In each foot, five metatarsal bones run from your arch to your toe joints. The first metatarsal is shorter and thicker than the other four bones, which are usually similar in size. During the push-off phase when you walk, jump or run, your body weight is transferred to your toes and metatarsals. The first and second metatarsal bones take the brunt of this force.

Most metatarsal problems develop when something changes in the way your foot normally works (mechanics), affecting how your weight is distributed. This can put excess pressure on the metatarsals, leading to inflammation and pain, especially in the metatarsal heads — the rounded ends of the bones that connect with your toe bones.

Sometimes a single factor can lead to metatarsalgia. More often, several factors are involved, including:

  • Intense training or activity. Runners are at risk of metatarsalgia, primarily because the front of your foot absorbs significant force when you run. But anyone who participates in a high-impact sport is also at risk, especially if your shoes are ill-fitting or are worn out.
  • Certain foot shapes. A high arch can put extra pressure on the metatarsals. So can having a second toe that's longer than the big toe, which causes more weight than normal to be shifted to the second metatarsal head.
  • Hammertoe. This foot problem can develop when high heels or too-small shoes prevent your toes from lying flat. As a result, one of your toes — usually the second — curls downward because of a bend in the middle toe joint. This contraction depresses the metatarsal heads.
  • Bunion. This is a swollen, painful bump at the base of your big toe. Sometimes the tendency to develop bunions is inherited, but the problem can also result from wearing high heels or too-small shoes. Bunions are much more common in women than in men. A bunion can weaken your big toe, putting extra stress on the ball of your foot. Surgery to correct a bunion can also lead to metatarsalgia if you don't rest long enough for your foot to heal completely.
  • Excess weight. Because most of your body weight transfers to your forefoot when you move, extra pounds mean more pressure on your metatarsals. Losing weight may reduce or eliminate symptoms of metatarsalgia.
  • Poorly fitting shoes. High heels, which transfer extra weight to the front of your foot, are a common cause of metatarsalgia in women. Shoes with a narrow toe box or athletic shoes that lack support and padding also can contribute to metatarsal problems.
  • Stress fractures. Small breaks in the metatarsals or toe bones can be painful and change the way you put weight on your foot.
  • Morton's neuroma. This noncancerous growth of fibrous tissue around a nerve usually occurs between the third and fourth metatarsal heads. It causes symptoms that are similar to metatarsalgia and can also contribute to metatarsal stress. Morton's neuroma frequently results from wearing high heels or too-tight shoes that put pressure on your toes. It can also develop after high-impact activities such as jogging and aerobics.
Jan. 25, 2011