TKA after clamshell osteotomy for femoral diaphyseal malunion.

Proper component positioning is essential for successful total knee arthroplasty (TKA). Femoral component positioning presents a technical challenge when significant femoral deformity is present. Most commonly, an intramedullary guide is used to make an accurate distal femoral cut. However, in the presence of a significant femoral deformity, this is not a viable option.The use of clamshell osteotomy to restore anatomic alignment in patients with complex femoral diaphyseal deformity is described in the literature. This article describes a case of a patient who underwent staged TKA after clamshell osteotomy and retrograde femoral nailing to correct femoral diaphyseal malunion. The retrograde intramedullary nail was retained and used as an intramedullary guide, allowing for TKA in a routine manner. Using an intramedullary nail as an alignment guide may be more accurate than using extramedullary alignment and may avoid the increased surgical time and potential pin-site stress risers of navigation. It is a simple, effective way to treat complicated diaphyseal femoral deformities in the face of posttraumatic knee arthritis. Further study of this technique with longer follow-up and multiple surgeons is necessary to validate this treatment algorithm.