Knock knee (genu valgum) is a condition where a person has a large gap between their feet when they're standing with their knees together. Normal many children have knock knees, which becomes obvious at around the age of 4. It's just a normal part of their development, and their legs will normally straighten by the age of 7. However, knock knees can very occasionally be a sign of an underlying condition that needs treatment, especially if the condition develops in older children or adults, or doesn't improve with age.
Symptoms of knock knees
If someone with knock knees stands with their knees together, their lower legs will be spread out so that the distance between their and ankles is creating the gap more than 8cm.
Knock knees don't usually cause any other problems, although a few severe cases may cause knee pain, a limp or difficulty walking. Knock knees that don't improve on their own can also place your knees under extra pressure, which may increase your risk of developing arthritis.
When to get medical advice?
Knock knees in children aren't usually a cause for concern and should improve as your child gets older. However, visit Orthopaedic doctor, if you have following issues.
- the gap between the ankles is greater than 8cm while standing with the knees together
- there's a big difference between the angle of the lower legs when standing compared with the upper legs
- the problem seems to be getting worse
- a child under the age of 2 or over the age of 7 has knock knees
- only one leg is affected
- there are other symptoms, such as knee pain or difficulty walking
- you have any other concerns about the way your child stands or walks
- you develop knock knees in adulthood
What causes knock knees?
Knock knees are common in healthy children under the ages of 7, and are just a normal part of growth and development. The legs will usually gradually straighten as the child grows, although mild knock knees can last into adulthood.
Knock knees that develop later in childhood or don't improve with age can sometimes be associated with an underlying problem, such as:
- rickets– problems with bone development resulting from a lack of vitamin D and calcium
- loose knee ligaments
- an injury or infection affecting the knees or leg bones
- genetic conditions affecting the development of the bones or joints
- osteoarthritis or rheumatoid arthritis.
What is treatment for knock knees?
In most cases, knock knees don't need to be treated because the problem tends to correct itself as a child grows. Child doesn't need to avoid physical activity, wear supportive leg braces or shoes, or do any special exercises. Mild knock knees that persist into adulthood don't need to be treated unless they're causing problems, such as knee pain.
If knock knees are caused by an underlying condition, treatment for this may be necessary. For example, rickets can be treated with vitamin D and calcium supplements.
Adults with arthritis may benefit from wearing leg braces or special insoles to reduce the strain on their knees or sometimes surgery
Surgery for knock knees is rarely necessary, although it may be recommended if the condition is severe or persistent.
There are 2 main types of operation that may be carried out:
- In children whose growth is not complete small metal plates are placed on the inside of the knees, which helps correct their growth over a period of around 12 months; the plates are removed once the treatment is complete.
- When the growth is complete an osteotomy is performed, where the bone is cut at the level of deformity, realigned into the correct position; plates and screws are used to fix the bones in their new position.
A patient can usually return to all normal activities after having an osteotomy in few months.
We came across 21yrs old female presented to us with deformity involving both legs. Deformity was progressive which was causing difficulty in walking. On examination there was 15o valgus in both knees. Figure 1 shows whole lower leg x ray showing genu valgum.
Corrective Femoral Osteotomy is done where the thigh bone is cut and wedge shape piece of bone is removed and cut ends are fixed with plate and screws as shown in figure 2
Postoperatively the range of motion started on the day of surgery and weight bearing at 6wks. Patient resumed her pre surgery activities after 3months and was able to participate in sports after 5months of surgery which she was not able to because of knock knees. Patient reports that the surgery has improved her quality of life, confidence and ability to outperform her own expectations.