A single nucleotide polymorphism of IL6-receptor is associated with response to tocilizumab in rheumatoid arthritis patients.

Biological disease-modifying anti-rheumatic drugs (bDMARDs) have changed care of patients with rheumatoid arthritis (RA). However, bDMARDs are costly, can lead to serious infections, and induce a sustained remission in only 30% of RA patients. In this study, we sought to determine if the clinical response to treatment with Tocilizumab (TCZ), an IL-6 inhibitor, varied with genetic background. The efficacy of TCZ was assessed using the European League Against Rheumatism (EULAR) response criteria, measured after 3 months of treatment in two samples of French RA patients (TOCI and ROC studies). Single nucleotide polymorphisms (SNPs) in 21 candidate genes were genotyped using KasPar method (LGC-genomics, UK) and then analyzed to determine their contribution to variation in the response to treatment. One hundred twenty-three patients in the TOCI group (79.8%) and 48 patients in the ROC group (80%) experienced good or moderate EULAR response. The clinical response to treatment was associated with SNP genotype in the gene IL6R, with patients with the homozygous AA-genotype for rs12083537 (IL6R) showing a significantly better response than homozygous or heterozygous patients with the G allele [TOCI: 87.5% of responders for AA genotype vs. 72.2% for AG or GG genotype (p = 0.018); ROC patients: 89.2% of responders for AA genotype vs. 65.2% for AG or GG genotype, p = 0.044]. A meta-analysis combining data from the two cohorts confirmed the lower response rate in patients carrying a copy of the G allele (OR (95% CI) = 0.35 (0.16-0.61), p = 0.001). No association was found with any of the other SNPs tested.

Influence of body mass index on sagittal hip range of motion and gait speed recovery six months after total hip arthroplasty.

PURPOSE: In practice, obesity leads to poor functional outcomes after total hip arthroplasty (THA). However, in clinical research, the influence of body mass index (BMI) on the gait recovery and kinematics for THA is not well documented. The purpose of this study was to assess the influence of BMI on gait parameters pre-operatively and six months after THA for hip osteoarthritis (OA) patients. METHODS: We included 76 THA for hip OA: non-obese group (G1): 49 (BMI < 30 kg/2) and obese group (G2): 37 (BMI ≥ 30 kg/m2) with a control group of 61 healthy people. Clinical evaluation (HOOS) and a 3D gait analysis (gait speed and flexion range of the hip (ROM)) were performed before and six months after THA: The gains between the two visits were calculated and we looked for correlations between outcomes and BMI. RESULTS: Preoperative gait speed and hip ROM were significantly lower in obese patients (speed G1: 0.81 ± 0.22 m/s vs. G2: 0.64 ± 0.23 m/s, p = 0.004 and hip ROM G1: 26.1° ± 7.3 vs. G2: 21.4° ± 6.6, p = 0.005), and obese patients were more symptomatic. At six months, gait speed and hip ROM were significantly lower for all patients compared with the control group. No correlation between gait velocity, hip ROM, and BMI was found. Biomechanical and clinical gains were comparable in the two groups. CONCLUSIONS: All patients, including obese patients, have significant functional improvement after THA, objectively assessed by gait speed. Even if patients did not fully recover to the level of a healthy control person after THA, functional gain is comparable irrespective of BMI.

Röttinger approach with dual-mobility cup to improve functional recovery in hip osteoarthritis patients: biomechanical and clinical follow-up.

PURPOSE: We assumed that the combination of dual-mobility total hip arthroplasty (THA) using the minimally-invasive Röttinger anterolateral approach could guarantee hip stability with faster functional recovery. We objectively analyzed functional improvement after dual-mobility THA by quantitative gait analysis. METHODS: We compared the results achieved following two different surgical approaches: Röttinger's versus Moore's approach (posterolateral approach). We included 70 patients in an open prospective single-centre study: 38 by Rottinger's approach (age = 67yo) and 32 by Moores's approach (age = 68yo). Clinical and biomechanical analysis (kinematic and kinetic parameters of the hip) were conducted at the pre-operative period and at six months post-op RESULTS: We found a significant improvement in all clinical scores and all biomechanical parameters but no difference was found between the two approaches. However, the study showed marked clinical, biomechanical and functional improvements for patients treated with dual-mobility THA for osteoarthritis without complete hip recovery compared with a control group. CONCLUSIONS: The combination of the Röttinger approach with a dual-mobility cup remains a valid choice for primary THA without functional advantage at midterm.

