Genetic susceptibility to hip arthroplasty failure--association with the RANK/OPG pathway

The John Charnley Award: The Impact of Human Leukocyte Antigen Genotype on Bacterial Infection Rates and Successful Eradication in Total Hip Arthroplasty

BACKGROUND

Genetics play an important role in several medical domains; however, the influence of human leukocyte antigen (HLA) genotype on the development of periprosthetic joint infection (PJI) in total hip arthroplasty (THA) remains unknown. The primary aim of this study was to determine if HLA genotype is associated with the development of bacterial PJI in THA. Secondarily, we evaluated the association between HLA genotype and PJI treatment success.

METHODS

A retrospective, matched, case-control study was performed using prospectively collected data from a single institution. A total of 49 patients who underwent primary THA were included, with a mean follow-up of 8.5 years (range, 4.2 to 12.9). The 23 cases (PJI) and 26 controls (no PJI) were matched for age, sex, follow-up, body mass index, primary diagnosis, and comorbidities (P > .05). High-resolution genetic analysis targeting 11 separate HLA loci was performed in all patients using serum samples. The HLA gene frequencies and carriage rates were determined and compared between cohorts. A subgroup analysis of PJI treatment success (18) and failure (5) was performed. Statistical significance was set at P = .10 for genetic analysis and at 0.05 for all other analyses.

RESULTS

There were 4 HLA alleles that were significantly associated with the development of PJI. The 3 at-risk alleles included HLA-C∗06:02 (odds ratio 5.25, 95% CI [confidence interval] 0.96 to 28.6, P = .064), HLA-DQA1∗04:01 (P = .096), and HLA-DQB1∗04:02 (P = .096). The single protective allele was HLA-C∗03:04 (odds ratio 0.12, 95% CI 0.01 to 1.10, P = .052). There were no specific HLA alleles that were associated with treatment success or failure.

CONCLUSIONS

This study suggests that there are at-risk and protective HLA alleles associated with the development of PJI in THA. To our knowledge, this is the first study to demonstrate an association between patient HLA genotype and the development of PJI. A larger study of the subject matter is necessary and warranted.

Genetic Polymorphisms Associated with Perioperative Joint Infection following Total Joint Arthroplasty: A Systematic Review and Meta-Analysis

The number of orthopedic procedures, especially prosthesis implantation, continues to increase annually, making it imperative to understand the risks of perioperative complications. These risks include a variety of patient-specific factors, including genetic profiles. This review assessed the current literature for associations between patient-specific genetic risk factors and perioperative infection. The PRISMA guidelines were used to conduct a literature review using the PubMed and Cochrane databases. Following title and abstract review and full-text screening, eight articles remained to be reviewed—all of which compared single nucleotide polymorphisms (SNPs) to periprosthetic joint infection (PJI) in total joint arthroplasty (TJA). The following cytokine-related genes were found to have polymorphisms associated with PJI: TNFα (p < 0.006), IL-6 (p < 0.035), GCSF3R (p < 0.02), IL-1 RN-VNTR (p = 0.002), and IL-1B (p = 0.037). Protein- and enzyme-related genes that were found to be associated with PJI included: MBL (p < 0.01, p < 0.05) and MBL2 (p < 0.01, p < 0.016). The only receptor-related gene found to be associated with PJI was VDR (p < 0.007, p < 0.028). This review compiled a variety of genetic polymorphisms that were associated with periprosthetic joint infections. However, the power of these studies is low. More research must be conducted to further understand the genetic risk factors for this serious outcome.

Pressurized carbon dioxide lavage reduces the incidence of a radiolucent line around the tibial component two years after total knee arthroplasty

Introduction

In cemented total knee arthroplasty (TKA), pressurized carbon dioxide (CO₂) lavage prior to cement fixation can eliminate debris at the bone-cement interface and is considered effective for increasing cement penetration and preventing aseptic loosening. Regarding the risk of a preliminary diagnosis of implant loosening, a radiolucent line (RLL) is a valuable sign. The purpose of this study was to compare the incidence of a tibial RLL at 2 years after TKA with and without pressurized CO₂ lavage.

Methods

This is a retrospective study. One hundred knees from 98 patients were enrolled in this study. TKA was performed without pressurized CO₂ lavage (CO₂− group) for the first 47 knees, and with pressurized CO₂ lavage (CO₂+ group) for the next 53 knees. The depth of cement penetration was measured just after surgery, and the incidence of tibial RLL > 2 mm at 2 years after TKA was determined.

