Aims

Cam and pincer morphologies are potential precursors to hip osteoarthritis and important contributors to non-arthritic hip pain. However, only some hips with these pathomorphologies develop symptoms and joint degeneration, and it is not clear why. Anterior impingement between the femoral head-neck contour and acetabular rim in positions of hip flexion combined with rotation is a proposed pathomechanism in these hips, but this has not been studied in active postures. Our aim was to assess the anterior impingement pathomechanism in both active and passive postures with high hip flexion that are thought to provoke impingement.

Aims. Intra-articular (IA) injection may be used when treating hip osteoarthritis (OA). Common injections include steroids, hyaluronic acid (HA), local anaesthetic, and platelet-rich plasma (PRP). Network meta-analysis allows for comparisons between two or more treatment groups and uses direct and indirect comparisons between interventions. This network meta-analysis aims to compare the efficacy of various IA injections used in the management of hip OA with a follow-up of up to six months. Methods. This systematic review and network meta-analysis used a Bayesian random-effects model to evaluate the direct and indirect comparisons among all treatment options. PubMed, Web of Science, Clinicaltrial.gov, EMBASE, MEDLINE, and the Cochrane Library were searched from inception to February 2023. Randomized controlled trials (RCTs) which evaluate the efficacy of HA, PRP, local anaesthetic, steroid, steroid+anaesthetic, HA+PRP, and physiological saline injection as a placebo, for patients with hip OA were included. Results. In this meta-analysis of 16 RCTs with a total of 1,735 participants, steroid injection was found to be significantly more effective than placebo injection on reported pain at three months, but no significant difference was observed at six months. Furthermore, steroid injection was considerably more effective than placebo injection for functional outcomes at three months, while the combination of HA+PRP injection was substantially more effective at six months. Conclusion. Evidence suggests that steroid injection is more effective than saline injection for the treatment of hip joint pain, and restoration of functional outcomes. Cite this article: Bone Joint J 2024;106-B(6):532–539

Aims. This study aims to answer the following questions in patients with hip osteoarthritis (OA) who underwent total hip arthroplasty (THA): are patient-reported outcome measures (PROMs) affected by the location of the maximum severity of pain?; are PROMs affected by the presence of non-groin pain?; are PROMs affected by the severity of pain?; and are PROMs affected by the number of pain locations?. Methods. We reviewed 336 hips (305 patients) treated with THA for hip OA from December 2016 to November 2019 using pain location/severity questionnaires, modified Harris Hip Score (mHHS), Hip Outcome Score (HOS), international Hip Outcome Tool (iHOT-12) score, and radiological analysis. Descriptive statistics, analysis of covariance (ANCOVA), and Spearman partial correlation coefficients were used. Results. There was a significant difference in iHOT-12 scores between groups experiencing the most severe pain in the groin and the trochanter (p = 0.039). Additionally, more favourable mHHS scores were related to the presence of preoperative pain in trochanter (p = 0.049), lower back (p = 0.056), lateral thigh (p = 0.034), and posterior thigh (p = 0.005). Finally, the maximum severity of preoperative pain and number of pain locations had no significant relationship with PROMs (maximum severity: HHS: p = 0.928, HOS: p = 0.163, iHOT-12 p = 0.233; number of pain locations: HHS: p = 0.211; HOS: p = 0.801; iHOT-12: p = 0.112). Conclusion. Although there was a significant difference in iHOT-12 scores between patients with the most severe pain in the groin or trochanter, and the presence of pain in the trochanter, lower back, lateral thigh, or posterior thigh was related to higher mHHS scores, the majority of preoperative pain characteristics did not have a significant impact on outcomes. Therefore, a broad array of patients with hip OA might expect similar, favourable outcomes from THA notwithstanding preoperative pain characteristics. Cite this article: Bone Jt Open 2022;3(4):332–339

Aims. Femoroacetabular impingement (FAI) is a potential cause of hip osteoarthritis (OA). The purpose of this study was to investigate the expression profile of matrix metalloproteinases (MMPs) in the labral tissue with FAI pathology. Methods. In this study, labral tissues were collected from four FAI patients arthroscopically and from three normal hips of deceased donors. Proteins extracted from the FAI and normal labrums were separately applied for MMP array to screen the expression of seven MMPs and three tissue inhibitors of metalloproteinases (TIMPs). The expression of individual MMPs and TIMPs was quantified by densitometry and compared between the FAI and normal labral groups. The expression of selected MMPs and TIMPs was validated and localized in the labrum with immunohistochemistry. Results. On MMP arrays, most of the targeted MMPs and TIMPs were detected in the FAI and normal labral proteins. After data normalization, in comparison with the normal labral proteins, expression of MMP-1 and MMP-2 in the FAI group was increased and expression of TIMP-1 reduced. The histology of the FAI labrum showed disorderly cell distribution and altered composition of thick and thin collagen fibres. The labral cells expressing MMP-1 and MMP-2 were localized and their percentages were increased in the FAI labrum. Immunohistochemistry confirmed that the percentage of TIMP-1 positive cells was reduced in the FAI labrum. Conclusion. This study established an expression profile of MMPs and TIMPs in the FAI labrum. The increased expression of MMP-1 and MMP-2 and reduced expression of TIMP-1 in the FAI labrum are indicative of a pathogenic role of FAI in hip OA development. Cite this article:Bone Joint Res. 2020;9(4):173–181

