Oxidized zirconium (Oxinium) and highly cross-linked polyethylene (HXLPE) were developed with the purpose of minimizing wear, and subsequent osteolysis, in Total Hip Arthroplasty (THA). However, few articles have been published on long-term results of Oxinium on highly cross-linked polyethylene. The purpose of this investigation is to report minimum 10-year HXLPE wear rates and the clinical outcome of patients in this group and compare this population to a control group of cobalt chrome and ceramic. One hundred forty THAs were performed for 123 patients using an Oxinium head with an HXLPE liner. Ninety-seven had 10 years of clinical follow-up (avg. 14.5). Harris Hip Scores (HHS) were collected preoperatively and at the most recent follow-up. Radiographs of 85 hips were available for a minimum 10-year follow-up (avg. 14.5) and used to calculate wear using PolyWare software. Control groups of cobalt chrome and ceramic articulation on HXLPE with a minimum 10-year follow-up were studied. Clinical follow-up of the Oxinium group showed a statistical improvement compared to preoperative and was similar to the control group of patients. Radiographic evaluation found the linear and volumetric wear rates for the Oxinium group of 0.03 mm/year (range 0.00–0.08) and 3.46 mm. 3. /year (range 1.0 to 15.0) respectively. There was no statistically significant difference in linear or volumetric wear rate between the groups (P-value 0.92 and 0.55 respectively). None of these patients underwent revision of their hip for any reason. Oxinium on highly cross-linked polyethylene has performed exceptionally with wear rates comparable to those of cobalt chrome or ceramic on HXLPE

Purpose:. Although short term outcomes of reverse total shoulder arthroplasty (rTSA) have been promising, long-term success may be limited due to complications, including scapular notching. Scapular notching has been explained primarily as a mechanical erosion, however, generation of wear debris may lead to further biologic changes contributing to the severity of scapular notching. Highly cross-linked ultra-high molecular weight polyethylene (UHMWPE) has been used routinely in constrained joint applications such as total hip arthroplasty for reduction of wear debris particles. Although rTSA shares similarity in design conformity, conventional UHMWPE remains the gold standard. Methods:. A commercially available hip simulator was converted to a 12-station rTSA wear simulator. Conventional and highly cross-linked UHMWPE humeral liners were subjected to 5,000,000 cycles of alternating abduction-adduction and flexion-extension loading profiles. Every 250,000 cycles, liners were evaluated with gravimetric wear measurements and test serum was collected for morphological characterization of wear particles. Results:. Highly cross-linked UHMWPE liners (36.5 ± 10.0 mm. 3. /million cycle) exhibited significantly lower volumetric wear rates compared to conventional UHMWPE liners (83.6 ± 20.6 mm3/million cycle) (p < 0.001) (Figure 1). The flexion-extension loading profile exhibited significantly higher wear rates for both conventional (p < 0.001) and highly cross-linked UHMWPE (p < 0.001) compared to the abduction-adduction loading profile. Highly cross-linked wear particles had an equivalent circle diameter significantly smaller than wear particles from conventional UHMWPE (p < 0.001) (Figure 2). Highly cross-linked wear particles were also significantly less fibrillar than conventional UHMWPE particles with respect to particle aspect ratio (p < 0.001) and particle roundness (p < 0.001). Conclusion:. This is the first study to examine the effect of cross-linked PE in a rTSA wear simulation. Highly cross-linked UHMWPE liners significantly reduced UHWMPE wear and subsequent particle generation. More favorable wear properties with the use of highly cross-linked UHMWPE may lead to increased rTSA device longevity and fewer complications but must be weighed against the impact of reduced mechanical properties

Aims: Hipsimulator tests with highly cross-linked PE shows excellent results after 20 million cycles. Since March 99 we implanted hips with the Fitmore-Cup, Durasul-Inlay and an anatomical stem. In vivo investigations with 300 hips with highly cross-linked PE are introduced. Methods:. We used three methods to test the highly cross-linked PE in vivo: With Polyware-edge-detection we measured the penetration-rate of the Durasul ball-head. With electron scan microscopy we measured the wear rate in 5 retrierals. Histological examination of the periprosthetic tissue in 5 retrievals were done. Results: 1. The linear penetration rate after 1 year is 0,42 mm and after 2 years 0,096 mm. 2. Surface investigation shows no wear in the 5 retrieval cases. 3. Histological examination revealed extremely low depostion of smallest polyethylene particules. Conclusions:Now we have 3 years clinical experience with highly cross-linked PE. 3D-penetration results are as expected: we see no significant difference between conventional-PE and highly cross-linked PE (bedding in and creep). Surface investigation confirm the plastic deformation and the wear resistence of highly cross-linked PE. Histological examination shows ultra low depostion of PE particles and confirm the excellent in vitro results with highly cross-linked PE. The clinical investigation will be continued