Results

Significant differences between groups were not seen regarding pre- and postoperative clinical factors. The depth of cement penetration in each area was significantly higher in the CO₂+ group. The frequency of knees with RLL > 2 mm was significantly lower in the CO₂+ group than in the CO₂− group (p < 0.001).

Conclusions

Pressurized CO₂ lavage improved cement penetration and decreased the incidence of tibial RLL > 2 mm at 2 years after TKA.

Risk of Revision After Arthroplasty Associated with Specific Gene Loci: A Genomewide Association Study of Single-Nucleotide Polymorphisms in 1,130 Twins Treated with Arthroplasty

BACKGROUND

The risk of revision surgery following total joint arthroplasty (TJA) may be influenced by genetic factors. Therefore, we sought to identify genetic variants associated with the risk of revision surgery in a genomewide association study.

METHODS

We investigated a cohort of 1,130 twins from the Swedish Twin Registry treated with TJA. During a mean of 9.4 years of follow-up, 75 individuals underwent revision surgery for aseptic loosening (the primary outcome) and 94, for any reason (the secondary outcome). Genetic information was collected using the Illumina OmniExpress and PsychArray panels, and the Haplotype Reference Consortium served as the reference for gene imputation. Adjusted Cox regression models were fitted to calculate hazard ratios (HRs) with 95% confidence intervals (CIs).

RESULTS

Nine single-nucleotide polymorphisms (SNPs) reached genomewide significance for aseptic loosening. The first SNP, rs77149046, located in the endosome-lysosome associated apoptosis and autophagy regulator family member 2 (ELAPOR2) gene, conferred an HR of 5.40 (CI, 3.23-9.02; p = 1.32×10 -10 ), followed by 4 SNPs within the region coding for sodium-dependent taurine and beta-alanine transporter (SLC6A6), with HRs ranging from 3.35 to 3.43. The sixth SNP, rs7853989 (HR, 3.46; CI, 2.33-5.13; p = 6.91×10 -10 ), was located in a region coding for the ABO blood group system. This SNP has been described as predictive for blood type B. Seven significant SNPs were found for the risk of revision for any reason, with the first 4 again being located in the SLC6A6 region. The leading SNP, rs62233562, conferred an HR of 3.11 (CI, 2.19-4.40; p = 1.74×10 -10 ) for revision surgery. Similar HRs were found for SNPs 3:14506680 (p = 1.78×10 -10 ), rs2289129 (p = 1.78×10 -10 ), and rs17309567 (p = 3.16×10 -10 ). The fifth SNP, rs11120968, was located in the calmodulin-binding transcription activator 1 (CAMTA1) gene (HR, 2.34; CI, 1.74-3.13, p = 1.45×10 -8 ).

CONCLUSIONS

We identified 12 unique SNPs associated with an increased risk of revision surgery. Among these, 2 were in ELAPOR2, which is closely linked to bone formation. Another SNP is located in a gene region encoding for the ABO system, which merits further studies of causal relationships.

LEVEL OF EVIDENCE

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

The Genetic Variations Associated With Time to Aseptic Loosening After Total Joint Arthroplasty

BACKGROUND

Total joint arthroplasty (TJA) is one of the most frequent surgical procedures performed in modern hospitals, and aseptic loosening is the most common indication for revision surgeries. We conducted a systemic exploration of potential genetic determinants for early aseptic loosening.

METHODS

Data from 423 patients undergoing TJA were collected and analyzed. Three analytical groups were formed based on joint arthroplasty status. Group 1 were TJA patients without symptoms of aseptic loosening of at least 1 year, group 2 were patients with primary TJA, and group 3 were patients receiving revision surgery because of aseptic loosening. Genome-wide genotyping comparing genotype frequencies between patients with and without aseptic loosening (group 3 vs groups 1 and 2) was conducted. A case-control association analysis and linear modeling were applied to identify the impact of the identified genes on implant survival with time to the revision as an outcome measure.

RESULTS

We identified 52 single-nucleotide polymorphisms (SNPs) with a genome-wide suggestive P value less than 10^-5 to be associated with the implant loosening. The most remarkable odds ratios (OR) were found with the variations in the IFIT2/IFIT3 (OR, 21.6), CERK (OR, 12.6), and PAPPA (OR, 14.0) genes. Variations in the genotypes of 4 SNPs-rs115871127, rs16823835, rs13275667, and rs2514486-predicted variability in the time to aseptic loosening. The time to aseptic loosening varied from 8 to 16 years depending on the genotype, indicating a substantial effect of genetic variance.

