Scoliosis.

Scoliosis is a three-dimensional spinal deformity that can occur at any age. It may be idiopathic or secondary in children, idiopathic and degenerative in adults. Management of patients with scoliosis is multidisciplinary, involving rheumatologists, radiologists, orthopaedic surgeons, and prosthetists. Imaging plays a central role in diagnosis, including the search for secondary causes, follow-up, and preoperative work-up if surgery is required. Evaluating scoliosis involves obtaining frontal and lateral full-spine radiographs in the standing position, with analysis of coronal and sagittal alignment. For adolescent idiopathic scoliosis, imaging follow-up is often required, accomplished using low-dose stereoradiography such as EOS imaging. For adult degenerative scoliosis, the crucial characteristic is rotatory subluxation, also well detected on radiographs. Magnetic resonance imaging is usually more informative than computed tomography for visualizing associated canal and foraminal stenoses. Radiologists must also have a thorough understanding of postoperative features and complications of scoliosis surgery because aspects can be misleading.

Impact of a multidisciplinary team meeting on patient-reported outcomes at 2 years after lumbar surgery: A prospective comparative exploratory study.

Failed back surgery syndrome is a challenge. We hypothesized that a multidisciplinary team meeting (MTM) may be useful to select patients who are the most likely to benefit from lumbar surgery. We conducted an observational, prospective, comparative, exploratory study. We aimed to compare core clinical patient-reported outcomes at 2 years after lumbar surgery between patients who attended a MTM and those who did not. Patients who underwent lumbar surgery for a degenerative disease, in a single academic orthopedic department, between January and September 2018, were consecutively screened. Eligible patients were surveyed between April and June 2020. Patient-reported outcomes included lumbar and radicular pain, spine-specific activity limitations and health-related quality of life assessed via self-administered questionnaires. Outcomes were compared between respondents who attended the MTM and those who did not. Overall, 211 patients underwent lumbar surgery, 108 were eligible and 44 included: 11 attended the MTM and 33 did not. Mean participants' age was 57.4 (15.4) years, symptom duration was 14.8 (15.3) months, lumbar pain was 51.3 (18.2) and radicular pain was 53.4 (18.6). At 2 years, we found no evidence that lumbar and radicular pain, activity limitations and health-related quality of life differed between the 2 groups. The decrease was -26.8 (41.1) versus -20.8 (30.4) in lumbar pain and -25.5 (43.0) versus -19.5 (27.5) in radicular pain, in participants who attended the MTM versus those who did not, respectively. We found no evidence that core clinical patient-reported outcomes at 2 years after lumbar surgery differed between participants who attended the MTM and those who did not. However, the exploratory design of our study does not allow concluding that MTMs do not have an impact.

Determinants of apprehension to return to sport after reconstruction of the anterior cruciate ligament: an exploratory observational retrospective study.

BACKGROUND: Only 65% of people return to a level of sport equivalent to that before after anterior cruciate ligament (ACL) surgery. Persisting apprehension may in part explain this observation. We aimed to describe characteristics of people with ACL-Return to Sport after Injury (RSI) scores ≥ 60/100 (low apprehension) at 6 months after injury and to identify variables independently associated with low apprehension at 6 months. METHODS: We conducted a single-center retrospective study. People who had surgery for an ACL rupture and who participated in an outpatient post-operative rehabilitation program were included consecutively. The ACL-RSI questionnaire was self-administered at 6 months after injury. Baseline characteristics of people with ACL-RSI scores ≥ 60/100 and < 60/100 were described. Multiple logistic regression was performed to identify baseline variables associated with low apprehension at 6 months. RESULTS: We included 37 participants: 13/37 (35.1%) were women and mean age was 27.2 (9.2) years. At 6 months, 21/37 (56.8%) had an ACL-RSI score ≥ 60/100. Participants who had an ACL-RSI score ≥ 60/100 more often received a preoperative rehabilitation (16/21 [76.2%] vs 5/16 [31.2%]), and had less often knee pain (7/21 [33.3%] vs 7/16 [43.7%]) and effusion (5/21 [23.8%] vs 8/16 [50.0%]) at 1 month after surgery, than participants who had an ACL-RSI score < 60/100. In the multivariate analysis, preoperative rehabilitation was associated with low apprehension at 6 months (OR [95% CI] = 0.107 [0.023 to 0.488], p = 0.002). CONCLUSIONS: Preoperative rehabilitation was independently associated with low apprehension at 6 months. TRIAL REGISTRATION: Not applicable.

