Ten-year follow-up study of three alternative bearing surfaces used in total hip arthroplasty in young patients

Pediatric Patients Undergoing Total Hip Arthroplasty: A Single-Center Experience at Average 5.3-Year Follow-Up

BACKGROUND

Total hip arthroplasty (THA) is an increasingly popular option for pediatric end-stage hip disease. However, data regarding implant longevity and functional outcomes remain limited. This case series evaluated complication and revision rates, patient-reported outcome measures (PROMs), and implant survivorship in consecutive pediatric THA patients from a single surgeon. We hypothesized that pediatric patients would have low revision rates and excellent functional outcomes at 5-year follow-up.

METHODS

Following institutional review board approval, 74 patients under age 21 years who underwent 92 THAs between 2013 and 2023 were identified. Age, etiology, follow-up interval, complications, revisions, and preoperative and postoperative PROMs were recorded. The mean follow-up was 5.3 years (range, one to 11.2) and mean age at surgery was 16 years (range, 11 to 21). All patients underwent THA by the senior surgeon through a posterior (92.4%) or anterior (7.6%) approach; 90.2% received a ceramic on a highly cross-linked polyethylene bearing, with the remaining 9.8% receiving a metal femoral head. All patients received a cementless stem based on femoral morphology. No patients were lost to follow-up.

RESULTS

The most common etiologies were Perthes disease and corticosteroid-induced osteonecrosis (15.2% each). A patient (1.1%) with Mucopolysaccharidosis type IV required a femoral revision for aseptic loosening; no other patients were revised. All average postoperative PROMs improved significantly (P < 0.00001): Hip Disability and Osteoarthritis Outcome Score, Joint Replacement 53.4 (interquartile range [IQR], 46.7 to 70.4) to 89.9 (IQR, 85.3 to 100), EQ-5D 0.5 (IQR, 0.2 to 0.7) to 0.8 (IQR, 0.7 to 1), and EQ visual analog scale 81 (IQR, 70 to 95) to 85 (IQR, 80 to 100). Revision-free Kaplan-Meier survivorship at 5 and 10 years was 98.9%.

CONCLUSIONS

Total hip arthroplasty (THA) in patients under age 21 years yields substantial improvements in 5-year functional outcomes, regardless of etiology, with extremely low revision rates and excellent implant survivorship.

Ceramic-on-ceramic vs metal-on-crosslink polyethylene in a fully hydroxyapatite-coated total hip arthroplasty: Survivorship, complications and long-term results

Background

Few studies compare complications and results in ceramic-ceramic (CeCe) vs metal-on-crosslink polyethylene (Me-XLPE) hip prosthesis.

Methods

Prospective, non-randomized, observational analysis of 2 series of hydroxyapatite-coated Furlong Active implanted with identical protocol by 1 surgeon in 1 hospital from 2006 to 2014.

Bearing surface

CeCe (Biolox Forte/Delta) in 35 cases of 53.7 ± 10.6 years (25-69) (21 males, 60 %), Me-XLPE in 65 of 69.0 ± 8.9 years (42-81) (36 males, 55 %); age was different (p < 0.00001), but not sex (p = 0.6565). Head diameter: 28 mm in 19, 32 mm in 9 and 36 mm in 7 CeCe hips; 28 mm in 63, 32 mm in 1 and 36 mm in 1 Me-XLPe hips.

Follow-up

10.5 ± 3.1 years (1-15) in ceramic, 9.8 ± 3.8 years (2-15) in Me-XLPE.

Results

Survivorship without additional surgery or closed reduction at 15 years: 91.0 % in ceramic, 83.8 % in Me-XLPE joints. Survivorship without component exchange at 15 years: 93.9 % in ceramic, 93.6 % in Me-XLPE joints.

Complications

CeCe joints suffered 2 infections, 1 isolated dislocation, and 1 Vancouver-C fracture. Me-XLPE joints presented 2 infections (p = 0.6101), 5 isolated (p = 0.6621) and 2 recurrent dislocations (p = 0.5454), and 4 Vancouver-B fractures (p = 0.6548).At final follow-up, Harris Hip Score averaged 93.2 ± 13.7 (23-100) in ceramic and 94.3 ± 8.7 (65-100) in XLPE joints (p = 0.64552).Measured radiographic wear reached 0.06 ± 0.38 mm (0-1.5) (0.0057 mm/year) in CeCe and 0.16 ± 0.5 mm (0-2) (0.0163 mm/year) in Me-XLPE (p = 0.30302). At final radiographic follow-up, osteolysis was present in 8 Charnley-De Lee zones (6 patients) (17 %) of ceramic cups and in 25 zones (15 patients) (23 %) of XLPE cups (p = 0.980127).

Conclusion

At 10 years follow-up, metal-XLPE and ceramic-ceramic joints in Furlong-H-A.C. Active present no significant differences in complications, clinical score, wear, acetabular osteolysis, or survivorship without component exchange.Nevertheless, survivorship without any surgery or closed reduction is different because of the high rate of dislocation in 28 mm metal-poly joints.

Rate of revision and wear penetration in different polyethylene liner compositions in total hip arthroplasty: a Bayesian network meta-analysis

The present Bayesian network meta-analysis compared different types of polyethylene liners in total hip arthroplasty (THA) in terms of wear penetration (mm/year) and rate of revision. The type of liners compared were the crosslinked ultra-high molecular weight polyethylene (CPE/UHMWPE), Vitamin E infused highly cross-linked polyethylene (HXLPE-VEPE), modified cross-linked polyethylene (MXLPE), highly cross-linked polyethylene (HXLPE), Cross-linked polyethylene (XLPE). This study was conducted according to the PRISMA extension statement for reporting systematic reviews incorporating network meta-analyses of healthcare interventions. In June 2024, PubMed, Scopus, Embase, Google Scholar, and Cochrane databases were accessed. A time constraint was set from January 2000. All investigations which compared two or more types of polyethylene liners for THA were accessed. Only studies that clearly stated the nature of the liner were included. Data from 60 studies (37,352 THAs) were collected. 56% of patients were women. The mean age of patients was 60.0 ± 6.6 years, the mean BMI was 27.5 ± 2.0 kg/m2. The mean length of follow-up was 81.6 ± 44.4 months. Comparability was found at baseline between groups. XLPE and HXLPE liners in THA are associated with the lowest wear penetration (mm/year) and the lowest revision rate at approximately 7 years of follow-up.

