We examined the association between patient-related factors and the risk of initial, short- and long-term implant failure after primary total hip replacement. We used data from the Danish Hip Arthroplasty Registry between 1 January 1995 and 31 December 2002, which gave us a total of 36 984 patients. Separate analyses were carried out for three follow-up periods: 0 to 30 days, 31 days to six months (short term), and six months to 8.6 years after primary total hip replacement (long term). The outcome measure was defined as time to failure, which included re-operation with open surgery for any reason. Male gender and a high Charlson co-morbidity index score were strongly predictive for failure, irrespective of the period of follow-up. Age and diagnosis at primary total hip replacement were identified as time-dependent predictive factors of failure. During the first 30 days after primary total hip replacement, an age of 80 years or more and hip replacement undertaken as a sequela of trauma, for avascular necrosis or paediatric conditions, were associated with an increased risk of failure. However, during six months to 8.6 years after surgery, being less than 60 years old was associated with an increased risk of failure, whereas none of the diagnoses for primary total hip replacement appeared to be independent predictors

Progressive retroversion of a cemented stem is predictive of early loosening and failure. We assessed the relationship between direct post-operative stem anteversion, measured with CT, and the resulting rotational stability, measured with repeated radiostereometric analysis over ten years. The study comprised 60 cemented total hip replacements using one of two types of matt collared stem with a rounded cross-section. The patients were divided into three groups depending on their measured post-operative anteversion (< 10°, 10° to 25°, >  25°). There was a strong correlation between direct post-operative anteversion and later posterior rotation. At one year the < 10° group showed significantly more progressive retroversion together with distal migration, and this persisted to the ten-year follow-up. In the < 10° group four of ten stems (40%) had been revised at ten years, and an additional two stems (20%) were radiologically loose. In the ‘normal’ (10° to 25°) anteversion group there was one revised (3%) and one loose stem (3%) of a total of 30 stems, and in the > 25° group one stem (5%) was revised and another loose (5%) out of 20 stems. This poor outcome is partly dependent on the design of this prosthesis, but the results strongly suggest that the initial rotational position of cemented stems during surgery affects the subsequent progressive retroversion, subsidence and eventual loosening. The degree of retroversion may be sensitive to prosthetic design and stem size, but < 10° of anteversion appears deleterious to the long-term outcome for cemented hip prosthetic stems.

Cite this article: Bone Joint J 2013;95-B:23–30.

Arthroplasty in patients who are intravenous drug abusers presents a complex challenge, frequently requiring intervention at a younger age. The cohort suffer increased complication rates due to significant co-morbidities and poor engagement in medical services, in comparison to other patients undergoing lower limb arthroplasty. Multiple small studies show arthroplasty in this patient cohort is associated with high complication and mortality rates. A search of electronic databases were undertaken with the assistance of the library services from the Rotherham NHS Foundation Trust, including Chocraine, SCOPUS and PubMed. Abstracts were reviewed and relevant studies extracted for full review. Full text articles were reviewed based on strict inclusion and exclusion criteria. Searches identified Two thousand and forty-four papers; twenty-seven studies were identified for full review of the paper based on the inclusion criteria above. From this, nine studies were deemed appropriate to for data extraction. These nine papers present one hundred and thirty-two cases of lower limb arthroplasty, fifty nine Total Knee Arthroplasty and seventy three Total Hip Arthroplasty. From this the authors examined incidences of implant failure due to infection, revision, mortality, dislocation, aseptic loosening, peri-prosthetic fracture, or other causes. Of these, 58% of patients (n = 77) with a history of intravenous drug abuse suffered some form of significant complication; 4% of this cohort (n = 5) were lost to follow up. Infection was reported in 32% of cases and a mortality rate of 4.7%. The rising demand of lower limb arthroplasty for intra-venous drug abusers presents a very real problem for the modern Orthopaedic surgeon. Within the studies examined, more than half report implant failure. This study synthesises the available literature regarding treatment of these patients to help facilitate decision making and informed consent