Effect of Prehabilitation Before Total Knee Replacement for Knee Osteoarthritis on Functional Outcomes: A Randomized Clinical Trial.

Importance: Multidisciplinary prehabilitation before total knee replacement (TKR) for osteoarthritis may improve outcomes in the postoperative period. Objective: To compare multidisciplinary prehabilitation with usual care before TKR for osteoarthritis in terms of functional independence and activity limitations after surgery. Design, Setting, and Participants: This prospective, open-label randomized clinical trial recruited participants 50 to 85 years of age with knee osteoarthritis according to the American College of Rheumatology criteria for whom a TKR was scheduled at 3 French tertiary care centers. Recruitment started on October 4, 2012, with follow-up completed on November 29, 2017. Statistical analyses were conducted from March 29, 2018, to March 6, 2019. Interventions: Four supervised sessions of multidisciplinary rehabilitation and education (2 sessions per week, at least 2 months before TKR, delivered to groups of 4-6 participants at each investigating center; session duration was 90 minutes and included 30 minutes of education followed by 60 minutes of exercise therapy) or usual care (information booklet and standard advice by the orthopedic surgeon) before TKR. Main Outcomes and Measures: The short-term primary end point was the proportion of participants achieving functional independence a mean (SD) of 4 (1) days after surgery defined as level 3 on the 4 functional tests. The midterm primary end point was activity limitations within 6 months after TKR assessed by the area under the receiver operating characteristic curve of the self-administered Western Ontario Questionnaire and McMaster Universities Osteoarthritis Index function subscale. Results: A total of 262 patients (mean [SD] age, 68.6 [8.0] years; 178 women [68%]) were randomized (131 to each group). A mean (SD) of 4 (1) days after surgery, 34 of 101 (34%) in the experimental group vs 26 of 95 (27%) in the control group achieved functional independence (risk ratio, 1.4; 97.5% CI, 0.9-2.1; P = .15). At 6 months, the mean (SD) area under the curve for the Western Ontario Questionnaire and McMaster Universities Osteoarthritis Index function subscale was 38.1 (16.5) mm2 in the experimental group vs 40.6 (17.8) mm2 in the control group (absolute difference, -2.8 mm2; 97.5% CI, -7.8 to 2.3; P = .31 after multiple imputation). No differences were found in secondary outcomes. Conclusions and Relevance: This randomized clinical trial found no evidence that multidisciplinary prehabilitation before TKR for osteoarthritis improves short-term functional independence or reduces midterm activity limitations after surgery. Trial registration: ClinicalTrials.gov Identifier: NCT01671917.

Osteitis in Systemic Sclerosis: A Nationwide Case-Control Retrospective Study.

OBJECTIVE: Systemic sclerosis (SSc) is an autoimmune connective tissue disorder characterized by skin fibrosis, vasculopathy, and dysimmunity. Data regarding osteitis in SSc are scarce. METHODS: We performed a nationwide multicenter, retrospective, case-control study including patients with SSc, according to the 2013 American College of Rheumatology/European Alliance of Associations for Rheumatology classification, with a diagnosis of osteitis. The objectives of the study were to describe, to characterize, and to identify associated factors for osteitis in patients with SSc. RESULTS: Forty-eight patients were included. Twenty-six patients (54.1%) had osteitis beneath digital tip ulcers. Physical symptoms included pain (36 of 48, 75%), erythema (35 of 48, 73%), and local warmth (35 of 48, 73%). Thirty-one (65%) patients had median (interquartile range) C-reactive protein levels >2 mg/liter of 8 (2.7-44.3) mg/liter. On radiography, computed tomography, or magnetic resonance imaging, osteitis was characterized by swelling or abscess of soft tissues, with acro-osteolysis or lysis in 28 patients (58%). Microbiological sampling was performed in 45 (94%) patients. Most pathogens were Staphylococcus aureus (43.8%), anaerobes and Enterobacteriaceae (29.1%), and Pseudomonas aeruginosa (10.4%). Management comprised antibiotics in 37 (77.1%) patients and/or surgery in 26 (54.2%). Fluoroquinolones were used in 22 (45.8%) patients, and amoxicillin plus ß-lactamase inhibitor in 7 (14.6%). Six (12.6%) patients relapsed, 6 (12.6%) patients had osteitis recurrence, 15 (32%) sequelae, and 2 patients had septic shock and died. CONCLUSION: This study confirmed digital tip ulcers as an associated factor for osteitis and revealed a high rate of functional sequelae. Antimicrobial therapy with oral fluoroquinolone or intravenous amoxicillin and ß-lactamase inhibitor are used as first-line antibiotic therapy in SSc patients with osteitis.

