Aims. Pelvic incidence (PI) is considered an important anatomical parameter for determining the sagittal balance of the spine. The contribution of an abnormal PI to hip osteoarthritis (OA) remains controversial. In this study, we aimed to investigate the relationship between PI and hip OA, and the difference in PI between hip OA without anatomical abnormalities (primary OA) and hip OA with developmental dysplasia of the hip (DDH-OA). Methods. In this study, 100 patients each of primary OA, DDH-OA, and control subjects with no history of hip disease were included. CT images were used to measure PI, sagittal femoral head coverage, α angle, and acetabular anteversion. PI was also subdivided into three categories: high PI (larger than 64.0°), medium PI (42.0° to 64.0°), and low PI (less than 42.0°). The anterior centre edge angles, posterior centre edge angles, and total sagittal femoral head coverage were measured. The correlations between PI and sagittal femoral head coverage, α angle, and acetabular anteversion were examined. Results. No significant difference in PI was observed between the three groups. There was no significant difference between the groups in terms of the category distribution of PI. The DDH-OA group had lower mean sagittal femoral head coverage than the other groups. There were no significant correlations between PI and other anatomical factors, including sagittal femoral head coverage, α angle, and acetabular anteversion. Conclusion. No associations were found between mean PI values or PI categories and hip OA. Furthermore, there was no difference in PI between patients with primary OA and DDH-OA. From our evaluation, we found no evidence of PI being an independent factor associated with the development of hip OA. Cite this article: Bone Joint J 2021;103-B(11):1656–1661

Introduction. Early functional recovery following total hip arthroplasty (THA) has the potential to increase patient satisfaction and reduce resource utilization. The direct anterior approach (DA) has been shown to provide earlier recovery compared to the direct lateral (DL) approach based on functional tests and outcome scores. There are limited studies that objectively evaluate functional recovery comparing the two approaches in the early post-operative period. Activity trackers have emerged as a valid tool to objectively quantify physical activity levels and potentially better assess functional status compared to commonly reported functional questionnaires. The purpose of this study is to measure physical activity levels in patients undergoing THA with the DA approach and compare these to THA with the direct lateral approach in the immediate postoperative period. Methods. In a tertiary academic center we prospectively enrolled patients with primary OA that were eligible for a primary THA undergoing either the DA or the DL approach using the same prosthesis. Patients with comorbidities precluding them from ambulation, diagnoses of AVN or RA or undergoing bilateral THA were excluded. The number of steps walked per day were measured using wristband activity tracking technology for one week preoperatively, the first 2 weeks postoperatively and for 1 week leading up to their 6-week follow-up appointment. The University of California, Los Angeles (UCLA) activity score was also collected at the same two time points. Demographics were analyzed with descriptive statistics. A non-parametric Mann Whitney U test was used to determine whether a difference in physical activity levels exist between the DA and DL approach groups in the first 2 weeks and 6 weeks postoperatively. Results. One hundred and thirty-nine patients with primary OA were enrolled. Seventeen were withdrawn prior to beginning the study (7 – patient requested, 5 – could not work the activity tracker, 5 – health issues). Following enrolment 29 patients were withdrawn due to lack of data available for analysis. There were 53 patients in the DA group and 40 patients in the DL group. Patient demographics including age and gender were similar in both groups. Body mass index was higher in the DL group (32.4 ± 6.9) compared to the DA group (28.2 ± 3.9) (p=0.001). There was no difference in the average steps taken per day or the UCLA score between the two groups preoperatively. The UCLA score and the overall average steps walked collected at 2 weeks postoperatively were significantly higher in the DA group compared to the DL group (median 4(1–6) vs. 3(2–6), p<0.001 and median 1641(329 – 8678) vs. 890(87 – 4347), p<0.001) respectively. When each postoperative day was evaluated individually, the DA group had a greater number of steps per day for the entire two weeks. At 6 weeks, the average number of steps taken by the DA group (median 4734 (1703 – 16605) () were greater than those taken by the DL group (median 3534 (462–8665) ± 2263) (p=0.007). A similar finding was demonstrated for the UCLA with the DA having greater self-reported activity levels (median 6 vs. 4, p<0.001). Discussion/Conclusions. The DA approach provided faster functional recovery in the immediate postoperative period compared to the DL approach as measured by a wristband activity tracker. DA approach patients walked a greater number of steps at both 2 weeks and 6 weeks. Further examination regarding the economic implications of the improved early function from the perspective of the patient, caregiver, and care payer is indicated

