Pressure distribution in Morton's foot structure.

The Morton foot structure (MFS) is a foot having, as its most prominent distinguishing feature, a second metatarsal head which is more distally placed than the head of the first. This structure has been associated with a variety of foot problems in athletes. The origin of these foot problems has been hypothesized to be an abnormal metatarsal head loading pattern found in the MFS. This study was conducted to determine whether the MFS produced a metatarsal head pressure profile which was different from the non-Morton foot. Plantar pressure distributions during walking were collected using a 1000 element piezoceramic pressure platform from the feet of 45 subjects (30 classified as having the MFS and 15 non-Morton or control subjects). The protrusion of the head of the second metatarsal beyond the first metatarsal head was determined by palpation and varied between 0.8 and 2.8 cm for the experimental group. Pressure distributions were collected from a mid-gait step onto the platform at a speed of 1.6 to 2 m.s-1 using a 15 m runway. Peak pressures and impulse values were determined for three forefoot regions. Results show that peak loading in both groups occurred under the second metatarsal but that the magnitudes of second metatarsal peak pressures were significantly higher in the MFS group (P less than 0.005). The results suggest that, although the loading pattern between MFS and normal feet is similar, the significantly higher second metatarsal head peak pressure in the MFS may predispose this foot type to problems associated with excessive localized pressure.