TERMINOLOGY OF FOOT MALALIGNMENT

To accurately describe foot alignment dorso plantar and lateral radiographs should be performed weight bearing. In an acute trauma situation this is not practical and therefore foot alignment does not need to be part of the trauma report. In chronic foot problems the alignment is an important part of the report.

(A) Longitudinal arch (midfoot)

Long axis of talus normally aligns with long axis of first metatarsal

(i) Pes Cavus (high arch)

Long axis of talus is abnormally dorsiflexed with respect to first metatarsal on the lateral view.

(ii) Pes Planus (flat arch)

Long axis of talus is abnormally plantar flexed with respect to first metatarsal on lateral view.

(B) Os Calcis Position on Lateral Radiograph

Long axis of Os calcis is normally at 90 degrees or minimally dorsiflexed with respect to long axis of tibia.

(i) Equinus

Fixed plantar flexion of Os calcis with respect to tibia.

(ii) Calcaneus

Fixed prominent dorsiflexion of Os calcis with respect to tibia.

(C) Hindfoot (heel) alignment

This refers to the alignment of the Os calcis on the dorsoplantar radiograph. This needs to be deduced from the alignment of the talus because the Os calcis cannot be clearly visualised on this projection.

Normally the long axis of the talus aligns with the long axis of the first metatarsal.

(i) Heel Varus (Abnormal inward slanting of heel)

This results in a narrow talocalcaneal angle and causes the long axis of talus to be lateral to long axis of first metatarsal.

(ii) Heel Valgus (Abnormal outward slanting of heel)

This results in a wide talocalcaneal angle and causes the long axis of talus to be medial to long axis of first metatarsal.

(D) Forefoot (metatarsal) alignment

(i) Forefoot adduction

Forefoot is abnormally deviated towards the midline resulting in a stepladder appearance of metatarsals on the lateral view and overlapping of the bases of the metatarsals on the dorsoplantar view.

(iii) Forefoot abduction

Forefoot is abnormally deviated away from the midline resulting in the metatarsals being superimposed upon one another in the lateral radiograph and there is a decrease in the overlap of the bases of the metatarsals on the dorsoplantar view.

DEVELOPMENTAL FOOT ABNORMALITIES

(A) Flexible Flatfoot (never has equinus)

- Most common foot abnormality

- Often persists into adulthood

- Pes planus

- Heel valgus

- Forefoot abduction

- Treated with orthotics

(B) Congenital Vertical Talus (fixed flatfoot)

- Equinus

- Heel valgus

- Forefoot abduction

- Requires surgery (may ultimately require triple arthrodesis)

(C) Metatarsus Adductus (1 in 1000 births)

- Forefoot adduction

- Mild heel valgus

- May require serial plaster casting

(D) Clubfoot (1.25 per 1000 births)

- Heel varus

- Forefoot adduction

- Equinus

- Pes cavus

- Treatment of repeated manipulation and splints or serial casting

- May need surgery