Relation between heel position and the distribution of forefoot plantar pressures and skin callosities in rheumatoid arthritis.

OBJECTIVE: To investigate the relation between the position of the rearfoot and the distribution of forefoot plantar pressures and skin callosities in rheumatoid arthritis.
METHOD: Plantar pressures and callosity patterns were measured in 102 rheumatoid arthritis patients (120 feet with normal heel alignment and 84 feet with valgus heel alignment measured by goniometry) and in 42 (84 feet) age matched healthy adults. Peak pressures (kPa) were measured across the metatarsal heads in-shoe using an FScan system and the distribution of plantar callosities was visually mapped for each foot.
RESULTS: Peak pressures were significantly greater at all but the first metatarsal head in the rheumatoid normal heel alignment and healthy adult groups than in the rheumatoid valgus heel group. The feet of both the rheumatoid normal heel group and the healthy adult group behaved the same, the highest peak pressures registering on the central metatarsal heads. However, only in the rheumatoid group were plantar callosities found at these sites. In the rheumatoid valgus heel group, lateral metatarsal heads were frequently non-weightbearing, producing gross loading patterns with a dominant medial distribution. Peak pressures were shifted to the medial fore-foot accompanied by a higher prevalence of callosities. The results, however, failed to establish clearly an association between peak pressures and callus formation.
CONCLUSIONS: In rheumatoid arthritis there is an important interrelation between the rearfoot position and forefoot pressure sites.