A kinetic, biomechanical model of the foot and ankle and kinematic study of hallux valgus
Abstract
The goal of this project was to characterize the kinetic patterns of the foot and ankle during normal stance phase ambulation and to describe the kinematic characteristics of hallux valgus pathology. A kinetic model was developed and based on a four-segment rigid body model of the foot and ankle. Four joint centers were located through the use of radiographic and anthropometric measurements and included: first metatarsophalangeal (1MTP), talo-navicular (TV), subtalar (ST) and talocrural (AK) joints. The TV joint was modeled as ball-and-socket type while the others were modelled as revolute joints. A plantar pressure measurement system was used to locate the center of pressure for each segment of the model with reference to the generalized ground reaction forces determined with a multi-axis force plate. Internal joint moment ranges were found to be: 1MTP ($-$0.032% to 0.53%), TV1 ($-$0.15% to 3.30%), TV2 ($-$0.15% to 4.24%), TV3 ($-$1.83% to 0.47%), ST ($-$0.43% to 3.89%), AK ($-$1.00% to 7.26%). This kinetic data correlated well with that about the 1MTP, ST and AK joints as reported by Scott et al. in recent studies. Results for the TV joint have not been reported elsewhere and are presented here for the first time. In order to better understand the kinematic characteristics of hallux valgus deformity, the foot motion patterns of ten subjects were assessed. Each subject was matched by height, weight and age to a normal control. Motion of the hallux, forefoot, hindfoot and tibia were described in the sagittal, coronal and transverse planes during the gait cycle. Statistically significant differences (p $\leq$ 0.05) in the motion at the hallux were observed in the coronal and transverse planes of motion. Cadence, stance and swing times were similar between the two populations while stride lengths were found to be greater in the hallux valgus population.
This paper has been withdrawn.