Bow Legs and Knock Knees Correction Surgery
Short answer
Bow legs (genu varum) and knock knees (genu valgum) are deviations of the leg from its normal mechanical axis. When the deviation is significant, it can be corrected surgically by cutting the bone and fixing it in the correct alignment, a procedure called an osteotomy. Correction can also be combined with limb lengthening, and keeping the mechanical axis straight is essential in every lengthening.
What are bow legs and knock knees?
In bow legs (varus), the knees stay apart when the ankles touch. In knock knees (valgus), the knees touch while the ankles stay apart. Both change how load passes through the knee, which over time can stress one side of the joint.
The mechanical axis of the leg
The mechanical axis is the line from the centre of the hip to the centre of the ankle. In a well-aligned leg, it passes close to the centre of the knee. If the line passes inside the knee, the leg is in varus; if it passes outside, the leg is in valgus. Surgeons measure the axis on standing full-length X-rays. Read Importance of the mechanical axis during limb lengthening.
How correction works
The surgeon cuts the bone in a controlled way (osteotomy) and fixes it in the planned alignment, using an internal or external device. Healing takes several weeks to months, with physiotherapy to restore movement and strength.
Correction combined with lengthening
Lengthening a bone with an intramedullary nail can itself change the mechanical axis, which is why careful nail placement is essential to avoid creating bow legs or knock knees. When a patient already has a deviation, correction can often be planned together with lengthening. See How does limb lengthening work? and leg length discrepancy surgery.
Who needs surgery?
Mild curvature often needs no treatment. Surgery is considered when the deviation is significant, causes pain or affects function, or when you are planning limb lengthening. The surgeon decides after examining you and your X-rays.
Causes of bow legs and knock knees
• Normal development: many young children have bow legs or knock knees that correct themselves with growth.
• A fracture that healed with an angle.
• A growth plate injury in childhood.
• Wear of one side of the knee joint over many years, which can increase the deviation.
How the deviation is measured
On a standing full-length X-ray, the surgeon draws the mechanical axis from the centre of the hip to the centre of the ankle and measures where it passes the knee and the angles of the femur and tibia. This shows which bone is the source of the deviation and how much correction is needed.
Osteotomy: the principle of correction
In an osteotomy, the surgeon cuts the bone near the deformity and changes its angle so the axis passes close to the centre of the knee again. The bone is then fixed while it heals. With gradual correction methods, the angle can be changed slowly over days, similar to the gradual principle of limb lengthening.
Recovery
Recovery depends on the bone, the method and whether lengthening is done at the same time. Physiotherapy helps restore movement and strength. When correction is combined with lengthening, recovery follows the lengthening timeline.
Cosmetic patients with mild bow legs
Some patients who want to be taller also have mildly bowed legs. In the assessment, the surgeon explains whether a correction can be planned together with the lengthening.
Living with bow legs or knock knees
Many people with a mild deviation have no symptoms and do not need treatment. Others notice uneven shoe wear, knee pain on one side or feel self-conscious about the shape of their legs. The decision to correct is based on the measurements, the symptoms and your goals, and the surgeon explains the options after examining you.
Get an assessment
Send us standing full-length leg X-rays and your health history on WhatsApp (+90 533 016 45 62) for a free assessment with our surgeon.
FAQ
What is the difference between varus and valgus?
In varus (bow legs) the knees are apart; in valgus (knock knees) the knees touch while the ankles are apart.
Can bow legs be corrected in adults?
Yes. Significant deviations can be corrected surgically with an osteotomy.
Can correction be done together with limb lengthening?
Often yes. The surgeon plans the correction and the lengthening together.
Can limb lengthening cause bow legs?
If the nail is not placed with attention to the mechanical axis, lengthening can cause varus or valgus. Careful planning prevents this.
How is the mechanical axis measured?
On standing full-length X-rays of the leg.
Will I need physiotherapy after correction?
Yes. Physiotherapy helps restore movement and strength after any osteotomy.
Related pages
How Does Limb Lengthening Work?