Introduction. Exercise is recommended as first-line treatment for patients with hip osteoarthritis (OA). Interestingly, content and dose of exercise interventions seem to be important for the effect of exercise interventions, but the optimal content and dose is unknown. This warrants randomized controlled trials providing evidence for the optimal exercise program in Hip OA. The aim of this trial was to investigate whether progressive resistance training (PRT) is superior to neuromuscular exercise (NEMEX) for improving functional performance, hip pain and hip-related quality of life in patients with hip OA. Method. This was a multicenter, cluster-randomized, controlled, parallel-group, assessor-blinded, superiority trial. 160 participants with clinically diagnosed hip OA were recruited from hospitals and physiotherapy clinics and randomly assigned to twelve weeks of PRT or NEMEX. The PRT intervention consisted of 5 high-intensity resistance training exercises targeting muscles at the hip and knee joints. The NEMEX intervention included 10 exercises and emphasized sensorimotor control and functional stability. The primary outcome was change in the 30-second chair stand test (30s-CST). Key secondary outcomes were changes in scores on the pain and hip-related quality of life (QoL) subscales of the Hip Disability and Osteoarthritis Outcome Score (HOOS). Result. The mean changes from baseline to 12-week follow-up in the 30s-CST were 1.5 (95% CI, 0.9 to 2.1) chair stands with PRT and 1.5 (CI, 0.9 to 2.1) chair stands with NEMEX (difference, 0.0 [CI, 0.8 to 0.8] chair stands). For the HOOS pain subscale, mean changes were 8.6 (CI, 5.3 to 11.8) points with PRT and 9.3 (CI, 5.9 to 12.6) points with NEMEX. For the HOOS QoL subscale, mean changes were 8.0 (CI, 4.3 to 11.7) points with PRT and 5.7 (CI, 1.9 to 9.5) points with NEMEX. Conclusion. In patients with hip OA, PRT is not superior to NEMEX for improving functional performance, hip pain, or hip-related QoL

Total hip arthroplasty (THA) is an effective treatment for symptomatic hip osteoarthritis (OA). While computer-navigation technologies in total knee arthroplasty show survivorship advantages and are widely used, comparable applications within THA show far lower utilisation. Using national registry data, this study compared patient reported outcome measures (PROMs) in patients who underwent THA with and without computer navigation. Data from Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) PROMs program included all primary THA procedures performed for OA up to 31 December 2020. Procedures using the Intellijoint HIP® navigation system were identified and compared to procedures using other computer navigation systems or conventional instrumentation only. Changes in PROM scores between pre-operative and 6-month post-operative time points were analysed using multiple regression model, adjusting for pre-operative score, patient age, gender, ASA score, BMI, surgical approach, and hospital type. There were 65 primary THA procedures that used the Intellijoint HIP® system, 90 procedures used other types of computer navigation, and the remaining 5,284 primary THA procedures used conventional instrumentation. The estimated mean changes in the EuroQol visual analogue scale (EQ VAS) score and Oxford Hip score did not differ significantly when Intellijoint® was compared to conventional instruments (estimated differences of 2.4, 95% CI [-1.7, 6.5], p = 0.245, and −0.5, 95% CI [-2.5, 1.4], p = 0.592, respectively). The proportion of patients who were satisfied with their procedure was also similar when Intellijoint® was compared to conventional instruments (rate ratio 1.06, 95% CI [0.97, 1.16], p = 0.227). The preliminary data demonstrate no significant difference in PROMs when comparing the Intellijoint HIP® THA navigation system with both other navigation systems and conventional instrumentation for primary THAs performed for OA. Level of evidence: III (National registry analysis)

