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

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

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.

Aims

The aim of this study was to identify the effect of the manufacturing characteristics of polyethylene acetabular liners on the survival of cementless and hybrid total hip arthroplasty (THA).

The ideal bearing surface for young patients undergoing total hip replacement (THR) remains controversial. We report the five-year results of a randomised controlled trial comparing the clinical and radiological outcomes of 102 THRs in 91 patients who were <  65 years of age. These patients were randomised to receive a cobalt–chrome on ultra-high-molecular-weight polyethylene, cobalt–chrome on highly cross-linked polyethylene, or a ceramic-on-ceramic bearing. In all, 97 hip replacements in 87 patients were available for review at five years. Two hips had been revised, one for infection and one for peri-prosthetic fracture.

At the final follow-up there were no significant differences between the groups for the mean Western Ontario and McMaster Universities osteoarthritis index (pain, p = 0.543; function, p = 0.10; stiffness, p = 0.99), Short Form-12 (physical component, p = 0.878; mental component, p = 0.818) or Harris hip scores (p = 0.22). Radiological outcomes revealed no significant wear in the ceramic group.

Comparison of standard and highly cross-linked polyethylene, however, revealed an almost threefold difference in the mean annual linear wear rates (0.151 mm/year versus 0.059 mm/year, respectively) (p < 0.001).

Aims. The purpose of this study is to examine six types of bearing surfaces implanted at a single institution over three decades to determine whether the reasons for revision vary among the groups and how long it takes to identify differences in survival. Methods. We considered six cohorts that included a total of 1,707 primary hips done between 1982 and 2010. These included 223 conventional polyethylene sterilized with γ irradiation in air (CPE-GA), 114 conventional polyethylene sterilized with gas plasma (CPE-GP), 116 crosslinked polyethylene (XLPE), 1,083 metal-on-metal (MOM), 90 ceramic-on-ceramic (COC), and 81 surface arthroplasties (SAs). With the exception of the COC, all other groups used cobalt-chromium (CoCr) femoral heads. The mean follow-up was 10 (0.008 to 35) years. Descriptive statistics with revisions per 100 component years (re/100 yr) and survival analysis with revision for any reason as the endpoint were used to compare bearing surfaces. Results. XLPE liners demonstrated a lower cumulative incidence of revision at 15 years compared to the CPE-GA and CPE-GP groups owing to the absence of wear-related revisions (4% for XLPE vs 18%, p = 0.02, and 15%, p = 0.003, respectively). Revisions for adverse local tissue reactions occurred exclusively among the MOM (0.8 re/100 year) and SA groups (0.1 re/100 year). The revision rate for instability was lower among hips with 36 mm and larger head sizes compared to smaller head sizes (0.2% vs 2%, p < 0.001). Conclusion. The introduction of XLPE has eliminated wear-related revisions through 15-year follow-up compared to CPE-GP and CPE-GA. Dislocation incidence has been reduced with the introduction of larger diameter heads but remains a persistent concern. The potential for adverse local tissue reactions with MOM requires continued follow-up. Cite this article: Bone Joint J 2020;102-B(7 Supple B):105–111

The purpose of this randomized controlled trial was to evaluate serum metal levels in patients undergoing total hip arthroplasty (THA) with a conventional compared to a modular dual-mobility bearing. Patients undergoing primary THA for osteoarthritis were randomized to receive either a modular dual-mobility or conventional polyethylene bearing. All patients received the same titanium acetabular and femoral component and a ceramic femoral head. Serum metal levels were drawn pre-operatively then annually for a minimum of two years postoperatively. An a priori power analysis determined that 40 patients (20 per cohort) were needed to identify a clinically relevant difference in serum cobalt of 0.35 ng/ml (ppb) at 90% power. Forty-six patients were randomized to a modular dual-mobility (n=25) or conventional bearing (n=21) with 40 at a minimum follow-up of two years. No differences in serum cobalt (mean 0.14 ppb [range, 0.075–0.29] vs. 0.20 ppb [range, 0.075–0.57], p=0.39) or chromium levels (mean 0.14 ppb [range, 0.05–0.50] vs. 0.12 ppb [range, 0.05–0.35], p=0.65) were identified between the modular dual-mobility and conventional cohorts, respectively. There was no statistically significant difference in serum Co or Cr at two years postoperatively in subjects implanted with a ceramic head and this particular dual mobility bearing in comparison to a ceramic head and a conventional acetabular component. While modest expected elevations in serum Co and Cr were observed in the dual mobility group, in no case did the Co level exceed the laboratory reference range nor the threshold of one part per billion that has been associated with adverse local tissue reactions to mechanically-assisted crevice corrosion

