Forearm Muscle and Tendon Thickness in Rotator Cuff-Related Shoulder Pain

Ultrasonographic Assessment of Forearm Muscle and Tendon Thickness According to Symptom Duration in Individuals With Rotator Cuff-Related Shoulder Pain

Rotator cuff-related shoulder pain (RCRSP) is one of the most common musculoskeletal disorders affecting the shoulder and is frequently associated with pain, reduced muscle strength, and impaired upper extremity function. Although previous studies have primarily focused on structural and functional changes around the shoulder, little is known about the potential adaptations occurring in the distal upper extremity, particularly the forearm muscles and tendons.

Altered upper extremity use, pain-related muscle inhibition, and compensatory movement patterns associated with prolonged shoulder pain may lead to morphological changes in the forearm musculature and tendons. However, the relationship between symptom duration and these structural adaptations has not yet been investigated.

The aim of this cross-sectional study is to evaluate forearm muscle and tendon thickness using portable ultrasonography in individuals with RCRSP and to investigate whether these parameters differ according to symptom duration. In addition, hand grip strength, pain intensity, and upper extremity function will be assessed to explore their associations with ultrasonographic findings.

The findings of this study are expected to provide new insights into distal upper extremity adaptations associated with RCRSP and may contribute to the development of more comprehensive rehabilitation strategies that address not only the shoulder but also the forearm musculature.

Study Overview

• Status: Not yet recruiting
• Conditions: Rotator Cuff Syndrome

Detailed Description

Rotator cuff-related shoulder pain (RCRSP) is one of the leading causes of shoulder pain and disability in adults. In addition to local impairments such as pain, muscle weakness, and reduced range of motion, individuals with RCRSP frequently demonstrate altered upper extremity movement patterns and reduced functional performance. These adaptations may extend beyond the shoulder joint and influence distal segments of the upper extremity.

Previous research has primarily focused on structural changes in the rotator cuff muscles and tendons, scapular musculature, and shoulder biomechanics. However, the potential morphological adaptations of the forearm muscles and tendons remain largely unexplored. Persistent pain, reduced upper limb use, altered neuromuscular control, and compensatory motor strategies associated with prolonged shoulder symptoms may contribute to changes in forearm muscle and tendon morphology. Understanding these adaptations may improve the current understanding of the regional effects of RCRSP.

Musculoskeletal ultrasonography provides a valid, reliable, non-invasive, and accessible method for evaluating muscle and tendon morphology. The increasing availability of portable ultrasound devices has expanded the feasibility of assessing musculoskeletal structures in both clinical and research settings. Despite these advantages, ultrasonographic evaluation of forearm muscles and tendons has rarely been performed in individuals with RCRSP.

This cross-sectional study aims to investigate the association between symptom duration and forearm muscle and tendon thickness measured by portable ultrasonography in individuals with RCRSP. The study also seeks to explore whether structural changes in the forearm are accompanied by alterations in hand grip strength, pain intensity, and upper extremity function. The findings may contribute to a better understanding of distal musculoskeletal adaptations associated with prolonged shoulder pain and provide evidence for incorporating forearm assessment into rehabilitation programs for individuals with RCRSP.

• Study Type: Observational
• Enrollment (Estimated): 90

Contacts and Locations

• Study Contact: Name: Ömer ÖZÇELEP, PhD.; Phone Number: +905319463799; Email: omer.ozcelep@ahievran.edu.tr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

### Study Population Description

The study population will consist of adult individuals aged 18-65 years, including both patients with rotator cuff-related shoulder pain (RCRSP) and healthy control participants. Participants with RCRSP will be recruited based on clinical diagnosis confirmed by physical examination and positive clinical tests consistent with rotator cuff-related shoulder pain. Healthy controls will be recruited from the community and hospital staff and will have no history of shoulder pain or upper extremity musculoskeletal disorders.

Patients with RCRSP will be further categorized according to symptom duration into subgroups for comparative analysis. All participants will undergo a single assessment session including ultrasonographic evaluation of forearm muscle and tendon thickness, hand grip strength measurement, and standardized functional and pain assessments.