CONCLUSION

Development of the aseptic loosening is associated with several genetic variations and we identified at least 4 SNPs with a significant effect on the time for loosening. These data could help to develop a personalized approach for TJA and loosening management.

Does Patient-Specific Instrumentation Have a Higher Rate of Early Osteolysis Than Standard Referencing Techniques in Total Ankle Arthroplasty? A Radiographic Analysis

Introduction: Patient-specific instrumentation (PSI) has been developed for total ankle arthroplasty (TAA), with proven benefits. One concern regarding PSI is the need for more soft tissue dissection in order to accurately position the PSI guides, which has the theoretical disadvantage of increased osteolysis. The purpose of our study is to compare the incidence and magnitude of osteolysis for the INFINITY Total Ankle System between PSI and standard referencing (SR) techniques. Methods: Sixty-seven patients who underwent primary TAA using Prophecy (PSI) or SR technique between 2013 and 2015 were reviewed in a retrospective observational study. Osteolysis was assessed on radiographs at 2 years. The incidence was calculated by binomial distribution. The number of zones compromised and the magnitude of osteolysis was calculated using the median as a summary statistic and interquartile range as dispersion statistic. Fisher exact test was used to compare both groups, then a regression model was estimated to calculate the odds ratio for osteolysis. Results: Of the 67 TAAs, 51 were in the PSI group and 16 in the SR group. In the PSI group the incidence, number of compromised zones (CZ), and magnitude was 41% (25%-59%), 1 [1-2], and 2 [2-3], respectively. In the SR group these were 36% (13%-65%), 3 [2-3], and 3 [2-4], respectively. No significant differences were found (P = .46, P = .12, P = .33). A slightly higher risk of osteolysis was found in the PSI group (odds ratio = 1.33 [0.36-4.83]) (P = .46). The majority of lesions were in 1 zone with size of 2 to 5 mm (63% for all cohort, 64% PSI, 60% SR). Two cases underwent revision for aseptic loosening, 1 in the SR group and 1 in the PSI group. Conclusion: According to our data, there is no significant difference between PSI and SR in terms of risk, incidence, size and magnitude of osteolysis in the INFINITY Total Ankle System at 2 years. Levels of Evidence: Therapeutic, Level III, Retrospective cohort study.

Influence of single nucleotide polymorphisms (SNPs) in genetic susceptibility towards periprosthetic osteolysis

Wear debris-induced inflammatory osteolysis remains a significant limiting factor for implant replacement surgeries. Hence, a comprehensive understanding of the complex network of cellular and molecular signals leading to these inflammatory responses is required. Both macrophages and monocytes have a critical role in the instigation of the inflammatory reaction to wear debris but differ in the extent to which they induce cytokine expression in patients. Lately, single nucleotide polymorphisms (SNPs) have been associated with genetic susceptibility among individual patients with implant failure. Studies have shown that SNPs in key pro-inflammatory cytokines and their receptors are associated with osteolytic susceptibility. Likewise, SNPs within several genes involved in the regulation of bone turnover have also been found to be associated with wear debris induced osteolysis. It is presumed that SNP variance might play a decisive role in the activation and signaling of macrophages, osteoblasts, chondrocytes, fibroblasts and other cells involved in inflammatory bone loss. Understanding the extent to which SNPs exist among genes that are responsible for inflammatory bone loss may provide potential targets for developing future therapeutic interventions. Herein, we attempt to summarize the various susceptible genes with possible SNP variance that could contribute to the severity of periprosthetic osteolysis in patients with implants.

The 2018 Otto Aufranc Award: How Does Genome-wide Variation Affect Osteolysis Risk After THA?

BACKGROUND

Periprosthetic osteolysis resulting in aseptic loosening is a leading cause of THA revision. Individuals vary in their susceptibility to osteolysis and heritable factors may contribute to this variation. However, the overall contribution that such variation makes to osteolysis risk is unknown.

QUESTIONS/PURPOSES

We conducted two genome-wide association studies to (1) identify genetic risk loci associated with susceptibility to osteolysis; and (2) identify genetic risk loci associated with time to prosthesis revision for osteolysis.

