Extramedullary versus intramedullary alignment guides in total knee arthroplasty.

Use of extramedullary and intramedullary guides to prepare the tibia was studied comparatively in 100 consecutive primary total knee arthroplasties done by a single surgeon. Each type of guide was used in 50 consecutive cases, for a total of 100 cases. In all cases, an intramedullary guide was used to prepare the distal femur. Long (hip to ankle) anteroposterior radiographs were taken postoperatively to measure the mechanical angle, tibial component angle, femoral component angle, physiologic valgus angle, and tibiofemoral angle. No significant differences between the extramedullary and intramedullary groups were found; each system allowed satisfactory alignment. It is important for the surgeon to appreciate the benefits and deficiencies of each guide and to use whichever is suited most properly in each particular case.