Aims. The purpose of this study was to evaluate unexpected positive cultures in total hip arthroplasty (THA) revisions for presumed aseptic loosening, to assess the prevalence of low-grade infection using two definition criteria, and to analyze its impact on implant survival after revision. Methods. A total of 274 THA revisions performed for presumed aseptic loosening from 2012 to 2016 were reviewed. In addition to obtaining intraoperative tissue cultures from all patients, synovial and sonication fluid samples of the removed implant were obtained in 215 cases (79%) and 101 cases (37%), respectively. Histopathological analysis was performed in 250 cases (91%). Patients were classified as having low-grade infections according to institutional criteria and Musculoskeletal Infection Society (MSIS) International Consensus Meeting (ICM) 2013 criteria. Low-grade infections according to institutional criteria were treated with targeted antibiotics for six weeks postoperatively. Implant failure was defined as the need for re-revision resulting from periprosthetic joint infection (PJI) and aseptic reasons. The mean follow-up was 68 months (26 to 95). Results. Unexpected positive intraoperative samples were found in 77 revisions (28%). Low-grade infection was diagnosed in 36 cases (13%) using institutional criteria and in nine cases (3%) using MSIS ICM 2013 criteria. In all, 41 patients (15%) had single specimen growth of a low-virulent pathogen and were deemed contaminated. Coagulase-negative Staphylococcus and anaerobes were the most commonly isolated bacteria. Implant failure for PJI was higher in revisions with presumed contaminants (5/41, 12%) compared to those with low-grade infections (2/36, 6%) and those with negative samples (5/197, 3%) (p = 0.021). The rate of all-cause re-revision was similar in patients diagnosed with low-grade infections (5/36, 14%) and those with presumed contaminants (6/41, 15%) and negative samples (21/197, 11%) (p = 0.699). Conclusion. Our findings suggest that the presumption of culture contamination in aseptic revision hip arthroplasty may increase the detection of PJI. In this cohort, the presence of low-grade infection did not increase the risk of re-revision. Further studies are needed to assess the relevance of single specimen growth and the benefits of specific postoperative antibiotic regimens. Cite this article: Bone Joint J 2021;103-B(6):1070–1077

Aims. We evaluated a large database with mechanical failure of a single uncemented modular femoral component, used in revision hip arthroplasty, as the end point and compared them to a control group treated with the same implant. Patient- and implant-specific risk factors for implant failure were analyzed. . Methods. All cases of a fractured uncemented modular revision femoral component from one manufacturer until April 2017 were identified and the total number of implants sold until April 2017 was used to calculate the fracture rate. The manufacturer provided data on patient demographics, time to failure, and implant details for all notified fractured devices. Patient- and implant-specific risk factors were evaluated using a logistic regression model with multiple imputations and compared to data from a previously published reference group, where no fractures had been observed. The results of a retrieval analysis of the fractured implants, performed by the manufacturer, were available for evaluation. Results. There were 113 recorded cases with fracture at the modular junction, resulting in a calculated fracture rate of 0.30% (113/37,600). The fracture rate of the implant without signs of improper use was 0.11% (41/37,600). In 79% (89/113) of cases with a failed implant, either a lateralized (high offset) neck segment, an extralong head, or the combination of both were used. Logistic regression analysis revealed male sex, high body mass index (BMI), straight component design, and small neck segments were significant risk factors for failure. Investigation of the implants (76/113) showed at least one sign of improper use in 72 cases. Conclusion. Implant failure at the modular junction is associated with patient- and implant-specific risk factors as well as technical errors during implantation. Whenever possible, the use of short and lateralized neck segments should be avoided with this revision system. Implantation instructions and contraindications need to be adhered to and respected. Cite this article: Bone Joint J 2020;102-B(5):573–579

