Bilateral Atypical Subtrochanteric Femoral Fractures with Primary and Secondary Bone Healing in Pycnodysostosis.

Abstract: Atypical subtrochanteric femoral fractures are a common problem associated with pycnodysostosis. Pycnodysostosis is a rare sclerotic bone disease caused by a mutation in the cathepsin K gene. Fracture healing in pycnodysostosis cases is typically inferior. Here, we report a case of bilateral atypical subtrochanteric femoral fractures in one patient with pycnodysostosis. The right subtrochanteric fracture was treated with open reduction and internal fixation (open plating), and united through primary bone healing, while the left one was treated with closed reduction and internal fixation (submuscular plating), and united through secondary bone healing. Although the time to bony union was delayed, fracture union after extramedullary osteosynthesis was obtained in both atypical fractures, demonstrating that both primary and secondary bone healing is possible in patients with pycnodysostosis. Level of Clinical Evidence: 4. © Indian Orthopaedics Association 2022.