Understanding Terminology: Ankle and Knee

Often in physical therapy, we use certain terminology to describe the position or alignment of the legs at rest or during activity.  You have probably seen these terms in your child’s evaluations or progress reports and they probably didn’t make much sense.  Even if your therapist explained the meaning to you, it still might not have made much sense. Hopefully this article can help clear up the meaning of these strange words and what they indicate.

FOOT/ANKLE:

Pronation – This is a term used to describe the sum of three different motions that together cause the heel to slant inward, the arch to collapse toward the floor, and the foot to turn outward during standing and walking.  A certain amount of pronation is normal during the walking cycle. However, if there is an excessive amount present it can lead to stress on ligaments and muscles and can cause other alignment issues throughout the rest of the leg over time.  Excessive pronation is most common in individuals with low muscle tone but can also occur individuals with high muscle tone.

Supination – This term is used to describe the sum of three different motions that together cause the foot to point downward and turn inward. This foot position is common in individuals with increased muscle tone and in certain diagnoses such as Cerebral Palsy.

Pronation and supination can be present during standing or during isolated times of the walking cycle.

KNEE:

Genu Valgum (knock knees)- This term describes knees that are touching or close to touching while the lower leg is bent outwards and the ankles are separated more than normal (see picture below). This alignment is a normal part of development around 2-3 years of age and in most cases will naturally straighten out by 5-6 years of age. However, it may persist when other impairments are involved.  It is often seen in combination with ankle/foot pronation described above. Very severe cases may require surgical intervention.

Genu Varum (bow legs) – This term describes the opposite of genu valgum.  The knees are separated while the ankles come closer to the midline of the body (see picture below).  This alignment is normal in infants and during the first year but should decrease as weight is introduced through the legs with standing and walking.

From infancy to childhood, a typically developing child should progress from genu varum during the first year of life to a relatively straight position with the onset of walking and then into genu valgum around 2-3 years.  The legs should then again realign themselves into a relatively straight position by around 5-6 years.  Females will tend to have slightly more genu valgum than males due to the greater width of the pelvis.

From left to right, the pictures represent genu valgum (knock knees), normal alignment, and genu varum (bow legs).