Mid-foot disassociation in rheumatoid arthritis.

The mid-foot is commonly involved in rheumatoid arthritis with subchondral sclerosis and erosions at the talonavicular joint. There may be a mid-foot disassociation whereby the hindfoot is usually subluxed. Occasionally the forefoot may be subluxed with mid-foot disassociation. In long-standing cases of rheumatoid arthritis there is a loss of the normal plantar arch.