Posterior Cruciate Ligament Injury After Retrograde Nailing of Periprosthetic Distal Femur Fractures

Case: A 51-year-old man and 64-year-old woman with bilateral cruciate-retaining total knee arthroplasties (CR-TKAs) who sustained unilateral periprosthetic distal femur fractures above their CR-TKA and experienced knee instability secondary to an iatrogenic posterior-cruciate-ligament (posterior cruciate ligament [PCL]) injury from retrograde intramedullary nailing. Both patients recovered knee stability after undergoing revision surgery. Conclusion: Many CR-TKA designs have sufficient medial-lateral intercondylar distance to place a retrograde nail, femoral components with a relatively posterior transition from the trochlear groove to the intercondylar box will necessitate a nail starting point closer to the PCL origin. This may contribute to iatrogenic postoperative knee instability for patients with CR-TKA designs.