Crossover Toe Deformity
The medical term for when one toe crosses over another is "crossover toe deformity" (or "crossover toe"), most commonly affecting the second toe as it crosses over the great toe 1, 2.
Specific Terminology by Location and Direction
The terminology varies based on which toe is affected and the direction of crossing:
Crossover second toe: The most common presentation where the second toe deviates medially and dorsally, eventually crossing up and over the great toe 2. This occurs when the lateral collateral ligament and joint capsule of the second metatarsophalangeal joint deteriorate 2.
Overlapping fifth toe: A congenital varus deformity where the proximal phalanx dorsally subluxates and adducts on the fifth metatarsophalangeal joint, causing the fifth toe to overlap adjacent toes 3, 4.
Hallux valgus superductus: When the hallux (big toe) crosses over the second toe due to fibular deviation 5.
Hallux valgus subductus: When the hallux moves under the second toe 5.
Underlapping fifth toe (or "curly toe"): A congenital deformity where the proximal phalanx is in varus at the metatarsophalangeal joint with flexion, causing the toe to underlap rather than overlap 3.
Clinical Context
The crossover deformity occurs in both transverse and sagittal planes at the metatarsophalangeal joint 1. The second toe crossover deformity may be caused by hindfoot pronation and compression of the lateral plantar nerve, producing incompetence of the second dorsal interosseous muscle with increased extension-adduction pull by the lumbrical and first dorsal interosseous muscles 1.