The impact of femoral head size on the wear evolution at contacting surfaces of total hip prostheses: A finite element analysis

Total Hip Arthroplasty has been a revolutionary technique in restoring mobility to patients with damaged hip joints. The introduction of modular components of the hip prosthesis allowed for bespoke solutions based on the requirements of the patient. The femoral stem is designed with a conical trunnion to allow for assembly of different femoral head sizes based on surgical requirements. The femoral head diameters for a metal-on-polyethylene hip prosthesis have typically ranged between 22 mm and 36 mm and are typically manufactured using Cobalt-Chromium alloy. A smaller femoral head diameter is associated with lower wear of the polyethylene, however, there is a higher risk of dislocation. In this study, a finite element model of a standard commercial hip arthroplasty prosthesis was modelled with femoral head diameters ranging from 22 mm to 36 mm to investigate the wear evolution and material loss at both contacting surfaces (acetabular cup and femoral stem trunnion). The finite element model, coupled with a validated in-house wear algorithm modelled a human walking for 10 million steps. The results have shown that as the femoral head size increased, the amount of wear on all contacting surfaces increased. As the femoral head diameter increased from 22 mm to 36 mm, the highly cross-linked polyethylene (XLPE) volumetric wear increased by 61% from 98.6 mm3 to 159.5 mm3 while the femoral head taper surface volumetric wear increased by 21% from 4.18 mm3 to 4.95 mm3. This study has provided an insight into the amount of increased wear as the femoral head size increased which can highlight the life span of these prostheses in the human body.

Investigation of stair ascending and descending activities on the lifespan of hip implants

Total hip arthroplasty (THA) surgeries among young patients are on the increase, so it is crucial to predict the lifespan of hip implants correctly and produce solutions to improve longevity. Current implants are designed and tested against walking conditions to predict the wear rates. However, it would be reasonable to include the additional effects of other daily life activities on wear rates to predict convergent results to clinical outputs. In this study, 14 participants are recruited to perform stair ascending (AS), descending (DS), and walking activities to obtain kinematic and kinetic data for each cycle using marker based Qualisys motion capture (MOCAP) system. AnyBody Modeling System using the Calibrated Anatomical System Technique (CAST) full body marker set are performed Multibody simulations. The 3D generic musculoskeletal model used in this study is a marker-based full-body motion capture model (AMMR,2.3.1 MoCapModel) consisting of the upper extremity and the Twente Lower Extremity Model (TLEM2). The dynamic wear prediction model detailing the intermittent and overall wear rates for CoCr-on-XLPE bearing couple is developed to investigate the wear mechanism under 3D loading for AS, DS, and walking activities over 5 million cycles (Mc) by using finite element modelling technique. The volumetric wear rates of XLPE liner under AS, DS, and walking activities over 5-Mc are predicted as 27.43, 23.22, and 18.84 mm3/Mc respectively. Additionally, the wear rate was predicted by combining stair activities and gait cycles based on the walk-to-stair ratio. By adding the effect of stair activities, the volumetric wear rate of XLPE is predicted as 22.02 mm3/Mc which is equivalent to 19.41% of walking. In conclusion, in this study, the effect of including other daily life activities is demonstrated and evidence is provided by matching them to the clinical data as opposed to simulator test results of implants under ISO 14242 boundary conditions.

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.

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.

Dynamic computational wear model of PEEK-on-XLPE bearing couple in total hip replacements

Understanding wear mechanisms is a key factor to prevent primary failures causing revision surgery in total hip replacement (THR) applications. This study introduces a wear prediction model of (Polyetheretherketone) PEEK-on-XLPE (cross-linked polyethylene) bearing couple utilized to investigate the wear mechanism under 3D-gait cycle loading over 5 million cycles (Mc). A 32-mm PEEK femoral head and 4-mm thick XLPE bearing liner with a 3-mm PEEK shell are modeled in a 3D explicit finite element modeling (FEM) program. The volumetric and linear wear rates of XLPE liner per every million cycles were predicted as 1.965 mm³/Mc, and 0.0032 mm/Mc respectively. These results are consistent with the literature. PEEK-on-XLPE bearing couple exhibits a promising wear performance used in THR application. The wear pattern evolution of the model is similar to that of conventional polyethylene liners. Therefore, PEEK could be proposed as an alternative material to the CoCr head, especially used in XLPE-bearing couples. The wear prediction model could be utilized to improve the design parameters with the aim of prolonging the life span of hip implants.

Comparisons of Different Bearing Surfaces in Cementless Total Hip Arthroplasty: A Systematic Review and Bayesian Network Analysis

BACKGROUND

We aimed to make comparisons of different bearing surfaces in patients after cementless total hip arthroplasty.

METHODS

The network meta-analysis was guided by the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guideline. The primary outcomes were implant survival and Harris hip score (HHS). Secondary outcomes included linear wear rates and serum level of metal ions. Subgroup analyses were performed by: (1) classifying head sizes as small and large; (2) femoral heads as ceramic and metal; and (3) liners as metal, ceramic, polyethylene, highly cross-linked polyethylene (HXP), or vitamin E-infused highly cross-linked polyethylene (HXPE). A total of 64 eligible RCTs with different bearings were assessed. Overall inconsistency and heterogeneity were acceptable.

RESULTS

In the 10 years follow-up, metal-on-polythene and ceramic-on-polythene bearings with small heads showed higher risk for revisions compared with metal-on-HXP and ceramic-on-HXP bearings with small heads. Similarly, only metal or ceramic-on-polythene bearings with small heads showed inferiority in HHS compared with other bearings. Conventional polyethylene liners showed higher linear wear rates compared with HXP, HXPE, and ceramic liners at 5 and 10 years after surgery, while metal-on-metal and ceramic-on-metal bearings showed higher serum level of cobalt and chromium.

CONCLUSION

Bearings containing HXP, HXPE, and ceramic liners showed comparable survivorship and hip function at follow-up of 5 and 10 years. Hard-on-hard bearings containing metal had higher serum level of metal ions than others. Bearings containing conventional polyethylene had worse performance in terms of implant survival, hip function, and wear rates.

