Plantar plate dysfuncion is a common strain or tear of the strong ligament that is under the metatarsophalangeal joint of the foot and forms part of the joint capsule. The classic location of the symptoms are typically just over and just distal to the joint on palpation (see the typical area in the diagram below):
A rather odd symptom that some with plantar plate dysfunction can describe is that it can feel like a sock is bunched up under the area, but when they check the sock is not like that at all. The cause of a plantar plate tear is not really clear, but it occurs in people with a number of risk factors and is an overuse problem.
Fixing a plantar plate tear is not that difficult, but it can take a long time and patient is needed. The best approach is to use strapping to hold the toe plantarflexed. The tape needs to be used for quite a few months to rest the area to allow it to heal. A rocker sole shoe and also help restrict movement at the joint further rest the injured area. Surgery to repair the tear is indicated if this conservative approach does not help.