We conducted a systematic review and meta-analysis of randomised controlled trials comparing cross-linked with conventional polyethylene liners for total hip replacement in order to determine whether these liners reduce rates of wear, radiological evidence of osteolysis and the need for revision. The MEDLINE, EMBASE and COCHRANE databases were searched from their inception to May 2010 for all trials involving the use of cross-linked polyethylene in total hip replacement. Eligibility for inclusion in the review included the random allocation of treatments, the use of cross-linked and conventional polyethylene, and radiological wear as an outcome measure. The pooled mean differences were calculated for bedding-in, linear wear rate, three-dimensional linear wear rate, volumetric wear rate and total linear wear. Pooled risk ratios were calculated for radiological osteolysis and revision hip replacement. A search of the literature identified 194 potential studies, of which 12 met the inclusion criteria. All reported a significant reduction in radiological wear for cross-linked polyethylene. The pooled mean differences for linear rate of wear, three-dimensional linear rate of wear, volumetric wear rate and total linear wear were all significantly reduced for cross-linked polyethylene. The risk ratio for radiological osteolysis was 0.40 (95% confidence interval 0.27 to 0.58; I. 2. = 0%), favouring cross-linked polyethylene. The follow-up was not long enough to show a difference in the need for revision surgery

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

We present minimum 20 year results of a randomized, prospective double blinded trial (RCT) of cross-linked versus conventional polyethylene (PE), using a computer assisted method of PE wear measurement. After Ethics Committee approval, 122 patients were enrolled into an RCT comparing Enduron (non cross-linked PE) and highly cross-linked Marathon PE (DePuy, Leeds, UK). Other than the PE liners, identical components were used, a Duraloc 300 metal shell with one screw, a 28mm CoCr femoral head and a cemented Charnley Elite femoral stem. All patients were followed with anteroposterior (A∼P) and lateral radiographs at 3 days, 6 weeks, 3 months, 6 months, 1, 2, 3, 4, 5, 10 and 20 years. PE wear was measured with PolyMig, which has a phantom validated accuracy of ± 0.09mm. At minimum 20 year follow-up, 47 patients had died, 5 of which had been revised prior to their death. Another 32 patients were revised and alive, leaving 43 patients unrevised and alive (15 Enduron, 28 Marathon). No patients were lost to follow-up, but 2 were not able to be radiographed (dementia), leaving 41 patients (15 Enduron, 26 Marathon) available for PE wear measurement. After the bedding-in period, Enduron liners had a wear rate of 0.182 mm/year, and Marathon liners had a wear rate of 0.028 mm/year. At 20 years follow-up, 37 patients had required revision. Patients with conventional PE had three times the revision rate (28/37) of those who received XLPE (9/37). This is the longest term RCT showing substantially improved clinical and radiological results when XLPE is used as the bearing surface

Aims. The aim of this study was to compare the migration of the femoral component, five years postoperatively, between patients with a highly cross-linked polyethylene (HXLPE) insert and those with a conventional polyethylene (PE) insert in an uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary aims included clinical outcomes and patient-reported outcome measures (PROMs). We have previously reported the migration and outcome of the tibial components in these patients. Methods. A double-blinded randomized controlled trial was conducted including 96 TKAs. The migration of the femoral component was measured with radiostereometry (RSA) at three and six months and one, two, and five years postoperatively. PROMs were collected preoperatively and at all periods of follow-up. Results. There was no clinically relevant difference in terms of migration of the femoral component or PROMs between the HXLPE and PE groups. The mean difference in migration (maximum total point motion), five years postopeatively, was 0.04 mm (95% CI -0.06 to 0.16) in favour of the PE group. Conclusion. There was no clinically relevant difference in migration of the femoral component, for up to five years between the two groups. These findings will help to establish a benchmark for future studies on migration of femoral components in TKA. Cite this article: Bone Joint J 2024;106-B(8):826–833

