The big toe joint is an important joint for normal biomechanics and running or walking. While we are walking or running and the foot is flat on the ground, that big toe joint really should flex while the rearfoot come up off the ground. If this hallux joint is not going to flex then to be able to walk is going to be a lot more challenging. Much more energy is required so walking or running gets very fatiguing. As the motion this is not able to occur with the big toe or hallux joint still is required to occur, other joints could be forced to move more at a time that they are not supposed to be moving. This unnatural movement could become a problem.
There are actually a range of issues that could go wrong with this great toe joint and impact this normal movement. Among the more common ones is a disorder that usually will get called hallux rigidus and as its name signifies, the hallux joint is rigid and does not bend. The most common cause for hallux rigidus is osteoarthritis in that big toe joint. This could be fairly painful and the stiff hallux joint can make running or walking very difficult. The commonest therapy for hallux rigidus are drug treatments to decrease your pain, rocker sole shoes to allow for some motion to happen and surgical procedures about the big toe joint.
A less severe form of hallux rigidus can be a condition called hallux limitus in which the hallux joint is not inflexible but has a decreased range of flexion. Since a full range of motion is necessary at the big toe joint for normal gait, this restricted movement is still a problem. The most common cause for this condition is also osteoarthritis. Usually the treatments for hallux limitus is pain relief with medication, from time to time strapping can be used to limit movement even more so that it's not too painful. Foot orthoses will often be used to encourage a more normal motion of the big toe joint. In the most painful situations surgical treatment could be an option in which a joint replacements is often done or the big toe joint is surgically fused to prevent it moving.
Another very common problem is called a functional hallux limitus. This is what's called functional as on a non-weightbearing evaluation the hallux joint has a normal range of motion, however when functioning with the foot on the ground it just doesn't have the full range of flexion. The actual cause of a functional hallux limitus is simply not known and the rationale why that big toe or hallux joint doesn't work only when weightbearing isn't apparent. The limitation just seems to happens in some individuals. A variety of hypotheses have already been proposed, many of which seem plausible but there is hardly any direct data for one theory over the other.
There are a number of treatments for a functional hallux limitus that are directed at restoring normal biomechanics to the great toe joint. Foot doctors typically use foot supports with assorted adjustments for instance a first metatarsal cut out, the Kinetic Wedge or a Cluffy Wedge. Every one of these designs try to improve the flexion at the big toe or hallux joint to make the joint move more efficiently and stop the functional hallux limitus from occurring.