Peroneus quartus is seen in 17% and retrotrochlear eminence in all:
Radiology 2007;242:509-517
Saupe N et al studies 'Anatomic variants associated with peroneal tendons' in 65 volunteers (35 women, 30 men; age range, 23–70 years; median age, 45 years). Peroneus quartus was identified in 11 (17%). Retrotrochlear eminence was seen in all ankles.
