Biomechanical comparison of intramedullary nail and blade plate fixation for tibiotalocalcaneal arthrodesis.

OBJECTIVE

Tibiotalocalcaneal arthrodesis is used to manage severe bone loss, arthritis, and/or instability. The goal is to relieve pain through a stable, well-aligned hindfoot and ankle. The purpose of this study was 2-fold: to biomechanically compare 1) initial stability, and 2) the effect of bone density on the stability of intramedullary nail and blade plate fixation in tibiotalocalcaneal arthrodesis.

DESIGN

Biomechanical study using anatomic specimens.

METHODS

Ankle and subtalar joint capsules were exposed for 7 pairs of fresh-frozen anatomic specimens. One ankle from each pair was instrumented with an interlocked intramedullary nail inserted retrograde across the subtalar and ankle joint while the contralateral hind foot was stabilized with a lateral cannulated blade plate. Specimen stability was tested in plantar/dorsiflexion and inversion/eversion to a maximum bending moment of 12 Nm and in internal/external rotation to a maximum torque of 7 Nm. Physical measurements of bone density were made to determine its effect on stability.

MAIN OUTCOME MEASURES: Maximum angular displacement of the constructs in plantarflexion, dorsiflexion, inversion, eversion, internal rotation, and external rotation.

RESULTS

No significant differences were observed between the plated and nailed constructs in the 3 loading configurations (Power = 0.77). Only 6 pairs were included in the results because of fixation failures. A small but significant reduction in internal rotation alone of 1.8 degrees was found with the plated compared with the nailed construct (P = 0.045). Reduced stability was associated with lower bone density in torsion and inversion/eversion in the plated constructs (r = 0.67- 0.87) with a similar trend seen in torsion in the nailed constructs (r = 0.5).

CONCLUSION

Initial construct stabilities and the effect of reduced bone density were found to be similar between the blade plate and the intramedullary nail in tibiotalocalcaneal arthrodesis, thus implant choice may be based on other clinical factors, such as surgeon preference or soft-tissue status.