Highly cross-linked polyethylene improves wear and mid-term failure rates for young total hip arthroplasty patients

Global mapping of institutional and hospital-based (Level II-IV) arthroplasty registries: a scoping review

PURPOSE

Four joint arthroplasty registries (JARs) levels exist based on the recorded data type. Level I JARs are national registries that record primary data. Hospital or institutional JARs (Level II-IV) document further data (patient-reported outcomes, demographic, radiographic). A worldwide list of Level II-IV JARs must be created to effectively assess and categorize these data.

METHODS

Our study is a systematic scoping review that followed the PRISMA guidelines and included 648 studies. Based on their publications, the study aimed to map the existing Level II-IV JARs worldwide. The secondary aim was to record their lifetime, publications' number and frequency and recognise differences with national JARs.

RESULTS

One hundred five Level II-IV JARs were identified. Forty-eight hospital-based, 45 institutional, and 12 regional JARs. Fifty JARs were found in America, 39 in Europe, nine in Asia, six in Oceania and one in Africa. They have published 485 cohorts, 91 case-series, 49 case-control, nine cross-sectional studies, eight registry protocols and six randomized trials. Most cohort studies were retrospective. Twenty-three per cent of papers studied patient-reported outcomes, 21.45% surgical complications, 13.73% postoperative clinical and 5.25% radiographic outcomes, and 11.88% were survival analyses. Forty-four JARs have published only one paper. Level I JARs primarily publish implant revision risk annual reports, while Level IV JARs collect comprehensive data to conduct retrospective cohort studies.

CONCLUSIONS

This is the first study mapping all Level II-IV JARs worldwide. Most JARs are found in Europe and America, reporting on retrospective cohorts, but only a few report on studies systematically.

Head, acetabular liner composition, and rate of revision and wear in total hip arthroplasty: a Bayesian network meta-analysis

Total hip arthroplasty (THA) is a common procedure for patients suffering from hip pain e.g. from osteoarthritis, osteonecrosis, or hip fractures. The satisfaction of patients undergoing THA is influenced by the choice of implant type and material, with one key factor being the selection of the appropriate material combination for the bearing surface. In this Bayesian network meta-analysis, we investigated the impact of material combinations for the bearing surface on the longevity of hip implants. The wear penetration rate per year and the total wear penetration in the liner resulting from different material combinations, as well as the survival rate at last follow-up, were examined. We analyzed a total of 663,038 THAs, with 55% of patients being women. Mean patient age was 59.0 ± 8.1 years and mean BMI 27.6 ± 2.6 kg/m2. The combination of an aluminium oxide (Al2O3) head and an Al2O3 liner demonstrated the lowest wear penetration at last follow-up and the lowest rate of wear penetration per year. Additionally, the combination of a crosslinked polyethylene (XLPE) liner and a zircon oxide (ZrO2) head demonstrated the lowest rate of revision at last follow-up. These findings underscore the importance of careful material selection for hip implant bearing surfaces to optimize their longevity and patient satisfaction after THA.

Wear, Osteolysis, and Aseptic Loosening Following Total Hip Arthroplasty in Young Patients with Highly Cross-Linked Polyethylene: A Review of Studies with a Follow-Up of over 15 Years

Total hip arthroplasty (THA) has in recent years trended toward a younger, more physically demanding patient population. Mid- to long-term studies of all ages of THA patients using highly cross-linked polyethylene (HXLPE) have been favorable, but concerns about its long-term failure and wear-related complications remain for young THA patients. In this narrative review, a search of the PubMed/MEDLINE and Cochrane databases was performed, and we identified six studies with a minimum 15-year follow-up of HXLPE with various femoral head materials. Wear-related revisions were exceedingly low for patients under the age of 55, with variable reports of non-clinically significant osteolysis. Higher activity levels, a larger femoral head size, and femoral head material were not associated with greater long-term wear rates. Young THA with metal or ceramic on HXLPE is exceedingly durable with favorable outcomes at follow-ups of over 15 years.