Introduction. Highly cross-linked polyethylene has been introduced to decrease osteolysis secondary to polyethylene wear debris generation, but there are few long-term data on revision total hip arthroplasty using highly cross-linked polyethylene liners. The purpose of this study was to report the long-term radiographic and clinical outcomes of a highly cross-linked polyethylene liner in revision total hip arthroplasty. Materials & Methods. We analyzed 63 revision total hip arthoplasties that were performed in 63 patients using a highly cross-linked polyethylene liner between April 2000 and February 2005. Of these, nine died and four were lost to follow-up before the end of the 10-year evaluation. Thus, the final study cohort consisted of 50 patients (50 hips). There were 26 males and 24 females with a mean age at time of revision total hip arthoplasty of 53 years (range, 27–75 years). Mean duration of follow-up was 11 years (range, 10–14 years). Results. Mean Harris hip score improved from 44 points preoperatively to 85 points at final follow-up. No radiographic evidence of osteolysis was found in any hip. One hip required re-revision surgery for acetabular cup loosening at 6.5 years postoperatively. One required re-revision with a constrained liner because of recurrent dislocation. Three sustained deep infections requiring additional surgical procedures. Kaplan-Meier survivorship with an end point of re-revision for any reason was 91.0% and for aseptic cup loosening was 97.9% at 11 years (Figs. 1 and 2). Conclusions. At a minimum of 10 years, the highly cross-linked polyethylene liners showed excellent clinical performance and implant survivorship, and were not associated with osteolysis in our group of patients with revision total hip arthoplasties

Summary. Four highly cross-linked UHWMPEs except vitamin E-stabilised explants. Introduction. The development of both first and second generation highly cross-linked material focused on stabilizing radiation-induced free radicals as the sole precursor to oxidative degradation; however, secondary in vivo oxidation mechanisms have been identified in both conventional and highly cross-linked UHMWPE, induced by absorbed lipids and cyclic mechanical load. Retrieval studies are reporting in vivo oxidation highly cross-linked retrievals with up to ten year in vivo durations. Preclinical aging tests did not predict these in vivo material changes. With only a decade of these materials in clinical use, retrieval studies are limited to mid-term follow-up. In vitro studies face a challenge in effectively replicating the precise in vivo conditions that lead to this loss of oxidation resistance. In this study, we bypass replicating these in vivo variables by examining surgically-retrieved components, thereby testing material that has been affectively “pre-conditioned” by their in vivo service. After a preliminary post-operative analysis, we subjected retrievals to accelerated aging tests in order to predict the extent to which their oxidative stability had been uniquely compromised in vivo. Patients & Methods. Twenty-four highly cross-linked retrievals of four manufacturing methods (n=6 each of Longevity™, Prolong™, X3™ and E1™) and in vivo durations (1–4 years) were analyzed post-operatively and after accelerated aging (70°C, 5atm O. 2. for 2 weeks; ASTM F2003). Never-implanted components (n=1) of each material type were also aged. Infrared microscopy was used to evaluate lipid absorption, oxidation (per ASTM F2102-01ε1) and hydroperoxide levels after 16 hrs of nitric oxide staining for oxidation potential, and gravimetric swelling analysis assessed cross-link density (ASTM F2214). Results. All retrievals contained absorbed lipids penetrating below both loaded (penetration depth=1.3 ± 0.5 mm) and unloaded (0.6 ± 0.2 mm) surfaces. Each material type subset contained retrievals with and without detectable oxidation after in vivo service (Max OI=0.01–0.94). After aging, all post-irradiation thermally-treated, highly cross-linked retrievals, regardless of initial lipid levels or oxidation, showed oxidative degradation, demonstrated by subsurface oxidative peaks (MOI=0.30–2.63), increased hydroperoxides (3–5X), and decreased cross-link density (−34–90%). In contrast, vitamin E-stabilised retrievals showed below MOI<0.2 with no significant loss of cross-link density. Never-implanted controls for each material type showed no oxidative changes after accelerated aging. Discussion/Conclusion. Accelerating aging after in vivo service has shown oxidative instability characterised by high oxidation and material property loss in the three highly cross-linked materials without an incorporated antioxidant. This oxidative degradation took place regardless of post-operative oxidation levels, indicating that even without detectable oxidation the material had undergone changes during in vivo service, as compared to the lack of oxidative response in never-implanted controls. These findings also suggest that the presence of an antioxidant may be able to slow down and/or stabilise in vivo mechanisms compromising long-term oxidative stability and increase the longevity of highly cross-linked UHMWPE materials