LEVEL OF EVIDENCE

Level I.

How does bicycling affect the longevity of Total Hip Arthroplasty? A finite element wear analysis

As the number of young and active individuals undergoing Total Hip Arthroplasty (THA) are increasing yearly, there is a need for hip prostheses to have increased longevity. Current investigations into the longevity of these prostheses only include walking as the patient's activity as there is limited data on the amount and intensity of other activity performed by the patient. To further understand the evolution of wear and increase the longevity of these implants, the impact of different activities on the hip prosthesis needs to be investigated. In this study, a finite element model and wear algorithm was developed to simulate both walking and bicycling over a 5-year period. The XLPE acetabular cup volumetric wear rate was found to be 33 mm³/yr while the femoral head taper wear rates were between 0.01 - 0.39 mm³/yr. The results showed that by adding bicycling of up to 80 km per week with normal walking activity, the XLPE mean volumetric wear rate increased by 67% and the metallic mean volumetric wear rate by 11%. However, the patient may gain further health benefits from this additional activity. Assistive electric bikes may also be used to further reduce the loads on the hip joint, allowing for lower amounts of wear.

Ceramic Femoral Heads Exhibit Lower Wear Rates Compared to Cobalt Chrome: A Meta-Analysis

BACKGROUND

Wear between the femoral head and acetabular liners continues to limit the longevity of total hip arthroplasty implants despite advances in implant materials. The purpose of this meta-analysis was to compare linear wear rates of cobalt-chromium (CoCr) and fourth-generation ceramic femoral heads on highly cross-linked polyethylene (XLPE) liners.

METHODS

A systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was conducted to identify all studies between 2003 and 2020 that examined in vivo wear rates of either fourth-generation ceramics or CoCr femoral heads on XLPE liners. Studies were analyzed in a weighted means analysis of wear rates and a random effects meta-analysis.

RESULTS

A total of 36 studies met inclusion criteria (1,657 CoCr and 659 ceramic patients). The pooled, weighted mean wear rate was 0.063 mm/year (standard deviation [SD]: 0.061, confidence interval [CI]: 0.049-0.077) for CoCr and 0.047 mm/year (SD: 0.057, CI: 0.033-0.062; P < .01) for ceramic (P < .01). A meta-analysis of 4 studies directly comparing ceramic and CoCr found that CoCr heads demonstrated 0.029 mm/year more wear than ceramic heads (95% CI: 0.026-0.059, P = .306). Mean wear for 32-mm heads was significantly higher for ceramic (P < .01), while mean wear for 36-mm heads was significantly higher for CoCr (P < .01).

CONCLUSION

Fourth-generation ceramic femoral heads were found to have significantly lower wear rates than CoCr heads. Unlike previous studies, this meta-analysis included only in vivo studies and those with the same generation of highly XLPE liners.

Long-Term Wear-Related Complications of Cross-Linked Versus Conventional Polyethylene After Total Hip Arthroplasty: A Meta-Analysis

BACKGROUND

Highly cross-linked polyethylene (HXLPE) liners have been developed to address the wear-related problems associated with conventional polyethylene (CPE) such as osteolysis or aseptic loosening in total hip arthroplasty (THA). In this systematic meta-analysis, we compared the long-term efficacy in preventing radiological osteolysis and revision surgery between HXLPE and CPE.

METHODS

We included 14 studies that compared HXLPE and CPE reporting the incidence of wear-related complications with a minimum follow-up of 10 years. We investigated 5 wear-related complications: osteolysis, excessive wear, linear wear rate, revision surgery due to wear, and progress of osteolysis/aseptic loosening. We conducted a pair-wise meta-analysis to estimate odds ratio (OR) and a proportional meta-analysis to estimate the incidence of each complication.

RESULTS

Among 1,175 THAs, 220 osteolysis and 78 wear-related revisions were detected. The use of HXLPE reduced the risk of overall osteolysis (OR 0.30; P = .001), excessive wear (OR 0.10; P < .001), linear wear rate (weighted mean difference 0.09; P < .001), the risk of overall wear-related revisions (OR 0.06; P < .001), and revisions due to aseptic loosening (OR 0.23; P = .015). As per the proportional meta-analysis, the pooled prevalence of osteolysis, excessive wear, and the overall wear-related revision rate were 14%, 8%, and 3% in HXLPE and 25%, 33%, and 20% in CPE, respectively.

CONCLUSION

The current evidence shows that HXLPE dramatically reduced the rate of osteolysis and wear-related revision surgery. However, as polyethylene wear and osteolysis still lead to revision surgery, ongoing clinical and retrieval studies are required to analyze long-term outcomes.

New polyethylenes in total hip arthroplasty : a 20- to 22-year follow-up study

AIMS

A significant reduction in wear at five and ten years was previously reported when comparing Durasul highly cross-linked polyethylene with nitrogen-sterilized Sulene polyethylene in total hip arthroplasty (THA). We investigated whether the improvement observed at the earlier follow-up continued, resulting in decreased osteolysis and revision surgery rates over the second decade.

METHODS

Between January 1999 and December 2001, 90 patients underwent surgery using the same acetabular and femoral components with a 28 mm metallic femoral head and either a Durasul or Sulene liner. A total of 66 hips of this prospective randomized study were available for a minimum follow-up of 20 years. The linear femoral head penetration rate was measured at six weeks, one year, and annually thereafter, using the Dorr method on digitized radiographs with a software package.

RESULTS

In the Durasul group, no patients underwent revision due to loosening or showed radiological evidence of osteolysis. In the Sulene group, four patients (four hips) were revised due to femoral component loosening. The 20-year cumulative failure incidence in the presence of the competing event of death for revision surgery was 4.5% (95% confidence interval (CI) 0.8 to 13.6) in the Durasul group, and 8.9% (95% CI 2.8 to 19.5) in the Sulene group. The mean wear one year after surgery was 0.09 mm (SD 0.007) in the Durasul group and 0.24 (SD 0.015) in the Sulene group (p < 0.001). From one to 20 years after surgery, the mean total penetration was 0.32 mm (SD 0.045) in the Durasul group and 1.07 mm (SD 0.13) in the Sulene group (p < 0.001). Mean femoral head penetration at 20 years was approximately 70.0% less in the Durasul group than the Sulene group.

