Ankle Equinus

EQUINUS

Anatomy

Gastrocnemius muscle originates on the femur and crosses three joints (knee, ankle, STJ).

Soleus muscle originates on the tibia/fibula and crosses two joints (ankle, STJ).

Plantaris muscle originates on the femur and crosses three joints (knee, ankle, STJ). Plantaris runs between the gastrocnemius and soleus muscle and inserts on the medial aspect of the posterior calcaneus. This muscle is absent 7% of time.

The triceps surae muscle is referred to the two heads of the gastrocnemius muscle and the soleus muscle.

Silfverskiold Test

▪ Tests for gastrocnemius equinus

Passive dorsiflexion is measured with the knee extended and again with the knee flexed. If the amount of dorsiflexion increases with knee flexion, there is an equinus due to a tight gastrocnemius, because the gastrocnemius crosses the knee joint and the soleus does not.

Types/Causes

Muscular

Spastic equinus

CP (hyperreflexia, +babinski, +clonus)

Duchenne’s (post muscle contractions, weak/atrophic muscles, absent reflexes)

Congenital equinus

Birth history, childhood diseases

Note: Toe walking for the first 3 to 6 months of ambulation is a normal variant.

Acquired

Improper casting with the foot plantarflexed

Repetitive use of high-heel shoes

Iatrogenic

Osseous

Talotibial exostosis

Clinically there is a hard and abrupt end ROM upon dorsiflexion.

Stress lateral x-ray may aid diagnosis.

Pseudoequinus

Apparent equinus due to cavus foot type

GAIT AND PHYSICAL EXAM

Biomechanics: Look for STJ ROM, ankle joint ROM, rigid vs flexible deformity.

Equinus

Uncompensated	Partially Compensated	Fully Compensated
Hypertrophic calves	Early heel off	Forefoot supinatus
STJ supinated	STJ pronation	STJ pronation
Walking plantarflexed	Mild HAV	Heel valgus, HAV deformity
Smaller steppage gait		+ + + most pathological
RF inverted