Involvement and prognosis value of CD8(+) T cells in giant cell arteritis.

CD8(+) T cells participate in the pathogenesis of some vasculitides. However, little is known about their role in Giant Cell Arteritis (GCA). This study was conducted to investigate CD8(+) T cell involvement in the pathogenesis of GCA. Analyses were performed at diagnosis and after 3 months of glucocorticoid treatment in 34 GCA patients and 26 age-matched healthy volunteers. Percentages of CD8(+) T-cell subsets, spectratype analysis of the TCR Vß families of CD8(+) T cells, levels of cytokines and chemokines and immunohistochemistry of temporal artery biopsies (TAB) were assessed. Among total CD8(+) T cells, percentages of circulating cytotoxic CD8 T lymphocytes (CTL, CD3(+)CD8(+)perforin(+)granzymeB(+)), Tc17 (CD3(+)CD8(+)IL-17(+)), CD63(+)CD8(+) T cells and levels of soluble granzymes A and B were higher in patients than in controls, whereas the percentage of Tc1 cells (CD3(+)CD8(+)IFN-γ(+)) was similar. Moreover, CD8(+) T cells displayed a restricted TCR repertoire in GCA patients. Percentages of circulating CTL, Tc17 and soluble levels of granzymes A and B decreased after treatment. CXCR3 expression on CD8(+) T cells and its serum ligands (CXCL9, -10, -11) were higher in patients. Analyses of TAB revealed high expression of CXCL9 and -10 associated with infiltration by CXCR3(+)CD8(+) T cells expressing granzyme B and TiA1. The intensity of the CD8 T-cell infiltrate in TAB was predictive of the severity of the disease. This study demonstrates the implication and the prognostic value of CD8(+) T-cells in GCA and suggests that CD8(+) T-cells are recruited within the vascular wall through an interaction between CXCR3 and its ligands.

Tocilizumab induces corticosteroid sparing in rheumatoid arthritis patients in clinical practice.

OBJECTIVE: . The aim of this study was to evaluate the impact of introducing tocilizumab (TCZ) as co-therapy with CS in patients with RA. METHODS: This study was an open, observational, retrospective multicentre study. RA patients treated with oral CS for >3 months who started treatment with TCZ between December 2009 and June 2011 in five centres were included. Variables included demographic data, disease history, co-treatments, disease activity and dose of CS at inclusion and at weeks 4, 8, 12 and 24. The evolution of disease activity and of the dose of CS (analysis of variance with repeated measures) were analysed, searching for factors correlated with changes in the dose of CS. RESULTS: Inclusion of 130 patients [women 80.8%, mean age 56.7 years (s.d. 14.0), RA duration 16.3 years (s.d. 10.4), mean baseline 28-joint DAS (DAS28) 5.1 (s.d. 1.4), mean baseline dose of CS 10.0 mg/day (s.d. 8.2) prednisone equivalent. Decreases in the mean daily dose of CS and in the DAS28 were observed during follow-up [respectively 6.5 mg (s.d. 4.8) at week 24 (P < 0.0001) and 3.0 mg (s.d. 1.4) at week 24 (P < 0.0001)]. The only variable that correlated with the decrease in the dose of CS was the initial dose of the drug (r = 0.82, P < 0.001). CONCLUSION: The introduction of TCZ led to rapid and long-lasting CS sparing that did not correlate with the reduction in disease activity. It is possible that in patients treated with high-dose CS, the main objective of the clinician is to reduce dosage of CS rather than RA activity.

Predictors of response and remission in a large cohort of rheumatoid arthritis patients treated with tocilizumab in clinical practice.

OBJECTIVE: The objective of this study was to identify predictors of response and remission to tocilizumab (TCZ) in RA patients seen in daily routine clinical practice. METHODS: The efficacy of TCZ was evaluated after 12 and 24 weeks of treatment by the European League Against Rheumatism (EULAR) response criteria. Regression analysis was performed to study the association between remission or EULAR response and the following characteristics: gender, age, current smokers, prior cardiovascular disease (CVD), 28-joint disease activity score (DAS28), CRP, RF or ACPA positivity, combination therapy with DMARDs and TCZ as the first biological therapy or after failure of at least one biological therapy. RESULTS: In total, 204 patients were included with a mean DAS28 score of 5.14. EULAR response and remission were obtained in 86.1% and 40% of patients, respectively, at week 24. In multiple regression analysis, a high baseline CRP level [odds ratio (OR) 4.454 (95% CI 1.446, 13.726)] was significantly associated with EULAR response at week 24 and, inversely, age >55 years [OR 0.285 (95% CI 0.086, 0.950)] and prior CVD [OR 0.305 (95% CI 0.113, 0.825)] were significantly associated with lower EULAR response at week 24. Older age was also associated with less remission at week 24 [OR 0.948 (95% CI 0.920, 0.978)]. No additional effectiveness was found when TCZ was used in combination with a DMARD or when patients were naive to biological agents. CONCLUSION: In daily practice we identified three predictors of a better response for TCZ therapy in RA: a younger age, a high baseline CRP level and no history of CVD.