CONCLUSION

The significant reduction in femoral head penetration obtained with the Durasul compared with Sulene in uncemented THA resulted in lower osteolysis and revision rates after 20 years.Cite this article: Bone Joint J 2022;104-B(9):1032-1038.

Oxidized zirconium versus cobalt-chrome femoral heads in total hip arthroplasty: a multicentre prospective randomized controlled trial with ten years' follow-up

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).

METHODS

Patients undergoing primary THA were recruited from four institutions and prospectively allocated to the following treatment groups: Group A, CoCr femoral head with XLPE liner; Group B, OxZr femoral head with XLPE liner; and Group C, OxZr femoral head with UHMWPE liner. All study patients and assessors recording outcomes were blinded to the treatment groups. The outcomes of 262 study patients were analyzed at ten years' follow-up.

RESULTS

Patients in Group C were associated with increased mean liner wear rates compared to patients in Group A (0.133 mm/yr (SD 0.21) vs 0.031 mm/yr (SD 0.07), respectively; p < 0.001) and Group B (0.133 mm/yr (SD 0.21) vs 0.022 mm/yr (SD 0.05), respectively; p < 0.001) at ten years' follow-up. Patients in Group C were also associated with increased risk of osteolysis and aseptic loosening requiring revision surgery, compared with patients in Group A (7/133 vs 0/133, respectively; p = 0.007) and Group B (7/133 vs 0/135, respectively; p = 0.007). There was a non-statistically significant trend towards increased mean liner wear rates in Group A compared with Group B (0.031 mm/yr (SD 0.07) vs 0.022 mm/yr (SD 0.05), respectively; p = 0.128). All three groups were statistically comparable preoperatively and at ten years' follow-up when measuring normalized Western Ontario and McMaster Universities Osteoarthritis Index (p = 0.410), 36-Item Short Form Health Survey (p = 0.465 mental, p = 0.713 physical), and pain scale scores (p = 0.451).

CONCLUSION

The use of UHMWPE was associated with progressively increased annual liner wear rates after THA compared to XLPE. At ten years' follow-up, the group receiving UHMWPE demonstrated an increased incidence of osteolysis and aseptic loosening requiring revision surgery compared to XLPE. Femoral heads composed of OxZr were associated with trend towards reduced wear rates compared to CoCr, but this did not reach statistical significance and did not translate to any differences in osteolysis, functional outcomes, or revision surgery between the two femoral head components. Cite this article: Bone Joint J 2022;104-B(7):833-843.

Highly Crosslinked Polyethylene Liners Have Negligible Wear at 10 Years: A Radiostereometric Analysis Study

BACKGROUND

The introduction of crosslinked ultra-high molecular weight polyethylene (XLPE) acetabular liners has been very successful, with decreased wear and reduction in the rates of revision hip arthroplasties. XLPE is the preferred articulation for most surgeons; however, there are concerns about the long-term performance of XLPE liners created with different manufacturing processes, which may lead to time-dependent failure, including accelerated wear, after several years.

QUESTIONS/PURPOSES

(1) What is the amount and rate of wear during the first 10 years using radiostereometric analysis (RSA) measurements of patients who had THAs that included a second-generation XLPE bearing? (2) Does the rate of wear change after 5 years in situ?

METHODS

This is a brief follow-up of a previous RSA study. In that study, we prospectively enrolled 21 patients with osteoarthritis who underwent primary cementless THA with an XLPE acetabular liner (three cycles of 3Mrad annealed) and 32-mm articulation. That group represented 44% of the 48 THAs performed by the surgeon at the hospital where RSA was available; 16 had cemented hips, leaving 32 who were invited to participate in this study. Of those, 11 lived rurally and declined to participate, leaving 21 patients who were included in the initial study. Since then, three patients died, one developed dementia and could not participate, and one had revision THA for reasons other than wear, leaving 16 patients available for analysis at 10 years. Tantalum markers were inserted during surgery, and all patients had RSA radiographs taken at 1 week, 6 months, and 1, 2, 5, and 10 years postoperatively. Femoral head penetration into the acetabular component was measured with RSA, including bedding-in during the first year and annual wear thereafter.

RESULTS

The median medial, proximal, anterior, two-dimensional (2D), and three-dimensional (3D) wear rates between 1 and 10 years were -0.001, 0.004, -0.012, 0.000, and 0.002 mm/year, respectively. No patient in this cohort had a proximal or 2D wear rate greater than 0.025 mm/year. The median proximal wear rate between 5 and 10 years (0.002 mm/year) was not greater than wear at 1 to 5 years (0.004 mm/year).

CONCLUSION

Femoral head penetration in this second-generation XLPE liner remained very low at 10 years and accelerated wear after 5 years in situ did not occur. Concerns about late-onset wear from oxidation of irradiated-annealed XLPE were not observed. The low level of wear remains encouraging for the future clinical performance of this material.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Use of Total Hip Arthroplasty in Patients Under 21 Years Old: A US Population Analysis

BACKGROUND

The purpose of this study is to evaluate trends in the use of total hip arthroplasty (THA) in the United States in patients under 21 years of age. Specifically, we examined the frequency of THA in this patient population over the past 2 decades, the epidemiologic characteristics of patients under 21 who underwent THA, and the characteristics of the hospitals where these procedures were performed.

METHODS

We retrospectively reviewed the Kids' Inpatient Database, an inpatient US national weighted sample of hospital admissions in patients under 21 from approximately 4200 hospitals in 46 states. We queried the database using Current Procedural Terminology codes for elective and non-elective primary THA for the years 2000-2016. We utilized the International Classification of Diseases, Ninth Revision and International Classification of Diseases, Tenth Revision codes to determine primary diagnoses.

RESULTS

The weighted total number of THAs performed in patients under 21 in the Kids' Inpatient Database increased from 347 in 2000 to 551 in 2016. The most common diagnoses were osteonecrosis, osteoarthritis, and inflammatory arthritis. The frequency of THA for osteonecrosis increased from 24% in 2000 to 38% in 2016, while the frequency of THA for inflammatory arthritis decreased from 27% in 2000 to 4% in 2016.