Risk factors for liner wear and head migration in total hip arthroplasty: a systematic review

Total hip arthroplasty (THA) is a successful orthopaedic surgical procedure, and its longevity depends on bearing components and implant fixation. Optimizing polyethylene and ceramics has led to improved wear parameters and contributed to improved long-term outcomes. The present systematic review investigated whether time span from implantation, patient characteristics and performance status exert an influence on liner wear and head migration in THA. This study was conducted in conformity to the 2020 PRISMA guidelines. All the clinical investigations which reported quantitative data on the amount of liner wear and head migration in THA were considered. Only studies which reported quantitative data at least on one of the following patient characteristics were suitable: mean age, mean BMI (kg/m2), sex, side, time span between the index THA and the last follow-up (months) were eligible. A multiple linear model regression analysis was employed to verify the association between patient characteristics and the amount of liner wear and/or head migration. The Pearson Product-Moment Correlation Coefficient was used to assess the association between variables. Data from 12,629 patients were considered. The mean length of the follow-up was 90.5 ± 50.9 months. The mean age of patients at surgery was 58.4 ± 9.4 years, and the mean BMI was 27.2 ± 2.5 kg/m2. 57% (7199 of 12,629 patients) were women, and in 44% (5557 of 12,629 patients) THAs were performed on the left. The mean pre-operative Harris hip score was 46.5 ± 6.0 points. There was evidence of a moderate positive association between the amount of liner wear and the time elapsed between the index surgery to the follow-up (P = 0.02). There was evidence of a moderate positive association between the amount of head migration and the time elapsed between the index surgery to the follow-up (P = 0.01). No further statistically significant association was found. The time elapsed between the index surgery to the follow-up was the most important factor which influence the head migration and liner wear in THA. Patients' characteristics and preoperative physical activity did not influence the amount of head migration and liner wear.

Highly crosslinked polyethylene liner thickness does not influence survival in primary total hip arthroplasty after mean follow-up of 13 years: a study of 2,565 hips with a single design liner

BACKGROUND

Concerns remain that thinner highly crosslinked polyethylene (HXLPE) liners in modern total hip arthroplasty (THA) may lead to premature liner-related failures or revision. The aim of this study was to evaluate the effect of liner-thickness on survival and revision rates of HXLPE in primary THA after more than 10 years.

METHODS

We retrospectively identified 2,565 primary THA using HXLPE with a mean follow-up of 13 years (range, 11 to 19). Patients were grouped for each millimeter (mm) of polyethylene thickness. Liner thickness varied from 4.9 to 12.7 mm, with one third measuring less than 6 mm. Primary outcomes were reoperation, all-cause revision, and liner-related revision.

RESULTS

The reoperation rate was 7.3%, the all-cause revision rate was 5.6%, and the liner-related revision rate was 0.04%. There was no significant difference in all-cause revision when stratified by liner thickness (P=0.286) and liner thickness was not associated with liner-related revision (n=1). There was a statistically, but not clinically significant difference in mean liner thickness for the cohort that underwent reoperation (7.09 vs 6.89 mm, P=0.01) and all-cause revision (7.16 vs 6.89 mm, P=0.031).

CONCLUSION

In our cohort, liner thickness was not associated with all-cause revision-free survival and there was no clinically significant difference in liner thickness between those patients who did require a reoperation or all-cause revision, and those who did not. There was only 1 liner related failure in the entire cohort. Our results indicate that using thinner HXPE liners to maximize femoral head size in THA is a safe practice that does not lead to increased revision rates or liner failure at a mean 13 years follow-up.

Mid-Term Survival of Total Hip Arthroplasty in Patients Younger Than 55-year-old

BACKGROUND

Survivorship of total hip arthroplasty (THA) in younger patients is concerning given the inverse relationship between age and lifetime risk for revision. The purpose of this study is to determine if risk of revision has improved for patients aged 55 years or younger who undergo primary THA using modern polyethylene liners.

METHODS

A retrospective review identified 2,461 consented patients (2,814 hips) with minimum 2-year follow-up who underwent primary THA at our institution between September 2007 and August 2014 using components from a single manufacturer (Zimmer Biomet), all with vitamin E-infused highly crosslinked polyethylene acetabular inserts. There were 561 patients (643 THA; 23%) aged 55 or younger and 1,900 (2,171 THA; 77%) older than 55.