Severe hypovitaminosis D correlates with increased inflammatory markers in HIV infected patients.

BACKGROUND: Even though it has been suggested that antiretroviral therapy has an impact on severe hypovitaminosis D (SHD) in HIV infected patients, it could be speculated that the different levels of residual inflammation on HAART (Highly Active Anti Retroviral Therapy) could contribute to SHD and aggravate bone catabolism in these patients. METHODS: A cross-sectional study was carried out in an unselected cohort of 263 HIV infected outpatients consulting during Spring 2010. Clinical examinations were performed and medical history, food habits, sun exposure and addictions were collected. Fasting blood samples were taken for immunological, virological, inflammation, endocrine and bone markers evaluations. RESULTS: Ninety-five (36%) patients had SHD. In univariate analysis, a significant and positive association was found between SHD and IL6 (p = 0.001), hsCRP (p = 0.04), increased serum C-Telopeptides X (CTX) (p = 0.005) and Parathyroid Hormon (PTH) (p < 0.0001) levels. In multivariate analysis, SHD deficiency correlated significantly with increased IL-6, high serum CTX levels, lower mean daily exposure to the sun, current or past smoking, hepatitis C, and functional status (falls), but not with the time spent on the current HAART (by specific drug or overall). CONCLUSIONS: SHD is frequent and correlates with inflammation in HIV infected patients. Since SHD is also associated with falls and increased bone catabolism, it may be of interest to take into account not only the type of antiretroviral therapy but also the residual inflammation on HAART in order to assess functional and bone risks. This finding also suggests that vitamin D supplementation may be beneficial in these HIV-infected patients.

Brief report: inhibition of interleukin-6 function corrects Th17/Treg cell imbalance in patients with rheumatoid arthritis.

OBJECTIVE: From an immunologic standpoint, the mechanisms by which treatment with tocilizumab (TCZ), a humanized anti-interleukin-6 (anti-IL-6) receptor antibody, results in improvement in rheumatoid arthritis (RA) patients are still not fully understood. In vitro studies and studies in mouse models have demonstrated the critical role of IL-6 in Th17 cell differentiation. Th17 lymphocytes have been shown to be strongly involved in RA pathogenesis, and the purpose of this study was to investigate the effect of IL-6 blockade on the balance between Th17 cells and Treg cells in patients with active RA. METHODS: Patients with active RA for whom TCZ had been prescribed by a rheumatologist were enrolled in this study. Phenotypic analyses of T cell populations were performed, and the Disease Activity Score in 28 joints (DAS28) was assessed. Serum cytokine levels and other parameters of inflammation were measured before the first infusion and after the third infusion of TCZ (8 mg/kg). RESULTS: Compared to controls, levels of Th17 cells (CD4+IL-17+) were increased and Treg cells (CD4+CD25(high) FoxP3+) were decreased in the peripheral blood of patients with active RA. The suppressive function of circulating Treg cells was not impaired in patients with active RA. TCZ treatment induced a significant decrease in the DAS28 associated with a significant decrease in the percentage of Th17 cells (from a median of 0.9% to 0.45%; P = 0.009) and an increase in the percentage of Treg cells (from a median of 3.05% to 3.94%; P = 0.0039) in all patients. CONCLUSION: This study demonstrates for the first time that inhibition of IL-6 function by TCZ corrects the imbalance between Th17 cells and Treg cells in patients with RA.

Th1 and Th17 lymphocytes expressing CD161 are implicated in giant cell arteritis and polymyalgia rheumatica pathogenesis.