Introduction. Technological advances in the processing of polyethylene have led to improved survivorship of total hip arthroplasty. The purpose of this study was to determine if a second generation highly cross-linked polyethylene could improve upon wear rates compared to conventional and first generation cross-linked polyethylene in patients undergoing primary total hip arthroplasty. Methods. Linear and volumetric wear rates of a second generation highly cross-linked polyethylene were evaluated following primary total hip arthroplasty. There were 44 patients with an average age of 68.6 years and mean follow-up of 5.3 years. Patients were evaluated at six weeks, one, two and five years. Wear rates were determined from digitized AP Pelvis radiograph by an independent observer using Martell's software. Acetabular inclination and femoral head size were also evaluated to determine variability in wear rates. Results. The mean linear wear rate for the entire group was 0.015mm/year (±0.055). There was a 64% decrease in linear wear rate when compared to a first generation highly cross-linked polyethylene from the same institution. There was a 90% decrease in wear rate compared to conventional polyethylene. There were no differences in the linear wear rate between the 32mm vs. larger head sizes (36mm and 40mm). However, there was a 30% increase in volumetric wear rate with larger head sizes. The mean wear rate in patients with cup inclination less than 45 degrees was 0.006mm/year compared with 0.024mm/year for those with an inclination greater than 45 degrees. The amount of linear wear was increased by 4 times in patients with a cup inclination of greater than 45 degrees. There was no evidence of any osteolysis in this group of patients. Conclusion. Our data with a mean follow-up of 5.3 years, using a second generation highly cross-linked polyethylene, demonstrates a dramatic decrease in incidents of linear wear compared to conventional polyethylene and first generation highly cross-linked polyethylene (Figure 1). Of concern is the higher volumetric wear rate noted with larger head sizes and increased linear wear rates with cup inclination angles of greater than 45 degrees. Despite improvements in wear rates using a second generation highly cross-linked polyethylene, cup orientation and choice of head size play significant roles in implant survivorship

Aims. Limited implant survival due to aseptic cup loosening is most commonly responsible for revision total hip arthroplasty (THA). Advances in implant designs and materials have been crucial in addressing those challenges. Vitamin E-infused highly cross-linked polyethylene (VEPE) promises strong wear resistance, high oxidative stability, and superior mechanical strength. Although VEPE monoblock cups have shown good mid-term performance and excellent wear patterns, long-term results remain unclear. This study evaluated migration and wear patterns and clinical and radiological outcomes at a minimum of ten years’ follow-up. Methods. This prospective observational study investigated 101 cases of primary THA over a mean duration of 129 months (120 to 149). At last follow-up, 57 cases with complete clinical and radiological outcomes were evaluated. In all cases, the acetabular component comprised an uncemented titanium particle-coated VEPE monoblock cup. Patients were assessed clinically and radiologically using the Harris Hip Score, visual analogue scale (pain and satisfaction), and an anteroposterior radiograph. Cup migration and polyethylene wear were measured using Einzel-Bild-Röntgen-Analyze software. All complications and associated treatments were documented until final follow-up. Results. Clinical assessment showed persistent major improvement in all scores. On radiological assessment, only one case showed a lucent line (without symptoms). At last follow-up, wear and migration were below the critical thresholds. No cup-related revisions were needed, indicating an outstanding survival rate of 100%. Conclusion. Isoelastic VEPE cups offer high success rates and may prevent osteolysis, aseptic loosening, and the need for revision surgeries in the long term. However, longer follow-up is needed to validate our findings and confirm the advantages offered by this cup. Cite this article: Bone Jt Open 2024;5(10):825–831

Aims. Radiostereometric analysis (RSA) is the most accurate radiological method to measure in vivo wear of highly cross-linked polyethylene (XLPE) acetabular components. We have previously reported very low wear rates for a sequentially irradiated and annealed X3 XLPE liner (Stryker Orthopaedics, USA) when used in conjunction with a 32 mm femoral heads at ten-year follow-up. Only two studies have reported the long-term wear rate of X3 liners used in conjunction with larger heads using plain radiographs which have poor sensitivity. The aim of this study was to measure the ten-year wear of thin X3 XLPE liners against larger 36 or 40 mm articulations with RSA. Methods. We prospectively reviewed 19 patients who underwent primary cementless THA with the XLPE acetabular liner (X3) and a 36 or 40 mm femoral head with a resultant liner thickness of at least 5.8 mm. RSA radiographs at one week, six months, and one, two, five, and ten years postoperatively and femoral head penetration within the acetabular component were measured with UmRSA software. Of the initial 19 patients, 12 were available at the ten-year time point. Results. The median proximal, 2D, and 3D wear rates calculated between one and ten years were all less than 0.005 mm/year, with no patient recording a proximal wear rate of more than 0.021 mm/year. Importantly, there was no increase in the wear rate between five and ten years. Conclusion. The very low wear rate of X3 XLPE liners with larger articulations remains encouraging for the future clinical performance of this material. Cite this article: Bone Jt Open 2023;4(11):839–845