Introduction. The biological pathways responsible for adverse reactions to metal debris (ARMD) are unknown. Necrotic and inflammatory changes in response to Co-Cr nanoparticles in periprosthetic tissues may involve both a cytotoxic response and a type IV delayed hypersensitivity response. Our aim was to establish whether differences in biological cascade activation exists in tissues of patients with end-stage OA compared to those with aseptic loosening of a metal on polyethylene (MoP) THR and those with ARMD from metal-on-metal (MoM) THR. Patients & Methods. A microarray experiment (Illumina HT12-v4) was performed to identify the range of differential gene expression between 24 patients across 3 phenotypes: Primary OA (n=8), revision for aseptic loosening of MoP THR (n=8) and ARMD associated with MoM THR (n=8). Results were validated using Taqman Low Density Array (TLDA) selecting the top 36 genes in terms of fold-change (FC)>2 and a significant difference (p<0.05) on ANOVA. Pathways of cellular interaction were explored using Ingenuity IPA software. Results. There is a similar pattern of gene expression between MoP and MoM phenotypes versus primary OA across 33,777 genes. One hundred and thirty significantly differentially expressed genes across 3 phenotypes were identified. Fifteen pathways were associated with differentially expressed genes between MoP and MoM phenotypes. TLDA demonstrated qualitative mirroring of the expression pattern observed in the microarray and consistency in the direction of change for individual genes. Discussion. There were no signature pathways in which multiple genes are differentially expressed such that inferences between the contributions of innate macrophage and adaptive T-cell responses can be made. TIMP3 & MMP12 were consistently identified in 15 pathways that were associated with differential gene expression between MoP and MoM phenotypes. Conclusion. Analyses of the expression of individual genes such as PRG4 (lubricin) have demonstrated patterns that may provide avenues for further research into biomarkers for periprosthetic osteolysis and ARMD

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This study aimed to investigate the incidence of ≥ 5 mm asymmetry in lower and whole leg lengths (LLs) in patients with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH-OA) and primary hip osteoarthritis (PHOA), and the relationship between lower and whole LL asymmetries and femoral length asymmetry.

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The aims of the study were to report for a cohort aged younger than 40 years: 1) indications for HRA; 2) patient-reported outcomes in terms of the modified Harris Hip Score (HHS); 3) dislocation rate; and 4) revision rate.

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The Exeter short stem was designed for patients with Dorr type A femora and short-term results are promising. The aim of this study was to evaluate the minimum five-year stem migration pattern of Exeter short stems in comparison with Exeter standard stems.

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The aim of this study was to evaluate the reliability and validity of a patient-specific algorithm which we developed for predicting changes in sagittal pelvic tilt after total hip arthroplasty (THA).

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Osteoporosis is common in total hip arthroplasty (THA) patients. It plays a substantial factor in the surgery’s outcome, and previous studies have revealed that pharmacological treatment for osteoporosis influences implant survival rate. The purpose of this study was to examine the prevalence of and treatment rates for osteoporosis prior to THA, and to explore differences in osteoporosis-related biomarkers between patients treated and untreated for osteoporosis.