Although total hip arthroplasty (THA) is beneficial for many patients with hip osteoarthritis (OA), a subset of patients experience minimal benefit. It is therefore pertinent to understand the predictors of poor functional outcome to facilitate shared decision making. One such predictor is preoperative radiographic OA severity. The aim of this systematic review was to determine whether preoperative radiographic OA severity could predict postoperative patient-reported outcome measures (PROMs) and satisfaction rates after THA. This systematic review was conducted according to PRISMA guidelines, and the protocol published in PROSPERO (ID:Â CRD42023445918). A literature search was performed using Embase, MEDLINE and Cochrane Library databases. Demographics, radiographic OA severity, PROMs, satisfaction, and complications after THA were collected. A meta-analysis was performed, where appropriate, using a random-effects model. Of 631 identified articles, 12 were included in the final analysis (8,034 participants; mean age 65.2, 38.1% male, mean BMI 29.1 kg/m2). There were three key findings. Firstly, those with mild OA are less likely to achieve a meaningful clinical improvement in PROMs (odds ratio (OR) 0.50, 95% confidence interval (CI) 0.38, 0.65; p < 0.00001). Secondly, two studies indicates that postoperative patient satisfaction was lower in participants with mild OA. Thirdly, participants with mild arthritis experience less improvement in SF-36 physical functioning (mean difference (MD) -8.31, 95% CI -10.97, -5.64; p < 0.00001) and role physical (MD -5.59, 95% CI -8.40, -2.77; p < 0.0001), but showed higher improvement in general health (MD 1.68, 95% CI 0.31, 3.06; p = 0.02). Patients with mild OA, as determined radiographically, are less likely to achieve meaningful clinical improvements in PROMs and have lower postoperative satisfaction after THA. This information will improve collaborative decision-making in the preoperative period

Total hip arthroplasty (THA) is an effective treatment for symptomatic hip osteoarthritis (OA). Computer-navigation technologies in total knee arthroplasty show evidence-supported survivorship advantages and are used widely. The aim of this study was to determine the revision outcome of hip commercially available navigation technologies. Data from the Australian Orthopaedic Association National Joint Replacement Registry from January 2016 to December 2020 included all primary THA procedures performed for osteoarthritis (OA). Procedures using the Intellijoint HIP® navigation were identified and compared to procedures inserted using ‘other’ computer navigation systems and to all non-navigated procedures. The cumulative percent revision (CPR) was compared between the three groups using Kaplan-Meier estimates of survivorship and hazard ratios (HR) from Cox proportional hazards models, adjusted for age and gender. A prosthesis specific analysis was also performed. There were 1911 procedures that used the Intellijoint® system, 4081 used ‘other’ computer navigation, and 160,661 were non-navigated. The all-cause 2-year CPR rate for the Intellijoint HIP® system was 1.8% (95% CI 1.2, 2.6), compared to 2.2% (95% CI 1.8, 2.8) for other navigated and 2.2% (95% CI 2.1, 2.3) for non-navigated cases. A prosthesis specific analysis identified the Paragon/Acetabular Shell THAs combined with the Intellijoint HIP® system as having a higher (3.4%) rate of revision than non-navigated THAs (HR = 2.00 (1.01, 4.00), p=0.048). When this outlier combination was excluded, the Intellijoint® system group demonstrated a two-year CPR of 1.3%. There was no statistical difference in the CPR between the three groups before or after excluding Paragon/Acetabular Shell system. The preliminary data presented demonstrate no statistical difference in all cause revision rates when comparing the Intellijoint HIP® THA navigation system with ‘other’ navigation systems and ‘non-navigated’ approaches for primary THAs performed for OA. The current sample size remains too small to permit meaningful subgroup statistical comparisons

Wearable inertial sensors can detect abnormal gait associated with knee or hip osteoarthritis (OA). However, few studies have compared sensor-derived gait parameters between patients with hip and knee OA or evaluated the efficacy of sensors suitable for remote monitoring in distinguishing between the two. Hence, our study seeks to examine the differences in accelerations captured by low-frequency wearable sensors in patients with knee and hip OA and classify their gait patterns. We included patients with unilateral hip and knee OA. Gait analysis was conducted using an accelerometer ipsilateral with the affected joint on the lateral distal thighs. Statistical parametric mapping (SPM) was used to compare acceleration signals. The k-Nearest Neighbor (k-NN) algorithm was trained on 80% of the signals' Fourier coefficients and validated on the remaining 20% using 10-fold cross-validation to classify the gait patterns into hip and knee OA. We included 42 hip OA patients (19 females, age 70 [63–78], BMI of 28.3 [24.8–30.9]) and 59 knee OA patients (31 females, age 68 [62–74], BMI of 29.7 [26.3–32.6]). The SPM results indicated that one cluster (12–20%) along the vertical axis had accelerations exceeding the critical threshold of 2.956 (p=0.024). For the anteroposterior axis, three clusters were observed exceeding the threshold of 3.031 at 5–19% (p = 0.0001), 39–54% (p=0.00005), and 88–96% (p = 0.01). Regarding the mediolateral axis, four clusters were identified exceeding the threshold of 2.875 at 0–9% (p = 0.02), 14–20% (p=0.04), 28–68% (p < 0.00001), and 84–100% (p = 0.004). The k-NN model achieved an AUC of 0.79, an accuracy of 80%, and a precision of 85%. In conclusion, the Fourier coefficients of the signals recorded by wearable sensors can effectively discriminate the gait patterns of knee and hip OA. In addition, the most remarkable differences in the time domain were observed along the mediolateral axis