METHODS

The Norway cohort comprised 2624 patients after THA recruited from the Norwegian Arthroplasty Registry, of whom 779 had undergone revision surgery for osteolysis. The UK cohort included 890 patients previously recruited from hospitals in the north of England, 317 who either had radiographic evidence of and/or had undergone revision surgery for osteolysis. All participants had received a fully cemented or hybrid THA using a small-diameter metal or ceramic-on-conventional polyethylene bearing. Osteolysis susceptibility case-control analyses and quantitative trait analyses for time to prosthesis revision (a proxy measure of the speed of osteolysis onset) in those patients with osteolysis were undertaken in each cohort separately after genome-wide genotyping. Finally, a meta-analysis of the two independent cohort association analysis results was undertaken.

RESULTS

Genome-wide association analysis identified four independent suggestive genetic signals for osteolysis case-control status in the Norwegian cohort and 11 in the UK cohort (p ≤ 5 x 10). After meta-analysis, five independent genetic signals showed a suggestive association with osteolysis case-control status at p ≤ 5 x 10 with the strongest comprising 18 correlated variants on chromosome 7 (lead signal rs850092, p = 1.13 x 10). Genome-wide quantitative trait analysis in cases only showed a total of five and nine independent genetic signals for time to revision at p ≤ 5 x 10, respectively. After meta-analysis, 11 independent genetic signals showed suggestive evidence of an association with time to revision at p ≤ 5 x 10 with the largest association block comprising 174 correlated variants in chromosome 15 (lead signal rs10507055, p = 1.40 x 10).

CONCLUSIONS

We explored the heritable biology of osteolysis at the whole genome level and identify several genetic loci that associate with susceptibility to osteolysis or with premature revision surgery. However, further studies are required to determine a causal association between the identified signals and osteolysis and their functional role in the disease.

CLINICAL RELEVANCE

The identification of novel genetic risk loci for osteolysis enables new investigative avenues for clinical biomarker discovery and therapeutic intervention in this disease.

Genetic susceptibility to prosthetic joint infection following total joint arthroplasty: A systematic review

BACKGROUND

Prosthetic joint infection (PJI) is the most common cause of total joint arthroplasty failure and revision surgery. Genetic polymorphisms could be determinant factors for PJI.

METHODS

We performed a systematic research of Medline, Pubmed, Embase, Cochrane Library, and Google Scholar, and identified 11 studies with 34 kinds of gene polymorphisms, were included in the synthesis.

RESULTS

Our data suggest that the C allele and genotype C/C for MBL-550 SNP, genotype A/A for MBL-54 SNP and G allele for MBL-221 SNP increase the risk of PJI, while G allele and genotype G/G for MBL-550 SNP decrease the risk of PJI in Caucasian populations. Several other genes reported by single-center studies also contribute to the genetic susceptibility to septic PJI. No definitive conclusions could be achieved due to the small amount of data in the included studies.

CONCLUSION

Several genes contribute to the genetic susceptibility to PJI following total joint arthroplasty. Further studies will enhance the understanding of PJI, and may inform and direct early interventions.

Genetic variation in inflammatory and bone turnover pathways and risk of osteolytic responses to prosthetic materials

Wear particle-induced inflammatory bone loss (osteolysis) is the leading cause of total hip arthroplasty (THA) failure. Individual susceptibility to osteolysis is modulated by genetic variation. In this 2-stage case-control association study we examined whether variation within candidate genes in inflammatory and bone turnover signaling pathways associates with susceptibility to osteolysis and time to prosthesis failure. We examined two cohorts, comprising 758 (347 male) Caucasian subjects who had undergone THA with a metal on polyethylene bearing couple; 315 of whom had developed osteolysis. Key genes within inflammatory, bone resorption, and bone formation pathways were screened for common variants by pairwise-SNP tagging using a 2-stage association analysis approach. In the discovery cohort four SNPs within RANK, and one each within KREMEN2, OPG, SFRP1, and TIRAP (p < 0.05) were associated with osteolysis susceptibility. Two SNPs within LRP6, and one each within LRP5, NOD2, SOST, SQSTM1, TIRAP, and TRAM associated with time to implant failure (p < 0.05). Meta-analysis of the two cohorts identified four SNPs within RANK, and one each within KREMEN2, OPG, SFRP1, and TIRAP associated with osteolysis susceptibility (p < 0.05). Genetic variation within inflammatory signaling and bone turnover pathways may play a role in susceptibility to osteolysis.

