Stress concentration near pin holes associated with fracture risk after computer navigated total knee arthroplasty.

During computer navigated total knee arthroplasty, pin holes are drilled in the femur and tibia to allow the placement of navigation trackers, and fractures associated with these pin holes have recently been reported. We hypothesized that an increase in stress around the pin holes is one of the most relevant factors contributing to the fracture. In this study, we used finite element analysis to investigate the stresses around femoral pin holes with respect to the mode of pin penetration, the diameter of the pin holes, and the degree of osteoporosis. Our results indicate that increases in pin hole diameter and reduction in bone strength as a result of osteoporosis intensify the stresses around the pin holes, especially in cases of transcortical pin penetration.