In total hip arthroplasty (THA), cementless cup without screw holes has the putative benefits of maximizing host bone contact and reducing osteolysis by eliminating channels to backside wear particles. However, supplemental trans-acetabular screws cannot be used. 74 hips in 60 patients receiving same model of cementless cup without screw holes (Depuy Duraloc 100 HA cup) from 6/1999 to 3/2003 were prospectively followed up. All patients were allowed to have immediate full weight bearing. Age at THA was 53 ± 13 (range 24–74) years. Osteonecrosis was the leading hip disease (45% of hips). Survivorship was assessed using revision of the cup as the end point. Radiological parameters, including lateral opening angle, vertical and horizontal migration distances of the cups were measured. Paired t-test was used to compare between the measurements in early postoperative period and at final follow up. 51 hips were assessed at minimum 20 years follow-up. The mean follow-up was 22.6 (range 21 – 25) years. All the cups were well fixed. There were two cup revisions. Conventional polyethylene (PE) was used in both hips; osteolysis occurred 17 and 18 years later. Both cups were well fixed but were revised, one due to cup mal-positioning, one due to need in upsizing the articulation. 14 other hips were revised but these cups were well fixed and not revised; 9 loosened stems (most were cemented Elite plus stems), 5 PE wear and osteolysis (all were conventional PE). At 20 years, the survivorship of cups was 96.1%. Changes in lateral opening angle, vertical and horizontal migration distances were 0.44±1.59°, 0.01±1.52mm and -0.32±1.47mm respectively, without statistical significance. This study provided evidence of excellent long-term survivorship of cementless cup without screw holes. Immediate postoperative weight-bearing also did not lead to cup migration in the long-term

Aims. Radiostereometric analysis (RSA) studies of vitamin E-doped, highly crosslinked polyethylene (VEPE) liners show low head penetration rates in cementless acetabular components. There is, however, currently no data on cemented VEPE acetabular components in total hip arthroplasty (THA). The aim of this study was to evaluate the safety of a new cemented VEPE component, compared with a conventional polyethylene (PE) component regarding migration, head penetration, and clinical results. Patients and Methods. We enrolled 42 patients (21 male, 21 female) with osteoarthritis and a mean age of 67 years (. sd. 5), in a double-blinded, noninferiority, randomized controlled trial. The subjects were randomized in a 1:1 ratio to receive a reverse hybrid THA with a cemented component of either argon-gas gamma-sterilized PE component (controls) or VEPE, with identical geometry. The primary endpoint was proximal implant migration of the component at two years postoperatively measured with RSA. Secondary endpoints included total migration of the component, penetration of the femoral head into the component, and patient-reported outcome measurements. Results. In total, 19 control implants and 18 implants in the VEPE group were analyzed for the primary endpoint. We found a continuous proximal migration of the component in the VEPE group that was significantly higher with a difference at two years of a mean 0.21 mm (95% confidence interval (CI) 0.05 to 0.37; p = 0.013). The total migration was also significantly higher in the VEPE group, but femoral head penetration was lower. We found no difference in clinical outcomes between the groups. Conclusion. At two years, this cemented VEPE component, although having a low head penetration and excellent clinical results, failed to meet noninferiority compared with the conventional implant by a proximal migration above the proposed safety threshold of RSA. The early proximal migration pattern of the VEPE component is a reason for continued monitoring, although a specific threshold for proximal migration and risk for later failure cannot be defined and needs further study. Cite this article: Bone Joint J 2019;101-B:1192–1198

Introduction. Prior to the introduction of alternative bearing surfaces, patients were typically counseled to expect that their total hip arthroplasty (THA) using conventional polyethylene would last for 10 years. With the introduction of crosslinked polyethylene and hard-on-hard bearing surfaces, revisions related to bearing surface wear were expected to decrease. We examined six different bearing surfaces used at our institution over three decades to evaluate how the overall survivorship, reasons for revision and Harris Hip Scores have changed with time. Methods. We identified six cohorts of patients with 754 primary hips done between 1983 and 2007. With the exception of 81 Birmingham hip resurfacings (BHR), all femoral components were straight, extensively porous-coated cylindrical (EPC) stems (AML and Prodigy). All cups were porous coated. In addition to the BHRs, the bearing surfaces included 223 conventional polyethylene (CPE) in a non-modular shell, 114 CPE in a modular shell, 116 crosslinked polyethylene (XLPE), 130 metal-on-metal (MOM), and 90 ceramic-on-ceramic (COC). The mean follow-up for all hip replacements is 13.0±6.0 years. Kaplan-Meier survivorship using revision for any reason as an endpoint with log rank testing was used to evaluate differences among groups. Results. Although there were no differences in survivorship at 10-year follow-up among the groups (p=0.53), the XLPE liners demonstrated improved survivorship at 15-years compared to both CPE groups owing to the absence of wear-related revisions (97% versus 83% for non-modular and 85% for modular cups respectively, p=0.001 and p=0.008). Revisions for femoral loosening have only occurred among 0.6% (4/673) of EPC stems. Revisions for cup loosening have occurred among 4% (10/223) of the non-modular cups but there are none among the other groups. The incidence of dislocation was reduced with the MOM, BHR and COC bearings that used 36-mm or larger femoral heads compared to the THAs that used 28-mm or 32-mm heads [1.1 % (3/261) versus 5.1% (25/493), p<0.01]. Infection has led to revision among 2 THAs with CPE in non-modular cups (0.9%), 2 MOM (1.5%), and 2 COC (2.2%). At 10-year follow-up, Harris Hip Scores tended to be higher among the BHRs compared to the other groups (92.1 versus 82.9, p<0.01). Discussion. The introduction of XLPE has eliminated wear-related revisions through 15-year follow-up. Hard-on-hard bearing surfaces are performing relatively well but differences are not yet discernable compared to CPE. Dislocation incidence has been reduced with the introduction of larger diameter heads but remains a persistent concern. Infection continues to occur although the incidence remains low. For any tables or figures, please contact the authors directly

