The possible causes of big toe crooked inward include congenital developmental abnormality, acquired deformity, rheumatoid arthritis, metatarsophalangeal arthritis and so on. 1. Congenital developmental abnormality: due to genetic defects, resulting in congenital developmental abnormality, the phenomenon of big toe being crooked inward may occur. 2. Acquired deformity: It may be due to wearing high-heeled shoes, pointy shoes for a long time standing or walking for a long time, which causes external pressure on the big toe, resulting in acquired deformity, and the phenomenon of big toe crooked inward. 3. Rheumatoid arthritis: due to autoimmune and infectious factors, it involves the joint parts of the feet, causing deformation of the joints, which leads to the phenomenon of big toe being crooked inward. 4. Metatarsophalangeal arthritis: If there is a bursa on the inner side of the big toe, it may also lead to metatarsal bone osteophytes, hypertrophy and other conditions, which will lead to the phenomenon of big toe being crooked inward. There may also be other reasons for the big toe to be crooked, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.