfracturing in one area only. DISCUSSION: Displacement of the CPEG implants away from the inferior subchondral bone may represent a suboptimal condition for long-term implant survival. Cement around the back of the implant is suggested to improve initial stability of all polyethylene glenoid implants. CLINICAL RELEVANCE: Full cementation provides greater implant stability when compared to limited cementation techniques for insertion of glenoid implants. Loading characteristics are more favorable when cement is placed along the entire back of the implant contacting the subchondral bone.

The application and progress of high-density porous polyethylene in the repair of orbital wall defect.

High-density porous polyethylene is a type of polymeric biomaterial. When used to efficiently fill the extensive orbital volume and correct enophthalmos caused by orbital wall defect, it has a significant advantage of biocompatibility, which results in a low rate of postoperative exposure and infection. The major disadvantage of this material is its radiolucency. However, with the development of imaging techniques, it is now possible to use multidetector computed tomography to directly contour the implant and describe its position. The use of tissue engineering involving high-density porous polyethylene will further improve its biocompatibility. At the same time, composite materials will play an important role in the repair of orbital wall defect.

Biotribology of a vitamin E-stabilized polyethylene for hip arthroplasty - Influence of artificial ageing and third-body particles on wear.

The objective of our study was to evaluate the influence of prolonged artificial ageing on oxidation resistance and the subsequent wear behaviour of vitamin E-stabilized, in comparison to standard and highly cross-linked remelted polyethylene (XLPE), and the degradation effect of third-body particles on highly cross-linked remelted polyethylene inlays in total hip arthroplasty. Hip wear simulation was performed with three different polyethylene inlay materials (standard: γ-irradiation 30 kGy, N2; highly cross-linked and remelted: γ-irradiation 75 kGy, EO; highly cross-linked and vitamin E (0.1%) blended: electron beam 80 kGy, EO) machined from GUR 1020 in articulation with ceramic and cobalt-chromium heads. All polyethylene inserts beneath the virgin references were subjected to prolonged artificial ageing (70°C, pure oxygen at 5 bar) with a duration of 2, 4, 5 or 6 weeks. In conclusion, after 2 weeks of artificial ageing, standard polyethylene shows substantially increased wear due to oxidative degradation, whereas highly cross-linked remelted polyethylene has a higher oxidation resistance. However, after enhanced artificial ageing for 5 weeks, remelted XLPE also starts oxidate, in correlation with increased wear. Vitamin E-stabilized polyethylene is effective in preventing oxidation after irradiation cross-linking even under prolonged artificial ageing for up to 6 weeks, resulting in a constant wear behaviour.

Direct subcutaneous injection of polyethylene particles over the murine calvaria results in dramatic osteolysis.

PURPOSE: The murine calvarial model has been widely employed for the in vivo study of particle-induced osteolysis, the most frequent cause of aseptic loosening of total joint replacements. Classically, this model uses an open surgical technique in which polyethylene (PE) particles are directly spread over the calvarium for the induction of osteolysis. We evaluated a minimally invasive modification of the calvarial model by using a direct subcutaneous injection of PE particles. METHODS: Polyethylene (PE) particles were injected subcutaneously over the calvaria of C57BL6J ten-week-old mice ("injection" group) or were implanted after surgical exposure of the calvaria ("open" group) (n = 5/group). For each group, five additional mice received no particles and served as controls. Particle-induced osteolysis was evaluated two weeks after the procedure using high-definition microCT imaging. RESULTS: Polyethylene particle injection over the calvaria resulted in a 40% ± 1.8% decrease in the bone volume fraction (BVF), compared to controls. Using the "open surgical technique", the BVF decreased by 16% ± 3.8% as compared to controls (p < 0.0001). CONCLUSIONS: Direct subcutaneous injection of PE particles over the murine calvaria produced more profound resorption of bone. Polyethylene particle implantation by injection is less invasive and reliably induces osteolysis to a greater degree than the open technique. This subcutaneous injection method will prove useful for repetitive injections of particles, and the assessment of potential local or systemic therapies.

Relationship between gastrointestinal transit time and anesthetic fasting protocols in the captive chimpanzee, Pan troglodytes.

