Objective. To identify OA subtypes based on cartilage transcriptomic data in cartilage tissue and characterize their underlying pathophysiological processes and/or clinically relevant... Show moreObjective. To identify OA subtypes based on cartilage transcriptomic data in cartilage tissue and characterize their underlying pathophysiological processes and/or clinically relevant characteristics.Methods. This study includes n = 66 primary OA patients (41 knees and 25 hips), who underwent a joint replacement surgery, from which macroscopically unaffected (preserved, n = 56) and lesioned (n = 45) OA articular cartilage were collected [Research Arthritis and Articular Cartilage (RAAK) study]. Unsupervised hierarchical clustering analysis on preserved cartilage transcriptome followed by clinical data integration was performed. Protein-protein interaction (PPI) followed by pathway enrichment analysis were done for genes significant differentially expressed between subgroups with interactions in the PPI network.Results. Analysis of preserved samples (n = 56) resulted in two OA subtypes with n = 41 (cluster A) and n = 15 (cluster B) patients. The transcriptomic profile of cluster B cartilage, relative to cluster A (DE-AB genes) showed among others a pronounced upregulation of multiple genes involved in chemokine pathways. Nevertheless, upon investigating the OA pathophysiology in cluster B patients as reflected by differentially expressed genes between preserved and lesioned OA cartilage (DE-OA-B genes), the chemokine genes were significantly downregulated with OA pathophysiology. Upon integrating radiographic OA data, we showed that the OA phenotype among cluster B patients, relative to cluster A, may be characterized by higher joint space narrowing (JSN) scores and low osteophyte (OP) scores.Conclusion. Based on whole-transcriptome profiling, we identified two robust OA subtypes characterized by unique OA, pathophysiological processes in cartilage as well as a clinical phenotype. We advocate that further characterization, confirmation and clinical data integration is a prerequisite to allow for development of treatments towards personalized care with concurrently more effective treatment response. Show less
Osteoarthritis (OA) has a strong genetic component but the success of previous genome-wide association studies (GWAS) has been restricted due to insufficient sample sizes and phenotype... Show moreOsteoarthritis (OA) has a strong genetic component but the success of previous genome-wide association studies (GWAS) has been restricted due to insufficient sample sizes and phenotype heterogeneity. Our aim was to examine the effect of clinically relevant endophenotyping according to site of maximal joint space narrowing (maxJSN) and bone remodelling response on GWAS signal detection in hip OA..A stratified GWAS meta-analysis was conducted in 2118 radiographically defined hip OA cases and 6500 population-based controls. Signals were followed up by analysing differential expression of proximal genes for bone remodelling endophenotypes in 33 pairs of macroscopically intact and OA-affected cartilage.We report suggestive evidence (p<5×10−6) of association at 6 variants with OA endophenotypes that would have been missed by using presence of hip OA as the disease end point. For example, in the analysis of hip OA cases with superior maxJSN versus cases with non-superior maxJSN we detected association with a variant in the LRCH1 gene (rs754106, p=1.49×10−7, OR (95% CIs) 0.70 (0.61 to 0.80)). In the comparison of hypertrophic with non-hypertrophic OA the most significant variant was located between STT3B and GADL1 (rs6766414, p=3.13×10−6, OR (95% CIs) 1.45 (1.24 to 1.69)). Both of these associations were fully attenuated in non-stratified analyses of all hip OA cases versus population controls ( p>0.05). STT3B was significantly upregulated in OA-affected versus intact cartilage, particularly in the analysis of hypertrophic and normotrophic compared with atrophic bone remodelling pattern (p=4.2×10−4).Our findings demonstrate that stratification of OA cases into more homogeneous endophenotypes can identify genes of potential functional importance otherwise obscured by diseaseheterogeneity. Show less
In this thesis we demonstrated that several known risk factors for knee OA development i.e. ACL ruptures, meniscal tears, the presence of hand OA and increased BMI, are already associated with knee... Show moreIn this thesis we demonstrated that several known risk factors for knee OA development i.e. ACL ruptures, meniscal tears, the presence of hand OA and increased BMI, are already associated with knee OA development as demonstrated on radiographs and MR images early in life. Identifying these factors in young to middle aged patients suffering from knee complaints helps to define high risk patients who may benefit from early preventive exercise therapy or maybe disease modifying drugs which might be developed in the future. Meniscectomy and ACL reconstruction have no effect on knee OA development after 10 years in patients with sub-acute knee complaints. The in this thesis validated automatic JSW quantification method is sensitive to small changes in JSW of the finger joints. The first signs of hand OA development with this method can be detected within one or two years. In patients with traumatic meniscal tears but without knee locking symptoms, there may be some benefits from treatment with meniscectomy in long-term Sports and Recreation knee function outcomes compared to conservative treatment. Future randomized controlled trials may elucidate the effect of surgical treatment of traumatic meniscal tears. Show less
Huetink, K.; ' t Klooster, R. van; Kaptein, B.L.; Watt, I.; Kloppenburg, M.; Nelissen, R.G.H.H.; ... ; Stoel, B.C. 2012
