The Effect of Lipedema on Knee Osteoarthritis

The Effect of Lipedema on Knee Osteoarthritis: A Cross-Sectional Analysis of Clinical Symptoms and Ultrasonographic Findings

This study will be one of the few to examine the effect of lipedema on knee osteoarthritis in a comparative manner with a control group within the same osteoarthritis context. Although the relationship between obesity and osteoarthritis has been extensively studied in the literature, the effect of specific adipose tissue pathologies, such as lipedema, on osteoarthritis has not been sufficiently investigated. This study aims to demonstrate the independent effect of lipedema on osteoarthritis, evaluate clinical and ultrasonographic parameters together, and contribute to early diagnosis and targeted rehabilitation strategies.

Study Overview

• Status: Not yet recruiting
• Conditions: Knee Osteoarthritis; Knee; Knee Arthropathy; Lipedema; Knee Acute and Chronic Pain; Knee Arthritis Osteoarthritis; Knee Cartilage Lesions; Knee Cartilage Defects

• Study Type: Observational
• Enrollment (Estimated): 76

Contacts and Locations

• Study Contact: Name: Kadir Songür, Assoc. Prof.; Phone Number: +905054529231; Email: kadir.93@gmail.com

Study Locations

• Turkey (Türkiye)
  • İzmir
    • Izmir, İzmir, Turkey (Türkiye), 35570
      • Izmir Democracy University
      • Contact: Kadir Songür; Phone Number: +905054529231; Email: kadir.93@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

This study will include patients aged 30 and older who presented to the Physical Medicine and Rehabilitation Outpatient Clinic at Buca Seyfi Demirsoy Training and Research Hospital, Izmir Democracy University, between July 15, 2026, and July 15, 2027, and who were diagnosed with knee osteoarthritis based on clinical and radiological evaluations. Previously obtained knee X-rays will be retrospectively reviewed, and patients with osteoarthritis findings on X-rays according to the Kellgren-Lawrence grading system will be included in the study. The diagnosis of lipedema will be made by an experienced physical therapy and rehabilitation specialist based on a combined evaluation of clinical and ultrasonographic findings. The clinical diagnosis will be based on the Wold criteria: bilateral and symmetrical fat distribution in the lower extremities, foot sparing, tenderness and pain on palpation, a history of easy bruising, and fat accumulation resistant to diet and exercise.

Description

Inclusion Criteria:

All participants (Group 1 + Group 2)

• Women aged 30-65
• With a clinical and radiological diagnosis of knee osteoarthritis
• Who agreed to participate in the study

Group 1 (knee osteoarthritis with lipedema):

• Patients who meet the Wold criteria for a clinical diagnosis of lipedema
• An increase in subcutaneous fat thickness confirmed by ultrasound

Group 2 (knee osteoarthritis without lipedema):

• No diagnosis of lipedema
• Exclusion of lymphedema and venous diseases

Exclusion Criteria:

• Inflammatory arthritis
• History of knee surgery
• Intra-articular injection within the past 6 months
• Acute trauma
• Systemic connective tissue disease
• Severe venous insufficiency or lymphedema
• History of malignancy
• Use of gabapentinoids/SNRIs/SSRIs due to fibromyalgia or psychiatric illness
• Severe cognitive impairment or communication problems that would prevent participation in the study
• Pregnancy
• Participants who were informed about the study and refused to participate

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Group 1; Knee osteoarthritis with lipedema
Group 2; Knee osteoarthritis without lipedema

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Ultrasonography-based measurements of femoral cartilage thickness	During femoral cartilage thickness measurements, participants will be positioned in the supine position, and the knee will be brought to maximum flexion for evaluation through the suprapatellar window. The probe will be positioned in the transverse plane, and measurements will be taken at the level of the medial and lateral femoral condyles and the intercondylar groove. For standardization, each measurement will be repeated three times, and the average will be recorded. Cartilage thickness will be defined as the distance between the hypoechoic cartilage layer and the subchondral bone surface. Lower values indicate that osteoarthritis has caused more structural damage.	Day 1

