The ball of the foot is a term commonly given to the structure located at the end of the foot's metatarsal bones, where they form a joint with each toe. The technical term is: metatarsal heads.
The metatarsal heads play an important role in balance, weight distribution and locomotion. They also happen to be the point of considerable force with weight bearing, walking and running. Inflammation of the metatarsal heads can cause pain in the balls of the feet.
Bunions
In the case of bunions, other pathology is in play as well--not merely the presence of a bone spur on the side of the first metatarsal bone. One example is splaying of the foot. Splaying is the term given to the functional widening of the foot secondary to spreading that occurs between the metatarsal heads. As the widening progresses, it causes abnormal forces upon the great toe, causing it to develop an angular deformity. This deformity allows for increased exposure of the first metatarsal head to direct pressure from shoe wear as well as the ground itself. This chronic pressure causes inflammation of the metatarsal head, or ball of the foot.
Morton's Neuroma
Morton's Neuroma is a condition in which there's an enlargement of a nerve that passes between two metatarsal heads as it courses to the toes. The nerve becomes inflamed and swollen due to pressure from the adjacent metatarsal heads during weight bearing and can be quite painful.
Morton's Neuroma can occur between any two metatarsal heads but is more common between the second and third and third and fourth.
Hammer Toes
Hammer toes develop from an imbalance between the muscles that bend and straighten the toes. This condition typically occurs between the second through fourth toes. Causes include badly fitting shoe wear, heredity, neuromuscular diseases and are often seen in conjunction with bunions.
A common deformity associated with hammer toes is the cock-up deformity, in which the toe is pulled into a state of hyper-extension. The more the deformity worsens in the toes, the fat pad beneath the metatarsal heads is also pulled up, exposing the underlying bony heads to potential direct pressure injury.
Avascular Necrosis / Freiberg's Disease
Freiberg's Disease is more a condition than a disease entity. It occurs as a result of loss of blood supply to the second metatarsal head, typically caused by increased pressure within the bone marrow of the metatarsal head. The most common cause is trauma by either a singular incident or chronic repetitive injury from weight bearing and bad footwear.
As blood supply dwindles, the bone begins to literally die; this can be quite painful as well. People with a Morton's foot (excessively long second metatarsal bone) are at increased risk because of increased pressure on the metatarsal head.
Metatarsalgia
Metatarsalgia refers to a relatively nondescript condition of painful metatarsal heads. Causes range from trauma to obesity. In some people, there is a loss of the protective fat pad that 's located at the bottom of the balls of the feet. It's caused by such things as obesity, diabetes and hammer toe formation, not to mention excessively high-heeled shoes.