Summary Statement. In the most recent type of highly cross-linked UHMWPE, stabilised by vitamin E, the majority of this anti-oxidant cannot be leached out. Even more, the vitamin E molecules are grafted to the UHMWPE polymer backbone by an ether bond. Introduction. Today, highly cross-linked, vitamin E stabilised UHMWPE is clinically accepted as bearing material in joint replacements. Little is known about the chemistry of this antioxidant in the polymer after irradiation. The present investigation presents a model for the chemical nature of the trapping of vitamin E in PE. Method. UHMWPE type GUR 1020 (Ticona GmbH, Kelsterbach/Germany) was blended with 0.1 % vitamin E (Merck KGaA, Darmstadt/Germany), compression moulded at Mathys Ltd Bettlach in-house and cross-linked with γ-irradiation dose of nominally 100 kGy. To assess the extent of vitamin E leachable out, three 0.3 mm sections were cut from the centre of the samples. By extraction in heptane for 48 h at 98 °C, this amount of vitamin E trapped in the polymer was determined by Fourier transform infrared spectroscopy (FTIR) as relative vitamin E index (RVEI). The nature of the extracted substances was analysed by GC-MS. For solids, many of modern spectroscopic methods are not applicable. Therefore, 0.1 % vitamin E were dissolved in two model hydrocarbons (cyclohexane and n-octane) and irradiated at the same 100 kGy γ-dose. In order to determine the chemical bond vitamin E – hydrocarbon after irradiation, these liquid solution samples were analysed by different spectroscopic methods, such as GC-MS, MALDI-TOF-SIMS, HPLC and NMR. Results. Extraction experiments showed that only 23 % of the vitamin E could be extracted by heptane after irradiation whereas from a non-irradiated control sample, all vitamin E was extracted. GC-MS confirmed that the extracted vitamin E was chemically unchanged. Analysing the model hydrocarbons after irradiation, the GC-MS-chromatogram of the cyclohexane solution showed a single peak of the formal cyclohexene adduct of vitamin E. Illustrates this adduct, cyclohexyl-6-O-α-tocopherolether. Contrariwise, the same analysis of the n-octane solution revealed three formal octane adducts. By preparing references substances these three peaks could be attributed to ethers of vitamin E bonded at three different, but chemically equivalent CH. 2. positions on the eight carbon atom chain of n-octane. The single mass peak of the cyclohexane solution arises from the six chemically equivalent carbon atoms in this cyclic hydrocarbon. The 100 kGy γ-dose transformed 76 % of the vitamin E in the n-octane solution to the corresponding ethers and 68 % of the vitamin E in the cyclohexane to cyclohexyl ether. Therefore we postulate that in highly cross-linked, vitamin E stabilised UHMWPE the vitamin E is grafted to the polymer carbon backbone by an ether bond at the phenolic OH group of the vitamin E molecule. Conclusion. Upon irradiation, vitamin E is grafted to the UHMWPE polymer backbone to a large amount. This portion of antioxidant cannot leach out. Therefore, vitamin E stabilised HXLPE is protected from oxidation and ageing by a chemically grafted, quasi internal antioxidant

Introduction and Aims: Modular acetabular designs are widely used in THA procedures and now accommodate highly cross-linked polyethylene liners. However, polymer processing influences material properties, including a decrease in resistance to crack propagation. This study comparatively evaluated locking mechanism integrity of three modular acetabular designs, which employ conventional and highly cross-linked polyethylene liners. Method: Locking mechanism integrity was established for both conventional and highly cross-linked polymers through push-out (n=3) and lever-out (n=3) testing of fully seated liners. When possible, liners were reinserted and forcibly disassembled. Results: The push out and lever out strengths measured for the highly cross-linked polyethylene acetabular liners in this study indicated that short-term disassociation of these components is no more likely than that for the conventional polyethylene liners of each design. Student t-tests confirmed the null hypothesis. In addition, when compared to the strengths of clinically successful modular designs none of the systems evaluated presents any great risk of short-term disassociation. Significant reductions in locking mechanism strength after liner reinsertion were also noted for both polymers. Conclusion: Short-term static disassociation failure of highly cross-linked polyethylene liners were found to be equivalent to conventional polyethylene liners. Given their touted improvement in wear reduction, they would appear to be a reasonable alternative in the young patient requiring THA. Secondarily, neither conventional nor highly cross-linked polymers should be re-inserted for any reason at the time of surgery

Introduction: Wear simulator studies have predicted that highly cross-linked polyethylenes can reduce linear wear by 50–90% when compared to traditional polyethylene (gamma sterilized in air). Clinical experience with a highly cross-linked polyethylene which was irradiated to 10 megarads and cold anneled but not remelted (Crossfire) began in October 1998. Methods: 72 Crossfire implants (69 patients) were implanted and have a minimum 3 year follow-up (mean 3.85 years). 31 of these implants (29 patients) have a minimum 4 year follow-up (mean 4.64 years). Linear wear utilizing a validated computerized technique was measured and compared to 38 hips (37 patients) implanted with a non-cross-linked polyethylene (gamma irradiated – N2 vac) with a mean follow-up of 4.96 years. Results: The mean wear in millimeters per year for the highly cross-linked Crossfire polyethylene with minimum 3 year follow-up was 0.054 (sd=0.032). At minimum 4 year follow-up wear was 0.057 mm/yr (sd=0.036). The wear for the N2 vac non-cross-linked polyethylene was 0.138 mm/yr (sd=0.066). Using a standard t-test the difference in wear was highly significant at p=< 0.001. Discussion & Conclusion: Cross-linking is the only material characteristic shown to improve wear performance of polyethylene. Our clinical experience demonstrates a 50% reduction in wear over N2 vac irradiated polyethylene during the first three years with no significant change out to a mean of 4.64 years. Cross-linked polyethylenes hold great hopes for significant reduction in wear and osteolysis and prolonged life of hip arthroplasty in patients of all ages