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Western Ontario and McMaster Universities (WOMAC) score	The WOMAC Osteoarthritis Index questionnaire, consisting of 5 questions using a Likert scale, is provided in the attached case report form to assess pain, stiffness, and daily living functions. The WOMAC Osteoarthritis Index consists of 24 questions covering three subscales: pain (5 questions), stiffness (2 questions), and function (17 questions). The scoring system consists of the WOMAC pain score, WOMAC stiffness score, WOMAC function score, and WOMAC total score. A Turkish validity and reliability study has been conducted.	Day 1
Visual analog scale	Visual analog scale measures pain as it is subjectively perceived. It uses a 0-10 cm scale, the most commonly used tool for quantitatively determining pain intensity, with one end representing no pain and the other end representing the most severe pain possible. '0' indicates no pain, while '10' indicates the most severe pain. The individual is asked to select the numerical value that best represents their condition. This marked value is used as numerical data to determine the level of pain perception. A higher score indicates a higher level of pain.	Day 1
Joint Range of Motion measurement	Knee flexion and extension will be measured bilaterally using universal goniometry to assess patients' joint range of motion, and the angles will be recorded.	Day 1
Kellgren-Lawrence Classification	The Kellgren and Lawrence system is a widely used method that classifies the severity of knee osteoarthritis into five grades.	Day 1
Assessment of osteophytes via ultrasonography	During osteophyte assessment, participants will be positioned in the supine position with the knee flexed approximately 30 degrees; the probe will be placed along the medial and lateral joint lines in the longitudinal and transverse planes to examine bony projections. Osteophytes will be scored according to the Outcome Measures in Rheumatology knee osteoarthritis scale criteria as small (<2 mm - Grade 1), moderate (2-4 mm - Grade 2), and large (>4 mm - Grade 3).	Day 1
Assessment of synovial hypertrophy via ultrasonography	In the ultrasound assessment of synovial hypertrophy, the thickness of hypoechoic tissue in the suprapatellar region that does not shift upon probe compression will be measured, and values exceeding 2 mm will be recorded as synovial hypertrophy.	Day 1
Assessment of synovial effusion via ultrasonography	Ultrasonographic assessment of joint effusion will be performed at the suprapatellar recess level; participants will be positioned in the supine position with the knee in near-extension or slight flexion. During the longitudinal plane examination, anechoic fluid collections will be measured, and values of 4 mm or greater will be considered pathological synovial effusions.	Day 1
Assessment of meniscal protrusions via ultrasonography	During the ultrasound assessment of meniscus protrusion, the knee will be positioned with approximately 30 degrees of flexion, and the extent to which the meniscus tissue extends beyond the tibial margin will be evaluated in measurements taken in the longitudinal plane along the medial joint line; protrusions exceeding 3 mm will be considered pathological meniscus protrusions.	Day 1
Ultrasonography-based measurements of quadriceps muscle thickness	For ultrasonographic measurements of quadriceps muscle thickness, participants will be positioned in the supine position with the knee extended and the muscles fully relaxed; measurements taken in the transverse plane at the midpoint between the anterior superior iliac spine and the superior pole of the patella will assess the thicknesses of the rectus femoris and vastus intermedius muscles together.	Day 1
Ultrasonography-based measurements of quadriceps tendon thickness	Ultrasonographic measurements of the quadriceps tendon will be taken in the longitudinal plane immediately proximal to the superior pole of the patella while the knee is flexed to approximately 30 degrees, and the average of the measurements taken 5, 10, and 15 mm proximal to this point will be recorded	Day 1
Ultrasonography-based measurements of patellar tendon thickness	Ultrasonographic assessment of the patellar tendon is performed with the knee flexed to 30 degrees, in the longitudinal plane from the apex of the patella distally, and the anteroposterior thickness is measured approximately 5 mm distal to the apex.	Day 1

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Ultrasonography-based measurements of pre-tibial and thigh subcutaneous thickness	The diagnosis of lipedema will be supported by ultrasonographic measurements of subcutaneous fat thickness in the thigh and pretibial regions. With the patient in the supine position and the lower extremities relaxed and in a neutral position, the probe is placed in the transverse plane (anterior surface of the tibia), at the midpoint between the tibial tuberosity and the medial malleolus, and on the thigh, at the midpoint along the midline between the iliac crest and the lower edge of the patella, and the total thickness of the skin and subcutaneous tissue will be measured in millimeters by applying minimal pressure. Each measurement will be taken three times, and the average will be calculated. In the literature, diagnostic threshold values have been established as a thickness measurement of >11.7 mm in the pre-tibial region and >17.9 mm in the thigh.	Day 1

Collaborators and Investigators

• Sponsor: Izmir Democracy University

Study record dates

Study Major Dates

• Study Start (Estimated): July 15, 2026
• Primary Completion (Estimated): July 15, 2027
• Study Completion (Estimated): August 15, 2027

Study Registration Dates

• First Submitted: May 3, 2026
• First Submitted That Met QC Criteria: May 3, 2026
• First Posted (Actual): May 8, 2026

Study Record Updates

• Last Update Posted (Actual): May 8, 2026
• Last Update Submitted That Met QC Criteria: May 3, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: knee osteoarthritis; knee; lipedema; knee joint
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Connective Tissue Diseases; Osteoarthritis; Pathological Conditions, Signs and Symptoms; Skin and Connective Tissue Diseases; Signs and Symptoms; Osteoarthritis, Knee; Chronic Pain; Lipedema
• Other Study ID Numbers: 2026/26

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data (IPD) will not be shared because the data contain

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No