It was one of those Sundays when I had taken my son for his swimming class in our residential society only. I noticed that there was a 10-year-old girl who was struggling to swim fast in spite of her best efforts!! I had a casual conversation with the mother who told me that her daughter used to be the swimming champion of the school in interschool competitions but off late her performance had deteriorated significantly. She had knock knees!!!

Q-What is Knock Knee?

In a standing position normally, the gap between the knees should be a couple of cms. However even with ankles apart if the knees touch each other it’s called knock knees / Genu Valgum.

Q-Is it normal to have knock knees?

There is a classical developmental pattern that changes with age. Up to 2 years the children walk with bow legs (physiological genu varum). By 2-4 years the alignment changes to “knocking” (physiological genu valgum) & by 4-6 years it becomes straight. So any age group above 4-6 years with knock knees is abnormal& Any asymmetrical genu valgum will be always pathological unless proven otherwise.

Q- How can I check whether my child needs treatment for knock knees?

Just make the child stand with knees just touching each other & bearing weight equally on both legs. Distance between the bony prominence (medial malleolus) on the inner side of the ankle joint should be less than 6-8 CM. Anything above 10 cm should be treated as a warning signal. 

Q- What are the causes of abnormal knock knees?

  • Rickets- most common cause. Vitamin D deficiency occurs due to the lack of exposure of skin to sunlight. With the worldwide lockdown due to Covid 19, the incidence of vitamin D. deficiency has risen alarmingly in all socioeconomic strata.
  • Renal Osteodystrophy- Kidneys have a major role in the synthesis of vitamin D. Children with chronic renal failure present with gradual progressive deformity.
  • Malunion- Bones healed in abnormal position of valgus
  • Physeal Injury- Fractures that involve the medial half of the physis of the distal femur or proximal tibia will cause genu valgum which progresses rapidly because of the Physealbar formation.
  • Infection- Septic arthritis &/or osteomyelitis 
  • Bone tumours- Osteochondromas around the physis of the distal femur or proximal tibia stimulate growth 
  • Obesity- Excess thigh girth forces the child to assume valgus posture to walk effectively.

Q- What are the symptoms of knock knees?

The most prominent symptom of the knock knee is a separation of a person’s ankles when their knees are positioned together. Other symptoms, including pain, are often a result of the gait (manner of walking) adopted by people with knock knees.

These symptoms may include:

  • Knee or hip pain
  • Foot or ankle pain
  • Feet not touching while standing with knees together
  • Stiff or sore joints
  • A limp while walking
  • Reduced range of motion in hips
  • Difficulty walking or running
  • Knee instability
  • Progressive knee arthritis in adults
  • Patients or parents may be unhappy with aesthetics

Q- What is the treatment for knock knees?

For mild cases of knock knee in children or adolescents, bracing may reposition the knees. When this does not work, or if the patient is an adult at the time of diagnosis, a knee-realignment osteotomy is done to prevent or delay the need for knee replacement.

If knock knee is caused by an underlying disease or infection, that condition will be addressed before any orthopedic correction begins. Treatment for mild cases of knock knee in children or adolescents may include braces to help bones grow in the correct position.

If a gradual correction does not occur, surgery may be recommended. 

Q- Does age matter in the line of management?

In the growing child, guided-growth minimal-incision surgery may be used to encourage the leg to gradually grow straight. Adolescents or those who are nearing skeletal maturity will need deformity correction surgery by osteotomy & plating. Very severe cases or those with metabolic problems can be treated with Ilizarov method. Thus the morbidity of surgery highly increases in such late presenters!!!

Q- How long does it take for the child to resume activity after surgery?

If growth modulation is done child can start walking the next day & depending on pain tolerance they can resume all activities in a couple of weeks. Osteotomy takes a longer time of rehabilitation of 6-8 weeks.