Introduction and Aims: While highly cross-linked polyethylene has achieved widespread clinical use based on laboratory testing showing significant wear reduction, there is little clinical information demonstrating its benefits in vivo. This study reports the early clinical and wear performance of a prospective randomised controlled trial comparing highly cross-linked to standard polyethylene. Method: One hundred patients were enrolled in a prospective randomised controlled trial in which all patients received a hybrid THR (cemented Versys stem, Triology cementless acetabulum). The two groups were virtually identical in terms of age, weight, male/female ratio and received identical hip implants, except that one half (50 patients) randomly received a highly cross-linked polyethylene liner. Clinical outcomes were determined using Harris hip, WOMAC and SF-12 scores. Two-dimensional (2D) and three-dimensional (3D) wear rates were determined using a validated radiographic technique based on AP and lateral radiographs at six weeks and one, two and three years post-operatively. Results: At two years minimum follow-up (range two to four years), there were no differences in Harris hip, WOMAC or SF-12 scores. No patients were lost to follow-up, although five patients had died of unrelated causes. There were no infections, dislocations or revisions to date. Wear analysis at one-year post-op showed high penetration rates for both groups (mean 3D wear approximately 0.25 mm/year) consistent with the bedding-in phenomena. At most recent radiographic follow-up (two or three years), there was a statistically significant although modest difference in wear rates between the two groups with a 2D and 3D wear rate of 0.14±0.10 mm/yr and 0.15±0.02 mm/yr respectively for conventional polyethylene compared to 0.09±0.04 mm/yr and 0.11±0.02 mm/yr for cross-linked polyethylene. This represented a 32 and 29 percent reduction in 2D and 3D wear rates respectively with cross-linked polyethylene. Conclusion: At early follow-up, there were no clinical differences. There was a modest wear reduction (approximately 30%) with highly cross-linked polyethylene, considerably less than expected based on laboratory testing. Longer follow-up, after the bedding-in process is completed, is required to demonstrate the wear reduction afforded by highly cross-linked polyethylene

Highly cross-linked polyethylene (HXLPE) is now a common used bearing surface in total hip arthroplasty. Current studies report superior wear rates with the use of HXLPE in total hip arthroplasty. However, there are few studies to support its long term use. The aim of this study is to measure the long term wear of HXLPE and evaluate patient satisfaction at more than 10 years follow up. 44 total hip arthroplasties were performed through a direct lateral approach by a single surgeon. All patients received the same uncemented acetabular component, mean liner thickness was 6.91mm (SD= 0.68). 16 of the femur components were cemented. Outcomes analysed include wear rates, osteolysis, revision rates, SF12 and Oxford hip scores. Wear rate was calculated using computer software (Polyware®) using edge detection software. Mean age at surgery was 58.9 years (SD= 11.67). The mean follow up was 11.3 years (SD= 1.19). There was no evidence of osteolysis and none had undergone revision surgery. Mean two dimensional wear was 0.38mm (SD= 0.25) and mean wear rate per year was 0.03mm (SD= 0.02, range 0.009 to 0.078). Oxford hip score at last follow up indicated satisfactory joint function (mean= 42 SD= 6.2). Our results support the use of highly cross-linked polyethylene in primary total hip replacements. The absence of osteolysis and need for revision surgery over a mean of 11.3 years is very encouraging

Introduction A biomechanical model was developed to measure wear of all-polyethylene patellar components as it relates to femoral component mal-rotation. The model, based on high load and flexion activities such as stair climbing, was used to differentiate the effects of femoral mal-rotation and differing materials on a single patellar design. Methods The patellar components (Scorpio®, Stryker-Howmedica-Osteonics) were cemented onto metal fixtures and articulated against “aligned” and “mal-aligned” (six degrees internally rotated) femoral components. The patellar components were subjected to a constant force and articulated against femoral components flexing from 600 to 1200. Patellae of identical geometry, made of conventional and highly cross-linked ultra-high molecular weight polyethylene, were tested to 1x106 cycles. Following testing, patellar wear was determined by gravimetric measurement relative to soaked control specimens. Results All conventional polyethylene patellae demonstrated damage in the form of burnishing and scratching of the articular surface. The mal-aligned conventional ultra-high molecular weight patellae demonstrated increased weight loss or wear relative to the aligned components (p=.048). All rotationally mal-aligned highly cross-linked polyethylene components sustained polyethylene fracture or catastrophic failure of the cement-polyethylene construct. Conclusions Rotational mal-alignment of the femoral component will result in increased wear of polyethylene patellar components. The newer highly cross-linked materials failed to resolve this wear problem and sustained catastrophic failure when mal-aligned. Attention needs to be given to the patella-femoral articulation when implanting knee components and when developing new polyethylene as the forces in this articulation may result in polyethylene behaviour that varies dramatically from the femoraltibial articulation. In relation to the conduct of this study, one or more of the authors has received, or is likely to receive direct material benefits