Conservative treatment for chronic coccydynia: a 36-month prospective observational study of 115 patients.

PURPOSE: To describe long-term outcomes of conservative treatment for chronic coccydynia. METHODS: We conducted a 36-month prospective observational study. Adults with chronic coccydynia (> 2 months) were included. The first-line treatment was coccygeal corticosteroid injection. The second-line treatment was either manual therapy or coccygectomy. The primary endpoint was the mean variation from baseline of coccydynia intensity at 6 and 36 months, using a numeric rating scale (0, no pain; 10, maximal pain). Evolution was considered unfavorable when coccydynia intensity was > 3 of 10 points at 36 months or coccygectomy had been performed. We carried out bivariate and multivariate analyses to identify variables associated with an unfavorable evolution. RESULTS: We included 115 participants. Mean (SD) age was 43.5 (12.3) years, duration of coccydynia 18.4 (21.6) months and coccydynia intensity 6.5 (2.0) of 10 points. Mean variations for coccydynia intensity were - 1.5 (3.0) at 6 months and - 2.8 (3.2) at 36 months. At 36 months, 59/115 (51%) participants had an unfavorable evolution. In bivariate analysis, posterior coccyx dislocations were numerically more frequent in participants with an unfavorable evolution compared to others (29/59 (48%) versus 17/56 (30%), p = 0.057). In multivariate analysis, longer duration of coccydynia was associated with an unfavorable evolution (OR = 1.04, 95% CI from 1.01 to 1.07, p = 0.023). CONCLUSION: In adults with chronic coccydynia receiving conservative treatment, symptoms decrease overtime, but significantly persist at 36 months in more than half of them. For patients with posterior coccyx dislocation, coccygectomy may be considered rapidly.

Development of a new patient-reported outcome measure assessing activities and participation in people with lumbar spinal stenosis: The Cochin Spinal Stenosis 19-item questionnaire.

BACKGROUND: Lumbar spinal stenosis (LSS) is the leading cause of spinal surgery in people over 65-years old. In people with LSS, generic self-administered questionnaires are the most commonly used PROs to assess health-related quality of life, global activity limitation, and low back pain-located activity limitation. AIM: The aim was to develop a new patient-reported outcome measure assessing activities and participation in people with LSS. DESIGN: Observation, prospective and qualitative study. SETTING: For the qualitative study, were enrolled in- and outpatients with LSS from 2 French tertiary care centers (Department of PRM of Cochin Hospital and Department of Rheumatology of Limoges Hospital). For the Internet E-survey, screened the electronic medical records of the Department of PRM of Cochin Hospital. POPULATION: From February to April 2018 were enrolled patients older than 50-years and symptomatic LSS. METHODS: We used a 2-step approach. In a first step, we conducted a qualitative study using in-depth semi-structured interviews in 20 patients with LSS to collect meaningful concepts and to develop a provisional questionnaire. In a second step, using the provisional questionnaire, we conducted an Internet E-survey in an independent sample of 200 patients with LSS. RESULTS: Concepts collected from patients generated a 48-item provisional questionnaire. Overall, 63/200 (31.5%) patients completed the provisional questionnaire. Item reduction resulted in a 19-item questionnaire, the Cochin Spinal Stenosis 19-item (CSS-19) questionnaire. Principal component analysis extracted 3 factors. In confirmatory analysis, factor 1 influenced all items. We found convergent validity with low back pain, LSS-specific disability and divergent validity with mental health-related quality of life. Cronbach α coefficient (95% CI) was 0.96 (0.94; 0.97). ICC was 0.90 (0.70; 0.97). Bland and Altman analysis found no systematic trend for test-retest. CONCLUSIONS: CSS-19 is a new patient-reported outcome measure assessing activities and participation in people with LSS. Its construction prioritized patients' perspectives at all stages. Its content and construct validities are good. CLINICAL REHABILITATION IMPACT: Instruments able to capture specific needs of people with LSS in terms of activities and participation are lacking.

Diagnosis and management of lumbar spinal stenosis in primary care in France: a survey of general practitioners.