OBJECTIVE: Giant cell arteritis (GCA) is the most frequently occurring vasculitis in elderly individuals, and its pathogenesis is not fully understood. The objective of this study was to decipher the role of the major CD4+ T cell subsets in GCA and its rheumatologic form, polymyalgia rheumatica (PMR). METHODS: A prospective study of the phenotype and the function of major CD4+ T cell subsets (Th1, Th17, and Treg cells) was performed in 34 untreated patients with GCA or PMR, in comparison with 31 healthy control subjects and with the 27 treated patients who remained after the 7 others withdrew. RESULTS: Compared with control subjects, patients with GCA and patients with PMR had a decreased frequency of Treg cells and Th1 cells, whereas the percentage of Th17 cells was significantly increased. Furthermore, an analysis of temporal artery biopsy specimens obtained from patients affected by GCA for whom biopsy results were positive demonstrated massive infiltration by Th17 and Th1 lymphocytes without any Treg cells. After glucocorticoid treatment, the percentages of circulating Th1 and Th17 cells decreased, whereas no change in the Treg cell frequency was observed. The frequency of CD161+CD4+ T cells, which are considered to be Th17 cell precursors, was similar in patients and control subjects. However, these cells highly infiltrated GCA temporal artery biopsy specimens, and their ability to produce interleukin-17 in vitro was significantly enhanced in patients with GCA and patients with PMR and was correlated with a decrease in the phosphorylated form of STAT-1. CONCLUSION: This study is the first to demonstrate that the frequency of Treg cells is decreased in patients with GCA and patients with PMR, and that CD161+CD4+ T lymphocytes, differentiated into Th1 cells and Th17 cells, are involved in the pathogenesis of GCA and PMR.

A tool to identify recent or present rheumatoid arthritis flare from both patient and physician perspectives: the 'FLARE' instrument.

INTRODUCTION: There is a lack of consensus about the definition of flare of rheumatoid arthritis (RA) and a measurement tool. OBJECTIVES: To develop a self-administered tool integrating the perspectives of the patient and the rheumatologist, enabling the detection of present or recent-past RA flare. METHODS: The patient perspective was explored by semistructured individual interviews of patients with RA. Two health psychologists conducted a content analysis to extract items best describing flare from the interviews. The physician's perspective was explored through a Delphi exercise conducted among a panel of 13 rheumatologists. A comprehensive list of items produced in the first round was reduced in a four-round Delphi process to select items cited by at least 75% of the respondents. The identified elements were assembled in domains-each converted into a statement-to constitute the final self-administered Flare Assessment in Rheumatoid Arthritis (FLARE) questionnaire. RESULTS: The content of 99 patient interviews was analysed, and 10 domains were identified: joint swelling or pain, night pain, fatigue and different emotional consequences, as well as analgesic intake. The Delphi process for physicians identified eight domains related to objective RA symptoms and drug intake, of which only four were common to domains for patients. Finally, 13 domains were retained in the FLARE questionnaire, formulated as 13 statements with a Likert-scale response modality of six answers ranging from 'absolutely true' to 'completely untrue'. CONCLUSION: Two different methods, for patient and physician perspectives, were used to develop the FLARE self-administered questionnaire, which can identify past or present RA flare.

Predictive Factors of Giant Cell Arteritis in Polymyalgia Rheumatica Patients.

Polymyalgia rheumatica (PMR) is an inflammatory rheumatism of the shoulder and pelvic girdles. In 16 to 21% of cases, PMR is associated with giant cell arteritis (GCA) that can lead to severe vascular complications. Ruling out GCA in patients with PMR is currently a critical challenge for clinicians. Two GCA phenotypes can be distinguished: cranial GCA (C-GCA) and large vessel GCA (LV-GCA). C-GCA is usually suspected when cranial manifestations (temporal headaches, jaw claudication, scalp tenderness, or visual disturbances) occur. Isolated LV-GCA is more difficult to diagnose, due to the lack of specificity of clinical features which can be limited to constitutional symptoms and/or unexplained fever. Furthermore, many studies have demonstrated the existence-in varying proportions-of subclinical GCA in patients with apparently isolated PMR features. In PMR patients, the occurrence of clinical features of C-GCA (new onset temporal headaches, jaw claudication, or abnormality of temporal arteries) are highly predictive of C-GCA. Additionally, glucocorticoids' resistance occurring during follow-up of PMR patients, the occurrence of constitutional symptoms, or acute phase reactants elevation are suggestive of associated GCA. Research into the predictive biomarkers of GCA in PMR patients is critical for selecting PMR patients for whom imaging and/or temporal artery biopsy is necessary. To date, Angiopoietin-2 and MMP-3 are powerful for predicting GCA in PMR patients, but these results need to be confirmed in further cohorts. In this review, we discuss the diagnostic challenges of subclinical GCA in PMR patients and will review the predictive factors of GCA in PMR patients.