Introduction. Total hip arthroplasty (THA) is gaining popularity as a treatment for displaced femoral neck fractures (FNF), especially in physiologically younger patients. While elective THA for primary osteoarthritis (OA) has demonstrated low rates of complications and readmissions, the outcomes of THA for FNF are less predictable. Additionally, these THA procedures are equally included in various alternative payment bundles. Therefore, the aim of this study is to assess postoperative complication rates after THA for primary OA compared with FNF. Methods. The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database from 2008 to 2016 was queried. Patients were identified using the Current Procedural Terminology (CPT) code for THA (27130) and divided into groups by diagnosis; OA in one group and FNF in another. Univariate statistics were performed. T-test compared continuous variables between groups, and Chi-square test compared categorical variables. Multivariate and propensity matched logistic regression analyses were performed to control for risk factors of interest. The primary outcomes for this study were death or serious morbidity (surgical site infection (SSI), infection, respiratory complication, cardiac complication, sepsis, or blood loss anemia requiring postoperative transfusion). Additional secondary outcomes included the incidence of specific complications, total operative time (time from incision to closure), length of hospital stay and proportion of patients that were discharged home. Results. Analyses included 139,635 patients undergoing THA. OA was the indication in 135,013 cases and FNF in 4,622 cases. Unadjusted analysis showed a significantly higher rate of mortality when THA was done for hip fracture (2.1% vs. 0.1%; p<0.001). There was also a significantly increased rate of serious morbidity for hip fracture patients; including cardiac complications (3.5% vs 0.96%; p<0.001), respiratory complications (1.3% vs 0.2%; p<0.001), postop transfusion (23.1% vs 9.36%; p<0.001), sepsis (0.95% vs 0.3%; p<0.001). There was a significantly higher percentage of patients requiring reoperation (4.5% vs 2.0%; p<0.001) and readmission (8.0% vs 3.5%; p<0.001) in the hip fracture group. There was a significantly higher percentage of patients in the hip fracture groups having operative time >90min (16.4% vs 10.1%; p<0.001), length of stay longer than 5 days (53.8% vs 7.5%; p<0.001), and a significantly lower percentage of patients who were discharged home (39.0% vs 78.0%; p<0.001). Propensity score matching resulted in a cohort of 6,968 patients; 3,484 in both the hip fracture and osteoarthritis groups. Mortality within 30 days was 530% higher, and major morbidity was 36% higher among FNF patients. Reoperation was 40% higher, readmission was 36% higher, operative length at the 90th percentile was 74% higher, prolonged length of stay was 838% higher, and discharge to home was 62% lower for the FNF group compared with OA patients. Logistic, reverse stepwise regression model () results were consistent with the propensity-matched analysis. Discussion and Conclusion. This large database study showed a higher risk of postoperative complications including mortality, major morbidity, reoperation, readmission, prolonged operative time, increased length of stay, and decreased likelihood of discharge home in patients undergoing THA for FNF compared with OA. Without risk adjustment, the bundled payment methods that are applied to THA procedures including those performed for FNF are at a disadvantage and likely inadequate to cover the more costly episode of care related to treating hip fracture patients

