Risk Factors for Carpometacarpal (CMC) Arthritis
Female sex is the most significant demographic risk factor for thumb CMC arthritis, with postmenopausal women showing dramatically higher prevalence (40% in women over 75 years versus 25% in men), representing a relative risk of 1.23 for hand osteoarthritis. 1, 2, 3
Demographic and Constitutional Risk Factors
Age over 40 years is a major risk factor with a likelihood ratio of 3.73, as CMC arthritis rarely develops before age 40 but incidence increases dramatically after this threshold 1
Menopausal status appears influential, evidenced by the gender difference that becomes pronounced after age 40, though hormone replacement therapy has not shown protective effects 1
Family history is an established risk factor for hand osteoarthritis including CMC joint involvement 1
Obesity increases the risk of developing hand osteoarthritis, including the CMC joint 1
Biomechanical and Physical Risk Factors
Higher bone density is associated with increased risk of hand osteoarthritis 1
Greater forearm muscle strength has been identified as a risk factor, potentially through increased joint loading 1
Joint laxity and hypermobility contribute to CMC arthritis development, with hypermobility specifically reported as a risk factor for thumb base osteoarthritis 1, 4
Prior hand injury significantly increases the risk of developing CMC osteoarthritis 1
Altered metacarpophalangeal (MCP) joint motion may serve as a gateway to CMC arthritis, with females demonstrating 31% more MCP motion than males, potentially altering loading paths through the CMC joint and increasing osteoarthritis risk 5
Occupational and Activity-Related Risk Factors
Repetitive occupational hand tasks such as cotton picking increase risk in a dose-dependent manner, with differential joint distribution depending on specific repetitive task patterns 1
Occupational activities requiring repetitive finger movements can contribute to CMC arthritis development, particularly when involving specific joint loading patterns 1
Heavy work activities including farming and construction work that require frequent kneeling, heavy lifting, or repetitive joint use are associated with osteoarthritis development 6
Clinical Implications
The thumb CMC joint obtains its stability primarily through ligamentous support, making it vulnerable when risk factors compromise this stability 2. The combination of female sex, age over 40, and joint laxity creates a particularly high-risk profile for developing symptomatic CMC arthritis 1, 4, 2. Patients with polyarticular hand osteoarthritis affecting the CMC joint are at increased risk for generalized osteoarthritis at other sites including knee and hip 7.