First described by Steindler (1929) as the “supinatory, compensatory torsion of the forefoot in pes valgus”. Often mistaken for forefoot varus.
An acquired soft tissue contracture of the forefoot in a supinated/inverted postion about the joints of the midfoot.
Assumed to be caused by any pronatory force of the rearfoot that causes the forefoot to assume an inverted position relative to the rearfoot. Overtime the soft tissue will adapt to this position (Davis’s law). May also be due to a lack of a functioning windlass mechanism – lack of windlass function could result in a dorsiflexion of the medial column.
Unknown, but clinically seen much more frequently than a forefoot varus.
May coexist with forefoot varus
* some patients may have had an everted forefoot (eg flexible forefoot valgus) compensatory midtarsal joint supination soft tissue contracture forefoot may now be perpendicular to rearfoot and appear normal differential diagnosis is difficult.
Comparison between forefoot varus and supinatus*:
Forefoot varus Forefoot supinatus
Cause of excessive STJ pronation Result of excessive STJ pronation
Single plane deformity (frontal plane) Triplane deformity
Osseous Soft tissue
“Hard”/osseous feel to end of MTJ ROM “Soft”/soft tissue feel to end of MTJ ROM
No arch on non-weightbearing Slight arch on non-weightbearing
Cannot be reduced with patient standing with STJ in neutral Can be reduced with patient standing with STJ in neutral
Normal MTJ ROM (unless supinatus coexists) Restricted MTJ ROM
* Differential may be difficult due to soft end range of midtarsal joint motion and the possible co-existence of varus and supinatus.
Treatment of forefoot supinatus:
The cause of the abnormal rearfoot pronation needs to be treated.
Options for orthoses:
1) Serial orthoses as corrects can be expensive option
2) Cast supinatus out orthoses will be uncomfortable initially as adaptation occurs use mobilisation and manipulation techniques to facilitate this
Inappropriate use of a forefoot varus/medial post when a supinatus is present probably prevent the first ray from plantarflexing lack of windlass establishment and dorsal ‘jamming’ of first MPJ compensations.