Do genetic susceptibility, Toll-like receptors, and pathogen-associated molecular patterns modulate the effects of wear?

Overwhelming evidence supports the concept that wear particles are the primary initiator of aseptic loosening of orthopaedic implants. It is likely, however, that other factors modulate the biologic response to wear particles. This review focuses on three potential other factors: genetic susceptibility, Toll-like receptors (TLRs), and bacterial pathogen-associated molecular patterns (PAMPs). WHERE ARE WE NOW?: Considerable evidence is emerging that both genetic susceptibility and TLR activation are important factors that modulate the biologic response to wear particles, but it remains controversial whether bacterial PAMPs also do so. WHERE DO WE NEED TO GO?: Detailed understanding of the roles of these other factors may lead to identification of novel therapeutic targets for patients with aseptic loosening. HOW DO WE GET THERE?: Highest priority should be given to polymorphism replication studies with large numbers of patients and studies to replicate the reported correlation between bacterial biofilms and the severity of aseptic loosening.

Risk factors for total hip arthroplasty aseptic revision

The purpose of this study was to evaluate patient, operative, implant, surgeon, and hospital factors associated with aseptic revision after primary THA in patients registered in a large US Total Joint Replacement Registry. A total of 35,960 THAs registered from 4/2001-12/2010 were evaluated. The 8-year survival rate was 96.7% (95% CI 96.4%-97.0%). Females had a higher risk of aseptic revision than males. Hispanic and Asian patients had a lower risk of revision than white patients. Ceramic-on-ceramic, ceramic-on-conventional polyethylene, and metal-on-conventional polyethylene bearing surfaces had a higher risk of revision than metal-on-highly cross-linked polyethylene. Body mass index, health status, diabetes, diagnosis, fixation, approach, bilateral procedures, head size, surgeon fellowship training, surgeon and hospital volume were not revision risk factors.

Risk factors for revision of primary total hip arthroplasty: a systematic review

BACKGROUND

Numerous papers have been published examining risk factors for revision of primary total hip arthroplasty (THA), but there have been no comprehensive systematic literature reviews that summarize the most recent findings across a broad range of potential predictors.

METHODS

We performed a PubMed search for papers published between January, 2000 and November, 2010 that provided data on risk factors for revision of primary THA. We collected data on revision for any reason, as well as on revision for aseptic loosening, infection, or dislocation. For each risk factor that was examined in at least three papers, we summarize the number and direction of statistically significant associations reported.

RESULTS

Eighty-six papers were included in our review. Factors found to be associated with revision included younger age, greater comorbidity, a diagnosis of avascular necrosis (AVN) as compared to osteoarthritis (OA), low surgeon volume, and larger femoral head size. Male sex was associated with revision due to aseptic loosening and infection. Longer operating time was associated with revision due to infection. Smaller femoral head size was associated with revision due to dislocation.

CONCLUSIONS

This systematic review of literature published between 2000 and 2010 identified a range of demographic, clinical, surgical, implant, and provider variables associated with the risk of revision following primary THA. These findings can inform discussions between surgeons and patients relating to the risks and benefits of undergoing total hip arthroplasty.

Variation in the IL1B, TNF and IL6 genes and individual susceptibility to prosthetic joint infection

Background

Prosthetic joint infection (PJI) is an important failure mechanism of total joint arthroplasty (TJA). Here we examine whether the particular genetic variants can lead to increased susceptibility to PJI development.

Results

We conducted a genetic-association study to determine whether PJI could be associated with functional cytokine gene polymorphisms (CGP) influencing on innate immunity response. A case–control design was utilized and previously published criteria for PJI were included to distinguish between cases and control subjects with/without TJA. Six single nucleotide polymorphisms (SNPs) located in the genes for interleukin-1beta (SNP: IL1B-511, +3962), tumour necrosis factor alpha (TNF-308, -238) and interleukin-6 (IL6-174, nt565) were genotyped in 303 Caucasian (Czech) patients with TJA (89 with PJI / 214 without PJI), and 168 unrelated healthy Czech individuals without TJA. The results showed that carriers of the less common IL1B−511*T allele were overrepresented in the group of TJA patients with PJI (69%) in comparison with those that did not develop PJI (51%, p = 0.006, p_corr = 0.037) and with healthy controls (55%, p = 0.04, p_corr = N.S.). There was no significant difference in the distribution of the remaining five investigated CGPs and their haplotypes between groups.