We determined the impact of deprivation and frailty at the time of diagnosis of hip osteoarthritis (OA) on the likelihood of receiving total hip arthroplasty (THA). We used routinely collected primary care data (Clinical Practice Research Datalink) linked to Hospital Episode Statistics. Frailty was assessed at the time of hip OA diagnosis using a validated frailty index based on coded data in the primary care record and categorised as fit, mild, moderate, and severe frailty. The association between quintile of index of multiple deprivation (IMD), frailty category and likelihood of receiving THA was assessed in separate Cox regression models, adjusted for year of OA diagnosis, age, and sex. 104,672 individuals with hip OA contributed. Compared to those in the first quintile of IMD (least deprived), those in the fourth and fifth quintile of IMD (most deprived), respectively, were less likely to receive THA, hazard ratio (HR) (95% CI), 0.92 (0.89, 0.95) and 0.80 (0.77, 0.83). Increasing frailty at OA diagnosis was associated with reduced likelihood of receiving THA. Compared to fit individuals, the HR (95% CI) for receiving THA among those with: mild frailty was 0.80 (0.78, 0.82); moderate frailty was 0.60 (0.58, 0.62); and severe frailty was 0.42 (0.39, 0.45). Increasing deprivation was associated with increasing frailty at the time of hip OA diagnosis, independent of age, sex, and year of OA diagnosis. However, those in the two most deprived quintiles were still less likely to receive THA after additionally adjusting for frailty category. Greater deprivation and greater frailty were associated with lower likelihood of receiving THA among people with hip osteoarthritis. Greater frailty among those most deprived did not explain the reduced likelihood of receiving THA among those most deprived

Introduction and Objective. Hip osteoarthritis (OA) is the leading cause for total hip arthroplasty (THA). Although, being considered as the surgery of the century up to 23% of the patients report long-term pain and deficits in physical function and muscle strength may persist after THA. Progressive resistance training (PRT) appear to improve several outcomes moderately in patients with hip OA. Current treatment selection is based on low-level evidence as no randomised controlled trials have compared THA to non-surgical treatment. The primary objective of this trial is to determine the effectiveness of THA followed by standard care compared to 12 weeks of supervised PRT followed by 12 weeks of optional unsupervised PRT, on changes in hip pain and function, in patients with severe hip OA after 6 months. Materials and Methods. This is a protocol for a multicentre, parallel-group, assessor blinded, randomised controlled superiority trial. Patients aged ≥50 years with clinical and radiographic hip OA found eligible for THA by an orthopaedic surgeon will be randomised to THA or PRT (allocation 1:1). The primary outcome will be change in patient-reported hip pain and function, measured using the Oxford Hip Score. Key secondary outcomes will be change in the Hip disability and Osteoarthritis Outcome Score subscales, University of California Los Angeles Activity Score, 40-meter fast-paced walk test, 30-second chair stand test, and number of serious adverse events. Results. The trial has been approved by The Regional Committees on Health Research Ethics for Southern Denmark (Project-ID: S-20180158) in February 2019 and registration was performed at . ClinicalTrials.gov. (NCT04070027) in August 2019. Recruitment was initiated on the 2. nd. of September 2019 and the final deadline will be on the 30. th. of June 2021, or when a sample size of 120 patients has been accomplished. Conclusions. The results of the current trial are expected to enable evidence-based recommendations, which may be used to facilitate the shared-decision making process in the discussion of treatment strategy for the individual patient with severe hip OA. All results will be presented in peer-reviewed scientific journals and international conferences

Introduction. Patients with reduced lumbar spine mobility are at higher risk of dislocation after THA as their hips have to compensate for spinal stiffness. Therefore our study aimed to 1) Define the optimal protocol for identifying patients with mobile hips and stiff lumbar spines and 2) Determine clinical and standing radiographic parameters predicting high hip and reduced lumbar spine mobility. Methods. This prospective diagnostic cohort study followed 113 consecutive patients with end-stage hip osteoarthritis (OA) awaiting THA. Radiographic measurements were performed for the lumbar lordosis angle, pelvic tilt and pelvic-femoral angle on lateral radiographs in the standing, ‘relaxed-seated’ and ‘deep-seated’ (i.e. torso maximally leaning forward) position. A “hip user index” was calculated in order to quantify the contribution of the hip joint to the overall sagittal movement performed by the femur, pelvis and lumbar spine. Results. Radiographs in the relaxed-seated position had an accuracy of 56% (95%CI:46–65%) to detect patients with stiff lumbar spines, compared to a detected rate of 100% in the deep-seated position. The mean ‘hip user index’ was 63±12% and ten patients (9%) were hip users, having an index of 80% or more. A standing pelvic tilt of ≥18.5° was the only predictor for being a hip user with a sensitivity of 90% and specificity of 71% (AUC 0.83). Patients with a standing pelvic tilt ≥18.5° and an unbalanced spine with a flatback deformity had a 30xfold relative risk (95%-CI:4–226; p<0.001) of being a hip user. Conclusion. Patients awaiting THA and having high hip and reduced lumbar spine mobility can be screened for with lateral standing radiographs of the spinopelvic complex and a thorough clinical examination. If the initial screening is positive, radiographs in the deep-seated position allow for better identification of patients being ‘hip users’ compared to radiographs in the relaxed-seated position