Current advice regarding implant choice is based on estimates of cost-benefit derived from implant survival to an endpoint of revision. Current estimates do not account for many implant failures which are treated with non-revision surgery and may not be accurate. The aim of this study was to estimate survival of major stem implant design groups to an endpoint of reoperation. Primary total hip replacement and linked revision form the National Joint Registry (NJR) and Hospital Episode Statistics (HES) data linked by unique identifier were used. Survival of femoral implant groups (cemented stainless steel polished taper [PTSS], cemented cobalt chrome polished taper [PTCC], cemented composite beam [CB], collarless cementless [NCOL] and collared cementless [COL]) was estimated using Kaplan-Meier method. 809,832 patients with valid NJR and HES data from England, were included. Cumulative failure at ten years for PTSS increased overall from 2.9% (95%CI 2.8–2.9) to 3.6% (95%CI 3.6–3.7) after inclusion of reoperations. Cumulative failure at ten years for PTSS increased from 2.5% (95%CI 2.5–2.6) to 3.3% (95%CI 3.2–3.4), for PTCC increased from 3.8% (95%CI 3.5–4.0) to 5.4% (95%CI 5.1–5.6), for CB increased from 3.1% (95%CI 2.9–3.3) to 4.1% (95%CI 3.8–4.3), for NCOL increased from 3.4% (95%CI 3.3–3.5) to 3.9% (95%CI 3.8–4.0), and for COL increased from 2.5% (95%CI 2.4–2.6) to 3.1% (95%CI 2.9–3.2), after inclusion of reoperations. Re-operation for internal fixation is as significant life event for the patient as revision. When a more inclusive metric is used, the patient and clinician's perspective on what constitutes a GIRFT implant may not be the same. Further work is required to update implant selection guidance in view of the change in implant performance

We aimed to use data from a randomized controlled trial (RCT) comparing the sliding hip screw vs. intramedullary nailing (IMN) for trochanteric fractures to examine complication rates between those managed with a short vs. long IMN. This is a secondary analysis using one arm of an RCT of patients ≥18 years with trochanteric fractures. We examined differences in fracture-related (femoral shaft fracture, implant failure, surgical site infection (SSI), nonunion, limb shortening, and pain) and medical (organ failure, respiratory distress, stroke, deep vein thrombosis [DVT] gastrointestinal upset, pneumonia, myocardial infarction, sepsis, or urinary tract infection) adverse events (AE), and readmission between short vs. long IMNs. We included 412 trochanteric fracture patients, 339 (82.2%) of whom received a short (170mm–200mm) nail, while 73 (17.7%) received a long (260mm–460 mm) nail. Patients in the long group were more likely to be admitted from home (vs. an institution), and have comorbidities, or more complex fracture types. Patients in the long group had higher rates of fracture-related AE (12.3%) vs. the short group (3.5%). Specifically, SSI (5.5% vs. 0.3%) and pain (2.7% vs. 0.0%) were significantly higher in the long group. Patients in the long group were also more likely to develop DVT (2.7% vs. 0.3%), and be readmitted to the hospital (28.8% vs. 20.7%). Following covariable adjustment, long nails remained associated with a higher odds of fracture-related AE (5.11, 1.96–13.33) compared to short nails. We found no association between the adjusted odds of readmission and nail length (1.00, 0.52–1.94). Our analyses revealed that trochanteric fracture patients managed with long IMN nails may have a higher odds of fracture-related AE compared to short nails. Future research is required to validate these findings with larger event rates, and further optimize IMN for trochanteric fracture patients

Aims. Advances in surgical technique and implant design may influence the incidence and mechanism of failure resulting in revision total hip arthroplasty (rTHA). The purpose of the current study was to characterize aetiologies requiring rTHA, and to determine whether temporal changes existed in these aetiologies over a ten-year period. Methods. All rTHAs performed at a single institution from 2009 to 2019 were identified. Demographic information and mode of implant failure was obtained for all patients. Data for rTHA were stratified into two time periods to assess for temporal changes: 2009 to 2013, and 2014 to 2019. Operative reports, radiological imaging, and current procedural terminology (CPT) codes were cross-checked to ensure the accurate classification of revision aetiology for each patient. Results. In all, 2,924 patients with a mean age of 64.6 years (17 to 96) were identified. There were 1,563 (53.5%) female patients, and the majority of patients were Caucasian (n = 2,362, 80.8%). The three most frequent rTHA aetiologies were infection (27.2%), aseptic loosening (25.2%), and wear (15.2%). The frequency of rTHA for adverse local tissue reaction (ALTR) was significantly greater from 2014 to 2019 (4.7% vs 10.0%; p < 0.001), while the frequency of aseptic loosening was significantly greater from 2009 to 2013 (28.6% vs 21.9%; p < 0.001). Conclusion. Periprosthetic joint infection was the most common cause for rTHA in the current cohort of patients. Complications associated with ALTR necessitating rTHA was more frequent between 2014 to 2019, while aseptic loosening necessitating rTHA was significantly more frequent between 2009 to 2013. Optimizing protocols for prevention and management of infection and ALTR after THA may help to avoid additional financial burden to institutions and healthcare systems. Cite this article: Bone Joint Open 2020;2(1):16–21