The benefits of HXLPE in total knee arthroplasty (TKA) have not been as evident as total hip arthroplasty (THA). A systematic review and meta-analysis to assess the impact of highly-crosslinked polyethylene (HXLPE) on TKA outcomes compared to conventional polyethylene (CPE) is described. All studies comparing HXLPE with CPE for primary TKA were included for analysis. The minimum dataset included revision rates, indication for revision, aseptic component loosening and follow-up time. The primary outcome variables were all-cause revision, aseptic revision, revision for loosening, radiographic component loosening, osteolysis and incidence of radiolucent lines. Secondary outcome measures included postoperative functional knee scores. A random-effects meta-analysis allowing for all missing data was performed for all primary outcome variables. Six studies met the inclusion criteria. In total, there were 2,234 knees (1,105 HXLPE and 1,129 CPE). The combined mean follow-up for all studies was 6 years. The aseptic revision rate in the HXLPE group was 1.02% compared to 1.97% in the CPE group. There was no difference in the rate of all-cause revision (p = 0.131), aseptic revision (p = 0.298) or revision for component loosening (p = 0.206) between the two groups. Radiographic loosening (p = 0.200), radiolucent lines (p = 0.123) and osteolysis (p = 0.604) was similar between both groups. Functional outcomes were similar between groups. The use of HXLPE in TKA yields similar results for clinical and radiographic outcomes when compared to CPE at midterm follow-up. HXLPE does not confer the same advantages to TKA as seen in THA

Introduction. Highly cross-linked (HXL) polyethylene has demonstrated clinical advantages as a wear resistant acetabular bearing material in total hip arthroplasty (THA) [1]. In vitro wear testing has predicted a tenfold reduction in the wear rate of HXL polyethylene, as compared to its conventional, non-HXL counterpart [2]. To date, radiographic studies of head penetration represent the state-of-the-art in determining clinical wear of polyethylene hip liners [3]. However, as the amount of wear drops to very low levels, it becomes important to develop a precise and reliable method for measuring wear, facilitating a comparison of clinical results to expectations. This study focuses on locating and quantifying the maximum linear wear of retrieved acetabular poly liners using a coordinate measuring machine (CMM). Specifically, HXL liners are compared to a baseline of conventional, non-HXL bearings. Methods. An IRB-approved retrieval laboratory received 63 HXL acetabular bearing retrievals from 5 manufacturers with in vivo durations of 1.01–14.85 years. These were compared with 32 conventional, non-HXL controls (including gas plasma, gamma-barrier and EtO) from 3 manufacturers with in vivo durations of 1.03–20.89 years. Liners were mounted in a tripod of axial contacts with the liner face positioned in a vertical plane. Each bearing was scanned with a CMM dual-probe head, with one horizontal probe scanning the articular surface and the other scanning the non-articular, sequentially. Surface-normal wall thickness values along each latitude were calculated using a custom developed algorithm (Figure 1). Because the liners are axially symmetric as manufactured, deviation in wall thickness at a given latitude represents linear wear [4]. Results. Total wear penetration for the HXL liners ranged from 0.02 to 1.03 mm, and for the conventional, non-HXL controls ranged from 0.07 to 6.85 mm. The HXL liners had an average linear wear rate of 0.02 mm/year, compared to 0.20 mm/year for the conventional, non-HXL controls (Figure 2). The direction of maximum wear, as measured in degrees from the cup pole, ranged from 8.32 to 73.86 degrees. Differences in wear rates as a function of crosslinking dose, as well as presence/absence of a lip can be identified. Discussion. This wear measurement study of retrievals is the first application of a novel CMM technique to locate and quantify wear in HXL liners compared to conventional polyethylene controls. The study confirms the expectations of a tenfold reduction in wear rates that were based on in vitro testing [2]. The results are consistent with those of radiographic studies that have documented lower wear of HXL polyethylene in the hip compared to conventional polyethylene [3]. However, the current technique offers higher precision and reliability, and eliminates the large proportion of negative wear measurements common amongst radiographic methods. A sufficient number of liners have been measured to begin to differentiate wear between different radiation doses