Conclusion

A functional variant of the gene encoding for IL-1beta was preliminarily nominated as a genetic factor contributing to the susceptibility to PJI. Our results should be independently replicated; studies on the functional relevance of IL1B gene variants in PJI are also needed.

Genetic susceptibility to aseptic loosening following total hip arthroplasty: a systematic review

Introduction Aseptic loosening is the most common cause of total hip arthroplasty (THA) failure and revision surgery. Genetic polymorphisms could be determinant factors for implant loosening. Source of data We performed a comprehensive search of Medline, CINAHL, Googlescholar, Embase and Cochrane databases, using various combinations of the keyword terms 'aseptic loosening', 'gene', 'hip arthoplasty', 'genetics', 'loosening'. Twelve studies detailing the genetic investigation of patients with aseptic loosening of a THA were identified. Areas of agreement SNPs of GNAS1, TNF-238 A allele, TNF-α promoter (-308G→A) transition, IL6-174 G allele, interleukin (IL)-6 (-597) and (-572), MMP-1-promoting gene, C/C genotype for the MMP1, MT1-MMP, MMP-2, transforming growth factor-beta1 signal sequence (29T→C) transitions, A/A genotype for the OPG-163, and MBL were overexpressed in patients with aseptic loosening and periprosthetic osteolysis. Areas of controversy Data from single centre studies do not allow one to compare the results of different studies. Conclusion Several gene pathways and genes contribute to the genetic susceptibility to aseptic loosening following THA. Further studies will enhance the understanding of prosthesis failure, and may inform and direct pharmaceutical interventions. Growing points Further multi-centre prospective studies are necessary to confirm the general validity of the findings reported. Single-centre findings should be replicated in other centres and populations to open new avenues for pre-surgical genetic testing and to investigate immune response modulation in THA. Areas timely for developing research Research in this field could lead to better understanding of mechanisms behind aseptic osteolysis, and improve the results of THA.

Do tissues from THA revision of highly crosslinked UHMWPE liners contain wear debris and associated inflammation?

BACKGROUND

Polyethylene wear debris is a major contributor to inflammation and the development of implant loosening, a leading cause of THA revisions. To reduce wear debris, highly crosslinked ultrahigh-molecular-weight polyethylene (UHMWPE) was introduced to improve wear properties of bearing surfaces. As highly crosslinked UHMWPE revision tissues are only now becoming available, it is possible to examine the presence and association of wear debris with inflammation in early implant loosening.

QUESTIONS/PURPOSES

We asked: (1) Does the presence of UHMWPE wear debris in THA revision tissues correlate with innate and/or adaptive immune cell numbers? (2) Does the immune cell response differ between conventional and highly crosslinked UHMWPE cohorts?

METHODS

We collected tissue samples from revision surgery of nine conventional and nine highly crosslinked UHMWPE liners. Polarized light microscopy was used to determine 0.5- to 2-μm UHMWPE particle number/mm2, and immunohistochemistry was performed to determine macrophage, T cell, and neutrophil number/mm2.

RESULTS

For the conventional cohort, correlations were observed between wear debris and the magnitude of individual patient macrophage (ρ=0.70) and T cell responses (ρ=0.71) and between numbers of macrophages and T cells (ρ=0.77) in periprosthetic tissues. In comparison, the highly crosslinked UHMWPE cohort showed a correlation between wear debris and the magnitude of macrophage responses (ρ=0.57) and between macrophage and T cell numbers (ρ=0.68). Although macrophages and T cells were present in both cohorts, the highly crosslinked UHMWPE cohort had lower numbers, which may be associated with shorter implantation times.

CONCLUSIONS

The presence of wear debris and inflammation in highly crosslinked UHMWPE revision tissues may contribute to early implant loosening.

Osteolysis propensity among bilateral total hip arthroplasty patients

Because some patients with high wear rates demonstrate extensive osteolysis whereas other patients with similarly high wear rates show little or no evidence of osteolysis, we hypothesized that both polyethylene wear and a patient-specific propensity mediate the development of osteolysis. We evaluated wear and osteolysis using computed tomography and radiographs among 46 patients who had undergone bilateral total hip arthroplasties (THAs). A radiographic patient-specific propensity for osteolysis associated with each THA was quantified by dividing the amount of osteolysis by the volumetric wear. Using a multivariate regression analysis to simultaneously consider the influence of polyethylene wear and patient propensity, we found that both factors are associated with the amount of osteolysis around a THA and that they appear to be of similar importance.