Introduction. Periprosthetic osteolysis resulting in aseptic loosening is a leading cause for total hip arthroplasty (THA) failure. Individuals vary in their susceptibility to osteolysis, and it is thought that heritable factors contribute to this variation. We conducted two genome-wide association studies to identify genetic risk loci associated with osteolysis and genetic risk loci associated with time to prosthesis failure due to osteolysis. Patients/Materials & Methods. The Norway cohort comprised 2,624 subjects after THA recruited from the Norwegian Arthroplasty Registry, 779 with revision surgery for osteolysis. The UK cohort comprised 890 subjects recruited from hospitals in the north of England, 317 with radiographic evidence or revision surgery for osteolysis. All subjects had received a fully cemented or hybrid THA using small-diameter metal or ceramic-on-conventional polyethylene bearing. Osteolysis susceptibility case-control analyses and quantitative trait analyses for time to prosthesis failure were undertaken after genome-wide genotyping. Finally, a meta-analysis of the discovery datasets was undertaken. Results. Genome-wide association analysis identified 4 and 11 independent suggestive genetic signals for osteolysis susceptibility at P≤5×10. −6. in the Norwegian and UK cohorts, respectively. Following meta-analysis, 5 independent genetic signals showed suggestive association with osteolysis at P≤5×10. −6. , with the strongest comprising 18 correlated variants on chromosome 7 (lead signal rs850092, Figure 1, p=1.13×10. −6. ). Genome-wide quantitative trait analysis in cases only showed a total of 5 and 9 independent genetic signals for time to prosthesis failure at P≤5×10. −6. , respectively. Following meta-analysis, 11 independent genetic signals showed suggestive evidence of association with time to failure at P≤5×10. −6. , with the largest association block comprising 174 correlated variants in chromosome 15 (lead signal rs10507055, Figure 2, p=1.40×10. −7. ). Discussion. These studies provide the first genome-wide insights into the heritable biology of osteolysis, a major complication of joint replacement surgery. Although there were no dominant signals of genome-wide significance, we find replicating evidence for several independent genetic loci both for osteolysis susceptibility and time to prosthesis failure at P≤5×10. −6. , consistent with the complex aetiology of the disease. Conclusion. The heritable contribution to osteolysis is modest. The identified genetic loci may however provide novel avenues for therapy development in this condition. For any figures and tables, please contact the authors directly

To date there is no medical treatment alternative to surgery for osteolysis after THA. In this proof-of-concept clinical trial we examined the effect of a human monoclonal antibody against osteoclasts versus placebo on osteolytic lesion activity in patients undergoing revision surgery. Patients scheduled for revision for symptomatic osteolysis were randomised (1:1) to receive either denosumab 60mg or placebo subcutaneously eight weeks prior to operation. At surgery, biopsies from the osteolytic membrane-bone interface were taken for histomorphometric analysis of osteoclast number. Secondary outcome measures included systemic bone turnover markers. 22 subjects completed the study (10 denosumab). The denosumab group had 83% (−63 to −97), P=0.011 fewer osteoclasts at osteolytic lesion sites, 87% lower osteoclast surface (−65 to −95, P=0.009), and 72% lower eroded surface (−35 to −93, P=0.020) versus the placebo group. At surgery, serum CTX-I, TRAP5b and PINP were 80% (−65 to −95, p<0.001), 57% (−40 to −90, p<0.001), and 44% (−41 to −65, p<0.001) lower in the denosumab versus placebo groups, respectively. The rate of adverse events (denosumab 6, placebo 7) were similar between groups (P>0.05). These data provide a biological basis for a definitive clinical trial using pain, function and prosthesis survival as the study endpoints. As osteolysis/ aseptic loosening is the leading cause of prosthesis failure world-wide, the establishment of a non-surgical solution would reduce patient suffering and dramatically reducing the cost to healthcare economies

