An observational study in Knee Osteoarthritis, sponsored by Afyonkarahisar Health Sciences University. Recruiting at 1 site in Turkey (Türkiye). Open to female participants aged 40 Years to 70 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-15.
Sponsored by Afyonkarahisar Health Sciences University · Observational
The aim of this study is to investigate the serum levels of lysyl hydroxylase, lysyl oxidase, and the lysyl oxidase-like enzymes in patients with different stages of knee osteoarthritis and to compare these findings with those of healthy control subjects.
Osteoarthritis (OA) is a chronic degenerative disease affecting synovial joints, characterized by structural abnormalities of the hyaline articular cartilage, subchondral bone loss, increased synovial vascularity, tissue hypertrophy, and ligament or tendon instability. These changes lead to pain, swelling, and reduced range of motion. The pathogenesis of OA involves inflammation, genetic predisposition, mechanical stress, biochemical alterations, and environmental factors, all of which disrupt the balance between cartilage synthesis and degradation.
The extracellular matrix (ECM) of articular cartilage is composed mainly of collagen, proteoglycans, and non-collagenous proteins, providing biomechanical strength and resilience. Collagen cross-linking, which stabilizes the ECM, depends on post-translational modifications regulated by specific enzymes such as lysyl hydroxylase and lysyl oxidase.
Lysyl hydroxylases catalyze the hydroxylation of lysine residues to hydroxylysine, a key step in collagen cross-link formation. Lysyl oxidase (LOX) and its related isoenzymes (LOXL1-4) are copper-dependent amine oxidases that mediate oxidative deamination of lysine and hydroxylysine residues, forming aldehydes that initiate covalent cross-links between collagen and elastin molecules. Proper LOX activity is crucial for maintaining the mechanical integrity of cartilage, while dysregulation of LOX family enzymes may contribute to matrix fragility and degeneration.
The expression and activity of LOX family enzymes in OA cartilage appear to vary by disease stage. LOXL2 and LOXL3 have been implicated in both anabolic and catabolic responses, suggesting complex regulatory roles. Understanding these enzyme dynamics may provide insights into the pathophysiology of OA and identify potential biomarkers or therapeutic targets.
The present study aims to evaluate serum levels of lysyl hydroxylase, lysyl oxidase, and LOXL1-4 in patients with different stages of knee osteoarthritis and compare them with healthy control subjects.
3,391 studies on the registry are indexed under Osteoarthritis, Knee; 628 are open to participants now.
This study's planned enrollment of 200 is above the median of 100 across 484 observational studies indexed under Osteoarthritis, Knee.
Browse Osteoarthritis, Knee studies →Afyonkarahisar Health Sciences University is the lead sponsor of 111 studies on the registry; 36 are open to participants now.
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The study population will consist of female volunteers aged 40-70 years who are either diagnosed with knee osteoarthritis or are healthy controls without clinical or radiographic evidence of osteoarthritis. Participants will be recruited from the outpatient clinic of the Department of Physical Medicine and Rehabilitation, Afyonkarahisar Health Sciences University (AFSU). All participants will meet the inclusion criteria and provide written informed consent prior to enrollment. Individuals with metabolic diseases, inflammatory arthritis, or significant comorbidities will be excluded.
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Exclusion Criteria:
Radiographically confirmed knee OA, Kellgren-Lawrence grade 1
Radiographically confirmed knee OA, Kellgren-Lawrence grade 2
Radiographically confirmed knee OA, Kellgren-Lawrence grade 3
Radiographically confirmed knee OA, Kellgren-Lawrence grade 4
Age- and sex-matched individuals without clinical or radiographic knee OA
Biochemical Analysis
Serum levels of lysyl oxidase (LOX), lysyl oxidase-like enzymes (LOXL1, LOXL2, LOXL3, LOXL4), and lysyl hydroxylase (LH) will be quantified using validated, commercially available sandwich-type ELISA kits. Venous blood samples will be obtained from fasting participants, centrifuged to separate serum, aliquoted, and stored at -80 °C under single freeze-thaw conditions until analysis. Each ELISA plate will include standard curves and control samples. Optical density will be read at 450 nm, and results will be expressed as ng/mL or pg/mL according to manufacturer instructions. Intra-assay coefficients of variation (CV) exceeding 15% will be repeated to ensure analytical accuracy. All samples will be anonymized and analyzed under strict confidentiality.
Time frame: At the time of enrollment
Femoral Cartilage Thickness (Ultrasound Measurement)
Ultrasonographic evaluation will be performed using a linear transducer (4-15 MHz, MyLab X8 series, Esaote S.p.A., Italy). Participants will be examined in the supine position with knees flexed at 120-135°, and the probe will be placed axially over the suprapatellar region. The distal femoral cartilage will be visualized as an anechoic band between the sharp hyperechoic cortical line and the suprapatellar fat pad. Three measurements will be taken from each knee at standard reference points: right lateral condyle (RLC), intercondylar area (RIA), and right medial condyle (RMC). All images will be reviewed by a physician with over three years of musculoskeletal ultrasound experience, and images with poor quality or incorrect technique will be excluded from the analysis.
Time frame: At the time of enrollment
Knee Joint Range of Motion (ROM)
Active and passive range of motion (flexion and extension) of the affected knee joint will be measured using a universal goniometer in a standardized sitting or supine position. Measurements will be performed by the same examiner to ensure consistency, and results will be recorded in degrees (°). The purpose is to assess the relationship between joint mobility and disease severity.
Time frame: At the time of enrollment
Pain Intensity (VAS Score)
Pain intensity will be assessed using a 10-cm Visual Analog Scale (VAS), where 0 indicates "no pain" and 10 indicates "worst imaginable pain." Participants will be asked to rate their average knee pain during daily activities. The mean VAS score will be compared across osteoarthritis stages and correlated with biochemical and ultrasound findings.
Time frame: At the time of enrollment
Functional Status (WOMAC Index - Likert Scale)
Functional impairment will be evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), scored on a 5-point Likert scale (0 = none, 4 = extreme). The WOMAC index assesses pain, stiffness, and physical function through 24 questions (5 on pain, 2 on stiffness, and 17 on physical function). Total and subscale scores will be calculated to quantify the impact of knee osteoarthritis on daily living activities and functional capacity. The total WOMAC score ranges from 0 to 96. Higher scores indicate greater pain, stiffness and functional impairment, reflecting worse clinical outcomes.
Time frame: At the time of enrollment
Started May 2025 (actual). Primary completion is estimated for Jan 2027, 19 months after the start.
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From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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