Introduction:. Although commonly used, the clinical performance of highly crosslinked polyethylene in total knee arthroplasty (TKA) remains unknown and concerns exist regarding fatigue resistance and oxidation, particularly in posterior-stabilized (PS) designs. The purpose of this study is to compare highly crosslinked and conventional polyethylene in a PS TKA design at a minimum of 5-years. Methods:. A prospective cohort study of 114 consecutive TKAs in 83 patients was performed as a subset of a multi-center prospective study. All TKAs utilized an identical PS design. Conventional polyethylene inserts were used in 50 knees and second-generation highly cross-linked polythethylene inserts were implanted in 64 TKAs. All patients were followed with clinical outcome measures (Short-Form 36, Knee Society Scores, WOMAC and LEAS) and radiographically for a minimum of 5 years. Results:. The mean age of the highly cross-linked polyethylene group was 4 years less than the conventional group (p = 0.03). There was no difference in BMI (p = 0.3) or preoperative outcome measures between groups with numbers available. Seven patients died or were lost to follow up and one underwent revision for infection at 3 months postoperatively. 103 TKAs obtained minimum 5-year follow up. Mean Knee Society Scores were 12 points higher (p = 0.01) and 14 points higher (p = 0.005) in the physical function subset of the SF-36 in the highly cross-liked polyethylene group. There was no difference in the other outcome measures with the numbers available. There was no radiographic osteolysis or mechanical failures related to the tibial polyethylene in either group. Conclusion:. Mechanical failure or radiographic osteolysis was not observed with either conventional or highly cross-linked polyethylene in this PS TKA design at mid-term follow up. To our knowledge, this is the first minimum 5-year follow-up of highly cross-linked polyethylene in a posterior-stabilized design. While the results support comparative safety, longer-term follow-up is warranted to determine if wear resistance and mechanical properties of highly crosslinked polyethylene are maintained. Significance: Concerns regarding early fatigue failure and mechanical complications related to the PS post-cam articulation of highly-crosslinked polyethylene in TKR were not substantiated at a minimum of 5 years clinical followup in this prospective cohort study. Highly cross-linked polyethylene demonstrated clinical equivalency compared to conventional polyethylene, even when used in a younger and presumably more active patient group

Purpose. Cross-linking of polyethylene greatly reduces its wear rate in hip simulator studies. We conducted a systematic review and meta-analysis of randomized controlled trials comparing cross-linked to conventional polyethylene liners for total hip arthroplasty to determine if there is a clinical reduction of: 1) wear rates, 2) radiographic osteolysis, and 3) need for total hip revision. Method. A systematic search of MEDLINE, EMBASE, and COCHRANE databases was conducted from inception to May 2010 for all trials involving the use of cross-linked polyethylene for total hip arthroplasty. Eligibility for inclusion in the review was: use of a random allocation of treatments; a treatment arm receiving cross-linked polyethylene and a treatment arm receiving conventional polyethylene for total hip arthroplasty; and use of radiographic wear as an outcome measure. Eligible studies were obtained and read in full by two co-authors who then independently applied the Checklist to Evaluate a Report of a Nonpharmacological Trial to each study. Pooled mean differences were calculated for the following continuous outcomes: bedding-in, linear wear rate, three dimensional linear wear rate, volumetric wear rate, and total linear wear. Pooled risk ratios were calculated for radiographic osteolysis and revision hip arthroplasty. Results. The literature search strategy identified 194 potential studies of which 12 met inclusion criteria. All studies reported a significant reduction in radiographic wear with cross-linked polyethylene. Pooled mean differences for linear wear rate, three dimensional linear wear rate, volumetric wear rate, and total linear wear were all significantly reduced for cross-linked polyethylene. The risk ratio for radiographic osteolysis was 0.40 (95% C.I. of 0.27 to 0.58; p<0.01; I2=0%), favoring cross-linked polyethylene. There were no significant differences in need for revision total hip arthroplasty or amount of bedding-in. Conclusion. Cross-linked polyethylene liners demonstrate reduced radiographic wear and osteolysis up to 8 years after implantation. Follow up is not long enough to show a difference in need for revision total hip arthroplasty. Cross-linked polyethylene should be considered for young patients undergoing total hip arthroplasty