CONCLUSION

The number of THAs in patients under 21 in the United States has increased over the past 2 decades and these procedures are increasingly performed in urban teaching hospitals. The decrease in THA for inflammatory arthritis in this population likely reflects improvements in medical management during the study period.

Ceramic Bearings Are Associated With a Significantly Reduced Revision Rate in Primary Hip Arthroplasty: An Analysis From the National Joint Registry for England, Wales, Northern Ireland, and the Isle of Man

BACKGROUND

Prosthetic joint infection (PJI) is a devastating complication. Studies have suggested reduction in PJI with the use of ceramic bearings.

METHODS

Adult patients who underwent total hip arthroplasty (THA) using an uncemented acetabular component with ceramic-on-ceramic (CoC), ceramic-on-polyethylene (CoP), or metal-on-polyethylene (MoP) bearing surfaces between 2002 and 2016 were extracted from the National Joint Registry for England, Wales, Northern Ireland, and the Isle of Man. A competing risk regression model to investigate predictors of each revision outcome was used. Time-to-event was determined by duration of implantation since primary surgery with competing risks being death or revision. The results were adjusted for age, gender, American Association of Anaesthesiologists grade, body mass index, surgical indication, intraoperative complications, and implant data.

RESULTS

In total, 456,457 THAs (228,786 MoP, 128,403 CoC, and 99,268 CoP) were identified. Multivariable modeling showed that the risk of revision for PJI was significantly lower with CoC (risk ratio 0.748, P < .001) and CoP (risk ratio 0.775, P < .001) compared to MoP. Significant reduction in risk of aseptic and all-cause revision was also seen. The significant protective effect of ceramic bearing was predominantly seen 2 years after implantation. Aseptic revision beyond 2 years reduced by 18.1% and 24.8% for CoC and CoP (P < .001), respectively. All-cause revision rate beyond 2 years reduced by 21.6% for CoC and 27.1% for CoP (P < .001) CONCLUSION: This study demonstrates an association between the use of ceramic as part of the bearing, with lower rates of revision for all causes, revision for infection, and revision for aseptic causes, supporting ceramic bearings in THA.

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.

Computational method for bearing surface wear prediction in total hip replacements

Total hip replacement (THR) is a revolutionary treatment when a hip joint becomes severely damaged. Wear is known as one of the main reasons for THR failure. Current experimental techniques to investigate the wear at the bearing surfaces of THRs are time-consuming, complicated and expensive. In this study, an in-house fretting wear algorithm has been further developed to investigate the wear damage that occurs on bearing surfaces of THRs and its consequence on the longevity of the implants. A 3D finite element model has been created with a 36 mm diameter Cobalt-Chromium femoral head and a 4 mm thick cross-linked polyethylene bearing liner. A gait loading cycle was used to simulate walking for up to 5 million cycles (Mc). The wear algorithm extracts relative displacements and contact shear stresses from the finite element package to predict the linear and volumetric wear rates. This method is shown to have modelled the evolution of wear effectively and found it to be similar to those from experimental analyses. The linear and volumetric wear per million cycles predicted in this study were 0.0375mm/Mc and 33.6mm³/Mc which are comparable to those measured in-vivo THRs. The wear patterns obtained from this study are also comparable to the wear patterns shown on available conventional polyethylene liners. This method can be used to further aid in the design and clinical technique to reduce wear rate in THRs.

Prevention of infection in primary THA and TKA

Rates of peri-prosthetic joint infection (PJI) in primary total hip and total knee arthroplasty range between 0.3% and 1.9%, and up to 10% in revision cases. Significant morbidity is associated with this devastating complication, the economic burden on our healthcare system is considerable, and the personal cost to the affected patient is immeasurable.

The risk of surgical site infection (SSI) and PJI is related to surgical factors and patient factors such as age, body mass index (BMI), co-morbidities, and lifestyle. Reducing the risk of SSI in primary hip and knee arthroplasty requires a multi-faceted strategy including pre-operative patient bacterial decolonization, screening and avoidance of anaemia, peri-operative patient warming, skin antisepsis, povidone-iodine wound lavage, and anti-bacterial coated sutures.

This article also considers newer concepts such as the influence of bearing surfaces on infection risk, as well as current controversies such as the potential effects of blood transfusion, laminar flow, and protective hoods and suits, on infection risk.

Cite this article: EFORT Open Rev 2020;5:604-613. DOI: 10.1302/2058-5241.5.200004

Overview of Randomized Controlled Trials in Primary Total Hip Arthroplasty (34,020 Patients): What Have We Learnt?

Aim:

To provide an overview of randomized controlled trials (RCTs) in primary total hip arthroplasty summarizing the available high-quality evidence.

Materials and Methods:

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA), we searched the Cochrane Central Register of Controlled Trials (2020, Issue 1), Ovid MEDLINE, and Embase. We excluded nonrandomized trials, trials on neck of femur fractures or revision surgery, systematic reviews, and meta-analyses. Trials that met our inclusion criteria were assessed using a binary outcome measure of whether they reported statistically significant findings. These were then classified according to the intervention groups (surgical approach, fixation, and component design use, among others).

Results:

Three hundred twelve RCTs met the inclusion criteria and were included. The total number of patients in those 312 RCTs was 34,020. Sixty-one RCTs (19.5%) reported significant differences between the intervention and the control groups. The trials were grouped into surgical approach 72, fixation 7, cement 16, femoral stem 46, head sizes 5, cup design 18, polyethylene 25, bearing surfaces 30, metal-on-metal 30, resurfacing 20, navigation 15, robotics 3, surgical technique 12, and closure/drains/postoperative care 13 RCTs.

Discussion:

The evidence reviewed indicates that for the vast majority of patients, a standard conventional total hip arthroplasty with a surgical approach familiar to the surgeon using standard well-established components and highly cross-linked polyethylene leads to satisfactory clinical outcomes. This evidence also offers arthroplasty surgeons the flexibility to use the standard and cost-effective techniques and achieve comparable outcomes.

