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.