Metatarsalgia is characterized by pain in the forefoot. The term literally means “pain on the metatarsal” (there are 5 metatarsal bones in the forefoot). Metatarsalgia is not a true diagnosis, but rather it is a symptom. Patients with metatarsalgia present with pain in their forefoot, usually in the ball of the foot (Figure 1). The pain is often described as aching, and it is typically aggravated by standing and walking. In general, metatarsalgia is caused by repetitive overloading of the forefoot, leading to chronic localized tissue injury. Often the most symptomatic area is at the base of the 2nd or 3rd toe. Factors that may predispose to the development of metatarsalgia include: a bunion deformity, arthritis of the great toe, ligament instability of the midfoot, an excessively tight calf muscle, a congenital foot deformity, and claw toe deformities.
The pain that is experienced in metatarsalagia typically occurs in the forefoot, at the base of the second or third toes (under the second or third metatarsal head). It often feels like walking “on stones or pebbles” or on “a rolled up sock” at the base of the involved toes. The pain is often described as aching, and it is aggravated by standing and walking, particularly on hard surfaces. There may also be a burning sensation extending into the tips of the toes.
As the condition progresses, it may be associated with increased clawing of the toes. This can cause the fatty tissue that provides shock absorption to the forefoot to no longer be located under the weight-bearing bones of the forefoot (distal migration of the plantar fat pad leaving the metatarsal heads and the metatarso-phalangeal joints (MTP) joints without the padding or “uncovered”). This results in less protection for the metatarsal heads; less shock absorption as they bear weight, callus formation, and worsening of the symptoms.
Unfortunately for some patients, the cause of metatarsalagia is hidden by the secondary clawtoe deformity that develops and worsens the symptoms. If an ink imprint of the weight bearing sole of the foot is obtained, such as with a Harris mat (a device that assesses how force is distributed throughout the foot), there is often an intense uptake in the area corresponding to the involved metatarsal head(s) (Figure 2). Continued, localized, repetitive loading to the involved area will predispose to chronic injury to the structures being loaded. The structures that are commonly injured include the MTP joint capsule, the plantar plate, and the metatarsal bone (head and/or neck). The irritation of the MTP joint is due to repetitive overload, and can lead to swelling of the joint itself. Patients are unable to bend the toes completely and show the ‘knuckles’ on the top. Often in early stages the toes start separating. This condition is called as MTP joint synovitis.
X-rays in patients with metatarsalgia often demonstrate a long second or third metatarsal, relative to the first and the fourth metatarsalgia. In rare instances, the MTP joint may actually be subluxed (partially out of joint) or even dislocated. Deformities of the 1st metatarsal, such as those present with a Bunion or with midfoot instability, may also be observed on x-ray.
Patients respond well to non-operative treatment. If the underlying cause can be addressed, non-operative treatment will be successful in the longterm. The principle of non-operative treatment is to off-load the involved area. This can be done with a combination of comfort shoes, metatarsal pads, soft accommodative orthotics, activity modifications, calf stretching, foot muscle strengthening, and NSAIDS (Non-steroidal anti-inflammatory drugs).
In a small percentage of patients, non-operative treatment will fail. In these patients, surgery may be helpful. There are a variety of procedures that have been proposed, either in isolation or in combination.
It is essential that the primary cause of the metatarsalgia be addressed. If a “clawtoe” is present, it may be necessary to address this deformity surgically. By successfully correcting the toe deformity, the shock-absorbing plantar fat pad can be reduced under the metatarsal heads. There are a variety of different ways to surgically correct a clawtoe deformity. The technique chosen will depend on the extent of the deformity, the stiffness of the toe, and the preference of the surgeon. If the joint at the base of the involved toe (MTP joint) is swollen and inflamed, it may be helpful to remove the inflamed synovial lining (synovectomy). This is often done in conjunction with other procedures. If the second and/or third metatarsal heads are long, it may be beneficial to perform a metatarsal shortening osteotomy, such as a Weil osteotomy. By shortening the metatarsal between 3 mm and 6 mm, the loading characteristics can be changed and the tendency to load one or more of the metatarsal heads can be altered. If a Bunion deformity is present, this deformity may need to be corrected in order to address the abnormal weight bearing of the forefoot. If a tight calf muscle is present and does not resolve with stretching, lengthening of the gastrocnemius muscle (Strayer procedure) may be beneficial.
The usual list of general post-surgical complications may occur with various procedures that are used to address metatarsalgia. This includes the potential for:
Surgery on the toes and forefoot is not as predictable or as easy as patients think. Specific complications depend on the procedure(s) that are performed but can include: