Objective : The valgus angle of the distal femur determines the axial alignment of limb. It is used to plan the realignment osteotomies in limb reconstruction surgery and to determine the angle of resection of the distal femur in total knee arthroplasty. The objective of this study was to analyse the variation of the valgus angle of the distal femur in a random Caucasian population with osteoarthritic knees presenting for total knee arthroplasty.

Method : A prospective study was undertaken involving a review of pre-operative CT scout films of osteoarthritic knees in 83 consecutive patients (44 males and 39 females; mean age 70.2 years) presented for total knee arthroplasty between May 1999 and October 2002. The valgus angle was calculated from the difference between the anatomical and mechanical axes of femur plotted on CT scanogram films.

Results : Mean valgus angle was 5.4 degrees (range 3.3 to 7.6 degrees) with a standard deviation of 1.1 degrees. Estimated 95% confidence interval of the mean for the population was 3.6 – 7.4 degrees. There were no significant differences for age, gender or laterality of the limb.

Conclusion : The value of mean valgus angle of the distal femur in osteoarthritic knees was found to be significantly lower than the one quoted in the literature in normal disease-free knees. This may have important implications on the preoperative planning of appropriate surgical planes for total knee arthroplasty or corrective osteotomies.