An observational study in Trapeziometacarpal Osteoarthritis, sponsored by University of Malaga. Not yet recruiting at 1 site in Spain. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-08.
Sponsored by University of Malaga · Observational
The aim of this study is to investigate whether there are differences in muscle activation of the first dorsal interosseous (FDI) and the abductor pollicis longus (APL) between individuals with and without thumb trapeziopometacarpal joint osteoarthritis (OA TMC) during the performance of activities of daily living (ADL).
The FDI muscle has been identified as a key stabilizer of the thumb TMC joint. However, scientific literature lacks information regarding the activation of the FDI and the APL during ADL, particularly in comparison with healthy individuals. OA TMC can lead to pain, reduced thumb strength, impaired hand function, and difficulty performing ADL. Determining whether differences in muscle activation patterns exist between individuals with and without OA TMC is crucial for understanding how this condition affects hand function and for guiding more specific and effective rehabilitation strategies.
Participants will perform six standardized functional tasks simulating everyday activities: turning a key to open, turning a key to close, picking up a coin, writing, squeezing a tube of toothpaste, and holding a glass of water. Muscle activity will be recorded using surface electromyography (sEMG) during all tasks.
Adults aged 30 years and older, both men and women, with thumb CMC osteoarthritis and healthy controls without osteoarthritis will be invited to participate.
Researchers will measure the activation patterns of the FDI and APL muscles during the ADL, with the aim of identifying differences between both groups and providing evidence to guide the rehabilitation of patients with thumb base osteoarthritis.
Trapeziometacarpal osteoarthritis (OA TMC) of the thumb is a chronic and progressive degenerative disease characterized by loss of articular cartilage, subchondral sclerosis, capsuloligamentous laxity, and osteophyte formation in the first metacarpal. Patients typically present with pain and muscle weakness, which impair hand function and limit activities of daily living (ADLs), resulting in a considerable personal and social burden, including reduced quality of life and work disability. Previous studies have highlighted the clinical importance of thumb TMC joint stabilizers. Research has demonstrated that the first dorsal interosseous (FDI) functions as the main stabilizer of the TMC joint, whereas the abductor pollicis longus (APL) acts as a primary destabilizer. However, despite the clinical importance of these muscles, the literature reports limited information on how the FDI and APL behave during activities of daily living, particularly in comparison with healthy individuals.
The aim of this study is to investigate whether there are differences in muscle activation of the FDI and APL between individuals with and without thumb OA TMC during the performance of activities of daily living. Understanding whether muscle activation patterns differ between groups during functional tasks is essential to comprehend how this condition affects hand function and to guide more specific and effective rehabilitation strategies.
This is a cross-sectional observational comparative study with a between-group analysis. The study includes two groups: adults aged 40 years and older, both men and women, with a clinical diagnosis of OA TMC and healthy controls without musculoskeletal or neurological disorders affecting the hand. Exclusion criteria include sensory disturbances such as numbness or tingling, cardiac pacemaker implantation, upper limb entrapment neuropathies or cervical radiculopathy, neuromuscular diseases, systemic conditions including diabetes or hypothyroidism, history of cancer, rheumatoid arthritis, anticoagulation therapy, chemotherapy, exposure to neurotoxins, or recent upper limb trauma or surgery.
Surface electromyography (sEMG) is used to record muscle activity of the FDI and APL. Skin is prepared by shaving if necessary and cleaning with alcohol to reduce impedance and ensure optimal adherence of surface electrodes. Bipolar surface electrodes with a diameter of 20 millimeters and an inter-electrode distance of 20 millimeters are placed according to SENIAM guidelines. For the FDI, electrodes are positioned over the dorsal belly of the muscle aligned with fiber direction, with one electrode in the distal ulnar region between the first and second metacarpals. For the APL, electrodes are placed approximately five centimeters distal to the wrist, medial to the radius, longitudinally aligned and transversely away from adjacent muscles. Electrode placement is verified by palpation and selective activation tasks.
Participants perform six standardized functional tasks simulating ADLs commonly affected in OA TMC of the thumb: turning a key toward the ulnar side, turning a key toward the radial side, picking up a coin, writing a word with a pen, squeezing a full tube of toothpaste, and holding a glass of water while performing a drinking gesture. Each task is performed in three consecutive three-second isometric repetitions with a thirty-second rest between repetitions to minimize fatigue.
It is hypothesized that individuals with thumb TMC osteoarthritis will demonstrate altered activation patterns of the FDI and APL compared with healthy controls during the performance of activities of daily living, providing evidence to guide the rehabilitation of patients with thumb base osteoarthritis.
University of Malaga is the lead sponsor of 119 studies on the registry; 34 are open to participants now.
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The study population will include adults aged 18 years and older, both men and women, divided into two groups. The first group will consist of individuals with a clinical diagnosis of thumb trapeziometacarpal osteoarthritis, and the second group will consist of healthy controls without musculoskeletal or neurological disorders affecting the hand.
Exclusion Criteria :
Adults aged 18 years and older with a clinical diagnosis of thumb trapeziometacarpal (TMC) osteoarthritis. Participants will perform six standardized functional tasks simulating activities of daily living while surface electromyography (sEMG) of the first dorsal interosseous (FDI) and abductor pollicis longus (APL) muscles is recorded. No pharmacological or physical intervention is administered; this is an observational measurement of muscle activation during functional tasks.
Adults aged 18 years and older without musculoskeletal or neurological disorders affecting the hand, and without thumb TMC osteoarthritis. Participants will perform the same six standardized functional tasks simulating activities of daily living while surface electromyography (sEMG) of the FDI and APL muscles is recorded, to serve as a comparison group.
Surface electromyographic amplitude of the First Dorsal Interosseous muscle.
Mean surface electromyographic amplitude of the First Dorsal Interosseous muscle recorded during each of the 6 activities of daily living
Time frame: Day 1
Surface electromyographic amplitude of the Abductor Pollicis Longus muscle
Mean surface electromyographic amplitude of the Abductor Pollicis Longus muscle recorded during each of the 6 activities of daily living.
Time frame: Day 1
Plan to share: Undecided
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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University of Malaga