extensor substitution

extensor substitution

unopposed action of extensor digitorum longus (EDL) muscle, allowing EDL to act as an auxiliary foot dorsiflexor; part of compensation for excessive pronation, occurring during later part of stance phase of gait; i.e. dorsiflexion of lesser toes at metatarsophalangeal joints (due to EDL contraction) is not balanced by flexor digitorum longus contraction, so that metatarsophalangeal joints hyperextend and lesser toes buckle on sagittal plane; leading over time to local soft-tissue adaptation (plantar contracture and dorsal stretching) and lesser-toe deformity