Master of Science
Sanders, David W.
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.
Summary for Lay Audience
Femur and hip fractures are a common problem in an aging population such as Canada. Allowing patients to move soon after surgery is an important goal of the care of hip fracture patients. The choice of surgery for hip fractures depends on the pattern of the fracture. One of the options involves a rod going into the main portion of the femur and a screw going into the head of the femur. This is called a cephalomedullary nail.
The positioning of each of the components of the cephalomedullary nail is critical to the success of the surgery. One complication of the the surgery is having the tip of the nail break through the front wall of the femur. The average femur has a curve, which may be more curved than many nails. Depending on the position of the nail, the risk of perforation caused by the tip breaking through the front wall may increase.
The studies currently published describe many examples of perforation, but there is no agreement on how to treat this problem. Options include revision surgery or not allowing patients to place weight through their operative leg, but this is associated with poor outcomes.
Our thesis shows that the perforation does not significantly weaken the femur, with no difference between the strengths of the femurs. A femur that is 35% weaker has been shown to have an increased risk of fracture. This means that patients with a perforation of the front of their femur may be allowed to place weight through their operative leg.
We present a case report of an 89-year-old female suffering a hip fracture that was treated with a long cephalomedullary nail. An anterior cortical perforation of the distal femur was noted intraoperatively and managed successfully without weightbearing restrictions or revision surgery.
Ching, Michael, "Biomechanics Analysis of Anterior Cortical Perforation in Antegrade Femoral Nailing" (2019). Electronic Thesis and Dissertation Repository. 6795.
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