A randomized trial was designed to compare the outcome of ceramic-on-ceramic with ceramic on conventional polyethylene. These patients have been followed for 15 years. 58 hips in 57 patients under 60 years of age were randomized into one of two groups. Patients were blinded to the type of hip they received. Both groups of patients were treated routinely with prophylactic peri-operative antibiotics and low molecular weight Heparin. All patients were seen at six weeks, three months and annually after surgery. Clinical and radiologic assessment was carried out at each visit. Fifty-eight hips were available for analysis, 28 in the CoP group and 29 patients in the CoC group. Mean age of both groups was less than 45 years. There were seven revisions (16%) among the 58 patients enrolled in the study. In the CoP group four patients underwent revision with head and liner exchange for eccentric polyethylene wear 16 years post-implantation. In the CoC group one patient had a cup revision at 15 years for acute aseptic instability of the acetabulum; two additional patients in the CoC group had femoral head exchange, one for fracture and one for trunnion corrosion. Both occurred 14 years after the index surgery. Functional outcome scores showed no difference between the two groups at 15 years. Radiographically there was a statistically difference in wear between the two groups. This study demonstrates that both ceramic-on-ceramic and ceramic-on-polyethylene produce satisfactory functional results with low revision rates in young patients

We compared a modular neck system with a non-modular system in a cementless anatomical total hip replacement (THR). Each group consisted of 74 hips with developmental hip dysplasia. Both groups had the same cementless acetabular component and the same articulation, which consisted of a conventional polyethylene liner and a 28 mm alumina head. The mean follow-up was 14.5 years (13 to 15), at which point there were significant differences in the mean total Harris hip score (modular/non-modular: 98.6 (64 to 100)/93.8 (68 to 100)), the mean range of abduction (32° (15° to 40°)/28 (0° to 40°)), use of a 10° elevated liner (31%/100%), the incidence of osteolysis (27%/79.7%) and the incidence of equal leg lengths (≥ 6 mm, 92%/61%). There was no disassociation or fracture of the modular neck. The modular system reduces the need for an elevated liner, thereby reducing the incidence of osteolysis. It gives a better range of movement and allows the surgeon to make an accurate adjustment of leg length

Introduction. Patients under the age of 50 who undergo a total hip arthroplasty (THA) are at high risk for wear-related complications due to their higher activity level. Previous studies have shown that highly crosslinked polyethylene (HXLPE) is more durable with no evidence of loosening compared to conventional polyethylene due to its improved wear characteristics. Unfortunately, there are few studies with long term follow-up of HXLPE in this patient population. The purpose of this study was to evaluate two questions related to this population of patients undergoing THA. First, what were the clinical outcomes for HXLPE in patients 50 years or younger at an average follow-up of 15 years? Second, was osteolysis observed in any of these hips?. Methods. Between November 1999 and April 2005, 105 THAs were performed for 90 patients 50 years of age or younger (mean, 42 years; range, 20–50 years). The mean body mass index (BMI) was 30 kg/m2 (range, 17–51 kg/m2). The mean follow-up was 15.25 years (range, 12–19 years). Eight patients (two bilateral) were lost to follow-up, which left 82 patients with 95 hips for analysis. HXLPE was the acetabular bearing for all hips. Harris Hip Scores were collected from all patients. Radiographs were obtained on all patients to evaluate for wear and osteolysis. Results. Clinical outcomes show excellent results in 81 hips, good results in ten, fair results in three, and a poor result in one hip using the Harris Hip Score. There have been no revisions, infections, or dislocations in this cohort of patients. Fourteen hips developed radiolucent lines in zone I, II, or III of the acetabulum, but none were circumferential. Two hips developed radiolucent lines in zones I and VII in the femur. None of the hips in our study developed osteolysis. Conclusions. The use of HXLPE in patients under the age of 50 who undergo THA shows excellent clinical and radiographic results at an average of 15 years follow-up

Aims

The Birmingham Hip Resurfacing (BHR) arthroplasty has been used as a surgical treatment of coxarthrosis since 1997. We present 20-year results of 234 consecutive BHRs performed in our unit.