Wear Rates of XLPE Nearly 50% Lower Than Previously Thought After Adjusting for Initial Creep: An RCT Comparing 4 Bearing Combinations

Background

The ideal bearing combination for total hip arthroplasty (THA) remains debatable. Highly cross-linked polyethylene (XLPE) is widely used, but long-term wear rates are not fully known, nor is how much the initial "creep," if any, affects overall wear. Additionally, the use of oxidized zirconium (OxZir) is purported to lower polyethylene wear rates, but this has not been proven. We present the 10-year data of a cohort of patients who underwent THA. Patients were prospectively randomized to 1 of 4 bearing combinations: a conventional ultra-high molecular weight polyethylene (UHMWPE) or XLPE acetabular liner coupled with either a cobalt-chromium (CoCr) or OxZir femoral head. The aims of the study were to (1) assess the extent to which creep affected overall wear rates and (2) assess wear rates between OxZir and CoCr with polyethylene.

Methods

A total of 92 hips (92 patients) between the ages of 22 and 65 years (mean, 52.2 ± 9.3 years) were randomized to 4 groups. At 10 years, 70 (76%) of the hips were available for analysis; patients who had undergone revision, had died, or were lost to follow-up were excluded from final analysis. Radiographic analysis was performed using a validated digital assessment program to determine linear, volumetric, and directional wear of the polyethylene for all 4 bearing couples. Radiographic assessments were performed immediately postoperatively, at 6 and 12 weeks, and then annually for a minimum of 10 years.

Results

XLPE had significantly lower wear rates than UHMWPE. Once creep was eliminated, annual and overall wear rates were nearly 50% lower than have been previously reported. This was proportionally more important in the XLPE group than in the UHMWPE group. There was a nonsignificant trend toward a lower wear rate with OxZir heads.

Conclusions

Creep plays a notably more important role than first thought. Once creep was eliminated, the overall wear rate was even lower than previously assumed. This has important implications for the overall survivorship of hip arthroplasty implants.

Level of Evidence

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

N-Acetyl-Cysteine Reduces Blood Chromium and Cobalt Levels in Metal-on-Metal Hip Arthroplasty

The most common reasons for revision of metal-on-metal hip arthroplasty are aseptic loosening and metal reaction. Failure of a metal-on-metal implant due to the aggressive destruction of periprosthetic tissues may require extensive reconstruction procedures. The aim of this case report is to describe the treatment in an asymptomatic patient with high levels of chromium and cobalt, using chelation therapy. The rational use of N-acetyl-cysteine (NAC) involves thiol groups to chelate sites for metals. More than 10 years after the metal-on-metal hip arthroplasty, the patient did not have to undergo revision surgery; the levels of the ions in the blood were considerably lowered (chromium from 4.51 mcg/L to 1.85 mcg/L; cobalt from 7.78 UG/L to 0.8 UG/L) after using NAC without adverse effects.

Eighteen-Year Follow-Up Study of 2 Alternative Bearing Surfaces Used in Total Hip Arthroplasty in the Same Young Patients

BACKGROUND

This study compares the long-term functional, radiographic, and computed tomography scan outcomes and implant survivorship of ceramic-on-ceramic total hip arthroplasty (C-O-C THA) and ceramic-on-highly cross-linked polyethylene total hip arthroplasty (C-O-HXLPE THA) in the same patients.

METHODS

In this randomized, prospective trial conducted between January 1999 and April 2003, 133 patients (266 hips) younger than 55 years were enrolled. Each patient received C-O-C THA in 1 hip and a C-O-HXLPE THA in the other. The mean follow-up was 17.1 years (range, 15-18 years); there were 84 men and 49 women with a mean age of 53 ± 7 years (range, 25-55 years).

RESULTS

At the latest follow-up, mean Harris hip scores (94 vs 93 points; P = .861), pain scores (43 vs 42 points; P = .651), and patient satisfaction scores (7.8 vs 7.6 points; P = .379) were not different between the 2 groups. Eight hips (3%) in the C-O-C THA had an audible squeaking sound. The mean annual penetration rate of HXLPE was 0.0162 ± 0.032 mm per year. No osteolysis was recorded on radiographs or computed tomography scans in either group. At 17.1 years, the survival rate of the acetabular component was 97% in the C-O-C bearing group and 98% in the C-O-HXLPE bearing group (P = .923). The survival rate of the femoral component was 99% in both groups.

CONCLUSION

Both C-O-C THA and C-O-HXLPE THA functioned well, with no osteolysis at mean of 17.1-year follow-up.

Crystalline Characteristics and Their Influence in the Mechanical Performance in Poly(ε-Caprolactone) / High Density Polyethylene Blends

Blends of poly(ε-caprolactone) (PCL) and high-density polyethylene (HDPE) have been prepared at different compositions in order to assess the effect of HDPE on gas transport and mechanical behaviors of PCL. Previous to this evaluation, a complete morphological, structural, and thermal characterization were performed using techniques, including SEM, contact angle, FTIR, differential scanning calorimetry, and X-ray diffraction with synchrotron radiation at small and wide angles. Low HDPE incorporations allow interactions to be established at interfaces in the amorphous regions and the enhancement of the mechanical performance. Consequently, the addition of a small amount of HDPE (ranging from 5 to 10 wt%) appears to be appropriate in certain bio-applications where a higher mechanical behavior is required.

The current role of robotics in total hip arthroplasty

Robotic total hip arthroplasty (THA) improves accuracy in achieving the planned acetabular cup positioning compared to conventional manual THA.

Robotic THA improves precision and reduces outliers in restoring the planned centre of hip rotation compared to conventional manual THA.

Improved accuracy in restoring hip biomechanics and acetabular cup positioning in robotic THA have not translated to any differences in early functional outcomes, correction of leg-length discrepancy, or postoperative complications compared to conventional manual THA.

Limitations of robotic THA include substantive installation costs, additional radiation exposure, steep learning curves for gaining surgical proficiency, and compatibility of the robotic technology with a limited number of implant designs.

Further higher quality studies are required to compare differences in conventional versus robotic THA in relation to long-term functional outcomes, implant survivorship, time to revision surgery, and cost-effectiveness.

