Biomechanics Analysis of Anterior Cortical Perforation in Antegrade Femoral Nailing
Abstract
Hip and femur fractures are a common problem in an aging population. The number of hip and femur fractures are on the rise in Canada. Cephalomedullary fixation is a common method of treating hip and femur fractures, with a known complication of anterior cortical perforation of the distal femur. The literature describes risk factors, such as the influence of the start point at the greater trochanter, but there is no consensus on management. Some cases are treated with restricted weightbearing and other cases with revision surgery. Restricted weightbearing increases perioperative complications including mortality and decreases functional outcomes.
We analyze the effect of an anterior, neutral, and posterior start point on the axial, bending, and torsional stiffness of the femur along with the proximal and distal stresses in axial stiffness. We also compare a femur with an anterior cortical perforation of the distal femur.
The posterior start point has increased sagittal stiffness compared to the neutral and anterior start points. There is no difference in axial, coronal bending, or torsional stiffness, or proximal or distal stresses. Between a femur with a posterior start point with perforation or without perforation, there is no difference in axial, bending, or torsional stiffness or proximal or distal stresses.
A case report is presented of an 89 year old woman with a basicervical fracture who underwent cephalomedullary nail fixation and suffered an anterior cortical perforation of the distal femur. Her weightbearing was not restricted postoperatively and she was ambulating at 6 weeks. She did not fracture at the perforation.