Sex as a patient selection criterion for metal-on-metal hip resurfacing arthroplasty

Short-term to midterm results of hip resurfacing arthroplasty suggest various contraindications, in particular the female sex. This study evaluates survivorship and clinical outcomes of a large patient cohort to determine whether sex itself has a detrimental effect on the results of hip resurfacing. We compared the clinical and survivorship results of men and women from a series of 1107 resurfaced hips in 923 patients (681 males and 242 females). Women saw greater positive changes in walking, function, and the mental component of the Short Form-12. There was no difference in complication rates between men and women. Although the revision rate was higher in the women's group, the effect of sex disappeared when adjusted for component size and surgical technique. These data suggest that there is no appreciable effect of sex on implant survivorship and that women may be excellent candidates for resurfacing with proper surgical technique. This is a level III, retrospective comparative study.

Functional variants of the P2RX7 gene, aseptic osteolysis, and revision of the total hip arthroplasty: a preliminary study

Periprosthetic osteolysis (OL) is a major long-term complication of the total hip arthroplasty (THA), which can result in aseptic loosening and revision surgery. Purinergic receptor P2X, ligand-gated ion channel 7 (P2RX7) is an important regulator of inflammation and bone turnover. We were therefore interested in whether functional variants of the P2RX7 gene may be associated with OL and risk of THA failure. A total of 205 unrelated Czech patients with cementless-type THA were stratified according to the severity of acetabular OL and revision of THA. Four "loss-of-function" P2RX7 single nucleotide polymorphisms (SNPs), namely Glu496Ala, Ile568Asn, Arg307Gln, and null allele (rs35933842), were genotyped by polymerase chain reaction with sequence-specific primers (PCR-SSP). No significant association of P2RX7 variants with severity of OL was observed. The carriers of rare variants P2RX7 568Asn, 307Gln and null allele, all causing complete loss of P2RX7 function, tended to be overrepresented among patients with THA revision (9.6%) by comparison with those with unrevised functional prosthesis (2.1%, p = 0.09). Furthermore, the carriage of the P2RX7 307Gln allele was associated with greater cumulative hazard of THA revision (p = 0.02). In this preliminary study, we could nominate but not clearly demonstrate rare P2RX7 loss-of-function variants being associated with THA failure. Investigation in large THA cohorts is therefore warranted.

Variation in cytokine genes can contribute to severity of acetabular osteolysis and risk for revision in patients with ABG 1 total hip arthroplasty: a genetic association study

BACKGROUND

The differences in total hip arthroplasty (THA) survivorship may be influenced by individual susceptibility to periprosthetic osteolysis. This may be driven by functional polymorphisms in the genes for cytokines and cytokine receptors involved in the development of osteolysis in THA, thereby having an effect on the individual's phenotype.

METHODS

We performed a study on 22 single-nucleotide polymorphisms (SNPs) for 11 cytokines and two cytokine receptor candidate genes for association with severity of acetabular osteolysis and risk to failure in THA. Samples from 205 unrelated Caucasian patients with cementless type THA (ABG 1) were investigated. Distribution of investigated SNP variants between the groups of mild and severe acetabular osteolysis was determined by univariate and multivariate analysis. Time-dependent output variables were analyzed by the Cox hazards model.

RESULTS

Univariate analysis showed: 1) TNF-238*A allele was associated with severe osteolysis (odds ratio, OR = 6.59, p = 0.005, population attributable risk, PAR 5.2%); 2) carriers of the IL6-174*G allele were 2.5 times more prone to develop severe osteolysis than non-carriers (OR = 2.51, p = 0.007, PAR = 31.5%); 3) the carriage of IL2-330*G allele was associated with protection from severe osteolysis (OR = 0.55, p = 0.043). Based on logistic regression, the alleles TNF-238*A and IL6-174*G were independent predictors for the development of severe acetabular osteolysis. Carriers of TNF-238*A had increased cumulative hazard of THA failure according to Cox model (p = 0.024). In contrast, IL2-330*G allele predicted lower cumulative hazard of THA failure (p = 0.019).

CONCLUSION

Genetic variants of proinflammatory cytokines TNF-alpha and IL-6 confer susceptibility to severe OL. In this way, presence of the minor TNF allele could increase the cumulative risk of THA failure. Conversely, SNP in the IL2 gene may protect carriers from the above THA complications.