Participants will be recruited from outpatient physiotherapy and orthopedic clinics of the participatin

Description

Inclusion Criteria:

RCRSP Group Adults aged 18-65 years. Clinical diagnosis of rotator cuff-related shoulder pain (RCRSP). Unilateral shoulder pain lasting at least 6 weeks. Pain localized around the anterolateral shoulder, aggravated by arm elevation and/or overhead activities.

Positive findings on at least three clinical tests suggestive of RCRSP (e.g., painful arc, Hawkins-Kennedy test, Neer test, Jobe/Empty Can test, resisted external rotation).

Ability to understand the study procedures and provide written informed consent.

Healthy Control Group Adults aged 18-65 years. No current shoulder pain. No history of shoulder pain, shoulder surgery, or upper extremity musculoskeletal disorders during the previous 12 months.

Ability to provide written informed consent.

Exclusion Criteria:

Previous shoulder surgery on either upper extremity. History of shoulder fracture, shoulder dislocation, or major upper extremity trauma.

Full-thickness rotator cuff tear or other shoulder pathology requiring surgical management.

Clinical signs of adhesive capsulitis. Cervical radiculopathy or other neurological disorders affecting the upper extremity.

Systemic inflammatory, rheumatologic, or neuromuscular diseases. Peripheral nerve entrapment (e.g., carpal tunnel syndrome, cubital tunnel syndrome).

Previous surgery or significant injury involving the forearm, wrist, or hand. Corticosteroid injection into the affected shoulder within the previous 3 months.

Current pregnancy. Inability to complete study assessments or provide informed consent.

Study Plan

How is the study designed?

Number of groups / cohorts

3

Cohorts and Interventions

Group / Cohort
Healthy Controls; Healthy individuals without shoulder pain or a history of shoulder pathology, matched to the patient groups by age and sex where possible.
Short-Duration RCRSP; Participants diagnosed with rotator cuff-related shoulder pain with symptom duration of less than 6 months.
Long-Duration RCRSP; Participants diagnosed with rotator cuff-related shoulder pain with symptom duration of 6 months or longer.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Forearm Muscle and Tendon Thickness	Forearm muscle and tendon thickness will be measured using portable B-mode ultrasonography. Measurements will be obtained from standardized anatomical landmarks with participants in a standardized position. The thickness (mm) of selected forearm flexor and extensor muscles and tendons will be recorded and compared between healthy controls and participants with rotator cuff-related shoulder pain according to symptom duration.	Baseline (single assessment)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Hand Grip Strength	Maximum isometric hand grip strength will be assessed using a calibrated hand dynamometer. Three consecutive measurements will be obtained from the affected upper extremity with standardized positioning, and the highest value (kg) will be used for analysis.	Baseline (single assessment)
Upper Extremity Function	Upper extremity disability and symptoms will be evaluated using the Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) questionnaire. Scores range from 0 to 100, with higher scores indicating greater disability.	Baseline (single assessment)
Shoulder Pain Intensity	Shoulder pain intensity will be assessed using a 10-cm Visual Analog Scale (VAS), where 0 indicates no pain and 10 indicates the worst imaginable pain.	Baseline (single assessment)
Symptom Duration	Symptom duration will be recorded in months based on participant self-report and clinical history. Participants with rotator cuff-related shoulder pain will be categorized into groups according to symptom duration for comparative analyses.	Baseline
Shoulder Proprioception	Shoulder joint position sense (JPS) will be assessed using a laser pointer repositioning test. Repositioning error will be recorded in centimeters, with greater deviation indicating poorer proprioceptive accuracy.	Baseline

Collaborators and Investigators

• Sponsor: Kirsehir Ahi Evran Universitesi

Study record dates

Study Major Dates

• Study Start (Estimated): July 18, 2026
• Primary Completion (Estimated): December 18, 2026
• Study Completion (Estimated): December 19, 2026

Study Registration Dates

• First Submitted: June 17, 2026
• First Submitted That Met QC Criteria: June 17, 2026
• First Posted (Actual): June 23, 2026

Study Record Updates

• Last Update Posted (Actual): June 23, 2026
• Last Update Submitted That Met QC Criteria: June 17, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: KAEÜFTR-4

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

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