Overview
This study looks at people who have osteoarthritis at the base of the thumb. It examines how well the thumb can sense its position and movement.
The study has three goals:
- To compare these measurements between people with thumb base osteoarthritis and healthy people.
- To find out whether this ability changes from milder to more advanced levels of osteoarthritis.
- To explore whether this ability is related to factors such as basic personal characteristics, thumb/hand muscle strength and hand use, pain and touch sensation, and emotional factors like fear of movement, anxiety, and depression.
This is an observational study. No treatment is given. Participants complete thumb measurements and several tests/questionnaires.
Description
This study aims to quantitatively evaluate thumb proprioception in individuals diagnosed with trapeziometacarpal (TMC) joint osteoarthritis (OA) and to compare the findings with healthy individuals. As a secondary aim, potential determinants that may influence proprioceptive function of the thumb joints will be examined systematically. In this context, relationships between thumb proprioception and participants' demographic characteristics (age, sex, body weight, occupational characteristics, and OA severity), motor functions (muscle strength of opponens pollicis, first dorsal interosseous, abductor pollicis brevis/longus, and flexor pollicis brevis/longus, as well as fine motor performance), sensory functions (pain, light touch/pressure sensation, and vibration sensation), and emotional status (fear of movement, anxiety, and depression) will be investigated. In addition, whether proprioceptive measures differ across radiographic severity levels will be evaluated within the TMC OA group.
The study is conducted using a cross-sectional case-control design. Individuals with TMC OA are compared with an healthy control group. In the TMC OA group, disease severity is classified based on radiographs according to the Eaton-Littler classification (Stages 1-4).
Thumb proprioception is assessed using two main outcomes: (1) joint position sense (JPS) error values for the TMC, metacarpophalangeal (MCP), and interphalangeal (IP) joints, and (2) pinch aperture proprioception error values. To evaluate the repeatability of pinch aperture proprioception measurement in individuals with TMC OA, an intra-rater test-retest approach is used; the same test is administered to 30 participants by the same assessor within one week.
Sample size is planned to support the primary hypothesis. For the primary group comparisons, at least 20 participants per group are targeted. To enable planned subgroup analyses by OA severity, the study aims to include 20 individuals for each Eaton-Littler stage (Stages 1-4) in the TMC OA group (total 80 individuals with TMC OA) and 20 healthy controls, resulting in a total target sample size of 100 participants.
Statistical analyses will be performed using SPSS for Windows version 22.0. Continuous variables will be reported as mean ± standard deviation or median (interquartile range), and categorical variables as frequency and percentage. Depending on data distribution, parametric or non-parametric methods will be used. Proprioceptive outcomes will be compared between the TMC OA group and the age-matched healthy control group using appropriate two-group comparison tests. Planned subgroup comparisons across radiographic severity levels (Eaton-Littler Stages 1-4) will be conducted within the TMC OA group. Associations between proprioceptive outcomes and demographic, motor, sensory, and emotional factors will be examined using correlation analyses and, where appropriate, multiple regression models. Statistical significance will be set at two-sided p \< 0.05, and effect sizes will be reported where applicable.
Ethics approval was obtained from the Hacettepe University Faculty of Physical Therapy and Rehabilitation Research Ethics Committee (Session date: 23 Oct 2025; Session number: 2025/22; Decision number: FTREK25/112; validity: 23 Oct 2025-23 Oct 2027). All participants received verbal and written information about the purpose and scope of the study, the assessments to be performed, potential discomfort, and their right to withdraw at any time without providing a reason; written informed consent was obtained prior to assessments. A safety approach was adopted such that measurements were discontinued if a participant reported discomfort during assessment. To ensure confidentiality, all participants were assigned a unique study code, and identifying information was stored separately from measurement data. Analyses were conducted using de-identified datasets. Data were stored in password-protected digital files, and any paper forms were kept in a locked cabinet with access restricted to the research team.
Eligibility
Inclusion Criteria (TMC OA group):
- Voluntary participation
- Radiographic Eaton-Littler stage I-IV confirmed by an orthopedic specialist
- Symptom duration ≥6 months
- Age 25-75 years
- Pain intensity ≥4/10 on the Visual Analog Scale (VAS) during daily activities at assessment
- Ability to actively perform ≥40° palmar abduction
- Adequate cognitive capacity to understand and perform study procedures (for participants aged ≥65 years: Montreal Cognitive Assessment \[MoCA\] score ≥21)
Inclusion Criteria (Control group):
- Voluntary participation
- No thumb pain
- Age 25-75 years
- No clinical signs of TMC OA
- Negative provocation tests
- Adequate cognitive capacity to understand and perform study procedures (for participants aged ≥65 years: MoCA score ≥21)
Exclusion Criteria (TMC OA group):
- Inability to abduct the thumb beyond 40° due to severe pain/deformity (especially advanced stage III-IV)
- Acute trauma or prior surgery of the hand/wrist
- Conservative treatment for hand/thumb pain in the same extremity within the previous 6 months
- Current use of anti-inflammatory medication
- Peripheral nerve disorders affecting proprioception (e.g., carpal tunnel syndrome, dorsal radial nerve irritation, cervical radiculopathy, double crush syndrome)
- Concomitant upper-extremity musculoskeletal disorders (e.g., trigger finger, De Quervain's disease)
- Generalized joint hypermobility (Beighton score ≥4)
- Neuromuscular, systemic peripheral neuropathic, autoimmune, rheumatic, or infectious diseases
- Active malignancy
- Neurological conditions affecting pain perception
- Visual impairment
- Pregnancy
Exclusion Criteria (Control group):
-Exclusion criteria identical to the TMC OA group