Optimization of dual energy computed tomography post-processing to reduce lower limb artifacts in gout.

BACKGROUND: In gout, several types of dual-energy computed tomography (DECT) artifacts have been described (nail bed, skin, beam hardening, submillimeter and vascular artifacts), which can lead to overdiagnosis. The objective of this study was to determine the optimal DECT settings for post processing in order to reduce the frequency of some common artifacts in patients with suspected gout. METHODS: Seventy-seven patients hospitalized for suspected gout (feet/ankles and/or knees) who received a DECT imaging were included (final diagnosis of 43 gout and 34 other rheumatic disorders). Different post-processing settings were evaluated using Syngovia software: nine settings (R1 to R9) were evaluated with a combination of different ratio (1.28, 1.36 and 1.55) and attenuation coefficient (120, 150, 170 HU). RESULTS: Among the nine settings tested, the R2 setting (170 HU, ratio =1.28) significantly reduced the presence of knee and foot/ankle artifacts compared to the standard R1 setting (85% and 94% decrease in beam hardening and clumpy artifacts in the ankle and foot, respectively (P<0.001); a decrease of 71%, 60% and 88% respectively of meniscal beam hardening, beam hardening and submillimeter artifacts in the knee (P<0.001). Compared to standard settings, the use of R2 settings decreased sensitivity [0.79 (95% CI: 0.65, 0.88) versus 0.90 (95% CI: 0.78, 0.96)] and increased specificity [0.86 (95% CI: 0.71, 0.93) versus 0.63 (95% CI: 0.47, 0.77)] (P<0.001). Settings using an attenuation coefficient to 120 HU and/or a ratio to 1.55 were all associated with a significant increasing of artifacts, especially clumpy and beam hardening artifacts. CONCLUSIONS: Applying a ratio of 1.28 and a minimum attenuation of 170 HU in DECT post-processing eliminates the majority of artifacts located in the lower limbs, particularly clumpy artifacts and beam hardening.

Gait analysis dataset of healthy volunteers and patients before and 6 months after total hip arthroplasty.

Clinical gait analysis is a promising approach for quantifying gait deviations and assessing the impairments altering gait in patients with osteoarthritis. There is a lack of consensus on the identification of kinematic outcomes that could be used for the diagnosis and follow up in patients. The proposed dataset has been established on 80 asymptomatic participants and 106 patients with unilateral hip osteoarthritis before and 6 months after arthroplasty. All volunteers walked along a 6 meters straight line at their self-selected speed. Three dimensional trajectories of 35 reflective markers were simultaneously recorded and Plugin Gait Bones, angles, Center of Mass trajectories and ground reaction forces were computed. Gait video recordings, when available, anthropometric and demographic descriptions are also available. A minimum of 10 trials have been made available in the weka file format and C3D file to enhance the use of machine learning algorithms. We aim to share this dataset to facilitate the identification of new movement-related kinematic outcomes for improving the diagnosis and follow up in patients with hip OA.

Dynamic global sagittal alignment in patients with lumbar spinal stenosis: Analysis of the effects of decompression surgery on gait adaptations.

BACKGROUND: Lumbar spinal stenosis (LSS) leads patients to adapt their posture and walking parameters. Pelvic retroversion might be a compensation mechanism of pain. Pelvic and lower limbs compensations during gait are still not precisely understood, as well as the effect of a surgical decompression on them. These dynamic parameters can be studied through three-dimensional gait analysis. RESEARCH QUESTION: Is the dynamic pelvic tilt modified after decompression surgery in LSS patients compared to asymptomatic subjects? MATERIAL AND METHODS: 50 asymptomatic subjects (C-group) and 37 patients operated on for lumbar decompression underwent a three-dimensional gait analysis one month before (M0) and six months after (M6) the surgery. 3D gait analysis was performed and hip and knee flexion, trunk kinematics, walking speed, stride length and pelvic tilt during gait or dynamic pelvic tilt (dPT) were recorded. Health-related quality of life (HRQL) scores (Oswestry Disability Index (ODI) and Visual Analogic Scales (VAS)) and radiological assessment were performed preoperatively and postoperatively. RESULTS: Mean values of maximum and minimum dPT in the LSS-group preoperatively were significantly higher compared to the C-group (respectively 10.9 (6.2)° versus 7.3 (5.6)°, p = 0.003; 7.7 (6.1)° versus 4.8 (5.8)°, p = 0.011), and were significantly lowered at M6 (respectively 10.9 (6.2)° versus 8.1 (4.8)°, p = 0.0087; and 7.7 (6.1)° versus 5.1 (4.7)°, p = 0.012), and became similar to the C-group. The dPT range of motion at M0 and M6 were similar, and were both significantly higher than control values. Mean values of maximum and minimum hip flexion were significantly higher at M0 compared to the C-group, and were significantly lowered at M6. No difference was found between the pre- and postoperative radiographic pelvic tilt. The VAS for lumbar pain, the VAS for radicular pain and the ODI were significantly decreased at M6. SIGNIFICANCE: Compared to asymptomatic people, LSS patients walked with a pelvic anteversion, a hip flessum and a knee flessum before surgery, which tended to disappear after the surgical decompression. These differences were not noticed on static radiographs.

