I. BALLET AND PHYSIQUE

Chapter 4. Knock-Knees

From this brief resume it will be clear that the shape of the pelvis and position of the thigh is an important factor in determining the straightness of the legs as a whole. If the slope inwards is exagger­ated, either because of the width of the pelvis, or as sometimes happens, an unusually small angle at the upper end of the femur, there will result the condition we recognise as knock-knees.

A small degree of this may be considered normal in girls—due as already pointed out, to the naturally wider pelvis and consequent greater slope inwards of the thigh. The simplest test can be made, back view for choice, by standing the child with feet only very slightly turned out, knees just touching. There should normally then be not more than 1i-in. between the heels (allowing that chubby ten-year-old may still have a certain amount of fat between the thighs which would prevent the knees closing completely). It is important that this test should be made with very little turn-out as otherwise the inner condyles of the femur—which may be large at this age and smaller in proportion later on—will prevent the heels from coming together and give a false impression as to the degree of knock-knee existing.

How much greater mal-alignment may be permitted is a matter for balancing up the general physique against this particular dis­advantage. The compact sturdy type can overcome a degree of knock-knee up to 2in. but in no case is more than this desirable. In a thin tall child with poor musculature there is likely to be some slackness of the knee joint indicating weakness and the possibility of trouble later on.

Moreover, there will be difficulty in acquiring speed, elevation and strong pointe work since the thrust from the floor when knock-knees are present is taken, not in a straight line from foot to hip, but in one weakened by an angle at the knee joint and imposing a strain both on foot and knee. Markedly knock-knees with or without laxness in the joint may subsequently account for many of the ligamentous strains, slipped cartilages or various inflammations within the knee joint which are met with from time to time, and even for those strains of the foot, often difficult to locate accurately, which seem to arise for no obvious reason. Figure 11 shows the limit desirable in this formation.

A word of warning must here be given against the hope that a child of ten will outgrow knock-knees. A very young child may do so for the reason that the condition is due to unequal development of the two condyles of the femur, the inner having grown faster than the outer; a child, boy or girl, then appears startlingly knock-kneed at three and recovers completely by five years old, but the type that is met with at ten does not belong to this category.