An observational study in Knee Osteoarthritis, sponsored by Mardin Artuklu University. Not yet recruiting at 1 site in Turkey (Türkiye). Open to participants aged 40 Years to 80 Years. Per ClinicalTrials.gov, last updated 2026-10-20.
Sponsored by Mardin Artuklu University · Observational
Small amounts of fluid in the knee joint may not always be visible during a standard ultrasound examination performed while the leg is relaxed. When the quadriceps muscle contracts, this fluid may move into the area above the kneecap and become visible. This finding is referred to in this study as occult suprapatellar effusion.
The aim of this study is to determine whether occult suprapatellar effusion is associated with knee pain and physical function in people with knee osteoarthritis. Participants will undergo ultrasound examination first at rest and then during quadriceps contraction. Based on these findings, they will be classified as having effusion visible at rest, occult effusion visible only during muscle contraction, or no effusion in either condition.
Knee pain, self-reported symptoms and function, and chair stand performance will be compared among these groups. The study will also examine whether greater effusion depth is associated with more severe pain, greater functional limitation, and poorer physical performance. No treatment will be assigned as part of the study.
Joint effusion is an ultrasound-detectable inflammatory feature of knee osteoarthritis and may be associated with pain and functional limitation. However, a small effusion may remain undetected during a conventional static examination. Voluntary quadriceps contraction can increase intra-articular pressure and move joint fluid into the suprapatellar recess, allowing an otherwise occult effusion to become visible. The clinical relevance of this dynamic finding has not been clearly established.
This single-center, observational, cross-sectional study will evaluate the suprapatellar recess using ultrasound both at rest and during voluntary quadriceps contraction. Participants will be classified into three groups according to the ultrasound findings: static effusion, defined as effusion visible during the resting examination; occult effusion, defined as effusion absent at rest but visible during quadriceps contraction; and no effusion, defined as the absence of effusion under both conditions.
The primary comparison will evaluate 30-second chair stand performance between participants with occult effusion and those with no effusion. Additional analyses will compare pain, self-reported symptoms and function, and chair stand performance across all three groups. The relationships between suprapatellar effusion depth and clinical and functional outcomes will also be examined. Adjusted analyses will assess whether effusion group is independently associated with physical performance after accounting for age, body mass index, and radiographic osteoarthritis severity.
3,391 studies on the registry are indexed under Osteoarthritis, Knee; 628 are open to participants now.
This study's planned enrollment of 105 is close to the median of 100 across 484 observational studies indexed under Osteoarthritis, Knee.
Browse Osteoarthritis, Knee studies →Mardin Artuklu University is the lead sponsor of 32 studies on the registry; 13 are open to participants now.
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The study population will consist of adults with symptomatic primary knee osteoarthritis attending the Physical Medicine and Rehabilitation outpatient clinic of Mardin Training and Research Hospital. Participants will be classified according to suprapatellar effusion findings obtained during static and quadriceps contraction ultrasound examinations.
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Exclusion Criteria:
Participants with suprapatellar effusion visible during the resting static ultrasound examination.
Diagnostic Test: Static and Dynamic Suprapatellar Ultrasonography
Participants without suprapatellar effusion during the resting static examination but with effusion visible during voluntary quadriceps contraction.
Diagnostic Test: Static and Dynamic Suprapatellar Ultrasonography
Participants without suprapatellar effusion during either the resting static examination or voluntary quadriceps contraction.
Diagnostic Test: Static and Dynamic Suprapatellar Ultrasonography
The suprapatellar recess will be examined by ultrasound with the participant resting in the supine position and the knee extended. The examination will first be performed at rest and then repeated during voluntary quadriceps contraction while the probe position is maintained. The presence of effusion and its maximum anteroposterior depth in millimeters will be recorded under both conditions. This assessment is used only to classify ultrasound findings and does not involve treatment.
Physical Performance Assessed by the 30-Second Chair Stand Test
The number of complete sit-to-stand repetitions performed within 30 seconds will be recorded. The score has a minimum of 0 repetitions and no predefined maximum. A higher number of repetitions indicates better lower-extremity physical performance. The primary comparison will be between the occult effusion group and the no effusion group.
Time frame: Baseline
Knee Pain Intensity Assessed by the Numerical Rating Scale
Average knee pain intensity during the previous week will be assessed using an 11-point numerical rating scale ranging from 0 to 10. A score of 0 indicates no pain, and a score of 10 indicates the worst imaginable pain. Higher scores indicate greater knee pain intensity.
Time frame: Baseline
Symptoms and Physical Function Assessed by the Western Ontario and McMaster Universities Osteoarthritis Index
The Western Ontario and McMaster Universities Osteoarthritis Index consists of 24 items scored from 0 to 4. It provides pain, stiffness, physical function, and total scores. Score ranges are 0-20 for pain, 0-8 for stiffness, 0-68 for physical function, and 0-96 for the total score. Higher scores indicate greater pain, stiffness, and functional limitation.
Time frame: Baseline
Suprapatellar Effusion Depth Assessed by Ultrasonography
The maximum anteroposterior depth of suprapatellar effusion will be measured in millimeters during the resting static ultrasound examination and during voluntary quadriceps contraction. Each contraction measurement will be repeated twice, and the highest value will be recorded. The measurement has a minimum value of 0 millimeters and no predefined maximum. Higher values indicate greater effusion depth.
Time frame: Baseline
Plan to share: No
Start is estimated for Nov 2026; primary completion for May 2027, 6 months later.
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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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Mardin Artuklu University