INTERNAL-FIXATION OF EXPERIMENTAL INTRAARTICULAR CALCANEAL FRACTURES - A BIOMECHANICAL ANALYSIS OF 2 FIXATION METHODS

Objective: To evaluate and compare the mechanical stability of two dif ferent fixation techniques on experimentally induced calcaneus fractur es. Methods: Thirteen fresh frozen cadaver lower limbs had intraarticu lar calcaneal fractures produced with an impact loading device. Intern al fixation was then performed through lateral and medial approaches u sing 3.5-mm interfragmentary screws fixed to the posterior facet. Next , either a five-hole 1/3 tubular or five-hole reconstruction plate was placed on the lateral cortex. Radiographs were obtained to confirm re duction. The foot was then cyclically loaded for 500 cycles with a com pressive load of 98 N, followed by loading to failure. Results: The di splacement at the posterior facet fracture line between the loaded and unloaded foot at the 500th cycle was 0.30 +/- 0.08 mm and 0.39 +/- 0. 18 mm for the tubular and reconstruction plates, respectively. These d isplacements were not statistically significant (Student's t test p > 0.3). The load and displacement at failure for the tubular plate were 2021 +/- 1050 N and 6.10 +/- 1.75 mm, respectively Those for the re co nstruction plate were 1923 +/- 697 N and 4.57 +/- 1.32 mm (p > 0.09). Conclusion: This study supports the mechanical viability of using less prominent plates for the fixation of intra-articular calcaneal fractu res.