BACKGROUND: Lumbar spinal stenosis (LSS) is a common spinal condition and the most frequent indication for spinal surgery in elderly people. General practitioners (GPs) are on the 1st line for its diagnosis and treatment. We aimed to assess how GPs diagnose and treat people with LSS in France. METHODS: We conducted a cross-sectional survey in a primary care setting. French GPs were selected by a random draw from the French Medical Board. The questionnaire was designed by 3 physicians specialized in physical and rehabilitation medicine and a resident in general practice. A provisional questionnaire was tested in a pilot survey of 11 French GPs. Participants' feedbacks served to build the final questionnaire. This latter was submitted by e-mail or mail to 330 GPs. GPs were surveyed about the 3 main domains relevant to the management of people with LSS in primary care: 1/ diagnosis, 2/ pharmacological treatments and 3/ non-pharmacological treatments, using self-administered open- and closed-ended questions and visual analog scales. RESULTS: Overall, 90/330 (27.3%) GPs completed the survey. 51/89 (57.3%) GPs were confident with managing people with LSS. Low back pain 51/87 (58.6%), neurogenic claudication 38/87 (43.7%) and paresthesia in the lower limbs 31/87 (35.6%) were the 3 most frequently cited clinical signs leading to the diagnosis of LSS. Improvement with lumbar flexion was mentioned by 9/87 (10.3%) GPs. 85/86 (98.8%) would consider prescribing lumbar imaging, 60/84 (71.4%) corticoid spinal injections and 42/79 (53.2%) would never prescribe lumbar flexion-based endurance training. All GPs would refer people with LSS to another specialist. CONCLUSIONS: French GPs lack confidence with diagnosing LSS and prescribing pharmacological and non-pharmacological treatments for people with LSS.

Resveratrol, Potential Therapeutic Interest in Joint Disorders: A Critical Narrative Review.

Trans-resveratrol (t-Res) is a natural compound of a family of hydroxystilbenes found in a variety of spermatophyte plants. Because of its effects on lipids and arachidonic acid metabolisms, and its antioxidant activity, t-Res is considered as the major cardioprotective component of red wine, leading to the "French Paradox" health concept. In the past decade, research on the effects of resveratrol on human health has developed considerably in diverse fields such as cancer, neurodegenerative and cardiovascular diseases, and metabolic disorders. In the field of rheumatic disorders, in vitro evidence suggest anti-inflammatory, anti-catabolic, anti-apoptotic and anti-oxidative properties of t-Res in various articular cell types, including chondrocytes and synoviocytes, along with immunomodulation properties on T and B lymphocytes. In preclinical models of osteoarthritis and rheumatoid arthritis, resveratrol has shown joint protective effects, mainly mediated by decreased production of pro-inflammatory and pro-degradative soluble factors, and modulation of cellular and humoral responses. Herein, we comprehensively reviewed evidence supporting a potential therapeutic interest of t-Res in treating symptoms related to rheumatic disorders.

Tumor necrosis factor-α blockade in recurrent and disabling chronic sciatica associated with post-operative peridural lumbar fibrosis: results of a double-blind, placebo randomized controlled study.

INTRODUCTION: The aim of this study was to assess the efficacy and safety of tumor necrosis factor (TNF)-α inhibition with infliximab (IFX) in treating recurrent and disabling chronic sciatica pain associated with post-operative peridural lumbar fibrosis. METHOD: A double-blind, placebo-controlled study randomized 35 patients presenting with sciatica pain associated with post-operative peridural lumbar fibrosis to two groups: IFX (n = 18), a single intravenous injection of 3 mg/kg IFX; and placebo (n = 17), a single saline serum injection. The primary outcome was a 50 % reduction in sciatica pain on a visual analog scale (VAS) at day 10. Secondary outcomes were radicular and lumbar VAS pain at day 0 and radicular and lumbar VAS pain, Québec disability score, drug-sparing effect and tolerance at days 10, 30, 90, and 180. RESULTS: At day 10, the placebo and IFX groups did not differ in the primary outcome (50 % reduction in sciatica pain observed in three (17.6 %) versus five (27.8 %) patients; p = 0.69). The number of patients reaching the patient acceptable symptom state for radicular pain was significantly higher in the placebo than IFX group after injection (12 (70.6 %) versus five (27.8 %) patients; p = 0.01). The two groups were comparable for all other secondary outcomes. CONCLUSION: Treatment with a single 3 mg/kg IFX injection for post-operative peridural lumbar fibrosis-associated sciatica pain does not significantly reduce radicular symptoms at day 10 after injection. TRIAL REGISTRATION: ClinicalTrials.gov NCT00385086 ; registered 4 October 2006 (last updated 15 October 2015).

