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Title:
The effect of forefoot and arch posting orthotic designs on first
metatarsophalangeal joint kinematics during gait

Authors:
Nawoczenski, DA; Ludewig, PA

Source:
JOURNAL OF ORTHOPAEDIC & SPORTS PHYSICAL THERAPY, 34 (6): 317-327; JUN 2004

Abstract:
Study Design: Repeated-measures analysis of variance.

Objective: To examine the effect of 2 different orthotic posting designs on
first metatarsophalangeal (first MTP) joint kinematics during gait.

Background: Common orthotic designs used to control abnormal pronation
incorporate the use of a medial post in the forefoot and/or rearfoot
locations. Although this design may favorably alter rearfoot and lower-limb
kinematics, the incorporation of a forefoot post has been theorized to
negatively impact first MTP joint function by limiting hallux dorsiflexion
during push off. An alternative design that has been proposed to be more
favorable for function of the hallux and first metatarsal is the medial arch
support.

Methods and Measures: Eighteen subjects with a mean age of 28.2 years (SD,
8.3 years) completed the study. All subjects were judged to have excessive
pronation based on a clinical orthopaedic examination. Two different pairs
of orthoses were custom molded for each subject. One design incorporated an
extrinsic rearfoot and forefoot post and the second design had a high medial
longitudinal arch in combination with an extrinsic rearfoot post. The "Flock
of Birds" electromagnetic tracking device was used to collect 3-dimensional
position and orientation data of 3 body segments (hallux, first metatarsal,
and calcaneus) during the stance phase of walking for 3 conditions (no
orthosis and each of the 2 different orthotic designs). A repeated-measures
analysis of variance was used to assess differences in first MTP joint
dorsiflexion at midstance and during the push-off period of gait, as well as
metatarsal declination angle changes during relaxed stance. An exploratory
regression a!
 nalysis was used to investigate factors that related to the change in peak
dorsiflexion for the orthotic conditions.

Results: Peak first MTP joint dorsiflexion averaged between 38degrees and
40degrees across all conditions. Although slight increases in first MTP
joint dorsiflexion values were noted with both types of orthotic designs,
these differences were not significant at either phase of the stance cycle
(P = .50). The metatarsal declination angle in relaxed stance significantly
increased (P = .001) under both orthotic conditions. Considerable individual
variability was present. For the rearfoot-forefoot posted orthosis, a change
in the declination angle of the first metatarsal during relaxed stance with
the orthosis was a significant nonlinear predictor of change in peak
dorsiflexion during push off.

Conclusions: Foot orthoses that incorporate a medial forefoot post do not
have a consistent negative effect of reducing first MTP joint dorsiflexion
during walking.

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