Introduction. Interactions between hip, pelvis and spine, as abnormal spinopelvic movements, have been associated with inferior outcomes following total hip arthroplasty (THA). Changes in pelvis position lead to a mutual change in functional cup orientation, with both pelvic tilt and rotation having a significant effect on version. Hip osteoarthritis (OA) patients have shown reduced hip kinematics which may place increased demands on the pelvis and the spine. Sagittal and coronal planes assessments are commonly done as these can be adequately studied with anteroposterior and lateral radiographs. However, abnormal pelvis rotation is likely to compromise the outcome as they have a detrimental effect on cup orientation and increased impingement risk. This study aims to determine the association between dynamic motion and radiographic sagittal assessments; and examine the association between axial and sagittal spinal and pelvic kinematics between hip OA patients and healthy controls (CTRL). Methods. This is a prospective study, IRB approved. Twenty hip OA pre-THA patients (11F/9M, 67±9 years) and six CTRL (3F/3M, 46±18 years) underwent lateral spinopelvic radiographs in standing and seated bend-and-reach (SBR) positions. Pelvic tilt (PT), pelvic-femoral-angle (PFA) and lumbar lordosis (LL) angles were measured in both positions and the differences (Δ) between standing and SBR were calculated. Dynamic SBR and seated maximal-trunk-rotation (STR) were recorded in the biomechanics laboratory using a 10-infrared camera and processed on a motion capture system (Vicon, UK). Direct kinematics extracted maximal pelvic tilt (PT. max. ), hip flexion (HF. max. ) and (mid-thoracic to lumbar) spinal flexion (SF. max. ). The SBR pelvic movement contribution (ΔPT. rel. ) was calculated as ΔPT/(ΔPT+ΔPFA)∗100 for the radiographic analysis and as PT. max. /(PT. max. +HF. max. ) for the motion analyses. Axial and sagittal, pelvic and spinal range of motion (ROM) were calculated for STR and SBR, respectively. Spearman's rank-order determined correlations between the spinopelvic radiographs and sagittal kinematics, and the sagittal/axial kinematics. Mann-Whitney U-tests compared measures between groups. Results. Radiograph readings correlated with sagittal kinematics during SBR for ΔPT and PT. max. (ρ=0.64, p<0.001), ΔPFA and HF. max. (ρ=0.44, p<0.0002), and ΔLL and SF. max. (ρ=0.34, p=0.002). Relative pelvic movements (ΔPT. rel. ) were not different between radiographic (11%±21) and biomechanical (15%±29) readings (p=0.9). Sagittal SRB spinal flexion correlated with the axial STR rotation (ρ=0.43, p<0.0001). Although not seen in CTRL, sagittal SRB pelvic flexion strongly correlated with STR pelvic rotation in OA patients (ρ=0.40, p=0.002). All spinopelvic parameters were different between the patients with OA and CTRL. CTRLs exhibited significantly greater mobility and less variability in all 3 segments (spine, pelvis, hip) and both planes (axial and sagittal) (Table 1). Conclusion. Correlation between sagittal kinematics and radiographical measurements during SBR validates the spinopelvic mobility assessments in the biomechanics laboratory. Axial kinematics of both pelvis and spine correlated significantly in OA patients, suggesting that patients with abnormal sagittal mobility are likely to also exhibit abnormal axial mobility, which can further potentiate any at-risk kinematics. Significantly lower OA ROM must be investigated post-THA. Pre-THA variability of both sagittal and axial movements indicates that both planes must be considered ahead of surgical planning with navigation and/or robotics. For any figures or tables, please contact the authors directly