Previous work has demonstrated increased implant failure in patients with DDH compared to osteoarthritis with historic methods and implants. This study examines outcomes of modern total hip arthroplasty (THA) techniques using uncemented fixation and cross-linked PE (XLPE) bearings for DDH. A consecutive series of 879 patients with DDH who underwent primary THA with uncemented components and a XLPE bearing at a single institution between 1999 and 2016 were identified. Mean age at index arthroplasty was 51 years, with 78% females. Mean follow-up was 8 years. 5- and 10-year survivorships free of revision were 98.4% and 98%, respectively. 5- and 10-year survivorships free of reoperation for any reason were 97% and 96%, respectively. Survivorship free of acetabular revision for aseptic loosening was 99.8% at 5 and 10 years, while survivorships free of femoral revision for aseptic loosening were 99.7% at 5 years and 99.5% at 10 years. Survivorship free of reoperation for PE damage (2 liner fractures, 2 rim damage from impingement) was 99.3% at 10 years. There were no revisions for bearing surface wear or osteolysis. 13% of patients experienced complications (4% dislocation, 3.3% wound complication rate). Ten-year survivorship free of reoperation for instability was 99.2%. 8 patients developed infection requiring operation (<1%). 100 patients had a prior pelvic osteotomy (11%), which did not increase rate of complications (p=0.22) or reoperations (p=0.51). Fixation with modern uncemented implants has dramatically reduced implant loosening in patients with DDH, and the use of XLPE bearings has markedly reduced revision for PE wear/osteolysis in this young patient population, leading to dramatically improved mid/long-term survivorship compared to historic series

Background. Sub-trochanteric fractures are challenging to treat due to various anatomical and biomechanical factors. High tensile forces contribute to the challenge of fracture reduction. Intramedullary nailing has become the treatment of choice. If anatomical reduction is not achieved, any mal-alignment will predispose to implant failure. Open reduction with cerclage wires can add to construct stability and improve the quality of reduction. There is no consensus or classification to guide surgeons on when to perform open reduction, which is often performed intra-operatively when closed reduction fails often with no planning. This can lead to intraoperative delays as theatre staff would not have prepared the correct equipment necessary for open reduction. Objectives. The purpose of this study was to assess outcomes of closed and open reduction of traumatic sub-trochanteric fractures treated with intramedullary nailing and to propose a new classification system to dictate management. Methods. After a review of current classification systems, a 3-tier classification was proposed (Type 1, 2 and 3). Type 1 indicated a transverse fracture, Type 2 was a spiral fracture with an intact posterior and medial wall and a Type 3 fracture were fractures with no posterior and/or medial walls. Over a two-year period (2013–2015), patients with sub trochanteric fractures were classified into Type 1, 2 or 3 injuries based on radiographic appearances by two senior clinicians. Patients with Type 3 injuries were divided into two groups based on whether they were treated with open or closed reduction. A clinical and radiographic review was performed. The primary outcome measure was the incidence of implant failure, whereas secondary outcome measures were related to fracture reduction. Statistical analysis was performed using GraphPad Prism Version 6 (GraphPad Software Inc. California, USA). Fisher's exact test was used for independent categorical data and Mann–U Whitney for continuous nonparametric data. Statistical significance was set at p<0.05. Results. 75 patients had intramedullary nailing for subtrochanteric fractures over the study period with a mean age of 82.6 years. There were 48 patients who had a Type 3 fracture pattern with a deficient medial and/or posterior wall. Reduction was achieved open with cerclage wires in 42% of patients (n=20 and closed in 58% (n=28). Overall there were a total of 18 (37.5%) major complications. In patients treated with closed reduction, 9 patients suffered mechanical complications (6 distal locking screw failures, 3 lag screw cut outs). There was a significantly increased risk of implant failure in patients treated with closed reduction compared to open reduction (p=0.006). No cases with cerclage wire had implant failure. Open reduction with cerclage wires improved the quality of reduction (p=0.0001) compared with closed reduction. There was no significant increase in operating time in patients treated with cerclage wires (p=0.4334). Conclusions. Open reduction with cerclage wires should be considered in patients with Type 3 sub-trochanteric fractures as it has shown to significantly reduce the risk of implant failure and improve the quality of reduction with no significant increase in operating time