Introduction. Ceramic femoral heads have proven to be more scratch resistant with better wettability and improved wear characteristics compared to metal heads in the laboratory setting. The objective of this study was to compare long-term survivorship and in vivo wear rates of ceramic and metal femoral heads against conventional polyethylene articulation in young patients. Materials and Methods. Thirty-one matched pair of alumina and metal femoral heads against conventional polyethylene in young patients (≤ 65 years) were analyzed for wear and failures for mechanical reasons. The match was based on gender and age at the time of surgery. All procedures were performed between June 1989 and May 1992 by a single surgeon via posterolateral approach, using non-cemented RB (Ranawat-Bernstein) stems, HG II (Harris-Galante) cups, 4150 conventional polyethylene and 28mm femoral heads. Hospital for Special Surgery (HSS) hip score was used for clinical analysis. Wear measurements were performed between the initial anteroposterior standing pelvis radiographs, at a minimum of one year after the index procedure to eliminate the effect of bedding-in period, and the latest follow-up. Two independent observers analyzed polyethylene wear rates using the computer-assisted Roman 1.70 software. In revision cases, the wear rates were calculated from radiographs prior to revision surgery. A pair student t test was performed to analyze the statistical difference. Two-tailed ρ values less than 0.05 were considered statistically significant. Results. The mean age was 54.5 ± 8.5 at the time of surgery (range 23.3–65). Average clinical and radiographic follow-up were 17 ± 2.1 (range 12.8–20) and 14.1 ± 2.6 years (range 10–19.1) respectively. The mean HSS score in ceramic and metal groups were 30.4 ± 8 (range 24–56) and 36.6 ± 4.7 (range 20–40) respectively. The mean wear rate for the ceramic group and the metal group were 0.086 ± 0.046 mm/year and 0.137 ± 0.052 mm/year, respectively which was statistically significant (p < 0.001). There were no revisions in the ceramic group for osteolysis or loosening, however one patient required a strut graft for femoral osteolysis that was distal to the tip of the implant due to non-circumferential porous coating of the stem. There were 3 cup revisions in the metal group, all for acetabular osteolysis, and no stem lysis or loosening. The Kaplan-Meier survivorship for revision for mechanical failure in the ceramic and metal group was 100% and 90.3% respectively. Discussion. The low mean wear rate of ceramic compared to metal in this study is consistent with previously published laboratory reports. There was no revision for loosening or osteolysis in the ceramic group, with 100% survivorship for revision due to mechanical failures, which demonstrates superior durability of this material compared to metal femoral heads. The strength of this study is that this the first long-term report comparing ceramic and metal femoral heads against conventional polyethylene using a matched pair analysis in young patients

Aims. The primary objective of this study was to compare the five-year tibial component migration and wear between highly crosslinked polyethylene (HXLPE) inserts and conventional polyethylene (PE) inserts of the uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary objectives included clinical outcomes and patient-reported outcome measures (PROMs). Methods. A double-blinded, randomized study was conducted including 96 TKAs. Tibial component migration and insert wear were measured with radiostereometric analysis (RSA) at three, six, 12, 24, and 60 months postoperatively. PROMS were collected preoperatively and at all follow-up timepoints. Results. There was no clinically relevant difference in terms of tibial component migration, insert wear, and PROMs between the HXLPE and PE groups. The mean difference in tibial component migration (maximal total point migration (MTPM)) was 0.02 mm (95% confidence interval (CI) -0.07 to 0.11), which is below the value of 0.2 mm considered to be clinically relevant. Wear after five years for HXLPE was 0.16 mm (95% CI 0.05 to 0.27), and for PE was 0.23 mm (95% CI 0.12 to 0.35). The mean difference in wear rate was 0.01 mm/year (95% CI -0.02 to 0.05) in favour of the HXLPE group. Wear is mainly present on the medial side of the insert. Conclusion. There is no clinically relevant difference in tibial component migration and insert wear for up to five years between the HXLPE conventional PE inserts. For the implant studied, the potential advantages of a HXLPE insert remain to be proven under clinical conditions at longer-term follow-up. Cite this article: Bone Joint J 2023;105-B(5):518–525

Purpose. The objective of this study was to compare the wear characteristics and damage scores in highly crosslinked (XLPE) and conventional polyethylene (CPE) acetabular liners. Methods. This was a retrieval analysis of 13 XLPE liners obtained from patients who underwent revision surgery from 1999 to 2011. These patients were matched on patient demographics (age, BMI, side, sex, and length of implantation) and implant characteristics (inner diameter, outer diameter, and lip angle) to another group with CPE who underwent revision in the same time period. The only difference between implants was the use of XLPE. Wear analysis was performed with micro-computed tomography (micro-CT), provided thickness measurements across four quadrants of the bearing surface. Surface damage was scored and the pattern documented. The mean duration of implantation was 5.00 ± 3.36 years in the XLPE group and 5.19 ± 3.69 years in the CPE group (p = 0.12), with the longest duration exceeding 10 years. Results. CPE demonstrated more wear at time of retrieval with a mean thickness of 8.18 ± 1.50 mm compared to XLPE with a mean thickness of 8.91 ± 1.76 mm (p < 0.001). Damage scoring was not significantly different between the two groups, with a total damage score of 13.77 ± 3.95 in XLPE and 15.23 ± 4.63 in CPE (p = 0.18). There was no difference in the distribution of wear and damage. Conclusion. XLPE undergoes less wear than CPE, however this may not be apparent by using damage scoring alone, which is the most common retrieval analysis technique. The superior wear properties of XLPE may reduce the need for revision surgery as a result of decreased wear and osteolysis

