Ganu Valgus and Kids

Here we look at genu valgus in kids. What she needs to know and how to keep track of it.

The Q angle and Kids: The Basics

Genu valgum in kids: What you need to know

We have all seen this. The kid with the awful “knock knees”.  It is a Latin word “which means “bent” or “knock kneed”. It appears to have 1st been used in 1884.

This condition, where the Q angle angle exceeds 15 degrees, usually presents maximally at age 3 and should resolve by age 9. It is usually physiologic in development due to obliquity of the femur, when the medial condyle is lower than the lateral. Normal development and weight bearing lead to an overgrowth of the medial condyle of the femur. This, combined with varying development of the medial and lateral epiphysies of the tibial plateau leads to the valgus development. Gradually, with increased weight bearing, the lateral femoral condyle (and thus the tibial epiphysis) bear more weight and this appears to slow, and eventually reverse the valgum.

Normal knee angulation usually progresses from 10-15 degrees varus at birth to a maximal valgus angle of 10-15 degreesat 3-3.5 years (see picture).  The valgus usually decreases to an adult angle of 5-7 degrees.  Remember that in women, the Q angle should be less than 22 degrees with the knee in extension and in men, less than 18 degrees. It is measured by measuring the angle between the line drawn from the ASIS to the center of the patella and one from the center of the patella through the tibial tuberosty, while the leg is extended.

Further evaluation of a child is probably indicated if:

• The angle is greater than 2 standard deviations for their age (see chart) 
• If their height is > 25th percentile 
• If it is increasing in severity 
• If it is developing asymmetrically

Management is by serial measurement of the intermalleolar distance (the distance between ankles when the child’s knee are placed together) to document gradual spontaneous resolution (hopefully). If physiologic genu valgum persists beyond 7-8 years of age, an orthopaedic referral would be indicated but certainly intervention with attempts at corrective exercises and gait therapy should be employed. Persistence in the adult can cause a myriad of gait, foot, patello femoral and hip disorders, and that is the topic on another post.

Promotion of good foot biomechanics through the use of minimally supportive shoes, encouraging walking on sand (time to take that trip to the beach!), walking on uneven surfaces (like rocks, dirt and gravel), gentle massage (to promote muscle facilitation for those muscles which test weak (origin/insertion work) and circulation), gait therapeutic exercises and acupuncture when indicated, can all be helpful.

Hmmm. We are fully internally rotating this gentleman’s lower leg (and thus hip) on each side. What can you tell us?

Look at the upper picture. Does the knee go past midline? NO! So we have limnited internal rotation of the hip. What are the possible causes?

• femoral retro torsion
• tight posterior capsule of hip
• OA of hip
• tight gluteal group (max or posterior fibers of medius)
• labral derangement

Now line up the tibial tuberosity and the foot. What do you see? The foot is externally rotated with respect to the leg. What are the possible causes?

• external tibial torsion
• subtalar valgus
• fracture/derangement causing this position

Now look at the bottom picture. Awesome forearm and nice choice of watch. Good thing we didn’t wear Mickey Mouse!

Look at upper leg. Hmm. Same story as the right side.

Look at the lower leg and line up the tibial tuberosity and the foot. What do you see? The foot is internally rotated with respect to the leg. What are the possible causes?

• internal tibial torsion
• subtalar varum
• fracture/derangement causing this position

So this individual will have very different lower leg mechanics on the right side compared to the left (external torsion right, internal left). We refere to this as “windswept” biomechanics, as it looks like the wind came in from the right and “swept” the feet together to the left.

What will this look like? Most likely increased pronation on the right and supination on the left. What may we see?

• calcaneal (rearfoot) valgus on right
• calcaneal (rearfoot) varum on the left
• bilateral knee fall to midline
• knee fall to midline on right occurring smoother than on left
   (the patient has an uncompensated forefoot varus bilaterally; he is already partially pronated on the right, so it may appear to be less abrupt)
• toeing off in supination more pronounced on the left (due to the internal torsion and forefoot varus)

The Gait Guys. Increasing your foot and gait IQ with each and every post.