Aims. We compared implant and patient survival following intraoperative periprosthetic femoral fractures (IOPFFs) during primary total hip arthroplasty (THA) with matched controls. Patients and Methods. This retrospective cohort study compared 4831 hips with IOPFF and 48 154 propensity score matched primary THAs without IOPFF implanted between 2004 and 2016, which had been recorded on a national joint registry. Implant and patient survival rates were compared between groups using Cox regression. Results. Ten-year stem survival was worse in the IOPFF group (p < 0.001). Risk of revision for aseptic loosening increased 7.2-fold following shaft fracture and almost 2.8-fold after trochanteric fracture (p < 0.001). Risk of periprosthetic fracture of the femur revision increased 4.3-fold following calcar-crack and 3.6-fold after trochanteric fracture (p < 0.01). Risk of instability revision was 3.6-fold after trochanteric fracture and 2.4-fold after calcar crack (p < 0.001). Risk of 90-day mortality following IOPFF without revision was 1.7-fold and 4.0-fold after IOPFF with early revision surgery versus uncomplicated THA (p < 0.001). Conclusion. IOPFF increases risk of stem revision and mortality up to ten years following surgery. The risk of revision depends on IOPFF subtype and mortality risk increases with subsequent revision surgery. Surgeons should carefully diagnose and treat IOPFF to minimize fracture progression and implant failure. Cite this article: Bone Joint J 2019;101-B:1199–1208

Aims. Our retrospective analysis reports the outcome of patients operated for slipped capital femoral epiphysis using the modified Dunn procedure. Results, complications, and the need for revision surgery are compared with the recent literature. Methods. We retrospectively evaluated 17 patients (18 hips) who underwent the modified Dunn procedure for the treatment of slipped capital femoral epiphysis. Outcome measurement included standardized scores. Clinical assessment included ambulation, leg length discrepancy, and hip mobility. Radiographically, the quality of epiphyseal reduction was evaluated using the Southwick and Alpha-angles. Avascular necrosis, heterotopic ossifications, and osteoarthritis were documented at follow-up. Results. At a mean follow-up of more than nine years, the mean modified Harris Hip score was 88.7 points, the Hip Disability and Osteoarthritis Outcome Score (HOOS) 87.4 , the Merle d’Aubigné Score 16.5 points, and the UCLA Activity Score 8.4. One patient developed a partial avascular necrosis of the femoral head, and one patient already had an avascular necrosis at the time of delayed diagnosis. Two hips developed osteoarthritic signs at 14 and 16 years after the index operation. Six patients needed a total of nine revision surgeries. One operation was needed for postoperative hip subluxation, one for secondary displacement and implant failure, two for late femoroacetabular impingement, one for femoroacetabular impingement of the opposite hip, and four for implant removal. Conclusion. Our series shows good results and is comparable to previous published studies. The modified Dunn procedure allows the anatomic repositioning of the slipped epiphysis. Long-term results with subjective and objective hip function are superior, avascular necrosis and development of osteoarthritis inferior to other reported treatment modalities. Nevertheless, the procedure is technically demanding and revision surgery for secondary femoroacetabular impingement and implant removal are frequent. Cite this article: 2020;1-4:80–87

Introduction. Total hip replacement failure due to fretting-corrosion remains a clinical concern. We recently described that damage within CoCrMo femoral heads can occur either by mechanically-dominated fretting processes leading to imprinting (via rough trunnions) and surface fretting (via smooth trunnions), or by a chemically-dominated etching process along preferential corrosion sites, termed “column damage”. These corrosion sites occur due to banding of the alloy microstructure. Banding is likely caused during thermo-mechanical processing of the alloy and is characterized by local molybdenum depletion. It was the objective of this study to quantify material loss from femoral heads with severe corrosion, identify the underlying damage modes, and to correlate the damage to the alloy's microstructure. Methods. 105 femoral heads with a Goldberg score 4 were evaluated. Coordinate measuring machine data was used to compute material loss and visualize damage features. Time in situ and stem alloy were identified. Metallographic samples were produced for each case. Grain size and banding were identified using light-microscopy. Mann-Whitney tests were conducted to compare material loss between groups. Results. Heads exhibited imprinting and column damage in 72 and 51 cases, respectively, with an overlap of 36 cases. 18 heads exhibited surface fretting only. All heads with column damage exhibited a banded microstructure. Heads with column damage had higher material loss (p=0.05) than those without. Also, heads with a banded microstructure had higher material loss (p=0.035) than those with a homogenous microstructure. Grain size, carbide content, and time did not correlate with material loss. Conclusion. Column damage is a detrimental damage mode within CoCrMo femoral heads that is directly linked to banding within its microstructure. It appears that banding even affects material loss before column damage is identifiable. These results indicate that implant alloy microstructure must be optimized to minimize the release of fretting-corrosion products and related implant failure

