2nd MTP instability and synovitis is the weakness and inflammation of the joint capsule of the 2nd metatarsophalangeal joint, which is located at the base of the toe where the long foot bone (metatarsal) meets the toe (phalanx).
Its cause may be genetics or any of a number of pre-existing conditions, including hallux valgus (a bunion), a long second metatarsal bone, and sometimes injury to the ligaments, such as a small tear to the plantar (underside) capsule of the 2nd joint.
Symptoms of this condition include pain and swelling at the base of the toe or under the 2nd toe near the ball of the foot, that worsens with activity or weight bearing, Deviation or curling up of the 2nd toe, either toward or away from the big toe, can also occur. Left untreated, it can lead to formation of a hammer or claw toe, where the toe will curl up and not straighten or lie flat. In severe cases the 2nd toe will cross over the big toe.
Diagnosis of 2nd MTP instability and synovitis is made through the evaluation of a patient’s symptoms and examination of the affected area. X-rays may show the deformity, meaning the deviation of the toe either up/down or left/right. The x-ray may also give clues as to the cause, such as hallux valgus (a bunion), a congenitally long 2nd metatarsal, or a very high arch (cavus foot). If the cause of the pain remains unclear, an MRI can be helpful for a definitive diagnosis as well as to rule out other causes of pain, such as a pinched nerve in the foot (neuroma) or a stress fracture. The MRI will often show mild changes, including increased fluid and ligament tears in and around the 2nd metatarsophalangeal joint.
Often, the pain and swelling will subside with time using conservative treatments, such as
• Activity modification – avoiding strenuous high impact sports or very tight shoes
• Taping the toe down or two the adjacent toe. Small straps and braces available online can mimic the taping.
• Certain orthotics or shoe inserts can help take the pressure off the painful area.
• Over the counter medicines such as ibuprofen (Advil/Motrin) or naproxen (Alleve) can help control symptoms by reducing inflammation throughout the body and blocking pain, however, they will not correct the condition.
• Injections can be helpful in controlling symptoms and pinpointing the source of pain. However, they are not a long term solution as repeated use can weaken the ligaments.
Surgery to correct the problem is recommended if conservative treatment fails to relieve pain to a satisfactory level. A surgical procedure would typically involve a combination of corrections depending on the structure and shape of the foot, such as ligament repair, shortening or lengthening the toe bones, shortening the metatarsal bone, and correction of other problems such as a bunion, toe straightening or a neuroma.