Which secondary pathology may start as a mildly subluxed navicular and progress to a convex foot with a rocker-bottom appearance?

The condition that may begin with a mildly subluxed navicular and progress to a convex foot with a rocker-bottom appearance is Charcot Foot. This condition is characterized by a progressive degeneration of the joints in the foot and ankle, typically associated with neuropathy, most commonly seen in patients with diabetes.

In the initial stages, the navicular may experience subluxation due to the combination of loss of proprioception and altered weight-bearing mechanics. As the deformity progresses, the foot develops a convex shape, creating the characteristic rocker-bottom appearance associated with Charcot Foot. This change is due to the structural instability and remodeling of the bones and joints in the foot, ultimately leading to a significant alteration in the foot's architecture.

Plantar fasciitis primarily affects the plantar fascia and does not result in a convex foot deformity. Flatfoot deformity involves a different type of structural alteration, often related to ligament laxity or muscle weakness rather than a subluxation of the navicular. Morton’s neuroma is a condition affecting the nerves of the foot and is more associated with pain in the forefoot rather than causing a convex foot shape or structural changes seen in Charcot Foot.