Neuropathic Pain in Knee Osteoarthritis: Pain Severity and Functional Status

January 17, 2026 updated by: Eser Kalaoglu, Istanbul Physical Medicine Rehabilitation Training and Research Hospital

Presence of Neuropathic Pain in Knee Osteoarthritis: Relationship Between Pain Severity and Functional Status

Osteoarthritis (OA) is a degenerative joint disease characterized by structural changes such as cartilage loss and osteophyte formation, leading to functional limitations and disability. Pain in knee OA involves a complex pathophysiological structure including both nociceptive and neuropathic mechanisms. Identifying the neuropathic pain component is clinically significant for improving quality of life and functional recovery. This cross-sectional controlled clinical study aims to determine the prevalence of neuropathic pain in patients with knee OA and evaluate its impact on pain severity and functional status. Patients will be categorized based on the Douleur Neuropathique 4 (DN4) questionnaire and assessed using various pain and functional scales.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Osteoarthritis (OA) is a degenerative joint disease characterized by structural alterations, including focal cartilage loss, osteophyte formation, subchondral sclerosis, and synovitis. Given the growing elderly population, the prevalence of OA is rising, frequently leading to significant functional limitations and disability. Pain, the most prominent symptom of OA, serves as a critical measure for monitoring disease activity and treatment efficacy.

Recent evidence suggests that OA-related pain involves a complex pathophysiological structure, incorporating both nociceptive and neuropathic mechanisms. Studies indicate that approximately 19-37% of patients with knee OA exhibit symptoms consistent with neuropathic pain. Identifying this neuropathic component is clinically essential, as it may respond differently to conventional analgesics; thus, recognizing it is vital for optimizing functional recovery and quality of life.

This cross-sectional controlled clinical trial aims to determine the prevalence of neuropathic pain in patients with knee OA and evaluate its impact on pain severity and functional status. Participants diagnosed with knee OA according to the American College of Rheumatology (ACR) criteria will be recruited and categorized into two groups based on a Douleur Neuropathique 4 (DN4) questionnaire score threshold of 4/10.

For all participants, comprehensive demographic and clinical data, including age, body mass index (BMI), educational level, occupation, and marital status, will be recorded. To ensure consistency and minimize measurement error, all anthropometric assessments will be performed by a single researcher. The following standardized assessment tools will be administered to all participants: Visual Analog Scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS).

Study Type

Observational

Enrollment (Estimated)

102

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Turkey (Türkiye)
      • Istanbul, Turkey (Türkiye), 34186
        • Recruiting
        • Istanbul Physical Medicine and Rehabilitation Training and Research Hospital
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

The source population for this cross-sectional controlled study is the adult patient population diagnosed with knee osteoarthritis (OA) according to the American College of Rheumatology (ACR) criteria, recruited from the Physical Medicine and Rehabilitation outpatient clinic at Istanbul Physical Therapy and Rehabilitation Training and Research Hospital.

Description

Inclusion Criteria:

  • Diagnosed with Knee OA according to ACR criteria.
  • Knee pain for more than 3 months.
  • Voluntary participation.

Exclusion Criteria:

  • History of surgical intervention in the affected knee.
  • History of trauma to the affected knee within the last 6 months.
  • History of intra-articular injections (e.g., corticosteroids, hyaluronic acid, PRP) or physical therapy involving the affected knee within the last 6 months.
  • Presence of severe psychiatric disorders such as severe depression, anxiety disorder, or psychosis.
  • Diagnosis of central nervous system diseases, including Parkinson's disease or multiple sclerosis.
  • Diagnosis of inflammatory arthritis, such as Rheumatoid Arthritis or Ankylosing Spondylitis.
  • Severe cognitive impairment.
  • Chronic decompensated cardiac, renal, or hepatic failure.
  • Severe psychiatric, neurological, or kognitive disorders.

Decompensated cardiac, renal, or hepatic failure.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Group 1 (Case)
Patients with Knee OA and Neuropathic Pain (DN4 score ≥ 4)
Other: Clinical and Functional Assessment
All participants will undergo a one-time, cross-sectional clinical assessment. Comprehensive demographic and clinical data, including age, body mass index (BMI), educational level, occupation, and marital status, will be recorded for each participant. Pain intensity will be measured using a 10-cm Visual Analog Scale (VAS). Functional status and symptoms related to knee osteoarthritis will be evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS). To ensure consistency and minimize measurement error, all anthropometric measurements, specifically weight and height, will be performed by the same researcher.
Group 2 (Control)
Patients with Knee OA without Neuropathic Pain (DN4 score < 4)
Other: Clinical and Functional Assessment
All participants will undergo a one-time, cross-sectional clinical assessment. Comprehensive demographic and clinical data, including age, body mass index (BMI), educational level, occupation, and marital status, will be recorded for each participant. Pain intensity will be measured using a 10-cm Visual Analog Scale (VAS). Functional status and symptoms related to knee osteoarthritis will be evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS). To ensure consistency and minimize measurement error, all anthropometric measurements, specifically weight and height, will be performed by the same researcher.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Visual Analog Scale (VAS)
Time Frame: at baseline assessment
Pain intensity was assessed using a 10 cm scale, where one end represents "no pain" and the other represents "most severe pain." Patients were asked to rate their pain on a scale from 0 (no pain) to 10 (most severe pain)
at baseline assessment
Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)
Time Frame: at baseline assessment
Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) consists of subscales evaluating pain (5 items), stiffness (2 items), and physical function (17 items). Using a 5-point Likert scale, scores range from 0 (representing the best status/no pain) to 96 (representing the worst status/extreme pain).
at baseline assessment

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Knee Injury and Osteoarthritis Outcome Score - Physical Function Short Form (KOOS-PS)
Time Frame: at baseline assessment
Knee Injury and Osteoarthritis Outcome Score - Physical Function Short Form (KOOS-PS) is used to evaluate physical functional limitations associated with knee osteoarthritis. It consists of seven items scored on a 5-point Likert scale. Raw scores are converted to a 0-100 scale, where higher scores indicate better physical function.
at baseline assessment

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Istanbul Physical Medicine Rehabilitation Training and Research Hospital

Investigators

  • Principal Investigator: Eser Kalaoglu, M.D., Istanbul Physical Medicine Rehabilitation Training and Research Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 20, 2025

Primary Completion (Estimated)

March 31, 2026

Study Completion (Estimated)

April 30, 2026

Study Registration Dates

First Submitted

January 17, 2026

First Submitted That Met QC Criteria

January 17, 2026

First Posted (Actual)

January 26, 2026

Study Record Updates

Last Update Posted (Actual)

January 26, 2026

Last Update Submitted That Met QC Criteria

January 17, 2026

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • İstPRMTRH-EK6

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data (IPD), including all demographic, clinical, and primary/secondary outcome measures will be shared with qualified researchers. The sharing period will commence 6 months after article publication and conclude 1 year thereafter. Data access requests must be accompanied by a methodologically sound proposal and will be granted upon the corresponding author's approval and the execution of a Data Use Agreement (DUA) to strictly ensure confidentiality and adherence to ethical guidelines.

IPD Sharing Time Frame

Beginning 6 months and ending 1 year following article publication

IPD Sharing Access Criteria

Qualified researchers who present a methodologically robust proposal aimed at fulfilling the objectives of the approved project

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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