Introduction. Aseptic loosening, the clinical endpoint of osteolysis, remains the leading cause of total hip arthroplasty (THA) failure, and is caused by a host response to wear debris that varies between individuals. Although several candidate gene studies have identified loci associated with osteolysis susceptibility, there have been no systematic studies at genome-wide level. We aimed to identify risk loci associated with osteolysis by conducting a genome-wide association study. Methods. 3,706 Caucasian European patients following THA were studied. The discovery cohort comprising 894 patients (317 with osteolysis) were genotyped using the Illumina-610 beadchip followed by 1000 Genome-based imputation covering 10 million single nucleotide polymorphisms (SNPs). Phenotypes were transformed to normality where required, regressed on important covariates and z-standardised. Following quality control, osteolysis case-control analysis and a quantitative trait association analysis for time to prosthesis failure were undertaken. Index SNPs p<9×10. −4. were taken forward for replication in a second cohort comprising 2,812 subjects (834 osteolysis cases) recruited from the Norwegian arthroplasty registry. Genotyping was undertaken using Sequenom MassARRAY iPLEX Gold assay and association analyses undertaken using logistic and linear regression. Summary statistics were combined in a fixed-effects meta-analysis framework. Results. The strongest signal associated with time to prosthesis failure lay within DEFB129 gene. The signal index SNP, rs6105394, approached genome wide significance at p=5.75×10. −7. Two signals in the susceptibility analysis also approached genome-wide significance, 1 within CAMK4 (rs306105, OR 0.41, p=6.54×10. −7. ) and 1 upstream of PLNXA2 (rs11119057, OR 0.96, p=6.44×10. −7. ). Following meta-analysis, the strongest signal in the susceptibility analysis remained that within CAMK4 (rs306105, p=3.79×10. −4. ). The strongest signal associated with time to failure was just upstream of CNTN3 (rs1374879, p=2.15×10. −5. ). Discussion. We have identified promising loci associated with osteolysis and time to prosthesis failure although not at genome-wide significance (p<5×10. −8. ). In order to further validate these loci, larger genome wide association analysis is required

Osteolysis secondary to ultra-high molecular weight polyethylene (UHMWPE) wear is a leading cause of late-term implant failure via aseptic loosening in patients treated with total hip arthroplasty (THA). Radiation crosslinking of UHMWPE has been shown to decrease wear. However, the resulting polymer (crosslinked-PE) has a high free radical content. Two different methods that have been used to reduce the remaining free radicals are mechanical annealing and chemical stabilization using Vitamin E, a free radical scavenger. The primary purpose of the current study was to evaluate and compare the wear properties of vitamin E-doped crosslinked-PE (VEPE) and one formulation of mechanically annealed crosslinked-PE using radiostereometric analysis (RSA) in patients five years after primary THA. We also sought to understand the association between polyethylene wear and patient-reported outcome measures (PROMs). Three-hundred and five patients from six international centers were enrolled. Seventy-six percent were treated with highly-crosslinked (95 kGy) VEPE liners, and the rest received moderately-crosslinked (50 kGy) (ModXL), mechanically annealed liners. Data was collected prospectively at one-, two-, and five-year intervals. At the 5-year follow-up, proximal femoral head penetration into the VEPE liners (median = 0.05mm (range, −0.03–1.20)) was significantly lower than the penetration into the ModXL liners (median = 0.15mm (range, −0.22–1.04)) (p<0.001). In the VEPE cohort the median proximal penetration did not increase from one- to five-year follow-up (p=0.209). In contrast, there was a significant increase in femoral head penetration for the ModXL group (p<0.001) during that same time. Multivariable regression showed that the only variable predictive of increased wear was ModXL liner type (B=0.12, p<0.001). There were no differences in PROMs between the liner groups, and there was no correlation between polyethylene wear and PROMs for the cohort as a whole. The current study is the largest analysis of polyethylene wear at five-year follow-up using the RSA technique. We observed similar bedding in through the two-year interval between the two liner types, however, there was significantly more wear in the ModXL cohort at five-years. Currently, the wear rates for both liner groups are below the osteolysis threshold and have not led to any implant failures via aseptic loosening. Continued follow-up will provide a better understanding of the association between wear rate and clinical outcomes