OBJECTIVE To investigate the validity of joint space width (JSW) measurements in millimeters (mm) in hand osteoarthritis (OA) patients by comparison to controls, grading of joint space narrowing ... Show moreOBJECTIVE To investigate the validity of joint space width (JSW) measurements in millimeters (mm) in hand osteoarthritis (OA) patients by comparison to controls, grading of joint space narrowing (JSN), and clinical features. METHODS Hand radiographs of 235 hand OA patients (mean age 65 years, 83% women) and 471 controls were used. JSW was measured with semi-automated image analysis software in the distal, proximal interphalangeal and metacarpal joints (DIPJs, PIPJs and MCPJs). JSN (grade 0-3) was assessed using the osteoarthritis research society international (OARSI) atlas. Associations between the two methods and clinical determinants (presence of pain, nodes and/or erosions, decreased mobility) were assessed using Generalized Estimating Equations with adjustments for age, sex, body mass index (BMI) and mean width of proximal phalanx. RESULTS JSW was measured in 5631 joints with a mean JSW of 0.98 mm (standard deviation (SD) 0.21), being the smallest for DIPJs (0.70 (SD 0.25)) and largest for MCPJs (1.40 (SD 0.25)). The JSN=0 group had a mean JSW of 1.28 mm (SD 0.34), the JSN=3 group 0.17 mm (SD 0.23). Controls had larger JSW than hand OA patients (P-value<0.001). In hand OA, females had smaller JSW than men (β -0.08, (95% confidence interval (95% CI) -0.15 to -0.01)) and lower JSW was associated with the presence of pain, nodes, erosions and decreased mobility (adjusted β -0.21 (95% CI -0.27, -0.16), -0.37 (-0.40, -0.34), -0.61 (-0.68, -0.54) and -0.46 (-0.68, -0.24) respectively). These associations were similar for JSN in grades. CONCLUSION In hand OA the quantitative JSW measurement is a valid method to measure joint space and shows a good relation with clinical features. Show less
OBJECTIVE: To validate a newly developed quantification method that automatically detects and quantifies the joint space width (JSW) in hand radiographs. Repeatability, accuracy and sensitivity to... Show moreOBJECTIVE: To validate a newly developed quantification method that automatically detects and quantifies the joint space width (JSW) in hand radiographs. Repeatability, accuracy and sensitivity to changes in JSW were determined. The influence of joint location and joint shape on the measurements was tested. METHODS: A mechanical micrometer set-up was developed to define and adjust the true JSW in an acrylic phantom joint and in human cadaver-derived phalangeal joints. Radiographic measurements of the JSW were compared to the true JSW. Repeatability, systematic error (accuracy) and sensitivity (defined as the smallest detectable difference (SDD)) were determined. The influence of joint position on the JSW measurement was assessed by varying the location of the acrylic phantom on the X-ray detector with respect to the X-ray beam and the influence of joint shape was determined by using morphologically different human cadaver joints. RESULTS: The mean systematic error was 0.052 mm in the phantom joint and 0.210 mm in the cadaver experiment. In the phantom experiments, the repeatability was high (SDD = 0.028 mm), but differed slightly between joint locations (p = 0.046), and a change in JSW of 0.037 mm could be detected. Dependent of the joint shape in the cadaver hand, a change in JSW between 0.018 and 0.047 mm could be detected. CONCLUSIONS: The automatic quantification method is sensitive to small changes in JSW. Considering the published data of JSW decline in the normal and osteoarthritic population, the first signs of OA progression with this method can be detected within 1 or 2 years. Show less
Purpose: To define localized development of knee osteoarthritis (OA) that arises from anterior cruciate ligament (ACL) and meniscal injuries identified at magnetic resonance (MR) imaging performed... Show morePurpose: To define localized development of knee osteoarthritis (OA) that arises from anterior cruciate ligament (ACL) and meniscal injuries identified at magnetic resonance (MR) imaging performed a decade ago and the subsequent management of those findings in patients with subacute knee symptoms. Materials and Methods: The present study was approved by local medical ethics review boards, and written informed consent was obtained. Three hundred twenty-six patients (mean age, 42 years; 108 female) from a previously reported series of 855 patients were followed up with regard to the effect of MR imaging-guided treatment for subacute knee problems. The mean follow-up period was 10 years. Initial findings and treatment were compared with the follow-up radiograph and 3.0-T MR image findings. Odds ratios (ORs), with corresponding 95% confidence intervals, were used to identify the effects between variables. Results: Patients with ACL ruptures had an increased risk of developing joint space narrowing (JSN), cartilaginous defects, osteophytes, bone marrow lesions, and subchondral cysts medially or laterally (OR, 2.4-9.8). Patients with medial meniscal tears had an increased risk of developing JSN, cartilaginous defects, osteophytes, and bone marrow lesions medially (OR, 2.0-15.3). Patients with lateral meniscal tears had an increased risk of developing JSN, cartilaginous defects, osteophytes, bone marrow lesions, and subchondral cysts laterally (OR, 2.1-10.5). Meniscectomy had no effect on the risk of developing OA. Conclusion: Localized knee OA developed from risk factors identified from the findings of MR imaging performed a decade ago in patients with subacute knee symptoms and did not depend on the surgical treatment of those findings. (C) RSNA, 2010 Show less