BACKGROUND: Lengthy social separation and prolonged fasting time contribute to increased risks associated with anesthesia in captive primates. This study is an initial attempt to identify a safe pre-anesthetic fasting procedure by identifying gastric emptying time (GET) and gastrointestinal transit time (GTT) of captive chimpanzees, Pan troglodytes. METHODS: Seven adult chimpanzees at the North Carolina Zoo immobilized for annual physical examinations were fed barium-impregnated polyethylene spheres to measure GET. Eleven animals were individually fed a color dye marker and fecal passage was observed to determine GTT. RESULTS: Gastric emptying time (GET) was approximated to be >3 hours but <16 hours. The mean GTT was 16.5 hours. CONCLUSIONS: This study indicates that a fasting time of 3 hours would allow for complete gastric emptying and could potentially replace the current overnight fast (≥16 hour) to help minimize complications associated with pre-anesthetic fasting in captive primates.

Evaluation of gastrointestinal tract transit times using barium-impregnated polyethylene spheres and barium sulfate suspension in a domestic pigeon (Columba livia) model.

Barium impregnated polyethylene spheres (BIPS) are used in small animal medicine as an alternative to barium sulfate for radiographic studies of the gastrointestinal tract. To determine the usefulness of BIPS as an alternative to barium suspension in measuring gastrointestinal (GI) transit time for avian species, ventrodorsal radiographs were used to follow the passage of BIPS and 30% barium sulfate suspension through the GI tracts of domestic pigeons (Columba livia). Gastrointestinal transit times of thirty 1.5-mm BIPS administered in moistened gelatin capsules and 30% barium sulfate suspension gavaged into the crop were compared in 6 pigeons. Although the barium suspension passed out of the GI tract of all pigeons within 24 hours, the 1.5-mm BIPS remained in the ventriculus for 368.0 +/- 176.8 hours and did not clear the GI tract for 424.0 +/- 204.6 hours. Although the times for passage of BIPS and 30% barium sulfate suspension from the crop into the ventriculus were not significantly different (P = .14), the times for passage of BIPS from the ventriculus into the large intestine-cloaca and for clearance from the GI tract of the pigeons were significantly longer (P < .001) than for the 30% barium sulfate suspension. From the results of this study, we conclude that BIPS are not useful for radiographically evaluating GI transit times in pigeons and are unlikely to be useful in other avian species that have a muscular ventriculus. BIPS may or may not be useful for evaluating GI transit times in species that lack a muscular ventriculus.

Polyethylene gel in the subcutaneous tissue of rats: histopathologic and systemic evaluation.

PURPOSE: To evaluate the histological and systemic response to subcutaneous injection of polyethylene gel in rats. METHODS: Twenty-one white male rats were divided into 3 groups (G): G1 and G2 received subcutaneous polyethylene gel injection in the dorsal midline and were sacrificed at 30 and 60 postoperative days, respectively. G3 was not exposed to the polyethylene gel and was sacrificed after 60 days. Blood levels of lactate dehydrogenase (LDH), creatine kinase (CK), and alkaline phosphatase (ALP) were evaluated. The heart, kidney, liver, adrenal gland, injection site, and adjacent tissues were histologically examined. The results were submitted to statistical analysis. RESULTS: There was no clinical evidence of extrusion, reduction of the injected volume, or abnormalities in the adjacent tissues. Blood levels of CK and LDH were normal and similar in all groups. ALP levels were significantly lower in G2 than in G1 and G3. The systemic organs were normal on histological examination in the 3 groups evaluated. Microscopically, the polyethylene gel was surrounded by a thin pseudocapsule formation and minimal inflammatory cell response, which decreased from G1 to G2. CONCLUSION: The subcutaneous injection of polyethylene gel in rats elicited minimal local inflammatory response and no systemic side effects.

An in vivo murine model of continuous intramedullary infusion of polyethylene particles.

Wear debris affects both initial osseointegration and subsequent bone remodeling of total joint replacements (TJRs). To study the complex cascade associated with the continuous generation of particles, a robust animal model is essential. To date, an animal model that incorporates continuously delivered particles to an intramedullary orthopaedic implant has not been available. In this study, we successfully infused clinically relevant ultra high molecular weight polyethylene particles, previously isolated from joint simulator tests, to the intramedullary space of the mouse femur for 4 weeks using a subcutaneous osmotic pump. Reduction of bone volume following the 4-week infusion of UHMWPE was detected by microCT. UHMWPE particles also changed the level of Alkaline Phosphatase expression in the infused femurs. Continuous infusion of particles to the murine bone-implant interface simulated the clinical scenario of local polymer wear particle generation and delivery in humans and can be used to further study the biological processes associated with wear debris particles.

Porous devices derived from co-continuous polymer blends as a route for controlled drug release.