RESULTS

Mean follow-up was 5.0 years for both groups. There were more male patients in the younger (55%) than older (41%) group. Body mass index (BMI) was higher in younger patients independent of gender. Improvement in Harris hip score (HHS) was similar between groups. Kaplan-Meier survival to endpoint of all cause revision was similar between groups at 12 years (P = .8808) with 97.5% (95% CI: ±0.7%) for younger versus 97.1% (95% CI: ±0.6%) for older patients. Most frequent reason for revision overall was periprosthetic femoral fracture (21; 0.75%); univariate analysis revealed risk factors were female gender (P = .28) and age ≥65 years (P = .012).

CONCLUSION

Use of modern polyethylene, such as vitamin E-stabilized highly cross-linked, liners during THA may improve survivorship in younger patients undergoing THA. Younger patients undergoing primary THA with highly cross-linked polyethylene liners had no increased rate of revision at mid-term follow-up.

Incidence of Osteolysis and Aseptic Loosening Following Metal-on-Highly Cross-Linked Polyethylene Hip Arthroplasty: A Systematic Review of Studies with Up to 15-Year Follow-up

BACKGROUND

This study compared the incidence of osteolysis, aseptic loosening, and revision following use of highly cross-linked polyethylene (HXLPE) or conventional polyethylene (CPE) at medium to long-term (>5 to 15 years) follow-up in primary total hip arthroplasty (THA). Incidences were quantified and compared with regard to age and method of implant fixation.

METHODS

Using the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines, 12 randomized controlled trials and 18 cohort studies were investigated for evidence-based outcomes following HXPLE and CPE use in 2,539 hips over a 5 to 15-year follow-up.

RESULTS

Lower rates of osteolysis, aseptic loosening, and implant revision were reported following use of HXLPE liners. Osteolysis was reduced from 25.4% with CPE to 4.05% with HXLPE in young patients, and from 29.7% to 6.6% in the older patient cohort. Similarities in osteolysis rates were observed when cemented (24.9% for CPE and 6.5% for HXLPE) and uncemented components (32.8% for CPE and 7.1% for HXLPE) were compared. No clear advantage in the type of HXLPE used was observed.

CONCLUSIONS

Over a follow-up period of up to 15 years, when compared with CPE, use of HXLPE liners reduced the incidence of osteolysis, aseptic loosening, and implant revision, regardless of the fixation method and including in younger and potentially more active patients.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Hip simulator testing of the taper-trunnion junction and bearing surfaces of contemporary metal-on-cross-linked-polyethylene hip prostheses

Adverse reaction to metal debris released from the taper-trunnion junction of modular metal-on-polyethylene (MoP) total hip replacements (THRs) is an issue of contemporary concern. Therefore, a hip simulator was used to investigate material loss, if any, at both the articulating and taper-trunnion surfaces of five 32-mm metal-on-cross-linked-polyethylene THRs for 5 million cycles (Mc) with a sixth joint serving as a dynamically loaded soak control. Commercially available cobalt-chromium-molybdenum femoral heads articulating against cross-linked polyethylene (XLPE) acetabular liners were mounted on 12/14 titanium (Ti6Al4V) trunnions. Weight loss (mg) was measured gravimetrically and converted into volume loss (mm³ ) for heads, liners, and trunnions at regular intervals. Additionally, posttest volumetric wear measurements of the femoral tapers were obtained using a coordinate measuring machine (CMM). The surface roughness (Sa) of femoral tapers was measured posttest. After 5 Mc, the mean volumetric wear rate for XLPE liners was 2.74 ± 0.74 mm³ /Mc. The CMM measurements confirmed material loss from the femoral taper with the mean volumetric wear rate of 0.045 ± 0.024 mm³ /Mc. The Sa on the worn area of the femoral taper showed a significant increase (p < 0.001) compared with the unworn area. No other long-term hip simulator tests have investigated wear from the taper-trunnion junction of contemporary MoP THRs. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:156-166, 2020.