The status of strontium in biological apatites: an XANES/EXAFS investigation.

Osteoporosis represents a major public health problem through its association with fragility fractures. The public health burden of osteoporotic fractures will rise in future generations, due in part to an increase in life expectancy. Strontium-based drugs have been shown to increase bone mass in postmenopausal osteoporosis patients and to reduce fracture risk but the molecular mechanisms of the action of these Sr-based drugs are not totally elucidated. The local environment of Sr(2+) cations in biological apatites present in pathological and physiological calcifications in patients without such Sr-based drugs has been assessed. In this investigation, X-ray absorption spectra have been collected for 17 pathological and physiological calcifications. These experimental data have been combined with a set of numerical simulations using the ab initio FEFF9 X-ray spectroscopy program which takes into account possible distortion and Ca/Sr substitution in the environment of the Sr(2+) cations. For selected samples, Fourier transforms of the EXAFS modulations have been performed. The complete set of experimental data collected on 17 samples indicates that there is no relationship between the nature of the calcification (physiological and pathological) and the adsorption mode of Sr(2+) cations (simple adsorption or insertion). Such structural considerations have medical implications. Pathological and physiological calcifications correspond to two very different preparation procedures but are associated with the same localization of Sr(2+) versus apatite crystals. Based on this study, it seems that for supplementation of Sr at low concentration, Sr(2+) cations will be localized into the apatite network.

Pathogenic role of basic calcium phosphate crystals in destructive arthropathies.

BACKGROUND: basic calcium phosphate (BCP) crystals are commonly found in osteoarthritis (OA) and are associated with cartilage destruction. BCP crystals induce in vitro catabolic responses with the production of metalloproteases and inflammatory cytokines such as interleukin-1 (IL-1). In vivo, IL-1 production induced by BCP crystals is both dependant and independent of NLRP3 inflammasome. We aimed to clarify 1/ the role of BCP crystals in cartilage destruction and 2/ the role of IL-1 and NLRP3 inflammasome in cartilage degradation related to BCP crystals. METHODOLOGY PRINCIPAL FINDINGS: synovial membranes isolated from OA knees were analysed by alizarin Red and FTIR. Pyrogen free BCP crystals were injected into right knees of WT, NLRP3 -/-, ASC -/-, IL-1α -/- and IL-1ß-/- mice and PBS was injected into left knees. To assess the role of IL-1, WT mice were treated by intra-peritoneal injections of anakinra, the IL-1Ra recombinant protein, or PBS. Articular destruction was studied at d4, d17 and d30 assessing synovial inflammation, proteoglycan loss and chondrocyte apoptosis. BCP crystals were frequently found in OA synovial membranes including low grade OA. BCP crystals injected into murine knee joints provoked synovial inflammation characterized by synovial macrophage infiltration that persisted at day 30, cartilage degradation as evidenced by loss of proteoglycan staining by Safranin-O and concomitant expression of VDIPEN epitopes, and increased chondrocyte apoptosis. BCP crystal-induced synovitis was totally independent of IL-1α and IL-1ß signalling and no alterations of inflammation were observed in mice deficient for components of the NLRP3-inflammasome, IL-1α or IL-1ß. Similarly, treatment with anakinra did not prevent BCP crystal effects. In vitro, BCP crystals elicited enhanced transcription of matrix degrading and pro-inflammatory genes in macrophages. CONCLUSIONS SIGNIFICANCE: intra-articular BCP crystals can elicit synovial inflammation and cartilage degradation suggesting that BCP crystals have a direct pathogenic role in OA. The effects are independent of IL-1 and NLRP3 inflammasome.

Adrenomedullin(22-52) combats inflammation and prevents systemic bone loss in murine collagen-induced arthritis.

