One of the most common causes of big toe joint pain and discomfort is known as hallux limitus (hallux meaning big toe & limitus meaning limited movement)
The big toe joint also is known as the 1st Metatarso-phalangeal joint (1st MTP joint) is made up from the long 1st metatarsal bone and the proximal phalanx of the big toe (hallux). Underneath the big toe joint, there are 2 small oval bones known as the sesamoids. (see here for a link to injury to the sesamoids)
The pain experienced is from a lack of movement from the joint, or a forced movement or mechanical jamming of the joint.
As the condition progresses, degeneration within the joint is seen with an increase of bony growth on the top of the joint known as an osteophyte. In combination with this, the big toe often starts to turn upwards to help the big toe joint at the pushing off phase.
Symptoms can include joint stiffness, pain when walking, completing exercise and wearing heeled or un-supportive shoes. The joint may change shape as it progresses with enlargement on the top of the joint.
Treatment is to reduce the stress and load going through the joint.