Plantar pressure distribution in older people with osteoarthritis of the first metatarsophalangeal joint (hallux limitus/rigidus).

The purpose of this study was to evaluate differences in dynamic plantar pressure distribution between older people with and without radiographically confirmed osteoarthritis (OA) of the first metatarsophalangeal joint (first MPJ) of the foot. Dynamic plantar pressure recordings using the TekScan MatScan system were obtained during barefoot level walking in 40 older participants; 20 with radiographically confirmed OA of the first MPJ displaying less than 55 degrees of passive dorsiflexion, and 20 with no evidence of OA in the first MPJ displaying greater than 55 degrees of passive dorsiflexion. Group comparisons between the variables maximum force and peak pressure were made for seven different regions underneath the right foot (heel, midfoot, first MPJ, second MPJ, third to fifth MPJs, hallux, and lesser toes). Compared to the control group, participants with OA of the first MPJ exhibited 34% greater maximum force (7.9 +/- 2.5 vs. 5.9 +/- 1.7 kg, p = 0.005) and 23% higher peak pressure (1.6 +/- 0.3 vs. 1.3 +/- 0.3 kg/cm(2), p = 0.001) under the hallux. Similar results were also found under the lesser toes with 43% greater maximum force (5.0 +/- 1.9 vs. 3.5 +/- 1.4 kg; p = 0.006) and 29% higher peak pressure (0.9 +/- 0.2 vs. 0.7 +/- 0.2 kg/cm(2), p = 0.018). No significant differences were found to exist between groups for any other plantar region. These findings indicate that OA of the first MPJ is associated with significant changes in load-bearing function of the foot, which may contribute to the development of secondary pathological changes associated with the condition, such as plantar callus formation and hyperextension of the hallux interphalangeal joint.