Introduction: Electron beam irradiated highly cros-slinked polyethylene has been used in total hip arthroplasty for over 8 years. Due to its low wear characteristics, the use of femoral heads that are greater than 32mm in diameter is now available, allowing for an increase in range of motion and increased stability against dislocation when necessary. The purpose of this study is to provide a summary report on the radiographic analysis of the longest term data available on primary THR patients receiving highly cross-linked polyethylene and to compare the results of two methods of measuring femoral head penetration. Methods: Three prospective clinical studies involving electron beam irradiated highly cross-linked polyethylene have been initiated at our center. To date, the results of: 200 hips with a minimum of 6 year follow-up with conventional sized femoral heads (primarily 28 and 32mm); 45 hips with minimum 5 year follow-up with larger sized femoral heads (primarily 36 and 38mm); and 30 hips with 5 year follow-up enrolled in a Radiostereometric analysis (RSA) study (15 patients with 28mm and 15 patients with 36mm diameter femoral heads); were available for this summary report. Data from patient administered questionnaires (Harris Hip score, UCLA activity score, and WOMAC), radiographic review, and wear analysis using RSA or the Martell Hip Analysis Suite™. In addition, for comparative purposes, wear was measured in a subset of patients using the Devane Polyware™ program. Results: All hips had good clinical outcome at longest follow-up regardless of which femoral head size was used. There were no revisions due to polyethylene wear and no evidence of peri-prosthetic osteolysis. In general, after the bedding in period, there was no significant increase in femoral head penetration regardless of head size. For RSA, the wear rate for the 28mm femoral head group was 0.05±0.02 while the 36mm femoral head group was 0.03±0.02, p=0.13. For the Martell analysis, the average steady-state wear rate was −0.002 ± 0.01 mm per year and −0.026 ± 0.13 mm per year for 28mm and 32mm head sizes, respectively, p=0.62. There was no correlation between wear and time in situ or femoral head size for any of the clinical studies. In comparing the Martell and Devane programs, the total average wear rates were significantly different, 0.07±0.05 and 0.03±0.06mm/year respectively, p=0.01. However, when the absolute values of the Martell results were used, there was no difference, p=0.22. Conclusion: The mid-term follow-up of a large group of primary THR patients receiving highly cross-linked polyethylene components have shown no problems related to the new bearing material. Extremely low wear and lack of peri-prosthetic osteolysis are encouraging results requiring further long-term study

Highly cross-linked polyethylene (HXLPE) has decreased wear and revision rates in total hip replacement (THR) at a long-term. However, the effect of HXLPE manufacturing characteristics on femoral head penetration has not been clearly defined yet. We report this single-institution study to investigate the clinical and radiological results of different HXLPE liners in THR. In this retrospective cohort analysis of our prospective database, we identified 904 THRs performed between 2000 and 2013. Seven different HXLPE liner types were assessed: remelted (3), annealed (2), sequentially annealed (1) and vitamin E-infused (1). The linear femoral head penetration rate was measured at six weeks, one year, and annually thereafter, using the Roman Software v1.70 package. Thirty hips were revised for the following reasons: aseptic loosening (11), dislocation (12), periprosthetic femoral fracture (6), and infection (1). No hip was revised for wear or osteolysis. 741 THRs were evaluated for a mean follow-up of 15 years (range, 10 to 20). The mean total penetration 15 years after THR was 0.17 mm in the sequentially annealed, and 0.16 mm in the vitamin E-infused groups, whereas it was 0.26 mm in the melted 95 kGy, 0.27 mm in the melted 5 Mrad and 0.25 mm in the melted 100 kGy groups (p=0.001). From one to 15 years after surgery, the mean wear was 0.206 mm in cups with an acetabular inclination greater than 50º and 0.105 mm in those placed between 35º and 50º (p<0.001). Although HXLPE characteristics can result in a different wear performance in patients undergoing THR at a mean follow-up of 15 years, the clinical results are excellent. The position of the acetabular component can influence on the femoral head penetration of modern HXLPEs. Nevertheless, these patients should continue to be monitored to detect future problems

