Sonographic Thigh Adjustment Ratio and Subcutaneous Fat Thickness as Predictors of Genicular Nerve Block Response in Knee Osteoarthritis (STAR-GNB)

July 14, 2026 updated by: Gaziosmanpasa Research and Education Hospital

Sonographic Thigh Adjustment Ratio and Subcutaneous Fat Thickness as Predictors of Genicular Nerve Block Response in Patients With Knee Osteoarthritis Undergoing Genicular Nerve Block: A Prospective Observational Study

Knee osteoarthritis (KOA) is a leading cause of chronic pain and disability. Although genicular nerve block (GNB) is an effective treatment for many patients, treatment response varies considerably. Identifying imaging biomarkers that predict clinical response may improve patient selection and optimize treatment outcomes.

This prospective observational study aims to evaluate whether the Sonographic Thigh Adjustment Ratio (STAR), calculated as anterior quadriceps muscle thickness divided by body mass index (BMI), and subcutaneous fat thickness are associated with pain relief following genicular nerve block in patients with symptomatic knee osteoarthritis. Ultrasound measurements will be obtained before the procedure, and clinical outcomes will be assessed during follow-up. The primary objective is to determine whether sonographic muscle parameters can predict treatment response after GNB.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Knee osteoarthritis is one of the most common musculoskeletal disorders worldwide and is frequently associated with chronic pain, impaired mobility, and reduced quality of life. Genicular nerve block has become an established minimally invasive treatment for patients with persistent pain despite conservative management. However, substantial variability exists in treatment response, highlighting the need for reliable predictors of clinical success.

Recent studies have suggested that ultrasound-derived muscle measurements may provide objective information regarding muscle quality and sarcopenia. The Sonographic Thigh Adjustment Ratio (STAR), defined as anterior quadriceps muscle thickness normalized to body mass index (BMI), has been proposed as an ultrasound-based indicator of muscle mass. Nevertheless, its potential role in predicting the response to interventional pain procedures has not been investigated.

This prospective observational cohort study will enroll patients with symptomatic knee osteoarthritis who undergo ultrasound-guided genicular nerve block as part of routine clinical care. Before the procedure, ultrasound measurements of anterior quadriceps muscle thickness and subcutaneous fat thickness will be obtained. STAR will be calculated by dividing anterior quadriceps muscle thickness by BMI. Clinical outcomes will be assessed using validated pain and functional outcome measures during follow-up.

The primary objective is to evaluate whether STAR predicts treatment response after genicular nerve block. Secondary objectives include investigating the predictive value of quadriceps muscle thickness and subcutaneous fat thickness individually and exploring their relationship with pain reduction and functional improvement.

Study Type

Observational

Enrollment (Estimated)

30

Contacts and Locations

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

Study Locations

  • Turkey (Türkiye)
      • Istanbul, Turkey (Türkiye), 34255
        • Recruiting
        • University of Health Sciences Gaziosmanpaşa Physical Therapy and Rehabilitation Training and Research Hospital
        • Contact:
        • Contact:
        • Principal Investigator:
          • Tuğçe Yavuz Mollavelioğlu, Medical Doctor

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

Adults with symptomatic bilateral Kellgren-Lawrence grade 3-4 knee osteoarthritis referred from the Department of Physical Medicine and Rehabilitation to the Pain Medicine Clinic for ultrasound-guided genicular nerve block after failure of conservative treatment. Consecutive eligible patients meeting the inclusion criteria will be enrolled prospectively.

Description

Inclusion Criteria:

  • Age ≥45 years.
  • Symptomatic bilateral knee osteoarthritis with Kellgren-Lawrence grade 3 or 4.
  • Visual Analog Scale (VAS) pain score ≥4 at rest or during movement.
  • Scheduled to undergo first ultrasound-guided genicular nerve block.
  • No intra-articular knee injection within the previous 3 months.
  • Considered unsuitable for or awaiting total knee arthroplasty.
  • Ability to provide written informed consent.

Exclusion Criteria:

  • Inflammatory arthritis, rheumatoid arthritis, or crystal arthropathy.
  • Previous knee surgery or knee prosthesis.
  • Active local or systemic infection.
  • Anticoagulant therapy or bleeding disorders.
  • Contraindication to corticosteroids (including uncontrolled diabetes mellitus).
  • Allergy to study medications.
  • Neurological disorders causing neuropathic knee pain.
  • Dementia or inability to complete study assessments.
  • Additional interventional procedures or surgery during follow-up.

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
Patients With Knee Osteoarthritis Undergoing Genicular Nerve Block
Adults with symptomatic Kellgren-Lawrence grade 3-4 knee osteoarthritis undergoing ultrasound-guided genicular nerve block as part of routine clinical care. Participants undergo baseline ultrasonographic assessment of quadriceps muscle thickness, subcutaneous fat thickness, and calculation of the Sonographic Thigh Adjustment Ratio (STAR), followed by clinical follow-up at 1 and 3 months.
Procedure: Ultrasound-Guided Genicular Nerve Block
Ultrasound-guided genicular nerve block was performed as part of routine clinical care in patients with symptomatic knee osteoarthritis. The superomedial, superolateral, and inferomedial genicular nerves were targeted using a standardized ultrasound-guided technique. A standardized injectate consisting of bupivacaine, dexamethasone, and normal saline was administered to each target nerve. The procedure was performed by an experienced pain physician using the same protocol for all participants.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Treatment Response at 1 Month Following Genicular Nerve Block
Time Frame: 1 month
Treatment response will be defined as a ≥50% reduction in Visual Analog Scale (VAS) pain score from baseline at 1 month after ultrasound-guided genicular nerve block. The predictive value of baseline Sonographic Thigh Adjustment Ratio (STAR) for 1-month treatment response will be evaluated.
1 month

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Responder Pattern After Genicular Nerve Block
Time Frame: 1 month, and 3 months
Participants will be classified according to pain response pattern after genicular nerve block: non-response, defined as less than 50% reduction in VAS pain score at 1 month; transient response, defined as at least 50% reduction at 1 month but less than 50% reduction at 3 months; and sustained response, defined as at least 50% reduction at both 1 and 3 months. The association between baseline STAR and responder pattern will be evaluated.
1 month, and 3 months
WOMAC Score
Time Frame: Baseline, 1 month, and 3 months
Change in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).
Baseline, 1 month, and 3 months
Five Times Sit-to-Stand Test
Time Frame: Baseline, 1 month, and 3 months
Change in functional performance assessed using the Five Times Sit-to-Stand (5xSTS) test.
Baseline, 1 month, and 3 months
Change in Pain Intensity
Time Frame: Baseline, 1 month, and 3 months
Change in Visual Analog Scale (VAS) pain score from baseline after ultrasound-guided genicular nerve block.
Baseline, 1 month, and 3 months

Collaborators and Investigators

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

Sponsor

Gaziosmanpasa Research and Education 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)

May 15, 2026

Primary Completion (Estimated)

September 1, 2026

Study Completion (Estimated)

November 1, 2026

Study Registration Dates

First Submitted

July 14, 2026

First Submitted That Met QC Criteria

July 14, 2026

First Posted (Actual)

July 17, 2026

Study Record Updates

Last Update Posted (Actual)

July 17, 2026

Last Update Submitted That Met QC Criteria

July 14, 2026

Last Verified

July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • MEDIPOL-EC-845-2026

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

The investigators have not yet made a final decision regarding individual participant data (IPD) sharing. Data sharing will be considered after study completion in accordance with institutional policies, ethical requirements, and applicable data protection regulations.

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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