Introduction. Custom flanged acetabular components (CFAC) have been shown to be effective in treating complex acetabular reconstructions in revision total hip arthroplasty (THA). However, the specific patient factors and CFAC design characteristics that affect the overall survivorship remain unclear. Once the surgeon opts to follow this treatment pathway, numerous decisions need to be made during the pre-operative design phase and during implantation, which may influence the ultimate success of CFAC. The goal of this study was to retrospectively review the entire cohort of CFAC cases performed at a large volume institution and to identify any patient, surgeon, or design factors that may be related to the long-term survival of these prostheses. Methods. We reviewed 96 CFAC cases performed in 91 patients between 2004 and 2017, from which 36 variables were collected spanning patient demographics, pre-operative clinical and radiographic features, intraoperative information, and implant design characteristics. Patient demographics and relevant clinical features were collected from individual medical records. Radiographic review included analysis of pre-operative radiographs, computer tomographic (CT) scans, and serial post-operative radiographs. Radiographic failure was defined as loosening or gross migration as determined by a board-certified orthopedic surgeon. CFAC implant design characteristics and intra-operative features were collected from the design record, surgical record and post-operative radiograph for each case respectively. Two sets of statistical analyses were performed with this dataset. First, univariate analyses were performed for each variable, comprising of a Pearson chi-square test for categorical variables and an independent t-test for continuous variables. Second, a random forest supervised machine learning method was applied to identify the most influential variables within the dataset, which were then used to perform a bivariable logistic regression to generate odds ratios. Statistical significance for this study was set at p < 0.05. Results. Radiographic failures occurred in 22/96 (23%) of cases with 12/96 (13%) undergoing re-revision (time to revision: Mean 25.1 months; Range: 3 – 84, SD 26.5). No relationship between radiographic failure and the preoperative Paprosky grade or the presence of a discontinuity was observed. The rate of radiographic failure (loosening and/or migration) was inversely associated with age, with increased failure seen in patients who were younger at the time of surgery; (mean age: 54.4±13.0 v. 64.8±11.4 years; p=0.007). Patients whose initial diagnosis was not osteoarthritis were more likely to fail than those with primary OA (OR: 3.79, p=0.0173) and were younger at the time of surgery (p=0.013). The presence of ischial screws from previous surgery (28%) was also an independent risk factor for failure (OR: 3.11, p=0.021). Random forest analysis identified the age at index procedure and the location of the inferior-most ischial screw as the most sensitive predictors of radiographic failure. As patient age at the time of surgery increased, there was subsequent a decreased rate of failure (OR: 0.93 odds ratio per year, p =0.005). When the bottom-most ischial screw was within the top half of the obturator foramen, it was 4 times more likely to fail than when this screw was located at the bottom half of the obturator foramen (OR = 3.98, p=0.046) (p < 0.05). Discussion and Conclusion. This study was able to identify the patient and design variables predictive of survival of CFAC prostheses used in complex revision THA. Younger patients (<55years) are at increased risk for failure either due to a more active lifestyle or because they have a non-OA primary diagnosis that predisposes them to earlier THA. Compromised ischial bone stock or inadequate ischial fixation both had a significant impact on CFAC implant survivorship as both the presence of pre-CFAC ischial screw fixation and lack of inferior ischial fixation correlated with increased rate of failure. These findings highlight the importance of rigid ischial fixation sufficient to resist the high pull-out forces generated during activities of daily living

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The aim of this study was to determine the outcome of all primary total hip arthroplasties (THAs) and their subsequent revision procedures in patients aged under 50 years performed at our institution.

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We aimed to evaluate the long-term outcome of highly cross-linked polyethylene (HXLPE) cemented acetabular components and assess whether any radiolucent lines (RLLs) which arose were progressive.

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The aim of this study was to evaluate the performance of first-generation annealed highly cross-linked polyethylene (HXLPE) in cementless total hip arthroplasty (THA).

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Septic arthritis of the hip often leads to irreversible osteoarthritis (OA) and the requirement for total hip arthroplasty (THA). The aim of this study was to report the mid-term risk of any infection, periprosthetic joint infection (PJI), aseptic revision, and reoperation in patients with a past history of septic arthritis who underwent THA, compared with a control group of patients who underwent THA for OA.

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Large-diameter metal-on-metal (MoM) total hip arthroplasty (THA) has demonstrated unexpected high failure rates and pseudotumour formation. The purpose of this prospective cohort study is to report ten-year results in order to establish revision rate, prevalence of pseudotumour formation, and relation with whole blood cobalt levels.

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To establish the survivorship, function, and metal ion levels in an unselected series of metal-on-metal hip resurfacing arthroplasties (HRAs) performed by a non-designer surgeon.

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The aim of this study was to determine whether total hip arthroplasty (THA) for chronic hip pain due to unilateral primary osteoarthritis (OA) has a beneficial effect on cognitive performance.

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Femoral bone preparation using compaction technique has been shown to preserve bone and improve implant fixation in animal models. No long-term clinical outcomes are available. There are no significant long-term differences between compaction and broaching techniques for primary total hip arthroplasty (THA) in terms of migration, clinical, and radiological outcomes.

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The aim of this study was to determine if uncemented acetabular polyethylene (PE) liner geometry, and lip size, influenced the risk of revision for instability or loosening.

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The direct anterior approach (DAA) for total hip arthroplasty (THA) has potential advantages over other approaches and is most commonly performed with the patient in the supine position. We describe a technique for DAA THA with the patient in the lateral decubitus position and report the early clinical and radiological outcomes, the characteristics of the learning curve, and perioperative complications.