Introduction. The purpose of this study was to evaluate the long term changes in bone mineral density (BMD) following implantation of a low-modulus composite femoral component designed to closely match the stiffness of the proximal femur and minimize stress shielding. Specifically, we asked: 1) How does BMD in the proximal femur change with time and with Gruen zone location; 2) Does BMD in the proximal femur stabilize after two years of implantation?. Methods. We retrospectively reviewed a subgroup of sixteen patients who had preoperative and postoperative DEXA scans in an FDA multi-center prospective trial of this composite stem. Five of these sixteen patients returned for long-term DEXA scans at a mean 22.0 years post-op (range 21.2–22.6 years). BMD in the 7 Gruen zones at final follow-up was compared to immediate post-operative and 2-year follow-up values. Percentage change was calculated and change in BMD was plotted against time from immediate post-operative measurements to each subsequent follow-up. Results. At the time of last follow-up, all stems were well fixed with signs of extensive osteointegration. There were no mechanical implant failures. In Gruen zone 1, patients underwent an overall decrease or little change in BMD, though one patient experienced a notable increase from initial post-op to the latest follow-up. The overall mean (+ SD) annual percent change in BMD in Gruen zone 1 was −0.31% ± 1.09%. When considering the change from the two-year DEXA scan to latest follow-up, two patients demonstrated a decrease in BMD and three patients demonstrated an increase in BMD in Gruen zone 1. All patients demonstrated progressive increase in BMD in Gruen zones 2, 3, 4, 5, and 6 from the initial post-op scan until last follow-up with mean annual percent changes ranging from 0.59% ± 0.50% in Gruen zone 6 to 2.78% ± 2.49% in Gruen zone 3. In our cohort, BMD progressively decreased with time in Gruen zone 7 for all patients with a mean decrease of 1.78% + 0.38% annually from the time of the initial post-op DEXA scan until last follow-up. This was consistent with prior reports with shorter term follow-up. Conclusions. Despite the extensively porous coated design of this stem and concerns about distal fixation and related stress shielding, we observed consistent DEXA scan evidence of increases in BMD in Gruen zones 2–6 and limitation of decreases in BMD exclusively to zone 7 and to a lesser extent zone 1. This is unlike reported results with several other extensively porous coated and proximally porous coated implants designed to obtain proximal fixation. These increases in BMD occurred despite the potential age-related decreases in BMD in the proximal femur that one would anticipate over the mean 22-year follow-up in this study. Clearly, “normal” physiologic loading of bone after THA is determined by a complex interaction between location of ingrowth, location and extent of endosteal contact of the implant in the proximal femur, stiffness of the stem and other implant design and patient related factors. The long-term observations of this study suggest that effective loading of the proximal femur occurs with this low-modulus stem and that this concept may have a role in the future of THA

Aims

This study aimed to determine whether lateral femoral wall thickness (LWT) < 20.5 mm was associated with increased revision risk of intertrochanteric fracture (ITF) of the hip following sliding hip screw (SHS) fixation when the medial calcar was intact. Additionally, the study assessed the association between LWT and patient mortality.

Aims

The risk of mechanical failure of modular revision hip stems is frequently mentioned in the literature, but little is currently known about the actual clinical failure rates of this type of prosthesis. The current retrospective long-term analysis examines the distal and modular failure patterns of the Prevision hip stem from 18 years of clinical use. A design improvement of the modular taper was introduced in 2008, and the data could also be used to compare the original and the current design of the modular connection.