In this study we examine the release profile of bovine serum albumin (BSA) from a porous polymer matrix derived from a co-continuous polymer blend. The porosity is generated through the selective extraction of one of the continuous phases. This is the first study to examine the approach of using morphologically tailored co-continuous polymer blends as a template for generating porous polymer materials for use in controlled release. A method for the preparation of polymeric capsules is introduced, and the effect of matrix pore size and surface area on the BSA release profile is investigated. Furthermore, the effect of surface charge on release is examined by surface modification of the porous substrate using layer-by-layer deposition techniques. Synthetic, nonerodible polymer, high-density polyethylene (HDPE), was used as a model substrate prepared by melt blending with two different styrene-ethylene-butylene copolymers. Blends with HDPE allow for the preparation of porous substrates with small pore sizes (300 and 600 nm). A blend of polylactide (PLA) and polystyrene was also used to prepare porous PLA with a larger pore size (1.5 microm). The extents of interconnectivity, surface area, and pore dimension of the prepared porous substrates were examined via gravimetric solvent extraction, BET nitrogen adsorption, mercury porosimetry, and image analysis of scanning electron microscopy micrographs. With a loading protocol into the porous HDPE and PLA involving the alternate application of pressure and vacuum, it is shown that virtually the entire porous network was accessible to BSA loading, and loading efficiencies of between 80% and 96% were obtained depending on the pore size of the carrier and the applied pressure. The release profile of BSA from the microporous structure was monitored by UV spectrophotometry. The influence of pore size, surface area, surface charge, and number of deposited layers is demonstrated. It is shown that an effective closed-cell structure in porous PLA can be prepared, effectively eliminating all short-term BSA release.

Keeping infants warm: challenges of hypothermia.

Hypothermia is a major cause of morbidity and mortality in infants; therefore, maintaining normal body temperatures in the delivery room is crucial. An understanding of how infants produce heat and what can be done to maintain normal body temperatures in full-term and preterm infants is essential for the preservation of thermal stability in this population. This article reviews the consequences of hypothermia, mechanisms of heat exchange and heat production in full-term and low birth-weight infants, and discusses interventions in the delivery room to alleviate hypothermia.

Bacterial growth on articulating spacers: an in vitro study.

We fashioned cement disk-shaped spacer models using antibiotic-loaded Palacos and embedded polyethylene and titanium into the surface of half of the models and inoculated the models with methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant S aureus (MRSA), or Staphylococcus epidermidis, and placed them in nutrient broth. Vancomycin was loaded into the cement of the MRSA spacer models and tobramycin into the MSSA and Staphylococcus epidermidis models. In the MSSA and MRSA models, no organisms survived beyond 48 hours in the antibiotic bath regardless of the presence of additional materials. At 96 hours, 86.6% of models with only antibiotic cement had viable Staphylococcus epidermidis, while 80% of models with antibiotic cement, polyethylene, and titanium had viable Staphylococcus epidermidis. Adding polyethylene and titanium to antibiotic-loaded cement does not promote bacterial survival.

The antifertility effectiveness of copper/low-density polyethylene nanocomposite and its influence on the endometrial environment in rats.

PURPOSE: The study was conducted to investigate the antifertility effectiveness of copper/low-density polyethylene nanocomposite (nano-Cu/LDPE) and its influence on the endometrial environment in rats. METHODS: One hundred and seventy sexually mature female Sprague-Dawley (SD) rats were randomly divided into five groups: sham-operated control group (SO group, n=10), bulk copper group (Cu group, n=40), LDPE group (n=40), and nano-Cu/LDPE groups I (n=40) and II (n=40). Twenty rats in each group except for the SO group were mated with male rats of proven fertility, from 30 days after insertion, and the antifertility rates (ATs) were observed at Day 11 of pregnancy. The concentrations of prostaglandin E(2) (PGE(2)) and tissue plasminogen activator (tPA) in the endometrium of the remaining rats in each group were measured by using ELISA at the 30th and 60th day after insertion, respectively. RESULTS: ATs in the Cu group and nano-Cu/LDPE groups I and II (100%) were significantly higher than those in the LDPE group (p<.05). Compared with those in the SO group, the concentrations of PGE(2) and tPA in all experimental groups except for PGE(2) levels in the LDPE group were significantly increased at Day 30 after insertion, and these parameters in the nano-Cu/LDPE groups were significantly lower than in the Cu group (p<.05). At Day 60 after insertion, tPA levels were still higher in the Cu and nano-Cu/LDPE groups, but there was no difference in PGE(2) levels in all groups except for the Cu group. CONCLUSION: Nano-Cu/LDPE exhibits satisfactory contraceptive efficacy with less influence on the endometrium PGE(2) and tPA levels.