[Post-traumatic osteoarthritis of the knee: special indication for navigated TKA].

Different studies confirmed the increased radiological implantation accuracy for computer-assisted total knee replacements. There was no study stating a significant influence of the navigation technique for total knee arthroplasties on the early clinical outcomes. In these two case reports we try to show special indications for a navigated total knee replacement to utilize the benefits of a navigation system as efficiently as possible.Case 1 had a femoral neck fracture 3 years ago and was treated with a long femoral gamma nail. The hardware was still retained. Case 2 had a fracture of the femoral diaphysis 31 years ago and showed an extra-articular deformity in the frontal and sagittal planes. Both patients developed osteoarthritis of the ipsilateral knee and were implanted with a total knee prosthesis using a navigation system.In both cases the prosthesis components showed perfect radiological alignment. The clinical outcomes at the 3-month follow-up were very satisfying. In case 1 the femoral nail did not have to be removed, thus decreasing surgery duration by 40-60 min.In both cases, the impossibility of using a femoral intramedullary alignment rod could be compensated for by the navigation system.