Introduction: Calcaneal lengthening osteotomy as a treatment for severe flat foot was described by Evans (1975) and his indications were expanded by Mosca (1995).

Materials and methods: We reviewed 28 feet operated on in 21 patients with neuromuscular processes (17) and with flat foot-valgus associated with congenital short Achilles tendon (11). The mean age was 12.2 (6–18) and mean follow-up was 7.3 years (4–11). In all cases the associated Achilles tendon was lengthened. We evaluated the subjective and objective clinical results (Kitaoka, 1994) and the radiological parameters.

Results: Subjective clinical: excellent and good 89.28% (100% in neuromuscular, 72.7 in short Achilles tendon). Objective clinical: (preop 64.25, postop 90.06 at 3 years, 86.13 at 7 years). The worsening of outcomes was due to three fair or poor results in the short Achilles tendon group (one required triple bone fusion).

All but one presented complete subtalar mobility. Normal alignment in all but one, with slight valgus; none in varus.

Conclusions: This surgical procedure gave excellent long-term results: subjective, nearly 90% excellent; objective: radiological anatomical correction, subtalar and tarsal mobility maintained. Its outcome was comparatively worse in the short Achilles tendon group than in the neuromuscular cases.