Background. Cross-linked polyethylene has much less wear than conventional polyethylene and can used in a more bone conserving thickness of 4 mm. We have used it for hip resurfacing since 2001. Questions/Purposes. This study evaluated the effectiveness of a highly cross-linked polyethylene acetabular component for hip resurfacing in patients under age 50. I posed 5 questions: (1) What are the functional results, (2) What are the complications, (3) What is the 10-year implant survivorship, (4) What is the femoral head penetration into the polyethylene, and (5) What is the bone conservation?. Participants and Methods. There were 160 resurfacing procedures (144 participants) using a 2 piece acetabular shell and a cobalt chromium femoral component (fig. 1). Participants averaged 43 years of age at the time of surgery (range, 23 – 49.5 years) and 70% were women. Inclusion criteria were patients with adequate acetabular bone and a high enough head-neck ratio so that the reconstruction would not violate the femoral neck cortices or medial acetabular wall. The largest cross-linked polyethylene available was 49 mm so only patients with smaller femoral geometries were included. The Harris, WOMAC, and UCLA hip scores were used to assess pain, activity, and function and participants were asked about their satisfaction with the procedure. Digital radiography and computed tomographic scans were used to evaluate femoral head penetration and osteolysis. Removed polyethylene liners were analyzed. Results. The median follow-up was 11.5 years (range, 10 – 14 years). One participant was lost to follow-up and 1 died. The mean Harris Hip Score was 95 and 95% of the participants rated the results of their procedure as excellent. The average UCLA activity score was 8. One patient underwent successful revision surgery for acetabular loosening. Four participants underwent successful revision to a total hip replacement because of femoral neck fracture (2), femoral loosening, or infection. The Kaplan-Meier survivorship was 96%. There were no revisions for polyethylene wear and there were no instances of osteolysis. The medial acetabular wall thickness averaged 7.3 mm (range, 1.5 mm – 14.9 mm). The mean inclination angle was 39°. The mean femoral head penetration was 0.05 mm/year (range, .028 – .09 mm/year). Conclusions. Hip resurfacing with a highly cross-linked polyethylene acetabular component is a reliable procedure at mid-term follow-up. The rate of polyethylene wear is below the osteolytic threshold of .1 mm/yr. The preservation of both acetabular and femoral bone is reasonable even in comparison to thin metal shells available for metal-on-metal resurfacing and total hip replacement. The functional results are comparable to those of metal-on-metal resurfacing without the concerns of a metal bearing couple. The procedures are demanding and patient selection is critical to the success of the procedure. Although long-term follow-up is needed to determine if implant survivorship with highly cross-linked polyethylene acetabular components will equal that of metal-on-metal prostheses, the low rate of femoral head penetration suggests that many years of use in young highly active participants are possible

Introduction:. The management strategy regarding optimally addressing polyethylene wear with a well-fixed acetabular shell remains controversial. The purpose of the present study was to document outcomes of cementation of a highly cross-linked polyethylene (PE) liner into a well-fixed acetabular metal shell in 36 hips. Materials & Methods:. We identified 37 patients (39 hips) who had undergone revision THA by cementation of a highly cross-linked PE liner into a well-fixed metal shell between June 2004 and April 2009. Of these patients, one (1 hip) died before the end of the 3-year evaluation and another was lost to follow-up. Thus, the study cohort consisted of 35 patients (36 hips). There were 23 males (24 hips) and 12 female (12 hips) patients with a mean age at time of revision surgery of 57.6 years (range, 38–79 years). All operations were performed by a single surgeon using only one type of liner. Clinical and radiographic evaluation was performed at a mean of 6.1 years (range, 3–8 years) postoperatively. Results:. Mean Harris hip score improved from 58.1 (range, 39–81 points) preoperatively to 91.3 (range, 45–100 points) postoperatively (p < 0.001). Of the 36 hips, 29 (80.1%) had an excellent result, 6 (16.7%) a good result, and 1 (2.8%) a poor result. The patient with a poor clinical result had aseptic cup loosening with a greater trochanteric fracture at 2 years postoperatively and was treated by acetabular cup revision and internal fixation of the fracture. However, no case of PE liner dislodgement from the cement or of dissociation of the PE-cement construct from the metal shell was encountered. At last follow-up, no new osteolytic lesion was identified and previous osteolytic lesions filled with bone graft were completely or partially incorporated. Other complications included 1 incomplete peroneal nerve palsy and 1 dislocation. Conclusions:. The results of this study and previous reports demonstrated that cementation of highly cross-linked PE liner into well-fixed metal shell could provide good midterm durability

