[Biomechanics of the foot--forces in the forefoot during walking and their clinical relevance].
Pathologic conditions of the toe and metatarsophalangeal (MP) joints, such as the commonly encountered hallux valgus but also the relatively rare idiopathic necrosis of the metatarsal heads (Freiberg-Koehler's disease) and many other disorders of the foot, call for precise investigation of the kinematic and dynamic behavior of the foot during walking. The success of surgery performed on bone or soft tissues in the forefoot depends on an understanding of the biomechanics of the region. Therefore, the plantar forces acting under the metatarsal heads of the 1st, 2nd and 5th rays and under the pads of the 1st and 2nd toes were measured during walking, so that with the aid of anthropometric information pertaining to the forefoot, reaction forces in the flexor tendons and in the joints could be estimated. Particularly evident was the large share of the load taken by the big toe. This necessitates correspondingly high tension forces in the flexor tendons of the 1st ray, which simultaneously have the function of supporting the longitudinal arch of the foot. Because of this, the 1st metatarsal bone is loaded mainly in compression. In sharp contrast to this, the 2nd metatarsal bone is heavily loaded in bending, similar to a cantilever that is firmly held at its base. The high bending stress, especially when the 1st ray is no longer taking its share of the total load, leads to fatigue or march fractures, typically in the shank of the bone. A possible explanation for the pathogenesis of locally restricted necrosis of the metatarsal heads (Freiberg-Koehler's disease) is suggested and, finally, the question of dislocation of the base of the 2nd toe in the MP joint is discussed.
Jacob
H A
HA
Forschungslabor für Biomechanik, Orthopädische Universitätsklinik, Klinik Balgrist Zürich.
Zollinger
H
H
D000328:Adult; D001696:Biomechanical Phenomena; D005528:Foot / Q000502:physiology*; D005534:Foot Diseases / Q000503:physiopathology; D005545:Forefoot, Human / Q000502:physiology; D006801:Humans; D008124:Locomotion / Q000502:physiology*; D008683:Metatarsophalangeal Joint / Q000502:physiology*; D008875:Middle Aged; D013710:Tendons / Q000502:physiology
Zur Biomechanik des Fusses--Kräfte beim Gehen im Vorfuss und ihre klinische Relevanz.