Introduction: Hip Simulator studies show that use of highly cross-linked polyethylene in total hip replacement reduces polyethylene (PE) wear by a factor of 85–98%. Early clinical studies using RSA or computer-aided techniques of polyethylene wear measurement show a reduction of 50–80%. There is speculation about why this discrepancy in the clinical and laboratory data should exist. The results of a randomized, prospective double blinded (surgeon and patient) trial (RCT) of cross-linked versus conventional polyethylene, using a 100% reproducible method of PE wear measurement, are reported. Materials And Methods: After Ethics Committee approval, the two authors enrolled 124 patients onto an RCT comparing Enduron (non cross-linked PE) and highly cross-linked Marathon PE (DePuy, Leeds, UK). Randomization was performed by the circulating nurse intra-operatively opening an envelope which determined whether the patient received an Enduron or Marathon liner appropriate to the size of the metal shell. Liners were implanted into identical metal shells (Duraloc 300) with one screw. They articulated with identical 28mm CoCr femoral heads and cemented Charnley Elite femoral stems. All patients were followed with anteroposterior and lateral radiographs at 3 days, 6 weeks, 3 months 6 months, 1, 2, 3 and 4 years. PE wear was measured with PWAuto, a validated computer-assisted technique with 100% reproducibility and accuracy of ±0.13mm. Results: One hundred and thirteen patients had appropriate radiographs and follow-up interval. Mean follow-up was 2.6 years (range 2–4 years). Fifty-eight patients received Enduron liners and 55 patients received Marathon liners. At 6 months (E=0.32, M=0.31mm) and one year (E=0.37, M=0.31mm) the three-dimensional PE wear was identical in both groups. Thereafter, all PE wear measurements showed a significant difference in PE wear between the two groups. Wear of the conventional Enduron group continued (0.51mm at 2 years, 0.70 at 3 years, 0.97 at 4 years), while the crosslinked Marathon group showed virtually no further wear (0.32mm at 2 years, 0.32mm at 3 years, 0.33mm at 4 years). Conclusions: This is the first study to confirm that Hip Simulator predictions of cross-linked PE wear can be reproduced in-vivo. Randomization, double-blinding, and the use of a 100% reproducible technique for wear measurement add further weight to this data

Introduction. Total knee replacement (TKR) implant designs and materials have been shown to have a significant impact on tibial insert wear. A medial-pivot (MP) design theoretically should generate less wear due to a large contact area in the medial compartment and lower contact stresses. Synovial fluid aspiration studies have confirmed that a first generation MP TKR system (ADVANCE®, MicroPort Orthopedics Inc., Arlington, TN, USA) generates less wear debris than is seen with other implant designs articulating against conventional polyethylene (CP). Objectives. The objective of this study was to evaluate the in vitro wear rate of a second generation MP TKR system (EVOLUTION® Cruciate-Sacrificing, MicroPort Orthopedics Inc., Arlington, TN, USA) using CP tibial inserts and compare to previously published values for other TKR designs with CP and first or second generation crosslinked polyethylene (XLPE) tibial inserts. Methods. In vitro wear was assessed for five MP CP tibial inserts, each loaded for 5 megacycles (Mc) of simulated gait in accordance with ISO 14243–3. Insert cleaning and wear measurements were performed every 0.5 Mc in accordance with ISO 14243–2. Manufacturer websites and the MEDLINE database were searched for previously published in vitro wear rates for other TKR designs used in combination with CP and first or second generation XLPE inserts. Second generation XLPE inserts are those with additives or additional manufacturing, such as sequentially annealed and irradiated XLPE (X3®, Stryker, Mahwah, NJ, USA) and vitamin E infused polyethylene (E1®, Biomet, Warsaw, IN, USA). All TKR designs utilized cobalt-chrome (CoCr) femoral components, except Legion-Verilast that included Oxinium™ femoral components (Smith & Nephew, Memphis, TN, USA). Results. The mean wear rate for the MP system (2.0+0.2 mg/Mc) was less than half the wear rates reported for other TKR designs using CP inserts (Figure 1). The wear was also reduced or similar to those reported for all but three designs used in combination with XLPE inserts (Figure 2). Interestingly, wear rates for the MP system were approximately one-third of those reported for E1 and X3 used in combination with the Scorpio and Triathlon CR TKR systems (Stryker, Mahwah, NJ, USA). The main limitation to the current study is the use of literature comparators. While the comparison studies were all conducted using similar methods on knee wear simulator machines, there were some experimental differences that could potentially impact wear rates (e.g. diluted vs. non-diluted serum, gait patterns, types of testing machines). Conclusions. In vitro wear for a second generation MP TKR system was similar or lower than what has been previously reported for other TKR systems used with CP or XLPE tibial inserts. These results suggest that implant design may play a larger role in TKR wear debris generation than the material used for the tibial insert