OBJECTIVE: Adrenomedullin(22-52) is a truncated peptide derived from adrenomedullin, a growth factor with antiapoptotic and immunoregulatory properties. It can act as an agonist or an antagonist depending on cell type. Its in vivo effects are unknown, but adrenomedullin(22-52) could possess immunomodulatory properties. This study was undertaken to evaluate the effect of adrenomedullin(22-52) in a mouse model of arthritis. METHODS: DBA/1 mice with collagen-induced arthritis (CIA) were treated with 1.2 µg/gm adrenomedullin(22-52) , adrenomedullin, or saline at arthritis onset. Bone mineral density was measured at the beginning of the experiment and when mice were killed. Mouse joints were processed for histologic analysis and protein studies, and spleens were examined for Treg cell expression. Cytokine expression was studied in mouse joint tissue and serum. RESULTS: In mice with CIA, adrenomedullin and adrenomedullin(22-52) reduced clinical and histologic arthritis scores and shifted the pattern of articular and systemic cytokine expression from Th1 to Th2, as compared to untreated mice with CIA (controls). Tumor necrosis factor α, interleukin-6 (IL-6), and IL-17A levels were significantly decreased in the joints of mice with CIA treated with adrenomedullin or adrenomedullin(22-52) as compared to controls, whereas IL-4 and IL-10 levels were increased. Adrenomedullin(22-52) was more effective than adrenomedullin in modulating cytokine content and enhanced Treg cell function without changing Treg cell expression compared to controls. Adrenomedullin receptor binding and transcriptional adrenomedullin receptor expression were markedly increased in joints from controls, whereas adrenomedullin receptor binding was considerably decreased in treated animals. Mice with CIA treated with adrenomedullin or adrenomedullin(22-52) had considerably fewer apoptotic chondrocytes and diminished cartilage degradation. Adrenomedullin(22-52) completely prevented systemic bone loss by preserving osteoblastic activity, but without changes in osteoclastic activity. CONCLUSION: Our findings indicate that adrenomedullin(22-52) , which has no vasoactive or tumor-inducing effects, is a potent antiinflammatory and bone-protective agent in this arthritis model.

Comparative study of MRI and power Doppler ultrasonography of the heel in patients with spondyloarthritis with and without heel pain and in controls.

INTRODUCTION: Imaging of heel enthesopathy in spondyloarthritis (SpA) could potentially be useful for diagnosis and monitoring. The aim of this study was to assess the diagnostic capacities of MRI and power Doppler ultrasonography (PDUS) of the heel to distinguish patients with SpA from controls and to distinguish between patients with SpA with and without enthesopathy. METHODS: A cross-sectional single-centre study was performed in 51 patients (102 heels) with definite SpA according to Amor's criteria. Patients with degenerative non-inflammatory low back pain (n=24, 48 heels) were included as controls. Bilateral heel MRI and PDUS were performed by two senior musculoskeletal radiologists blinded to the clinical and biological data on the same day as the clinical evaluation. The data were analysed by patient and by heel. RESULTS: Neither MRI nor PDUS could discriminate between patients with SpA and controls; bone oedema on MRI was the only abnormality specific to SpA (94%), but with a poor sensitivity (22%). However, among patients with SpA, painful heels had more inflammatory abnormalities (81% by MRI, 58% by PDUS) than heels with no pain (56% at MRI, 17% at PDUS). CONCLUSION: Heel MRI and PDUS frequently show inflammatory lesions in SpA, particularly in painful heels. However, they were also often abnormal in controls. These results suggest that heel MRI and PDUS cannot be used for the diagnosis of SpA. However, PDUS and MRI may be useful for the depiction and assessment of enthesis inflammatory lesions in patients with SpA with heel pain.

Calcifications in human osteoarthritic articular cartilage: ex vivo assessment of calcium compounds using XANES spectroscopy.

Calcium (Ca(2+))-containing crystals (CCs), including basic Ca(2+) phosphate (BCP) and Ca(2+) pyrophosphate dihydrate (CPPD) crystals, are associated with severe forms of osteoarthritis (OA). Growing evidence supports a role for abnormal articular cartilage mineralization in the pathogenesis of OA. However, the role of Ca(2+) compounds in this mineralization process remains poorly understood. Six patients, who underwent total knee joint replacement for primary OA, have been considered in this study. Cartilage from femoral condyles and tibial plateaus in the medial and lateral compartments was collected as 1 mm-thick slices cut tangentially to the articular surface. First, CCs presence and biochemical composition were assessed using Fourier transform infrared spectroscopy (FT-IR). Next, Ca(2+) compound biochemical form was further assessed using X-ray absorption spectroscopy (XAS) performed at the Ca(2+) K-absorption edge. Overall, 12 cartilage samples were assessed. Using FT-IR, BCP and CPPD crystals were detected in four and three out of 12 samples, respectively. Ca(2+) compound biochemical forms differed between areas with versus without CCs, when compared using XAS. The complete set of data shows that XANES spectroscopy can be used to accurately characterize sparse CCs in human OA cartilage. It is found that Ca(2+) compounds differ between calcified and non-calcified cartilage areas. In calcified areas they appear to be mainly involved in calcifications, namely Ca(2+) crystals.