The frequency of occult solid malignancy in patients with polymyalgia rheumatica-like symptoms.

AIMS: We aim to evaluate the clinical usefulness of systematic screening for occult cancer in patients with polymyalgia rheumatic (PMR)-like symptoms in real-life practice. METHODS: All patients seen by rheumatologists in Burgundy, France, between March 2016 and December 2018 for new-onset PMR that met the 2012 ACR/EULAR classification criteria were prospectively included. Patients underwent systematic screening including determination of the erythrocyte sedimentation rate, serum C-reactive protein levels, thoracic, abdominal and pelvic computed tomography (CT-TAP) and, in men, serum prostate-specific antigen. The standardized incidence ratio (SIR) for cancers was calculated using 2012 national estimates of cancer incidence. Potential predictive factors for the diagnosis of cancer were then evaluated using univariate and multivariate analyses. RESULTS: Among the 118 patients included, nine cases of cancer were confirmed and diagnosed with CT-TAP: kidney carcinoma (n = 4), lung cancer (n = 2), pancreatic, colon, and ampullary carcinoma (n = 1 each). Among these cancers, five were localized (four kidney, and one ampullary carcinoma) and were treated with complete surgical resection. The expected incidence of cancer in the general population was 1.95, leading to an overall SIR of 4.6 (95% CI 2.4-8.9, p < 0.0001). An additional analysis was performed for the kidney carcinoma, and it showed a highly significant increase in SIR: 80.8 (95% CI 30.3-215.4). In 80% of patients, the PMR-like syndrome regressed during cancer treatment. No other predictive factors for cancer were found. CONCLUSION: Systematic screening for cancer including CT-TAP in real-life practice revealed occult solid malignancy, mostly early-stage cancer, in a relevant proportion of patients presenting PMR-like symptoms. The high proportion of kidney cancer (40%) is worth highlighting, especially considering that it is not one of the most frequent cancers after 50 years of age.

Is the Pelvis-Thorax Coordination a Valuable Outcome Instrument to Assess Patients With Hip Osteoarthritis?

Objective: The evaluation of the disease severity in hip osteoarthritis (OA) patients being currently based on subjective instruments. It would be of interest to develop more objective instruments, for example based on gait analysis. The aims of this study were to explore if pelvis-thorax coordination parameters could be valuable instrument outcomes to achieve this evaluation by assessing their reliability, discriminant capacity and responsiveness. Methods: Three groups of subjects; healthy, hip OA patients with severe disease (defined as indication to surgery), hip OA patients with less severe disease (no indication to surgery) were included. Hip OA patients with severe disease were evaluated before and 6 months after surgery. Subjects had to perform a gait analysis at comfortable speed, and pelvis-thorax coordination was evaluated. The correlations with clinical and structural parameters, as well as reliability, discriminant capacities and responsiveness, were assessed. Results: The pelvis-thorax coordination in the coronal plane during walking was correlated to clinical and to structural severity in hip OA patients (R 2 = 0.13). The coronal plane coordination allowed to discriminate healthy subjects from all hip OA patients (sensibility = 0.86; specificity = 0.59). Moreover, when comparing OA patients only, coronal plane coordination allows to discriminate patients with indication of surgery from those with no indication of surgery (sensibility = 0.72; specificity = 0.72). Moreover, the pelvis-thorax coordination demonstrated an excellent reliability and a good responsiveness. Conclusion: Changes in the pelvis-thorax coordination might refer to different mechanisms, from analgesia to motor control plasticity, and might be a possible explanation for the weak correlation between structure and symptoms in hip OA patients. Moreover, such parameter might be used as an objective outcome in hip OA clinical trials. Clinical Trials Registration: www.ClinicalTrials.gov, identifier: NCT02042586 and NCT01907503.