Abstract
Proper ligament balancing, restoration of the mechanical axis and component alignment are essential for the success and longevity of a prosthesis. In conventional total knee arthroplasty (TKA), an intramedullary guide is used to improve the alignment. An extramedullary guide can be used in cases of severe femoral bowing or intramedullary nailing but its use is more subjective and relies on the surgeon's experience. This paper reports two successful cases of navigation-assisted TKA for severe right knee osteoarthritis retaining a femoral intramedullary nail, and left knee osteoarthritis retaining a distal femoral plate.