Background. The advent of highly cross-linked polyethylene has resulted in improved wear rates and reduced osteolysis with at least intermediate follow-up when compared to conventional polyethylene. However, the role of alternative femoral head bearing materials in decreasing wear is less clear. The purpose of this study was to determine in-vivo polyethylene wear rates across ceramic, Oxinium, and cobalt chrome femoral head articulations. Methods. A review of our institutional database was performed to identify patients who underwent a total hip arthroplasty using either ceramic or oxidized zirconium (Oxinium) femoral head components on highly cross-linked polyethylene between 2008 and 2011. These patients were then matched on implant type, age, sex and BMI with patients who had a cobalt chrome bearing implant during the same time period. RSA analysis was performed using the center index method to measure femoral head penetration (polyethylene wear). Secondary quality of life outcomes were collected using WOMAC and HHS Scores. Paired analyses were performed to detect differences in wear rate (mm/year) between the cobalt chrome cohorts and their matched ceramic and Oxinium cohorts. Additional independent group comparisons were performed by analysis of variance with the control groups collapsed to determine wear rate differences between all three cohorts. Results. A total of 75 patients underwent RSA analysis. 20 patients with a ceramic femoral head component and 16 patients with an Oxinium femoral head component along with the same number of matched patients with cobalt chrome femoral head component were included in the analysis. The time in vivo for the Oxinium (5.17 +/− 0.96 years), Oxinium matched cohort (5.13 +/− 0.72 years), ceramic (5.15 +/− 0.76 years) and ceramic matched cohort (5.36 +/− 0.63 years) were comparable. The demographics of all bearing surface cohorts were similar. The paired comparison between the Oxinium and cobalt chrome cohorts (0.32 vs. 0.28 mm/year, p=0.427) and ceramic vs cobalt chrome cohorts (0.28 vs. 0.22 mm/year, p=0.202) did not demonstrate a significant difference in wear rate. The independent groups analysis revealed a significantly higher wear rate of Oxinium (0.33 mm/year) compared to cobalt chrome (0.24 mm/year) (p = 0. 038). There were no differences in HHS and WOMAC scores between the Oxinium and cobalt chrome cohorts (HHS: p = 0.71, WOMAC: p=0.08) or the ceramic and cobalt chrome cohorts (HHS: p=0.15, WOMAC: p =023). Conclusion. This study presents evidence of a greater wear rate (mm/year) of the Oxinium femoral head component compared to a cobalt chrome femoral head component. This difference was not demonstrated in the ceramic femoral head component. Despite this difference, there were no clinical differences as measured by the HHS and WOMAC. Future research should focus on factors that may contribute to the higher wear rate seen in the Oxinium cohort. Level of Evidence – Level II. Disclosures - Institutional support provided by Depuy, Stryker, and Smith and Nephew

The advent of highly cross-linked polyethylene has resulted in improved wear rates and reduced osteolysis with at least intermediate follow-up when compared to conventional polyethylene. However, the role of alternative femoral head bearing materials in decreasing wear is less clear. The purpose of this study was to determine in-vivo polyethylene wear rates across ceramic, Oxinium, and cobalt chrome femoral head articulations. A review of our institutional database was performed to identify patients who underwent a total hip arthroplasty using either ceramic or oxidised zirconium (Oxinium) femoral head components on highly cross-linked polyethylene between 2008 and 2011. These patients were then matched on implant type, age, sex and BMI with patients who had a cobalt chrome bearing implant during the same time period. RSA analysis was performed using the centre index method to measure femoral head penetration (polyethylene wear). Secondary quality of life outcomes were collected using WOMAC and HHS Scores. Paired analyses were performed to detect differences in wear rate (mm/year) between the cobalt chrome cohorts and their matched ceramic and Oxinium cohorts. Additional independent group comparisons were performed by analysis of variance with the control groups collapsed to determine wear rate differences between all three cohorts. A total of 68 patients underwent RSA analysis. Fifteen patients with a ceramic femoral head component and 14 patients with an Oxinium femoral head component along with the same number of matched patients with cobalt chrome femoral head component were included in the analysis. The time in vivo for the Oxinium (5.17 +/− 0.96 years), Oxinium matched cohort (5.13 +/− 0.72 years), ceramic (5.15 +/− 0.76 years) and ceramic matched cohort (5.36 +/− 0.63 years) were comparable. The demographics of all bearing surface cohorts were similar. The paired comparison between the Oxinium and cobalt chrome cohorts (0.33 vs. 0.29 mm/year, p=0.284) and ceramic vs cobalt chrome cohorts (0.26 vs. 0.20 mm/year, p=0.137) did not demonstrate a significant difference in wear rate. The independent groups analysis revealed a significantly higher wear rate of Oxinium (0.33 mm/year) compared to cobalt chrome (0.24 mm/year) (p = 0. 038). There were no differences in HHS and WOMAC scores between the Oxinium and cobalt chrome cohorts (HHS: p = 0.71, WOMAC: p=0.08) or the ceramic and cobalt chrome cohorts (HHS: p=0.15, WOMAC: p=023). This study presents evidence of a greater wear rate (mm/year) of the Oxinium femoral head component compared to a cobalt chrome femoral head component. This difference was not demonstrated in the ceramic femoral head component. Despite this difference, there were no clinical differences as measured by the HHS and WOMAC. Future research should focus on factors that may contribute to the higher wear rate seen in the Oxinium cohort