Radiographic evaluation of linear wear of bipolar hemiarthroplasty devices in vivo

BACKGROUND

The indications for bipolar hemiarthroplasty (BHA) have been narrowing as those for total hip arthroplasty (THA) have been expanding in cases of femoral neck fracture and initial stages of osteonecrosis of femoral head (ONFH). It is difficult to measure wear in vivo after BHA because the equipment used has a dual bearing system with an inner head inside a metal outer cup. The present study aimed to (1) use a roentgenograph to measure linear wear in vivo after BHA with different acetabular conditions around the bipolar cup, and (2) compare the linear wear of polyethylene between integral bipolar cup (IBC) and Centrax prostheses.

METHODS

From among patients who had undergone BHA in our department after 1996, we analyzed 48 joints with osteoarthritis (OA) and without acetabular cartilage, as well as 25 joints with ONFH of stage 3 or less, in which the acetabular cartilage remains. Two types of bipolar cup prostheses were used: the IBC, which was gamma-sterilized in air using 2-Mrad irradiation, and the Centrax, which was gamma-sterilized in nitrogen using 3-Mrad irradiation. To image the inner head in vivo, we used high-pressure X-ray photography; we measured linear wear of the polyethylene with software using Martell Method 1.

RESULTS

Comparing mean annual linear wear between the OA and ONFH groups, using IBC prostheses in both groups, there was a significant difference (0.213 mm vs. 0.096 mm, respectively; P = 0.0177). There was a significant difference between the Centrax and IBC prostheses in OA patients in terms of linear wear (0.04 mm vs. 0.213 mm; P = 0.0181).

CONCLUSION

The linear wear of polyethylene in BHA implants can be affected by the material used to manufacture the bipolar cup. Such implants should only be used for appropriate indications.

Higher UHMWPE wear-rate in cementless compared with cemented cups with the Saturne® Dual-Mobility acetabular system

INTRODUCTION

Dual mobility (DM) total hip arthroplasty (THA) may reduce dislocation risk, but might increase the risk of high polyethylene (PE) wear due to double wearing surfaces.

METHODS

127 patients (97 female) with 129 hips operated with THA after displaced femoral neck fracture FNF between 2005 and 2011, were seen for a cross-sectional clinical follow-up. Acetabular components were Saturne® DM cups with 28mm chrome-cobalt heads in UHMWPE. Cementless cups (n = 73) were hydroxyapatite coated. Radiographs were obtained for analysis of cup placement, 2D polyethylene wear and wear-rate (PolyWare 3D), and further radiological evaluation. Activity measurements included Timed Up and Go test (TUG) and walking distance from Harris Hip Score (HHS).

RESULTS

At a mean follow-up of 2.83 (1.0-7.7) years the mean wear was 0.82 mm (range 0.17-4.51, SD 0.50), and the wear-rate was 0.37 mm (range 0.06-1.90, SD 0.29). Wear-rate of 0.43 mm/year (SD 0.30) in cementless cups was higher (p = 0.004) than 0.30 mm/year (SD 0.27) in cemented cups. Mean age at time of surgery was 75.1 years (range 30-95). There was no correlation between age at time of surgery and wear (p = 0.56). There was no correlation between cup inclination and wear-rate (p = 0.35). TUG was mean 13.4 seconds (range 4.5-30.1) and correlated with wear rate (p = 0.03).

CONCLUSIONS

At short term follow-up, the mean wear-rate in old and low demand patients was high, correlated to activity, and was above the generally accepted osteolysis threshold (0.1 mm/yr.). Cementless HA-coated cups had higher wear-rate than cemented cups.

In vivo analysis of the effects of CoCrMo and Ti particles on inflammatory responses and osteolysis

Metal wear particles play a major role in periprosthetic osteolysis and aseptic loosening in patients with total joint arthroplasty. The ability to induce osteolysis depends on the size, shape, dose, and type of the particles. However, much remains unknown regarding which type of metal particles are most reactive. We compared the inflammatory response and bone loss induced by two metal wear particles, cobalt-chromium-molybdenum (CoCrMo) and titanium (Ti), in a mouse calvaria model of osteolysis. We found that CoCrMo particles caused markedly greater bone resorption than Ti particles, according to three-dimensional images of the calvariae. CoCrMo particles activated more functional osteoclasts by significantly increasing the expression of the osteoclast-specific gene tartrate-specific acid phosphatase (Trap), calcitonin receptor (Ctr), and nuclear factor of activated T cells c1 (Nfatc1), and induced a greater increase in the ratio of receptor activator of nuclear factor kappa B ligand (RANKL)/osteoprotegerin (OPG) than Ti particles. CoCrMo particles also induced a stronger local inflammatory response, markedly increasing the expression and secretion of tumor necrosis factor-α and interleukin-1β compared with Ti particles. Therefore, CoCrMo particles induced a more severe inflammatory response and greater osteolysis than Ti particles in vivo.

