“Increased” femoral anteversion is one of the major impairments affecting walking in children with cerebral palsy. De-rotation osteotomies to correct this are a common orthopaedic procedure particularly as a component of single event multi-level surgery.  This post is the first of a series that will look at different aspects of anteversion and will focus on the published natural history data for the general population (i.e. those without CP).

There are several studies in the literature which have surveyed the natural history of femoral anteversion in the general population which together represent measurements of 1792 hips (Crane, 1959; Fabry, MacEwen, & Shands, 1973; Shands & Steele, 1958; von Lanz & Mayet, 1953).  The data from these series is plotted in the graph below. A couple of things are clear. Probably the most obvious is that is a huge range in measurements made at any given age (represented by the standard deviation). There is almost certainly a considerable measurement error but even so the conclusion should probably be that there is a wide range of femoral anteversion within the general population. Historical data from cadaveric specimens would appear to support this (Dunlap, Shands, Hollister, Gaul, & Streit, 1953).

The other consistent finding is that anteversion is high at birth and reduces with age. The data appears to suggest the mean value at birth is about 40° and has reduced to about 15° at age 16. The graph doesn’t appear to have flattened out completely by this time and other studies have suggested that the mean value amongst the general adult population may be less than 10° (Dunlap et al., 1953).

It should be noted that, at the age when children are generally being assessed for femoral derotations (8-10 years old), the average femoral anteversion is over 20° within the general population and a significant number of children (without CP) have anteversion in excess of 30° (remember that by definition 15% of the population have anteversion greater than the mean plus one standard deviation plotted here). Many kids with CP have measured anteversion in this range and for them the clinical question should perhaps not be whether they have high levels of anteversion or not but what it is that this causes them to walk with an intoed gait when many kids without CP have similar levels of anteversion but manage to walk with “normal” mild external foot progression?

It is perhaps worth pointing out that the measurements reported in these series used quite different techniques from the modern clinical measures of anteversion. The general trends are almost certainly valid but the actual values may differ when different measurement techniques are used.

Crane, L. (1959). Femoral torsion and its relation to toeing-in and toeing-out. J Bone Joint Surg Am, 41-A(3), 421-428.

Dunlap, K., Shands, A. R., Jr., Hollister, L. C., Jr., Gaul, J. S., Jr., & Streit, H. A. (1953). A new method for determination of torsion of the femur. J Bone Joint Surg Am, 35-A(2), 289-311.

Fabry, G., MacEwen, G. D., & Shands, A. R., Jr. (1973). Torsion of the femur. A follow-up study in normal and abnormal conditions. Journal of Bone and Joint Surgery, 55(8), 1726-1738.

Shands, A. R., Jr., & Steele, M. K. (1958). Torsion of the femur; a follow-up report on the use of the Dunlap method for its determination. J Bone Joint Surg Am, 40-A(4), 803-816.

von Lanz, T., & Mayet, A. (1953). Die gelenkorper des menschlichen hufge- lenkes in der progredienten phase inherer umweigigen ausformung. Zeitschrift Anatomie, 117, 317-345.