Percutaneous balloon calcaneoplasty versus open reduction and internal fixation (ORIF) for intraarticular SANDERS 2B calcaneal fracture: Comparison of primary stability using a finite element method.

Introduction: Fractures of the calcaneus are common, with 65% being intra-articular, which can lead to a major impairment of the patient's quality of life. Open reduction and internal fixation with locking plates can be considered as gold-standard technique but has a high rate of post-operative complications. Minimally invasive calcaneoplasty combined with minimally invasive screw osteosynthesis is largely drawn from the management of depressed lumbar or tibial plateau fractures. The hypothesis of this study is that calcaneoplasty associated with minimally invasive percutaneous screw osteosynthesis presents biomechanical characteristics comparable with conventional osteosynthesis.

Materials And Methods: Eight hind feet were collected. A SANDERS 2B fracture was reproduced on each specimen, while four calcanei were reduced by a balloon calcaneoplasty method and fixed with a lateral screw, four others were manually reduced and fixed with conventional osteosynthesis. Each calcaneus was then segmented for 3D finite element modeling. A vertical load was applied to the joint surface in order to measure the displacement fields and the stress distribution according to the type of osteosynthesis.

Results: Analyses of the intra-articular displacement fields showed lower overall displacements in calcaneal joints treated with calcaneoplasty and lateral screw fixation. Better stress distribution was found in the calcaneoplasty group with lower equivalent joint stresses. These results could be explained by the role of the PMMA cement as a strut, enabling better load transfer.

Conclusion: Balloon Calcaneoplasty combined with lateral screw osteosynthesis has biomechanical characteristics at least comparable to locking plate fixation in the treatment of SANDERS 2B calcaneal joint fractures in terms of displacement fields and stress distribution under the premise of anatomical reduction.