To study factors that affect femorotibial (F-T) alignment after valgus closing wedge tibial osteotomy.
A review of standardized standing radiographs. Femorotibial alignment was measured 1 year postoperatively for over- and under-correction. Changes in F-T alignment and in tibial plateau angle were measured.
An urban hospital and orthopedic clinic.
Eighty-two patients with osteoarthritis and varus femorotibial alignment underwent valgus closing wedge tibial osteotomy. Patients having a diagnosis of inflammatory arthritis or a prior osteotomy about the knee were excluded.
A 1 degree wedge removed from the tibia resulted in an average correction F-T alignment of 1.2 degrees. A knee that had increased valgus orientation of the distal femur had a greater degree of correction, averaging 1.46 degrees in F-T alignment per degree of tibial wedge. This resulted in excessive postoperative valgus alignment for some patients who had increased valgus tilt of the distal femur. Optimal F-T alignment of 6 degrees to 14 degrees valgus occurred when the postoperative tibial inclination was 4 degrees to 8 degrees of valgus.
There was a trend for knees with increased valgus orientation of the distal femur to have greater correction in F-T alignment after tibial osteotomy, likely because of a greater opening up of the medial joint space during stance. Surgeons need to account for this in their preoperative planning.