Cite this article: EFORT Open Rev 2019;4:618-625. DOI: 10.1302/2058-5241.4.180088

Is Oxidized Zirconium Femoral Head Superior to Other Bearing Types in Total Hip Arthroplasty? A Systematic Review and Meta-Analysis

BACKGROUND

Oxidized zirconium (OxZi) is a relatively new type of material that combines the strength of a metal with the surface/wears properties of a ceramic. Our aim was to investigate whether OxZi femoral heads lead to lower polyethylene wear, higher survival rate, and better clinical outcomes than the other bearing types in patients treated with total hip arthroplasty (THA).

METHODS

Two reviewers independently conducted a systematic search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses using the MEDLINE/PubMed database and the Cochrane Database of Systematic Reviews. These databases were queried with the terms: a. "oxidized" AND "zirconium" AND "total" AND "hip" AND "arthroplasty"; b. "oxinium" AND "total" AND "hip" AND "arthroplasty". The primary outcome measures were the survival rate of the bearing surfaces as well as the polyethylene wear.

RESULTS

The vast majority (85.7%) of the studies, which reported the mean polyethylene wear rate, showed that there was not any significant difference between OxZi and cobalt-chrome (CoCr) femoral heads (rate ratio: 0.836; 95% confidence interval: 0.362-1.928; P = .674). All studies comparing the survival rate of OxZi and CoCr femoral heads illustrated almost excellent survivorship with both implants.

CONCLUSION

OxZi femoral heads did not lead to lower polyethylene wear rate or higher survival rate, when compared with CoCr femoral heads in patients treated with THA. On the basis of these results and taking into account the higher cost of these implants, we would not recommend the routine use of OxZi femoral heads in primary THAs.

LEVEL OF EVIDENCE

Systematic review and meta-analysis of therapeutic studies I-III.

Cemented Exeter total hip arthroplasty with a 32 mm head on highly crosslinked polyethylene: Does age influence functional outcome, satisfaction, activity, stem migration, and periprosthetic bone mineral density?

Objectives

Our primary aim was to describe migration of the Exeter stem with a 32 mm head on highly crosslinked polyethylene and whether this is influenced by age. Our secondary aims were to assess functional outcome, satisfaction, activity, and bone mineral density (BMD) according to age.

Patients and Methods

A prospective cohort study was conducted. Patients were recruited into three age groups: less than 65 years (n = 65), 65 to 74 years (n = 68), and 75 years and older (n = 67). There were 200 patients enrolled in the study, of whom 115 were female and 85 were male, with a mean age of 69.9 years (sd 9.5, 42 to 92). They were assessed preoperatively, and at three, 12 and, 24 months postoperatively. Stem migration was assessed using Einzel-Bild-Röntgen-Analyse (EBRA). Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Harris Hip Score (HHS), Hip Disability and Osteoarthritis Outcome Score (HOOS), EuroQol-5 domains questionnaire (EQ-5D), short form-36 questionnaire (SF-36,) and patient satisfaction were used to assess outcome. The Lower Extremity Activity Scale (LEAS), Timed Up and Go (TUG) test, and activPAL monitor (energy expelled, time lying/standing/walking and step count) were used to assess activity. The BMD was assessed in Gruen and Charnley zones.

Results

Mean varus/valgus tilt was -0.77⁰ and axial subsidence was -1.20 mm. No significant difference was observed between age groups (p ⩾ 0.07). There was no difference according to age group for postoperative WOMAC (p ⩾ 0.11), HHS (p ⩾ 0.06), HOOS (p ⩾ 0.46), EQ-5D (p ⩾ 0.38), patient satisfaction (p ⩾ 0.05), or activPAL (p ⩾ 0.06). Patients 75 years and older had a worse SF-36 physical function (p = 0.01) and physical role (p = 0.03), LEAS score (p < 0.001), a shorter TUG (p = 0.01), and a lower BMD in Charnley zone 1 (p = 0.02).

Conclusion

Exeter stem migration is within normal limits and is not influenced by age group. Functional outcome, patient satisfaction, activity level, and periprosthetic BMD are similar across all age groups.

Cite this article: N. D. Clement, M. Bardgett, K. Merrie, S. Furtado, R. Bowman, D. J. Langton, D. J. Deehan, J. Holland. Cemented Exeter total hip arthroplasty with a 32 mm head on highly crosslinked polyethylene: Does age influence functional outcome, satisfaction, activity, stem migration, and periprosthetic bone mineral density? Bone Joint Res 2019;8:275–287. DOI: 10.1302/2046-3758.86.BJR-2018-0300.R1.

Cross-Linked Versus Conventional Polyethylene for Long-Term Clinical Outcomes After Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

Background: Cross-linked polyethylene (HXLPE) liners have been used for total hip arthroplasty (THA) to address the problem of osteolysis and revision surgery associated with conventional polyethylene (CPE) liners. This systematic review and meta-analysis investigated the long-term efficacy of HXLPE in preventing revision surgery and radiological osteolysis in comparison to CPE. Materials and Methods: A comprehensive search of PubMed, Embase, and the Cochrane Library from their respective inception to September 2018 was conducted to identify potential candidate articles. Data were pooled using Stata software 14.0. The quality of randomized controlled trials (RCTs) and observational studies was assessed by two different authors using the Cochrane risk-of-bias tool and the Newcastle-Ottawa scale (NOS), respectively. Results: Eight RCTs and six observational studies were included in this review. The pooled results significantly favored HXLPE over CPE in terms of total number of revisions and radiological osteolysis, with a risk reduction of 78% (95% confidence interval [CI] 0.13-0.36; p < 0.001) and 80% (95% CI 0.13-0.29; p < 0.001), respectively. Additionally, subgroup analyses of pooled data from RCTs and observational studies both showed the efficacy of HXLPE in the prevention of revision and osteolysis. Polyethylene wear in the HXLPE group was significantly less than that in the CPE group in terms of linear wear rates and head penetration rates (both p < 0.001). No significant differences were observed with regard to functional outcomes. Conclusions: The current evidence shows that HXLPE significantly improved the clinical and radiographic outcomes, but not the functional outcomes, in comparison to CPE in long-term follow-up.

Guidelines for the follow-up of total hip arthroplasty

Aims

The aim of this retrospective audit was to determine the route of referral or presentation of patients requiring revision following primary total hip arthroplasty (THA).

