Distal femoral valgus cut angle in degenerative varus knees of an Arabic population.

Abstract

This study aimed to determine the natural distribution of the distal femoral valgus cut angle (VCA) among an Arabic population; the percentage of patients whose VCA fell within the range of 5-6°; and whether demographic variables, severity of the pre-operative varus, and morphological femoral parameters would correlate with the VCA. To our knowledge, VCA measurement of degenerative varus knees among an Arabic population has not been reported previously in the literature. A total of 492 knees (246 patients) were included. The VCA was measured on pre-operative hip-to-ankle radiographs according to a standard protocol. Patient characteristics and radiographic parameters were recorded. The mean VCA was 6.03 ± 1.69°, with 230 knees (46.7%) falling within the (5-6°) range. The VCA significantly differed according to the patient's age (p = 0.02), sex (p = 0.009), height (p = 0.03), degree of varus (p < 0.001), hip offset (p = 0.013), and the presence of excessive lateral coronal bowing of the femur (p = 0.01). Among these, the degree of varus was the only significant factor on the multivariable regression analysis (p = 0.005). The mean VCA in our population was 6.03°; however, the wide distribution of the VCA in our patients does not support the use of a fixed value. The severity of the pre-operative varus seems to be an independent factor with a positive correlation to the VCA and may also provide a clue to the ideal VCA if measurement of this angle is not available.