Objective To analyze plantar pressure features of patients in injured and healthy sides of the lower limbs under different walking conditions after the trimalleolar fracture surgery, and compare these characteristics with healthy subjects. Methods Twelve Trimalleolar fracture patients and twenty-three healthy subjects were recruited and their plantar pressure characteristics under different walking conditions were tested, including peak pressure, contact area and contact time percentage. Results Comparison between injured and healthy sides: during level walking, peak pressure of the 3rd-5th toe in the injured feet were smaller than those in the healthy sides; in inversion position, peak pressure and contact area of the 3rd-5th toe area in the injured feet were smaller than those in the healthy side; in eversion position, peak pressure, contact area and contact time of the 3rd-5th toe in the injured feet were smaller than those in the healthy sides, and peak pressures of the hindfoot area were larger than those in the healthy sides. Comparison between patients and healthy subjects: under three kinds of walking conditions, peak pressures of the 2nd and 3rd metatarsus bones, the 2nd toe, the 3rd-5th toe, contact area of the 1st-5th toe and contact time percentage of the 2nd toe, the 3rd-5th toe area were all smaller than those of healthy subjects, while contact time of the hindfoot and mid-foot area were all smaller than those of healthy subjects. Conclusions The plantar pressure characteristics of Trimalleolar fracture patients were asymmetrical. Compared with healthy subjects, the plantar pressure features of patients were abnormal during stance phase. Compared with healthy subjects, the motor control ability and stability of patients in eversion positions were decreased. The plantar pressure characteristics at ankle eversion can be used to evaluate ankle joint function.

Objective To explore the characteristics of plantar pressure of ankle joints at different limb laterality and different stress positions. Methods Twenty-three healthy subjects were recruited to perform walking trails. Each subject was tested for plantar pressure in ankle neutral position, ankle inversion and ankle eversion through simple custom-designed walkways and plantar pressure plate. The evaluation indices were peak pressure, contact area, contact time percentage, M/L (ratio of sum of medial plantar peak pressure to sum of lateral peak pressure), A/P (ratio of sum of toe peak pressure to heel peak pressure). Results The peak pressure of the first metatarsus bone in the dominant foot was significantly larger than that in the non-dominant foot, and the peak pressure of the fifth metatarsus bone was significantly smaller than that on the non-dominant foot. The M/L of dominant side was significantly larger than that of the non-dominant side. Except for the peak pressures of the mid-foot and the first toe, there were significant differences in other regions among the three ankle positions. The percentage of contact time in each area during inversion was greater than that in neutral position, and the percentage of contact time of plantar regions during eversion was longer than that in neutral position except the second toe. The M/L in inversion, neutral and eversion position were 1.24±0.46, 1.06±0.26, 0.88±0.25. The M/L of dominant foot was greater than that of the non-dominant foot, and the A/P during inversion and eversion was greater than that in neutral positions. Conclusions The stability of the dominant foot was better than that of the non-dominant foot. The standing stability decreased during inversion and eversion. During inversion, the body shifted inward and forward to maintain the stability. During eversion, the center of gravity shifted outward and forward to maintain the stability.