Posterolateral Plate Fixation with Pantalarlock® is More Stable than Nail Fixation in Tibiotalocalcaneal Arthrodesis in a Biomechanical Cadaver Study

CATEGORY: Ankle; Ankle Arthritis INTRODUCTION/PURPOSE: Despite the promising results of ankle joint arthroplasty, the tibiotalocalcaneal (TTC) arthrodesis remains an established procedure in treatment of combined pathology of the ankle and subtalar joint. Despite the promising results in biomechanical investigations, nonunion rates of up to 24% are described in recent studies. The objective of this work was a comparative study of the biomechanical properties of the posterolateral plate fixation with retrograde intramedullary nail fixation. METHODS: Twenty four fresh-frozen human lower leg specimens (12 pairs) were used for the comparative biomechanical testing. Every specimen was preconditioned with 100N over 200 cycles. After every 250 cycles the force was increased by 50N from 200 to 600N. This was followed by cyclic loading in dorsi-/plantiflexion with 800N for 3000 cycles. All specimens were subjected to bone densitometry (DXA) and computed tomography. RESULTS: Significantly higher number of spacimens with nails (4) failed during the cycling testing in dorsi-/plantarflexion and futher two during the cyclic testing with 800N. Two specimens with plates failed during the cyclic testing with 800N. Statistical analysis showed that the specimens with the plate were significantly more stable in each test direction. The Pearson correlation demonstrated for the specimens with plate a linear relationship between the stiffness and the determined bone density. CONCLUSION: We expect a considerable reduction of the pseudarthrosis rate and shorten the postoperative treatment phase in clinical set up and appropriate advantages in the treatment of high risk patients with severe deformity of the ankle, bone defects, neuropathic deformity, poor bone quality and osteoporosis. The choice of most predictable and stable implant is essential for the successful fusion. In conclusion, the posterolateral plate ostesynthesis for TTC arthrodesis is significantly stiffer compared to the nail osteosynthesis in osteoporotic bone model.