Textural Analysis and Effect of ROI Size on Infrared Thermography in Athletes With Patellar Tendinopathy

NCT07095738 | Completed

• 1 other identifier: CE111803
• Study Type: observational
• Target: 54
• Locations: 1 country
• Sites: 1

Brief Summary

Patellar tendinopathy (PT) is a common knee disorder, particularly among elite athletes, with a reported prevalence of approximately 14.2%. Athletes affected by PT may experience persistent pain, functional impairment, reduced quality of life, decreased physical performance, and even premature career termination. Diagnosing PT remains challenging due to the absence of a gold standard diagnostic method. Although imaging techniques such as ultrasonography (US) and magnetic resonance imaging (MRI) can aid in confirming the diagnosis and assessing severity, MRI is costly and less accessible, and US shows poor correlation with clinical symptoms. Consequently, diagnosis largely relies on clinical examination and medical history. Infrared thermography (IT) has emerged as a potential alternative imaging technique, offering a low-cost, reliable, and non-invasive method to detect thermal asymmetries indicative of underlying pathologies. Technological advancements have enhanced the precision of IT, reducing the thermal asymmetry threshold from 2-3 ºC in the 1970s to 0.5 ºC in current knee assessments. First-order statistics, such as mean gray intensity, and second-order features based on the gray-level co-occurrence matrix (GLCM), have been extensively used in medical image analysis, including IT, to quantify structural and textural characteristics. The size of the region of interest (ROI) is also a critical factor in thermal and texture analyses, as it can influence sensitivity and diagnostic accuracy. Given these considerations, the objectives of this study were: (1) to evaluate differences in thermal and GLCM-based textural features between athletes with PT and healthy controls; (2) to compare the diagnostic performance of IT and GLCM features applied to thermographic images; and (3) to identify the most appropriate ROI size for optimal characterization of PT using both thermal and textural analysis.

Conditions

Patellar Tendinopathy; Diagnostic Accuracy; Infrared Thermography

Outcome Measures

Primary Outcomes (6)

• Textural analysis based on the Gray-Level Co-occurrence Matrix (GLCM)

  GLCM relies on the angular relationship between neighboring pixels and the distance between them. relies on the angular relationship between neighboring pixels and the distance between them.

  baseline

• Energy or angular second moment (ASM)

  ASM Measures the uniformity or regularity in the distribution of image values. Higher values indicate greater uniformity in the image.

  baseline

• Homogeneity or inverse difference moment (IDM)

  IDM reflects the homogeneity of image composition, associated with pixel pairs. Homogeneous images with minimal variations produce high IDM values

  baseline

• Contrast (CON)

  CON represents the degree of local variations in gray levels within the image.If the variation increases, the contrast increases.

  baseline

• Textural correlation (TCOR)

  TCOR expresses linear dependencies between gray levels in the image. Regions with similar gray levels tend to exhibit higher values.

  baseline

• Entropy (ENT)

  Indicates the level of disorder within the image. Homogeneous images result in lower entropy values

  baseline

Secondary Outcomes (4)

• Age (years)

  baseline

• Sex

  baseline

• Body Mass index (BMI)

  baseline

• time of evolution (months)

  baseline

Study Arms (2)

athletes with unilateral PT

diagnosed through a combination of clinical criteria, specific functional tests, and ultrasound evaluation. Additional inclusion criteria for this group include a symptom evolution time of more than 3 months, a VISA-P score of less than 80, and the performance of a differential diagnosis to rule out other potential causes of anterior knee pain

Diagnostic Test: thermal images (IT)

healthy volunteer athletes

recruited under the inclusion criteria of no previous history of PT and a VISA-P score of 100

Diagnostic Test: thermal images (IT)

Interventions

thermal images (IT) DIAGNOSTIC_TEST

The IT images were recorded with an OPTRIS PI 450 IRT camera coupled to Optris PI Connect Software (Germany). The IRT camera has a Noise Equivalent Temperature Difference \<40 mK with 38º x 29º FOV, a wide range of temperature from -20°C to +100°C, spectrum range of 7.5-13 μm, focal plane array sensor size of 382 × 288 pixels, emissivity set at 0.98 and a measurement uncertainty of ± 2% of the overall temperature reading. The size of the capture frame will be 55.4 × 40.63 cm (1.5 mm/px).

athletes with unilateral PT; healthy volunteer athletes

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Probability Sample

Study Population

All participants will be instructed not to engage in physical exercise; not to drink alcohol, coffee, or energy drinks 12 hours prior to measurements; not to smoke in the 6 hours prior to measurements; not to apply creams or lotions to their legs to avoid altering skin emissivity; to report any medication or treatments they were taking; and to try to avoid altering their rest and meal habits. These requirements minimise the influence of individual extrinsic factors on the IT results.

You may qualify if:

• Specific functional tests.
• Ultrasound evaluation.
• Symptom evolution time of more than 3 months.
• A VISA-P score of less than 80.
• The performance of a differential diagnosis to rule out other potential causes of anterior knee pain.

You may not qualify if:

• Lower limb pathology.
• Nerve or vascular disorder, or skin lesion in the knee area that could alter thermal information in the patellar tendon region.

Sponsors & Collaborators

• Cardenal Herrera University: lead

Study Sites (1)

Ceu Cardenal Herrera University

Elche, Alicante, 03204, Spain

Location

Related Links

• Group investigation

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: CROSS SECTIONAL
• Target Duration: 1 Day
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Clinical Professor

Study Record Dates

• First Submitted: July 23, 2025
• First Posted: July 31, 2025
• Study Start: August 1, 2025
• Primary Completion: August 20, 2025
• Study Completion: September 19, 2025
• Last Updated: September 24, 2025

Record last verified: 2025-09

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF
• Time Frame: baseline

Locations

ES (1)