Trends in total hip arthroplasty in young patients - results from a regional register

INTRODUCTION

In the United Kingdom, over 83,000 primary total hip arthroplasties (THAs) were performed last year, of which 20% are in patients under the age of 60 years. These patients generally have a longer life expectancy and a higher activity level than an older cohort, which may potentially translate to higher revision rates.

METHODS

We reviewed our Trent regional arthroplasty register to assess current surgical practice in younger patients undergoing total hip arthroplasty. The results were compared to a previous study published in 2005.

RESULTS

Between 2010 and 2012, 1,097 primary THAs were performed on patients aged 54 or less. There was an equal cohort of males to females with a mean age of 46 years of patients undergoing THA. Osteoarthritis was the commonest aetiology for patients having surgery. Reviewing the components used there were 32 different femoral and 30 different acetabular types along with 70 different combinations of components. There were 608 uncemented THAs, 313 hybrid THRs, 98 cemented THAs, 67 resurfacing arthroplasties and 11 reverse hybrid THAs.

DISCUSSION

The majority of implants were uncemented in both femur and acetabulum with consultants performing most of the procedures. There is a clear preference for uncemented femoral and acetabular fixation in the younger patient, and the trend towards uncemented components has increased over the last 10 years amongst the same surgeons. There continues to be a wide variety of cup and stem usage along with many different combinations of components, with no consensus on the ideal combination.

Higher UHMWPE wear-rate in cementless compared with cemented cups with the Saturne® Dual-Mobility acetabular system

INTRODUCTION

Dual mobility (DM) total hip arthroplasty (THA) may reduce dislocation risk, but might increase the risk of high polyethylene (PE) wear due to double wearing surfaces.

METHODS

127 patients (97 female) with 129 hips operated with THA after displaced femoral neck fracture FNF between 2005 and 2011, were seen for a cross-sectional clinical follow-up. Acetabular components were Saturne® DM cups with 28mm chrome-cobalt heads in UHMWPE. Cementless cups (n = 73) were hydroxyapatite coated. Radiographs were obtained for analysis of cup placement, 2D polyethylene wear and wear-rate (PolyWare 3D), and further radiological evaluation. Activity measurements included Timed Up and Go test (TUG) and walking distance from Harris Hip Score (HHS).

RESULTS

At a mean follow-up of 2.83 (1.0-7.7) years the mean wear was 0.82 mm (range 0.17-4.51, SD 0.50), and the wear-rate was 0.37 mm (range 0.06-1.90, SD 0.29). Wear-rate of 0.43 mm/year (SD 0.30) in cementless cups was higher (p = 0.004) than 0.30 mm/year (SD 0.27) in cemented cups. Mean age at time of surgery was 75.1 years (range 30-95). There was no correlation between age at time of surgery and wear (p = 0.56). There was no correlation between cup inclination and wear-rate (p = 0.35). TUG was mean 13.4 seconds (range 4.5-30.1) and correlated with wear rate (p = 0.03).

CONCLUSIONS

At short term follow-up, the mean wear-rate in old and low demand patients was high, correlated to activity, and was above the generally accepted osteolysis threshold (0.1 mm/yr.). Cementless HA-coated cups had higher wear-rate than cemented cups.

Late Dislocations After Total Hip Arthroplasty: Is the Bearing a Factor?

BACKGROUND

Dislocation is a leading cause of revision after primary total hip arthroplasty (THA). Although more common in the first few years after the procedure, dislocation can occur at any time. This study investigated the difference in late dislocation in ceramic-on-ceramic (CoC) bearings compared with metal-on-polyethylene and ceramic-on-polyethylene bearings in THA.

