Assessment of Knee Laxity following Retrograde Intramedullary Nailing for Periprosthetic Distal Femur Fractures: A Cadaveric Study

After TKA femoral preparation, retrograde IMN did not significantly impact the flexion gap when a femoral component was in place. Without a femoral component in place, the extension gap was unchanged after IMN placement. Although the flexion gap was statistically greater after IMN placement when measured without a femoral component, the clinical relevance is questionable given this difference was, on average, only 1.5 mm greater and a femoral component was not present. Similarly, the differences in AP translation observed without a femoral component were attenuated once the component was in place, which may have been further attenuated if a tibial component was able to be placed. These findings suggest limited clinical impact of retrograde IMN of the knee in the context of modern TKA femoral preparation.