Metatarsal Length Variations
The assumed normal metatarsal length formula is 2>1>3>4>5 or 2>1=3>4>5. Generally forms a parabola shape – has been referred to as curve of Hoffman-Leievre.
Variations in the length of the metatarsals will cause:
1) Changes in plantar pressures resulting in hyperkeratosis
2) Abnormal propulsion due to interference in the transfer from the oblique (low gear) to the transverse (high gear) metatarsal head axis system failure of the foot’s autosupport to get established.
Morton (1935) described the pathological foot with a short metatarsal. However it is considered that the first metatarsal needs to be shorter so it can plantarflex below the level of the second metatarsal for normal function ie the first ray must plantarflex to allow first MPJ dorsiflexion and the foot’s autosupports to get established. However, the first metatarsal can be abnormally short unable to participate in propulsion.
First metatarsal may also be elongated prevents first ray plantarflexion failure of the foot’s autosupports pathology from compensations.