METHODS

Data were used from the Australian Orthopaedic Association National Joint Replacement Registry, and the cumulative percent revision for dislocation was estimated using the Kaplan-Meier method for the different bearing surfaces. There were 192,275 THAs included in the study with 101,915 metal-on-cross-linked polyethylene (MoXLPE), 30,256 ceramic-on-cross-linked polyethylene (CoXLPE), and 60,104 CoC.

RESULTS

The cumulative percent revision for dislocation at 13 years for MoXLPE, CoXLPE, and CoC groups was 1.2 (95% confidence interval [CI], 1.1-1.3), 1.0 (95% CI, 0.7-1.4), and 0.9 (95% CI, 0.8-1.1), respectively. There was an increased risk of revision for dislocation for MoXLPE compared with CoXLPE and CoC. When stratified for head size, there was no difference in the risk of revision for dislocation between MoXLPE, CoXLPE, and CoC in the 28- and 32-mm head sizes. With a head size of 36 mm, MoXLPE had a higher rate of dislocation compared with other materials.

CONCLUSION

Bearing surface has little impact on revision for dislocation.

Tribology of total hip arthroplasty prostheses: What an orthopaedic surgeon should know

Articulating components should minimise the generation of wear particles in order to optimize long-term survival of the prosthesis.

A good understanding of tribological properties helps the orthopaedic surgeon to choose the most suitable bearing for each individual patient.

Conventional and highly cross-linked polyethylene articulating either with metal or ceramic, ceramic-on-ceramic and metal-on-metal are the most commonly used bearing combinations.

All combinations of bearing surface have their advantages and disadvantages. An appraisal of the individual patient’s objectives should be part of the assessment of the best bearing surface.

Cite this article: Rieker CB. Tribology of total hip arthroplasty prostheses: what an orthopaedic surgeon should know. EFORT Open Rev 2016;1:52-57. DOI: 10.1302/2058-5241.1.000004.

Intra-Articular Cellular Therapy for Osteoarthritis and Focal Cartilage Defects of the Knee: A Systematic Review of the Literature and Study Quality Analysis

BACKGROUND

Intra-articular cellular therapy injections constitute an appealing strategy that may modify the intra-articular milieu or regenerate cartilage in the settings of osteoarthritis and focal cartilage defects. However, little consensus exists regarding the indications for cellular therapies, optimal cell sources, methods of preparation and delivery, or means by which outcomes should be reported.

METHODS

We present a systematic review of the current literature regarding the safety and efficacy of cellular therapy delivered by intra-articular injection in the knee that provided a Level of Evidence of III or higher. A total of 420 papers were screened. Methodological quality was assessed using a modified Coleman methodology score.

RESULTS

Only 6 studies (4 Level II and 2 Level III) met the criteria to be included in this review; 3 studies were on treatment of osteoarthritis and 3 were on treatment of focal cartilage defects. These included 4 randomized controlled studies without blinding, 1 prospective cohort study, and 1 retrospective therapeutic case-control study. The studies varied widely with respect to cell sources, cell characterization, adjuvant therapies, and assessment of outcomes. Outcome was reported in a total of 300 knees (124 in the osteoarthritis studies and 176 in the cartilage defect studies). Mean follow-up was 21.0 months (range, 12 to 36 months). All studies reported improved outcomes with intra-articular cellular therapy and no major adverse events. The mean modified Coleman methodology score was 59.1 ± 16 (range, 32 to 82).

CONCLUSIONS

The studies of intra-articular cellular therapy injections for osteoarthritis and focal cartilage defects in the human knee suggested positive results with respect to clinical improvement and safety. However, the improvement was modest and a placebo effect cannot be disregarded. The overall quality of the literature was poor, and the methodological quality was fair, even among Level-II and III studies. Effective clinical assessment and optimization of injection therapies will demand greater attention to study methodology, including blinding; standardized quantitative methods for cell harvesting, processing, characterization, and delivery; and standardized reporting of clinical and structural outcomes.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Gender Differences in Wear Rates for 28- vs 32-mm Ceramic Femoral Heads on Modern Highly Cross-linked Polyethylene at Midterm Follow-Up in Young Patients Undergoing Total Hip Arthroplasty

BACKGROUND

We report on the midterm linear and volumetric wear of highly cross-linked polyethylene (HXLPE) and survivorship of 2 prospective young total hip arthroplasty (THA) cohorts that differed by the size of ceramic femoral head used: 28 vs 32 mm.

