Restoration of limb alignment in total knee arthroplasty: evaluation and methods

Obtaining adequate alignment is critical in the proper performance of total knee arthroplasty (TKA). This study prospectively evaluates 350 patients who had previous TKA. Its goals are to establish the best method of measuring limb alignment as well as the best method of restoring ideal alignment. Intramedullary alignment techniques were compared with extramedullary, and alignment of each limb was evaluated by both long (scanogram) and short films (14 inches x 17 inches). Conclusions reached were (1) that only data obtained from full limb radiographs are accurate for determining and reporting limb alignment in TKA, (2) that alignment values should be reported relative to the mechanical axis of the limb because of the variability of the femoral anatomic angle, (3) that intramedullary femoral guides are required to make accurate femoral bone cuts, (4) that extramedullary tibial guides permit accurate cuts of the proximal end of the tibia, and (5) that tibial intramedullary guides are not only unnecessary but also potentially misleading.