Since the universal failure of first generation smooth threaded cups in primary total hip arthroplasty (THA), the screw-in concept of cementless acetabular cup fixation has been largely abandoned. We hypothesised that grit-blasted titanium conical cement free threaded cup shows stable long-term fixation. 198 Alloclassic total hip arthroplasties were performed in 179 patients, mean age 66 years old (22–85). 193 hips were analyzed after a mean follow-up of 10 years (1–25 years). Results were excellent or good in 184 hips (95%). Postel-Merle d'Aubigne score increased from 10.3 (range 1 to 15) pre-operatively to 16.7 (12 to 18) points and 151 hips (78%) were pain free at last FU. Radiographic signs indicating successful cup osseointegration were noted in 92% of hips. Polyethylene wear > 0.1mm/year was observed in 6 hips (3%). The main cause of re-operation/revision surgery was recurrent dislocation (9/17cases, 53%). 2 threaded cups were revised for any reason and the revision per cent observed acetabular component years was 0.10 at 10 years average FU. 20 year-survival of the metal back was 98.8% (77.2–99.9%) and 100% (79.6–100%) for revision for any reason and revision for aseptic loosening, respectively. Despite minimum PE thickness of 6.5mm and use of alumina ceramic 28mm heads, conventional polyethylene liner wear was the weak link of the acetabular reconstruction;. This study shows excellent long-lasting bone anchorage through bone on-grown of grit-blasted titanium threaded cup. Despite universal outstanding longevity in the worldwide literature, CSF threaded cups were retrieved from the European market in March 2017 due to insufficient sales, indicating that evidence base medicine may not be the major criteria influencing surgeons' choice

Lewinnek's safe zone recommendation to minimise dislocations was a target of 5–25° for anteversion angle and 30–50° for inclination angle. Subsequently, it was demonstrated that mal-positioning of the acetabular cup can also lead to edge loading, liner fracture, and greater conventional polyethylene wear. The purpose of this study was to measure the effect of acetabular cup position on highly crosslinked polyethylene wear in total hip arthroplasty (THA) at long-term follow-up. We identified all patients that underwent primary THA with a minimum of 10 years follow-up using an institutional database in London, Ontario, Canada. Patients with a single implant design consisting of a 28 mm cobalt chromium head and highly crosslinked polyethylene liner (ram extruded, GUR 1050, 100 kGy gamma irradiated, remelted, ethylene oxide sterilised) were selected for inclusion. In total, 85 hips from 79 recruited patients were analysed. Patients underwent a supine radiostereometric analysis (RSA) exam in which the x-ray sources and detectors were positioned to obtain an anterior-posterior and cross-table lateral radiograph. Acetabular cup anteversion angle, inclination angle, and 3D penetration rate (including wear and creep) were measured from the stereo radiograph pairs. At a mean follow-up of 13 years (range, 10–17 years) the mean penetration rate was 0.059 mm/year (95% CI: 0.045 to 0.073 mm/year). Mean anteversion angle was 18.2° (range, −14 to 40°) and mean inclination angle was 43.6° (range, 27 to 61°). With respect to the Lewinnek safe zone, 67% hips met the target for anteversion angle, 77% met the target for inclination angle, and 51% met the target for both. There was no correlation between anteversion angle and penetration rate (r = −0.14, p = 0.72) or between inclination angle and penetration rate (r = 0.11, p = 0.35). There was also no difference (p = 0.07) in penetration rate between hips located within the Lewinnek safe zone for both anteversion angle and inclination angle (mean 0.057 mm/year, 95% CI: 0.036 to 0.079 mm/year) and those outside the safe zone (mean 0.062 mm/year, 95% CI: 0.042 to 0.083 mm/year). Acetabular cup position had no effect on the wear rate of highly crosslinked polyethylene at long-term follow-up. Although care should still be taken to correctly position the acetabular cup for stability, highly crosslinked polyethylene is a forgiving bearing material that can withstand a wide range of cup positions without negatively impacting longevity due to wear

Aims

This study reports the ten-year wear rates, incidence of osteolysis, clinical outcomes, and complications of a multicentre randomized controlled trial comparing oxidized zirconium (OxZr) versus cobalt-chrome (CoCr) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) and highly cross-linked polyethylene (XLPE) liners in total hip arthroplasty (THA).

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.