METHODS

We prospectively analyzed 220 consecutive primary THAs in patients aged ≤50 years who received a cementless THA with a ceramic femoral head on HXLPE liner (C-HXLPE). There were 101 patients (46%) with 28-mm heads and 119 patients (54%) who received 32-mm heads at a mean follow-up of 5.5 years (range, 60-109 months). Wear was calculated using Martell Software.

RESULTS

The 28-mm C-HXLPE cohort demonstrated average linear and volumetric wear of 0.020 mm/y (standard deviation [SD], 0.074; 95% CI, 0.003-0.037) and 18.775 mm(3)/y (SD, 21.743; 95% CI, 13.773-23.778) compared with 0.032 mm/y (SD, 0.087; 95% CI, 0.013-0.050]) and 29.847 mm(3)/y (SD, 35.441; 95% CI, 22.294-37.401) in the 32-mm C-HXLPE group. Subgroup analysis by gender and head size discovered significantly greater wear in females with 32-mm heads compared with 28-mm heads in both linear (0.01, 95% CI = -0.014 to 0.033 vs 0.048, 95% CI = 0.022-0.074 mm/y, P = .004) and volumetric wear (14.11, 95% CI = 8.957-19.271] vs 29.71, 95% CI = 17.584-41.840] mm(3)/y, P = .009). We found a 96% (95% CI = 92.30%-97.94%]) survivorship by Kaplan-Meier analysis at minimum 5 years with no failures because of osteolysis.

CONCLUSIONS

Ceramic on HXLPE demonstrates extremely low wear properties in young patients at midterm follow-up. We identified a gender-dependent difference in wear based on head size, with 32-mm heads being associated with increased wear in females.

Ceramic on ceramic arthroplasty of the hip

The leading indication for revision total hip arthroplasty (THA) remains aseptic loosening owing to wear. The younger, more active patients currently undergoing THA present unprecedented demands on the bearings. Ceramic-on-ceramic (CoC) bearings have consistently shown the lowest rates of wear. The recent advances, especially involving alumina/zirconia composite ceramic, have led to substantial improvements and good results in vitro.

Alumina/zirconia composite ceramics are extremely hard, scratch resistant and biocompatible. They offer a low co-efficient of friction and superior lubrication and lower rates of wear compared with other bearings. The major disadvantage is the risk of fracture of the ceramic. The new composite ceramic has reduced the risk of fracture of the femoral head to 0.002%. The risk of fracture of the liner is slightly higher (0.02%).

Assuming that the components are introduced without impingement, CoC bearings have major advantages over other bearings. Owing to the superior hardness, they produce less third body wear and are less vulnerable to intra-operative damage.

The improved tribology means that CoC bearings are an excellent choice for young, active patients requiring THA.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):14–17.

The epidemiology of revision total knee and hip arthroplasty in England and Wales: a comparative analysis with projections for the United States. A study using the National Joint Registry dataset

Total knee arthroplasty (TKA) and total hip arthroplasty (THA) are recognised and proven interventions for patients with advanced arthritis. Studies to date have demonstrated a steady increase in the requirement for primary and revision procedures. Projected estimates made for the United States show that by 2030 the demand for primary TKA will grow by 673% and for revision TKA by 601% from the level in 2005. For THA the projected estimates are 174% and 137% for primary and revision surgery, respectively. The purpose of this study was to see if those predictions were similar for England and Wales using data from the National Joint Registry and the Office of National Statistics. Analysis of data for England and Wales suggest that by 2030, the volume of primary and revision TKAs will have increased by 117% and 332%, respectively between 2012 and 2030. The data for the United States translates to a 306% cumulative rate of increase between 2012 and 2030 for revision surgery, which is similar to our predictions for England and Wales. The predictions from the United States for primary TKA were similar to our upper limit projections. For THA, we predicted an increase of 134% and 31% for primary and revision hip surgery, respectively. Our model has limitations, however, it highlights the economic burden of arthroplasty in the future in England and Wales as a real and unaddressed problem. This will have significant implications for the provision of health care and the management of orthopaedic services in the future.