Aims: Neutral alignment and soft tissue balance are universally accepted as the most important objectives when performing a total knee replacement regardless of the preoperative deformity and implant type. Nevertheless, there is scarce evidence in the scientific literature of the effect of surgical correction on varus/valgus alignment variation during follow-up. We wanted to verify if the femur-tibial alignment after a total knee replacement was maintained at three years’ follow-up, and whether any variation might be correlated to anatomical characteristics before surgery, and to position and fixation of the tibial component within bone.

Methods: We assessed thirty patients with a cemented TKR implant preoperatively, and at one and three years’ follow-up. Lower limb alignment and tibial component position were evaluated manually from antero-posterior radiographs in weight-bearing position. The tibial component varus/valgus migration was measured by Roentgen Stereophotogrammetry.

Results: In spite of the correct alignment obtained during surgery, at 3 years’ follow-up 40% of patients presented an alignment variation of over 3°. The variation of deformity was not correlated with the preoperative deformity, nor with the tibial component position with respect to the tibial shaft nor with its migration.

Conclusions: After total knee arthroplasty, the recurrence of deformity is a common finding in spite of correct alignment obtained during surgery, but it does not influence the clinical result at mid-term follow-up. Anyway the unbalanced forces determining variation in coronal alignment, at a longer follow-up might produce deficiency of soft tissue structures, loosening of the prosthesis component, or polyethylene failure, leading to revision surgery.