Total hip arthroplasty (THA) is one of the most successful and effective treatments for advanced hip osteoarthritis (OA). Over the last 5 years, Canada has seen a 17.8% increase in the number of hip replacements performed annually, and that number is expected to grow along with the aging Canadian population. However, the rise in THA surgery is associated with an increased number of patients at risk for the development of an infection involving the joint prosthesis and adjacent deep tissue – periprosthetic joint infections (PJI). Despite improved hygiene protocols and novel surgical strategies, PJI remains a serious complication. No previous population-based studies has investigated PJI risk factors using a time-to-event approach and none have focused exclusively on patients undergoing THA for primary hip OA. The purpose of this study is to determine risk factors for PJI after primary THA for OA using a large population-based database collected over 15 years. Our secondary objective is to determine the incidence of PJI, the time to PJI following primary THA, and if PJI rates have changed in the past 15 years. We performed a population-based cohort study using linked administrative databases in Ontario, Canada in accordance with RECORD and STROBE guidelines. All primary total hip replacements performed for osteoarthritis in patients aged 55 or older between January 1st 2002 – December 31st 2016 in Ontario, Canada were identified. Periprosthetic joint infection as the cause for revision surgery was identified with the International Classification of Diseases, 10th Edition (ICD-10), Clinical Modification diagnosis code T84.53 in any component of the healthcare data set. Data were obtained from the Institute for Clinical Evaluative Sciences (ICES). Demographic data and outcomes are summarized using descriptive statistics. We used a Cox proportional hazards model to analyze the effect of surgical factors and patient factors on the risk of developing PJI. Surgical factors include the approach, use of bone graft, use of cement, and the year of surgery. Patient factors include sex, age at surgery, income quintile and rurality (community vs. urban). We compared the 1,2,5 and 10 year PJI rates for patients undergoing THA each year of our cohort with the Cochran-Armitage test. Less than 0.1% of data were missing from all fields except for rurality which was lacking 0.3% of data. A total of 100,674 patients aged 55 or older received a primary total hip arthroplasty for osteoarthritis from 2002–2016. We identified 1034 cases of revision surgery for prosthetic joint infection for an overall PJI rate of 1.03%. When accounting for patients censored at final follow-up, the cumulative incidence for PJI is 1.44%. Our Cox proportional hazards model revealed that male sex, Type II diabetes mellitus, discharge to convalescent care, and having both hips replaced during one's lifetime were associated with increased risk of developing PJI following primary THA. Importantly, the time adjusted risk for PJI was equal for patients operated within the past 5 years, 6–10 years ago, or 11–15 years ago. The surgical approach, use of bone grafting or cement were not associated with increased risk of infection. PJI rates have not changed significantly over the past 15 years. One, two, five and ten-year PJI rates were similar for patients undergoing THA in all qualifying years. Analysis of a population-based cohort of 100,674 patients has shown that the risk of developing PJI following primary THA has not changed over 15 years. The surgical approach, use of bone grafting or cement were not associated with increased risk of infection. Male sex, Type II diabetes Mellitus and discharge to a rehab facility are associated with increased risk of PJI. As the risk of PJI has not changed in 15 years, an appropriately powered trial is warranted to determine interventions that can improve infection rate after THA

The arcOGEN study identified the 9q33.1 locus as associated with hip osteoarthritis (OA) in females. TRIM32 lies within this locus and may have biological relevance to OA; it encodes a protein with E3 ubiquitin ligase activity. Sanger sequencing of TRIM32 in the youngest 500 female patients with hip OA from the arcOGEN study identified genetic polymorphisms in the proximal promoter, and 3'untranslated region of TRIM32 that are disproportionately represented in female patients with hip OA compared to the control population. Reduced expression of TRIM32 was identified in femoral head articular chondrocytes from patients with hip OA compared to control patients. Trim32 knockout resulted in increased aggrecanolysis in murine femoral head explants. Murine chondrocytes deficient in Trim32 exhibited increased expression of mature chondrocyte markers following anabolic cytokine stimulation, and increased expression of hypertrophic chondrocyte markers following catabolic cytokine stimulation. Trim32 knockout mice demonstrated increased cartilage degradation and tibial subchondral bone changes after surgically-induced knee joint instability. Increased cartilage degradation and medial knee subchondral bone changes were also identified in aged Trim32 knockout mice. These results further implicate TRIM32 in the genetic predisposition to OA, and indicate a role for TRIM32 in the joint degeneration evident in OA. These results support the further study of TRIM32 in the pathophysiology of OA and development of novel therapeutic strategies to manage OA

Total Hip Replacement (THR) is widely assumed to resolve sleep disturbance commonly experienced by individuals with hip osteoarthritis (OA). We report a study of 329 THRs with mean age of 71.9 years comparing pre-operative and one and two year post-operative patient reported outcomes for sleep disturbance to determine the veracity of this expectation. Data was collected from the validated Oxford Hip Patient Reported Questionnaire. Specifically, Question 12: “During the past four weeks, have you been troubled by pain from your hip in bed at night?” Answers to the question were multiple choice: No nights (4 points), Only 1 or 2 nights (3 points), Some nights (2 points), Most nights (1 point) and Every Night (0 points). Pre-operatively, the mean score for patients with hip OA was 1.2/4. This increased to 3.5 at one year and was also maintained at two years. The pre- to post-operative improvement was significant at both one and two years for THR with p <0.00001. Pre-operatively, only 6% of patients with arthritic hips reported that they were never woken from sleep because of their painful hip. One year after THR 72% always enjoyed pain free sleeping and at two years this had risen to 75%. When patients who only experienced disturbance one or two nights per month were included, the three figures increased from 13% to 83% and 83% respectively. The study confirms that sleep disturbance affects over 90% of patients with arthritic hip joints. Over 80% of THR patients will enjoy sleep that is seldom or never disturbed by their artificial hip. The improvement achieved by THR occurs within a year of surgery and is preserved at two years. In this regard, hip replacement is a highly effective intervention

