Pain and or stiffness in the midfoot
Across the middle of the foot is a complex arrangement of multiple joints and the attachment joint of several strong tendons. There are therefore many possible reasons why the middle of the foot might become painful or stiff, each diagnosis having its characteristic features to make the diagnostic process frequently difficult. Gradual onset of pain, perhaps with a sinking down of the foot's arch is a common picture of osteo-arthritis in this location. Most of these midfoot joints do not move very much naturally but rather provide the foot with a shock absorbing springiness. The small bones act like the wedge shaped stones in the arch of a bridge and as the cartilage (the mortar between the stones) thins out the bones come together and the arch sinks.
Fairly sudden onset of pain across the top of the midfoot, perhaps the day after a session of unaccustomed walking, can be the result of a stress fracture through one of the bones. Extra activity can also cause inflammation of one or more of the tendons in the vicinity (tendonitis).
When this process occurs with wear and tear changes to one of the major tendons on the inside edge of the foot (posterior tibial tendon) the effect can again be one of a sinking arch, perhaps further reduction in the height of an arch - when it was already not very good to start with. The pain with this condition tends to be towards the ankle side of the midfoot. This tendon attaches to a midfoot bone called the navicular.
Some people have an extra bone just where the tendon attaches (accessory navicular) and this itself can become painful at the inside edge of the midfoot. It is important to remember that pains in the foot can be caused by irritation of nerves in the spine, perhaps due to a slipped disc. Such sciatica pains can be felt on the top or outside edge of the midfoot. Indeed, sometimes the pain in the back can be minimal or even absent.