Definition

Metatarsalgia refers to pain in the forefoot at the plantar surface in the region of the distal second and third metatarsals. This pain usually results from disruption of the normal transverse arch created at the region of the metatarsal heads with support from the transmetatarsal ligaments. The etiology is thought be related to one or a combination of three categories: primary, secondary, and iatrogenic. Primary metatarsalgia may result from anatomic abnormalities altering forces through the forefoot. Congenital and degenerative conditions affecting the great toe, including hallux valgus (bunion), hallux rigidus (degenerative arthritis), and sagittal plane first-ray hypermobility lead to a transfer of load to the lateral forefoot and lesser metatarsal heads ( Fig. 90.1 ). A hammertoe with an associated dorsal contracture of a metatarsophalangeal (MTP) joint will cause a retrograde plantar flexion force on the metatarsal head ( Fig. 90.2 ). Apart from the foot, conditions including ankle equinus, leg length discrepancy, scoliosis, and kyphosis may also result in increased forefoot pressures.

Cross-sectional view of metatarsal heads. Elevated first metatarsal head results in mechanical overload of lesser metatarsal heads.

Hammertoe with associated plantar plate tear. The hammertoe causes a retrograde plantar flexion force on the metatarsal head.

Secondary metatarsalgia results from abnormal forces applied to the metatarsal region through indirect mechanisms. MTP joint synovitis occurs in conditions including rheumatoid arthritis, psoriatic arthritis, reactive arthritis, and systemic lupus erythematosus. The inflammation leads to weakening or rupture of the stabilizing structures around the joint, leading to dorsal subluxation of the toes on the lesser metatarsal heads. Degenerative arthritis of the lesser MTP joint may be caused by Freiberg infraction (metatarsal head avascular necrosis).

As the number of forefoot surgeries has increased, so too has the incidence of iatrogenic metatarsalgia. First metatarsal osteotomy, used in correction of hallux valgus, may result in excessive shortening or elevation of the first metatarsal, which then overloads the adjacent rays.

Symptoms

Plantar forefoot pain is generally aggravated by weight bearing and is worse during the propulsive portion of the stance phase of gait (between heel lift and toe off). The sensation is often compared to stepping on a stone. There is usually insidious onset rather than a clearly identifiable inciting event. Lesser MTP joint morning stiffness may be present. Neuritic radiating pain may occur from irritation, inflammation, or tethering of neighboring plantar intermetatarsal nerves or may suggest another condition such as Morton neuroma. Poorly defined pain in the forefoot is a common early symptom in patients with rheumatoid arthritis. Other symptoms include MTP joint symmetric swelling and stiffness after rest.

Physical Examination

Examination identifies structural abnormalities that may predispose to metatarsalgia and provocative testing can either confirm or direct toward alternative diagnoses. On general inspection while weight bearing, note the presence of forefoot deformities including hallux valgus, hammertoes, medial or lateral subluxation of the toes, or MTP joint dorsal contractures. Pes planus alters the transmission of force through the foot and can predispose to metatarsalgia. Callus formation in the region of forefoot may indicate excessive loading in that region. The forefoot examination attempts to elicit pain on palpation directly beneath the metatarsal heads or MTP joints. Evaluate the excursion and pain of MTP joint passive range of motion and note the presence of swelling. Assess for first metatarsal hypermobility by applying a dorsiflexion force under the first metatarsal head. If hypermobility is present, the first metatarsal head will rise well above the second metatarsal head. Isolated gastrocnemius contracture, as confirmed by comparison of ankle dorsiflexion between the knee flexed and extended (Silfverskiӧld test), is associated with excessive pressure through the forefoot. Pain on palpation elicited with lateral compression of neighboring metatarsal heads that is accompanied by an audible click suggests a plantar intermetatarsal neuroma (Mulder sign). Stress fractures are commonly identified at the metatarsal neck, demonstrated by swelling, palpable pain, or bone fixation callus. Examine for dorsal translation of the proximal phalangeal base on the metatarsal head (drawer test) to identify plantar plate or capsule disruption. The “paper pull-out test” to evaluate toe purchase is performed by asking the patient to flex the toe against a piece of paper placed on the floor under the toe. The test result is positive if the paper cannot be pulled out from under the toe. If there is a V-shaped alignment of adjacent toes noted while the patient is standing, indicative of web space widening, early synovitis, plantar intermetatarsal neuroma, or other space-occupying mass may be present. Weight-bearing bilateral or unilateral heel raise while standing barefoot often aggravates metatarsalgia pain. During gait examination, observe for early heel-off, antalgic gait, excessive or insufficient subtalar joint pronation, asymmetry, and lack of toe purchase. Examine the shoe outsoles and insoles for signs of excessive or uneven wear indicative of areas of elevated pressure or abnormal foot mechanics.

Functional Limitations

Forefoot pain may limit standing, walking, and participation in high-impact activities, such as running or jumping. There will be a limitation to shoe style able to be worn comfortably. Metatarsalgia has its greatest impact on activities requiring prolonged standing or walking on hard floors (e.g., cashier, food preparation, or housekeeping jobs). Sales jobs requiring use of a dress shoe may be difficult. Walking speed may decrease while shopping or accessing public transportation. Recreational activities, such as walking, tennis, basketball, or running on a treadmill on an incline, may be particularly painful.