Purpose of the study: The limitations of conventional polyethylene are well known (osteolysis). New bearing surfaces have been proposed for hip arthroplasty including new-generation polyethylene products. Material and methods: We compared four bearings including one metal-on-metal and one ceramic-on-ceramic bearing with results not available for analysis at this 4 years 8 month follow-up. The comparative randomized study included 102 first intention total hip arthroplasties comparing a single variable: the bearing. Common elements were: metal-back press-fit cup (Fitmore) and cemented anatomic stem (Emeraude). Variable elements were: alpha Sulène insert + 28 metal head (n=53) versus alpha Dursul insert + 28 metal head (n=49). Clinical outcome was assessed with the Postel-Merle-d’Aubigné score and the Harris score. Radiological outcome was assessed with: wear (EBRA, semiautomatic linear radiographic penetration), cup migration according to EBRA, and radiographic changes in zone 7. Results: After checking the validity of the files studied, clinical outcome was strictly the same for the two series: wear Sulène polyethylene 0.21 mm; Durasul polyethylene 0.1 mm. Cup migration was: Sulène polyethylene 0.13 mm; Durasul polyethylene 0.08 mm. Modifications of zone 7 were: Sulène polyethylene 17.8%; Durasul polyethylene 6.6%. Conclusion: With 4 years 8 months follow-up, several elements are in favor of the new-generation polyethylene inserts, confirming theoretical results with mathematical models. This length of follow-up is insufficient to draw formal conclusions concerning in vivo aging

We report the outcome of 320 primary Total Hip Arthroplasties (THA) with minimum 10-year follow-up (range 10–17 years, mean 12.6 years), performed by a single surgeon in Tauranga New Zealand, with the Exeter Contemporary Flanged all-polyethylene cup and Exeter femoral stem via a posterior approach. The aim of the study is to compare the results with the published results from the design centre and create a baseline cohort for further outcomes research in this centre.

All patients were prospectively followed at 6 weeks, 1 year, 5 years, 10 years, (and 15 years when available). Of 333 cases that matched the inclusion criteria, 13 procedures in 12 patents were excluded because of concomitant bone grafting and/or supplementary cage fixation, leaving 320 primary THA procedures in 280 patients, including 26 bilateral procedures in 13 patients.

Mean follow-up of the surviving cases was 12.6 (range 5.0-17.1) years. There were 12 revisions – 2 for fracture, 5 for instability, 1 for impingement pain and 4 for infection. There were no revisions for aseptic cup loosening. Kaplan-Meier survivorship with revision for aseptic loosening as the endpoint was 100% at 15.0 years (with minimum 40 cases remaining at risk). All-cause acetabular revision in 12 cases result in a Kaplan-Meier survival of 95.9% (95% CI: 93.5 to 98.3%).

Cemented THA with the Exeter Contemporary Flanged cup and the Exeter stem is a durable combination with results that can be replicated outside of the design centre. The Exeter Contemporary Flanged cup has excellent survivorship at 15 years when used with the Exeter stem. Cemented THA with well-proven components should be considered the benchmark against which newer designs and materials should be compared.

