Pre-requisites for optimum centering of a tibiotalocalcaneal arthrodesis nail

• We compare alignment of different lengths of straight and curved ankle nails.
• We measure angles of incidence and reflection of nail at the inner tibial cortex.
• Angles are larger with short straight and less with long straight and curved nails.
• Both nail length and inbuilt valgus contribute to better central nail positioning.
• Stress risers and fractures occurred less frequently with long curved nails.

BackgroundPurpose of study was to compare nail alignment, incidence of stress riser and fracture with straight and curved nails of different lengths.MethodsWe conducted a retrospective review of consecutive, initially 13 straight and subsequently 15 curved nails implanted in 17 men and 11 women. Angles of incidence and reflection subtended by nail tip with inner tibial cortex were measured. Cortical hypertrophy was assessed on follow-up radiographs.ResultsAngles of incidence and reflection were greater with short straight nails, less with long straight nails and stayed close to zero with long curved nails.Stress fractures occurred in 2 patients with straight nails at the level of the proximalmost tibial screw. Cortical hypertrophy was present in 7 patients with straight nails and in only 1 patient with a curved nail (p = 0.01).ConclusionsBoth nail length and inbuilt valgus contribute to better central positioning within the tibia. However, cortical stress reactions occur less frequently with curved nails.