The most common reported cause of stiff fingers is joint and muscle strain. Activities that are strenuous on the fingers, such as weightlifting and golfing, can cause the fingers' ligaments to thicken, impeding movement. Numbness due to severe cold is another cause of stiff fingers. Finger stiffness can also be a symptom of rheumatoid arthritis, which causes inflammation in the joints. Carpal tunnel syndrome, a condition resulting from nerve damage, can cause joint stiffness in the hand. Other causes for stiffness in the fingers include allergic reactions and nutritional deficiencies.
High-impact hand activity can damage the ligaments connecting the tendons to the finger bones, which increases friction on the tendons. When the ligaments heal, they tend to thicken, stopping the tendons' movement altogether. This hinders the ability of the fingers' bones to move as the muscles contract, resulting in a degree of finger paralysis. This type of finger stiffness can be remedied with rest and proper hand positioning during the individual's activities.
Cold temperatures, on the other hand, can cause stiff fingers by numbing the hand's nerves. This is usually the cause for cases of finger stiffness in the morning; air temperatures tend to drop in the early hours of the day, especially in cooler climates. The cold air can also cause the muscles to contract, adding to the stiffness. In extreme cases, the stiffness can be an early indicator of frostbite, in which the body's fluids have begun to freeze. Barring any permanent nerve or muscle damage, a few minutes in warmer temperatures can remedy stiff fingers.
Finger stiffness can also be symptomatic of different medical conditions. Rheumatoid arthritis, for example, is a condition in which the body's immune systems mistakenly identify cells in the joints as harmful. Antibodies then attack the joints, which stimulates an inflammatory response. The inflammation of the joints can make movement either painful or difficult.
Carpal tunnel syndrome causes stiffness in the fingers through damage in the median nerve. Abnormal pressure on the nerve irritates the hand's tendons, which respond by swelling up and cutting off circulation to the median nerve. This can result in joint pain, stiffness, and weakness. Patients might also experience a tingling sensation in and at the tips of their fingers.
It is possible that finger stiffness is caused by the presence or absence of certain substances in an individual's system. A food allergy, for example, can cause a person's fingers to swell to the point that moving them is difficult. A lack of certain vitamins can also contribute to the development of stiff fingers; a vitamin B deficiency, for instance, can result in weakened nerves, which impedes finger movement.