Purpose: Efforts to decrease polyethylene wear have lead to advances in polyethylene and counter-face technology for total hip replacement. In particular, the use of highly cross-linked polyethylene (XLPE) and more recently, oxidized zirconium (Oxinium) heads, have demonstrated significant in-vitro improvements in THR wear. This study reports on the early clinical performance and wear (measured with RSA) of an randomized controlled trial (RCT) comparing Oxinium and CoCr heads on XLPE and conventional polyethylene (CPE). Method: Forty patients were enrolled in a RCT and stratified to receive either an Oxinium (Ox) or CoCr head against either XLPE or CPE (ie 10 patients in each group). All patients had otherwise identical THRs and had tantalum beads inserted in the pelvis and polyethylene for wear analysis. There were no significant differences between groups with respect to patient demographics and the average age was 68 years (range 57–76) at index procedure. RSA wear analysis was performed immediately post-op, at six weeks, three and six months and then at one and two years. All patients are a minimum of four years post-op (average 4.6, range 4 – 5.8). Patients were followed prospectively using validated clinical outcome scores (WOMAC, SF-12, Harris Hip scores) and radiographs. Results: All health-related outcomes were significantly improved from pre-operative with a mean Harris Hip score and WOMAC at last follow-up of 90.9 and 80.2, respectively. Total 3D femoral head penetration at two years for each group were the following: CoCrXLPE (0.068±0.029mm); OxXLPE (0.115±0.038mm); CoCrCPE (0.187±0.079mm); and OxCPE (0.242±0.088mm). Thus, OxCPE was significantly higher than OxXLPE and CoCrXLPE but not CoCrCPE (p=0.001, p> 0.0001 and p=0.094, respectively). In other words, head penetration was higher with CPE compared to XLPE but there was no significant difference between Ox and CoCr heads. Similarily, regardless of head type (ie combining similar poly types), there was a significant difference in 3D head penetration at two years between CPE and XLPE ( CPE 0.213±0.086; XLPE 0.093±0.041, p> 0.0001). Conclusion: The early results of this RCT, using RSA as the wear analysis tool, indicate a significant improvement in wear with XLPE compared to CPE. However, it failed to show a clear advantage to the use of Oxinium over CoCr against either polyethylene. Longer follow-up is required to determine steady-state wear rates (after bedding-in) and allow comparison between bearing groups

The Norwegian Arthroplasty Register has shown that several designs of uncemented femoral stems give good or excellent survivorship. The overall findings for uncemented total hip replacement however, have been disappointing because of poor results with the use of metal-backed acetabular components. In this study, we exclusively investigated the medium-to long-term performance of primary uncemented metal-backed acetabular components.

A total of 9113 primary uncemented acetabular components were implanted in 7937 patients between 1987 and 2007. These were included in a prospective, population-based observational study. All the implants were modular and metal-backed with ultra-high-molecular-weight polyethylene liners. The femoral heads were made of stainless steel, cobalt-chrome (CoCr) alloy or alumina ceramic. In all, seven different designs of acetabular component were evaluated by the Kaplan-Meier survivorship method and Cox regression analysis.

Most acetabular components performed well up to seven years. When the endpoint was revision of the acetabular component because of aseptic loosening, the survival ranged between 87% and 100% at ten years. However, when the endpoint was revision for any reason, the survival estimates were 81% to 92% for the same implants at ten years. Aseptic loosening, wear, osteolysis and dislocation were the main reasons for the relatively poor overall performance of the acetabular components. Prostheses with alumina heads performed slightly better than those with stainless steel or CoCr alloy in subgroups.

Whereas most acetabular components performed well at seven years, the survivorship declined with longer follow-up. Fixation was generally good. None of the metal-backed uncemented acetabular components with ultra-high-molecular-weight polyethylene liners in our study had satisfactory long-term results because of high rates of wear, osteolysis, aseptic loosening and dislocation.

The purpose of this study was to compare oxinium versus metal-on-polyethylene wear in two consecutive prospective randomized series of low friction total hip arthroplasty at a minimum 10-year follow-up.

A total of 100 patients with a median age of 60.9 years were randomized to receive either oxinium (50 hips) or metal (50 hips) femoral head. The polyethylene socket was EtO sterilized in the first 50 patients, whereas it was highly cross-linked and remelted (XLPE) in the following 50 patients. The primary criterion for evaluation was linear head penetration measurement using the Martell system by an investigator blinded to the material. Also, a survivorship analysis was performed using wear related loosening revised or not as the end point.

Complete data were available for analysis in 40 hips at a median follow-up of 12.9 years (11 to 14), and in 36 hips at a median follow-up of 12.3 years (10 to 13) in the EtO sterilized and XLPE series, respectively.