Patients and Methods

A total of 4802 patients were implanted with an Orthopaedic Data Evaluation Panel (ODEP) 10A* cementless implant (Corail/Pinnacle) between 2005 and 2015; 80 patients with a mean age of 67.8 years (sd 10.8) underwent a subsequent revision. The primary outcome measure was route of referral for revision.

Results

Of the 80 revisions, 31 (38.8%) took place within the first year and 69 (86.3%) took place within six years. Only two of the 80 patients were picked up at a routine review clinic, one for infection and the other for liner dissociation. A total of 36 revised patients (45.0%) were reviewed following self-referral. Of the remaining 44 revised patients (55.0%), 15 (18.8%) were General Practitioner referrals, 13 (16.3%) were other hospital referrals, six (7.5%) were inpatients, six (7.5%) were Emergency Department referrals, and two (2.5%) were readmitted from their homes. No revisions were carried out on asymptomatic patients.

Conclusion

Our experience suggests that if there is a robust system in place for self-referral, patients with an ODEP 10A* hip implant can, if asymptomatic, be safely discharged at the time of their first postoperative review. Cite this article: Bone Joint J 2019;101-B:536–539.

Temporal trends and survivorship of total hip arthroplasty in very young patients

Aims

The aim of this study was to describe temporal trends and survivorship of total hip arthroplasty (THA) in very young patients, aged ≤ 20 years.

Patients and Methods

A descriptive observational study was undertaken using data from the National Joint Registry (NJR) for England, Wales, Northern Ireland and the Isle of Man between April 2003 and March 2017. All patients aged ≤ 20 years at the time of THA were included and the primary outcome was revision surgery. Descriptive statistics were used to summarize the data and Kaplan–Meier estimates calculated for the cumulative implant survival.

Results

A total of 769 THAs were performed in 703 patients. The median follow-up was 5.1 years (interquartile range (IQR) 2.6 to 7.8). Eight patients died and 35 THAs were revised. The use of metal-on-metal (MoM) bearings and resurfacing procedures declined after 2008. The most frequently recorded indications for revision were loosening (20%) and infection (20%), although the absolute risk of these events occurring was low (0.9%). Factors associated with lower implant survival were MoM and metal-on-polyethylene (MoP) bearings and resurfacing arthroplasty ( vs ceramic-on-polyethylene (CoP) and ceramic-on-ceramic (CoC) bearings, p = 0.002), and operations performed by surgeons who undertook few THAs in this age group as recorded in the NJR ( vs those with five or more recorded operations, p = 0.030). Kaplan–Meier estimates showed 96% (95% confidence interval (CI) 94% to 98%) survivorship of implants at five years.

Conclusion

Within the NJR, the overall survival for very young patients undergoing THA exceeded 96% during the first five postoperative years. In the absence of studies that can better account for differences in the characteristics of the patients, surgeons should consider the association between early revision and the type of implant, the number of THAs performed in these patients, and the bearing surface when performing THA in very young patients. Cite this article: Bone Joint J 2018;100-B:1320–9.

[A retrospective study on the application of cemented polyethylene liner technique in hip revision]

Objective

To evaluate the effectiveness of cemented polyethylene liner technique in hip revision.

Methods

Based on inclusion criteria, the clinical data of 26 patients who were undergone hip revision between January 2011 and December 2013, were retrospectively reviewed. Among them, 14 cases were treated with isolated liner exchange (group A) and 12 cases were treated with cemented polyethylene liner technique (group B). There was no significant difference in gender, age, the time from primary total hip arthroplasty to revision, and the preoperative Harris score between 2 groups ( P>0.05). The post-operative Harris score and complications were compared between 2 groups, and X-ray findings of the hip joint were recorded to review the position of hip components.

Results

All patients were followed up 4.4-6.4 years (mean, 5.4 years). Except for two femoral fractures during the revision (1 in each group), there was no other complication in 2 groups. The hip pain relieved and the lame gait corrected in 2 groups. The hip's function of 2 groups improved gradually after operation, with a better Harris score at 3 months and the best at the last follow-up, compared with preoperative scores ( P<0.05). There was no significant difference in Harris score at difference time points after operation between 2 group ( P>0.05). X-ray films showed no dislocation, aseptic loosening, and other interface related complication.

Conclusion

For the cases without the chance to do change liner, cemented polyethylene liner technique has a good effectiveness. But restrict patient selection should be considered before hip revision.

Ten-year survivorship of primary total hip arthroplasty in patients 30 years of age or younger

Aims

For this retrospective cohort study, patients aged ≤ 30 years (very young) who underwent total hip arthroplasty (THA) were compared with patients aged ≥ 60 years (elderly) to evaluate the rate of revision arthroplasty, implant survival, the indications for revision, the complications, and the patient-reported outcomes.

Patients and Methods

We retrospectively reviewed all patients who underwent primary THA between January 2000 and May 2015 from our institutional database. A total of 145 very young and 1359 elderly patients were reviewed. The mean follow-up was 5.3 years (1 to 18). Logistic generalized estimating equations were used to compare characteristics and the revision rate. Survival was evaluated using Kaplan-Meier curves and hazard rates were created using Cox regression.

Results

The overall revision rate was 11% (16/145) in the very young and 3.83% (52/1359) in the elderly groups (odds ratio (OR) 2.58, 95% confidence interval (CI) 1.43 to 4.63). After adjusting for the American Society of Anesthesiologists (ASA) score, gender, and a history of previous surgery in a time-to-event model, the risk of revision remained greater in the very young (adjusted hazard ratio (HR) 2.48, 95% CI 1.34 to 4.58). Survival at ten years was 82% (95% CI, 71 to 89) in the very young and 96% (95% CI, 94 to 97) in the elderly group (p < 0.001). The very young had a higher rate of revision for complications related to metal-on-metal (MoM) bearing surfaces (p < 0.001). At last follow-up, the very young group had higher levels of physical function (p = 0.002), lower levels of mental health (p = 0.001), and similar levels of pain (p = 0.670) compared with their elderly counterparts.

Conclusion

The overall revision rate was greater in very young THA patients. This was largely explained by the use of MoM bearings. Young patients with non-MoM bearings had high survivorship with similar complication profiles to patients aged ≥ 60 years. Cite this article: Bone Joint J 2018;100-B:867-74.