Total Hip Arthroplasty (THA) is a successful operation for the management of end stage hip osteoarthritis (OA) but long term success is limited by wear of the polyethylene bearing surface. The aim of this study was to compare the rate of revision at 15 years in patients <55 who had a THA for OA, and received either cross-linked (XLPE) or conventional non cross-linked polyethylene (non-XLPE). The study population was all patients with primary THAs undertaken for OA from 1999 to 31 December 2016. Outcomes were determined for all procedures, comparing THA performed with non-XLPE and XLPE and including the effect of age, sex, and reason for revision. The principal outcome measure was time to first revision using Kaplan-Meier estimates of survivorship. There were 17,869 procedures recorded for younger patients <55 years of age undergoing THA for OA and using either non XLPE or XLPE. There was a fivefold increase in the rate of revision for procedures using non-XLPE after seven years. The 15 year cumulative percent revision of primary THA performed for OA in patients <55 with non XLPE was 17.4% (95% CI 15.5,19.5) and for XLPE was 6.6% (95%CI 5.5,7.8) HR >7 years =5.3, p<0.001. Non-XLPE and XLPE were combined with three different femoral head bearing surfaces: ceramic, metal and ceramicised metal. Within each bearing surface, XLPE had a lower rate of revision than non-XLPE. For the most common head size of 28mm XLPE had a lower rate of revision. The use of XLPE has resulted in a significant reduction in the rate of revision for younger patients undergoing THA for OA at 15 years. This evidence suggests that longevity of THA is likely to be improved and may enable younger patients to undergo surgery, confident of a reduced need for revision in the long term

TRIM32 is a candidate gene at the 9q33.1 genetic susceptibility locus for hip osteoarthritis (OA). Increased cartilage degradation typical of OA has previously been demonstrated in Trim32 knockout mice. Our aim is to investigate the role of TRIM32 in human and murine articular tissue. TRIM32 expression in human articular cartilage was examined by immunostaining. TRIM32 expression was compared in femoral head chondrocytes from patients with and without primary hip OA (n=6/group) and examined by Western blotting. Aggrecanolysis by femoral head explants from Trim32 knockout (T32KO) and wild-type (WT) mice was compared following stimulation with IL1α or retinoic acid (RA) and was assessed by DMMB assay (n=4/group). Expression of chondrocyte phenotype markers was measured by qPCR and compared between articular chondrocytes from WT and T32KO mice following catabolic (IL1α/TNFα) or anabolic (Oncostatin-M (OSM)/IGF1) stimulation. TRIM32 expression was demonstrated in human articular cartilage; TRIM32 expression by chondrocytes was reduced in patients with hip OA (p=0.03). Greater aggrecanolysis occurred in cartilage explants from T32KO mice after treatment with no stimulation (p=0.03), IL1α (p=0.02), and RA (p=0.001). Unstimulated T32KO chondrocytes expressed reduced Col2a1 (p=8.53×10. −5. ), and Sox9 (p=2.35×10. −6. ). Upon IL1α treatment, T32KO chondrocytes expressed increased Col10a1 (p=0.0003). Upon anabolic stimulation, T32KO chondrocytes expressed increased Col2a1 (OSM: p=0.001; IGF: p=0.001), and reduced Sox9 (OSM: p=0.0002; IGF: p=0.0006). These results indicate that altered TRIM32 expression in human articular tissue is associated with OA, and that Trim32 knockout results in increased cartilage degradation in murine femoral head explants. Predisposition to cartilage degeneration with reduced Trim32 expression may involve increased chondrocyte hypertrophy upon catabolic cytokine stimulation and dysregulation of Col2a1 and Sox9 expression upon anabolic stimulation