In the EtO sterilized series, the mean steady-state wear rate was 0.245 ± 0.080 mm/year in the oxinium group versus 0.186 ± 0.062 mm/year in the metal group (p = 0.009). In the XLPE series, the mean steady-state wear rate was 0.037±0.016 mm/year in the oxinium group versus 0.036±0.015 mm/year in the metal group (p = 0.94). The survival rate at 10 years was 100% in both XLPE series, whereas it was 82.9% (IC 95%, 65–100) and 70.5% (IC95%, 50.1–90.9) in the metal-EtO and oxinium-EtO series, respectively.

This RCT demonstrated that up to 14-year follow-up, wear was significantly reduced when using XLPE, irrespective of the femoral head material. Also, no osteolysis related complication was observed in the XLPE series. In the current study, oxinium femoral heads showed no advantage over metal heads and therefore their continued used should be questioned related to their cost.

The purpose of this study was to compare the effect of femoral head material (delta ceramic versus metal) on polyethylene wear in a consecutive prospective randomized series of low friction total hip arthroplasty.

A total of 110 patients with a mean age of 60.6 ± 9.3 (34–75) years were randomized (power of 90%, alpha of 5%) to receive either a metal (55 hips) or a delta ceramic (55 hips) femoral head. The polyethylene socket was moderately cross-linked (3 Mrads of gamma radiation in nitrogen) and annealed at 130°C in all hips. All other parameters were identical in both groups. The primary criterion for evaluation was linear head penetration measurement using the Martell system, performed by an investigator blinded to the material of the femoral head. Creep and steady state wear values were calculated.

At the minimum of 3-year follow-up, complete data were available for analysis in 38 hips at a median follow-up of 4.4 years (3.0 to 5.7), and in 42 hips at a median follow-up of 4.0 years (3.0 to 5.4) in the metal and delta ceramic groups, respectively. The mean creep, measured as the linear head penetration at one year follow-up, was 0.42 ± 1.0 mm in the metal group versus 0.30 ± 0.81 mm in the delta ceramic group (Mann and Whitney test, p = 0.56). The mean steady state penetration rate from one year onwards measured 0.17 ± 0.44 mm/year (median 0.072) in the metal group versus 0.074 ± 0.44 mm/year (median 0.072) in the delta ceramic group (Mann and Whitney test, p = 0.48). No case of delta ceramic femoral head fracture was recorded, and no hip had signs of periprosthetic osteolysis.

This study demonstrated that up to 5-year follow-up, delta ceramic femoral head did not significantly influence creep neither wear of a contemporary annealed polyethylene. Longer follow-up is necessary to further evaluate the potential clinical benefits of delta ceramic.

Introduction: Simulator wear studies of crosslinked polyethylene (PE) show promising results but long-term clinical investigations addressing concerns about in-vivo aging, PE deterioration, late wear and osteolysis are scarce. This study reports the longest published follow-up comparing conventional to crosslinked PE.

Methods: Crosslinked PE (Stryker Duration: 3MRad gamma irradiation in N2, post-irradiation annealed) was compared to conventional PE (3MRad gamma irradiation in air) in a MTS hip simulator and a prospective randomized clinical study involving 48 THA patients (Stryker ABG-II stem and cup, 28mm ball diameter) with a mean follow-up of 8 (7–9) years. Patients were followed-up annually using the HHS, radiographs and wear measurements applying a digital Livermore method.

Results: Forty patients (23 conventional, 17 Duration) were left for analysis (five premature deaths, 3 loss to follow-up). Both groups were statistically non-different (p> 0.1) regarding age (63.9 years), gender, BMI, stem size, cup size, cup inclination and liner thickness leaving the insert material as the only variable. Pre-op HHS (39.7) and post-op HHS (93.7) were also not different.

At 8-years the wear rate was significantly (p< 0.01) lower for Duration [0.088 ± 0.03 mm/yr (0.02–0.14)] than conventional PE [0.142 ± 0.07 mm/yr (0.05–0.31)]. This reduction (−38%) compared well to the simulator (−45%) and did not change over time (−33% at 5-years). Radiolucencies and signs of osteolysis were also less in the Duration group (n.s.).

Discussion: In-vivo wear reduction by crosslinked PE is similar as predicted by the simulator and does not seem to deteriorate over time. Concerns over higher levels of residual free radicals after annealing instead of remelting do not seem justified. The lower wear correlated with reduced radiographic signs of osteolysis which may result in superior survival at longer follow-up.