The influence of two different types of foot orthoses on first metatarsophalangeal joint kinematics during gait in a single subject.

OBJECTIVE: To quantify the effect of two distinct foot orthotic designs on in vivo multisegment foot and leg motion; in particular, the first metatarsal and first metatarsophalangeal (MTP) joint during gait.
METHODS: A 23-year-old man had an excessively pronated foot structure as measured during a clinical orthopedic examination. The Optotrak Motion Analysis System was used to collect three-dimensional position and orientation data from four modeled rigid body segments (hallux, first metatarsal, calcaneus, and tibia) during the stance phase of walking. The subject walked at a self-selected comfortable walking speed, and a minimum of five trials were collected under three different test conditions: no orthosis, semirigid orthosis with a varus post, and a semirigid orthosis with a varus post and a large medial flange. Data were normalized to the stance period, and descriptive statistics were calculated for dependent variables.
RESULTS: Both orthotic interventions equally modified first MTP joint motion when compared with the no orthotic condition. First MTP joint dorsiflexion was decreased (>2 SD) with the orthosis during terminal stance phase. This decrease was associated with a concomitant increase in first metatarsal plantar flexion.
CONCLUSION: A custom-made semirigid orthosis posted medially and made from a neutral position off-weight-bearing plaster cast can alter motion in the forefoot during the propulsive period by increasing first metatarsal plantar flexion and decreasing excessive first MTP joint dorsiflexion.