Common causes of pain in the forefoot in adults.

Abstract

A complaint of pain in the forefoot may be a potential source of frustration to the orthopaedic surgeon but the evaluation needed to give a definitive diagnosis is usually straightforward and the treatment uncomplicated. The forefoot includes the digits and extends as far proximal as the middle of the shafts of the metatarsals. The term metatarsalgia is often used to describe pain in the distal forefoot, but does not define a specific diagnosis or indicate a particular mode of treatment. Pain in the forefoot must be carefully analysed to establish a correct diagnosis. It is necessary to assist the patient in determining the exact location of the pain. This may not be easy since the initial complaint may be of a large area of ill-defined pain. With time, however, it is usually possible to isolate this to a small discrete site. Other pertinent information includes the presence of a deformity, inflammation of the soft tissue, pain on palpation of a specific region, and/or associated neuritic symptoms. Radiological studies are helpful in determining the presence and magnitude of deformities, although physical examination may be sufficient in the evaluation of many lesser abnormalities of the toes. Radiographs are most helpful in assessing the presence of intra-articular problems such as degenerative arthritis, Freiberg’s infraction, stress fracture of the metatarsal and inflammatory arthritis, but there is no substitute for an adequate physical examination. Radionucleide scanning, MRI and CT may be of value in establishing a diagnosis in the case of pain not associated with clinical or radiological deformity. Laboratory evaluation including a full blood count and measurement of the ESR, the level of uric acid and rheumatoid factor is occasionally helpful in the diagnosis of a patient with recalcitrant pain in the forefoot in whom inflammatory arthritis is suspected. Observation of the presence or absence of a callus associated with well-localised pain in the forefoot is the first step in the diagnostic evaluation (Fig. 1). A dorsal callus overlying a plantar flexed distal interphalangeal joint (DIP) occurs in a mallet-toe deformity and a similar callus overlying a plantar flexed proximal interphalangeal joint (PIP) in a hammer toe. With a claw toe, hyperextension of the metatarsophalangeal joint (MTP) and flexion of the PIP joint may be associated with a callosity beneath the involved head of the metatarsal, overlying the PIP joint, and even at the tip of the toe (Fig. 2). A callus localised to the lateral aspect of the fifth toe may indicate a hard corn while that in the webspace between the lesser toes occurs with a soft corn. A callus overlying the lateral aspect of the head of the fifth metatarsal is associated with a bunionette. With an intractable plantar keratosis (IPK) a callus develops beneath the head of a lesser metatarsal. The complaint of pain in the forefoot in the absence of a callus should alert the physician to other abnormalities of the soft tissue or joint. The presence of neuritic symptoms in the digits may indicate an interdigital neuroma. In the absence of such symptoms, capsulitis or instability of a lesser MTP joint should be considered. Palpation of the painful areas can differentiate many of these diagnoses. A positive drawer sign (Fig. 3) in a lesser MTP joint and/or malalignment of the symptomatic toe (Fig. 4) may help in the diagnosis of capsulitis, synovitis or instability of the joint. Often symptoms may be vague and ill-defined, necessitating repeated physical and radiological evaluation to establish a correct diagnosis. Problems in the first ray such as hallux valgus, hallux rigidus, and sesamoiditis are beyond the scope of this discussion, but have been thoroughly discussed in other