Introduction. Hip osteoarthritis (OA) results in reduced hip range of motion and contracture, affecting sitting and standing posture. Spinal pathology such as fusion or deformity may alter the ability to compensate for reduced joint mobility in sitting and standing postures. The effects of postural spinal alignment change between sitting and standing is not well understood. Methods. A retrospective radiographic review was performed at a single academic institution of patients with sitting and standing full-body radiographs between 2012 and 2017. Patients were excluded if they had transitional lumbosacral anatomy, prior spinal fusion or hip prosthesis. Hip OA severity was graded by the Kellgren-Lawrence grades and divided into two groups: low-grade OA (LOA; grade 0–2) and severe OA (SOA; grade 3–4). Spinopelvic parameters (Pelvic Incidence (PI), Pelvic Tilt (PT), Lumbar Lordosis (LL), and PI-LL), Thoracic Kyphosis (TK; T4-T12), Global spinal alignment (SVA and T1-Pelvic Angle; TPA; T10-L2) as well as proximal femoral shaft angle (PFSA: as measured from the vertical), and hip flexion (difference between change in PT and change in PFSA) were also measured. Changes in sit-stand radiographic parameters were compared between the LOA and SOA groups with unpaired t-test. Results. 548 patients were identified with sit-stand radiographs, of which there were 311 patients with LOA & 237 with SOA. After propensity score matching for Age, BMI, and PI, 183 LOA & 183 SOA patients were analyzed. Standing alignment analysis demonstrated that SOA patients had greater SVA (31.1 ± 36.68 vs 21.7 ± 38.83, p=0.02), and lower TK (−36.21 ± 11.98 vs −41.09 ± 11.47, p<0.001). SOA patients had lower PT, greater PI-LL, lower LL, lower T10-L2, and lower TPA (p>0.05). PFSA (9.09 5.19 vs 7.41 4.48, p<0.001) was significantly different compared to LOA while SOA KA was not significantly different compared to LOA. Sitting alignment analysis demonstrated that SOA patients had higher PT (29.69 ± 15.65 vs 23.32 ± 12.12, p<0.001), higher PI-LL (21.64 ±17.86 vs 12.44 ±14.84 p<0.001), lower LL (31.67 ± 16.40 vs 41.58 ± 14.73, p<0.001), lower TK (−33.22 ± 15.76 vs −38.57 ± 13.01, p=0.01), greater TPA (27.91 ± 14.7 vs 22.55 ± 11.38 p=0.01). TK, SVA, and PFSA were not significantly different compared to LOA. SOA and LOA groups demonstrated differences in standing and sitting spinopelvic alignment for all global and regional parameters except PI. When examining the postural changes from standing to sitting, there was less hip ROM in SOA than LOA (71.45 ± 18.55 vs 81.64 ± 12.57, p<0.001). As a result, SOA patients had more change in PT (15.24 ± 16.32 vs 7.28 ± 10.19, p<0.001), PI-LL (20.62 ± 17.25 vs 13.74 ± 11.16, p<0.001), LL (−21.37 ± 15.55 vs −13.09 ± 12.34, p<0.001), and T10-L2 (−4.94 ± 7.45 vs −1.08 ± 5.19, p<0.001) to compensate. SOA had a greater improvement in TPA (15.06 vs 9.59, p<0.001), and less change in PFSA (86.65 vs 88.81, p<0.001) compared to LOA. Conclusions. Spinopelvic compensatory mechanisms are adapted for reduced joint mobility associated with hip OA in standing and sitting

Background. Total Hip Arthroplasty (THA) has long been the standard treatment for cases in which non-surgical alternatives have failed to improve pain and function in hip osteoarthritis (OA) patients. Outcomes from THA have improved over time with better surgical techniques and improved implant designs. While conventional neck-sacrificing implants have been associated with favorable outcomes, there is evidence to suggest biomechanical advantages of newer, femoral neck-preserving short-stem implants, including the Corin MiniHip. However, there is a still a gap of knowledge regarding the potential benefits of the MiniHip stem over conventional neck-sacrificing stems in regards to patient-reported outcomes (PROs). In this study, we investigated the differences between a neck-sacrificing stem design and neck-preserving short-stem design (MiniHip, Corin Inc.) arthroplasty concerning PROs, and considering the known features of the short stem design, we hypothesized that MiniHip THA would be associated with improved PROs in comparison to a neck-sacrificing implant system. We further sought to investigate gender effects related to MiniHip or conventional stem surgery. Methods. Neck-sacrificing implant patients (n=90, age 57±7.9 years, female=58, male=32) and a matched (matching criteria: follow-up period, BMI, age) cohort group of MiniHip patients (n=105, age 55.16±9.88 years, female: 25, male: 80) reported both pre-operative and post-operative Hip disability and Osteoarthritis Outcome Scores (HOOS) at a minimum interval of 6 months post-operatively and up to three years postoperatively. We applied MANCOVA analysis to compare patient-reported outcome subscores from each group using follow-up period as a covariate and employing gender as an additional grouping factor to evaluate gender effects. Statistical significance was set at α=0.05 and Bonferroni corrections were applied to account for multiple comparisons. Results. There was a main effect of time, showing that all HOOS subscores of both groups increased significantly after surgery (p<0.001). There was a main effect of surgery for subscores Symptoms (p=0.038), ADL (p=0.046), and Sports and Recreation (p=0.039). There was a gender effect only for the subscore Symptoms (p=0.007). There were significant time by surgery interactions for HOOS subscores Symptoms (p=0.002), Pain (p=.009), Sports and Recreation (p=0.004), and QOL (p<0.001) subscores. We also observed a significant time by gender interaction effect for all HOOS subscores (p<0.001). Discussion. The interaction effects regarding most HOOS subscores and surgery/implant type indicate an advantage of MiniHip surgery regarding post-operative reported outcomes. The observed results may be due to previously described improved physiological loading and native hip structure preservation with neck-preserving short-stem designs. While longer-term studies are required for further investigation, evidence suggests the MiniHip may provide a significant benefit to primary THA patients. The additional gender/time interaction effect observed in our study highlights the necessity to consider potential sex differences regarding both the potential/expected improvement in PROs from THA and the requirement to account for such differences when designing osteoarthritis outcome studies based on PROs