Bow Legs

Bow legs are also referred to as genu varum, which is defined as the deformity in which the person’s legs seem to appear as a bow-shaped structure. In general, bow legs are the deformity in which the tibia gets bent outward rather than lying parallel with the femur, or we can say that one of the lower legs points medially toward the midline. This article will discuss the causes and bow legs correction techniques for the deformity. We will also include the bow legs symptoms to diagnose the issue.

Who is prone to the bow legs?

Infants are often born bow-legged because of their folded position while they are in their mother’s womb. During typical growth patterns, the child outgrows this as they stand and walk. So, for infants till the age of 2 years, bow legs deformity is not unusual. Mostly, a child’s legs start to straighten when they start standing and walking and bearing their body weight on them while walking or standing (usually 12-18 months).

It is suggested that parents talk to a doctor to understand whether their child has the tendency to develop knock knee deformity or bow leg, apart from the normal growth patterns. To determine whether your child is bow-legged, you can observe whether:

• The direction of the knee versus the direction of the foot falls outside the normal pattern.
• The angle of the child’s thighbone to shinbone falls outside the normal range.
• One leg of the child is significantly less or more angled than the other leg.

Causes of bow legs

There are several reasons due to which bow legs syndrome develops from illnesses like Blount’s diseases, vitamin deficiencies, improperly healed fractures, lead poisoning, etc. Some of the common conditions and illnesses that lead to bow leggedness are listed below:

• Fluoride poisoning 
• Improperly healed fractures
• Blount’s disease
• Lead poisoning 
• Paget’s disease 
• Damage to the growth plate 
• Rickets 
• Achondroplasia

What are the symptoms of a bow leg deformity?

The most common visible symptom related to bow leg deformity is that an individual’s knees do not touch when they stand with their ankles and feet together. This leads to bowing of legs which means if it continues beyond the age of 3 years, there is a risk of bowing deformity. Some of the common symptoms experienced by a person having bow legs deformity are:

• Reduced range of motion in the hips 
• Instability of the knees
• Unhappy feeling of appearance 
• Hip or knee pain
• Difficulty in running or walking 

The problem of progressive knee arthritis is quite common in adults who were not diagnosed or treated for bow legs deformity during childhood. Adults facing the problem of bow legs for many years tend to carry their body weight on the inner muscles of their legs, thereby stretching the outer muscles leading to instability, pain, and arthritis. To prevent and delay the need for knee replacement, it is recommended to undergo osteotomy to realign the knee.

Bow legs diagnosis

To determine the bow legs issue, typically, a doctor will examine the patient’s medical history, conduct a physical examination, and further provide a standing-alignment EOS or X-ray imaging of the leg bones from the ankle hip. The imaging process will assist the orthopedist in recognizing the position of deformity magnitude along with the mechanical axis that determines where the bend took place.

Intercondylar distance: The doctor first checks the child’s intercondylar distance, which can be calculated by holding the child’s ankle together and calculating the distance between the knees. This will give an idea regarding the bow legs; if the intercondylar distance is greater than 6 cm, the child has bow legs.

Clinical thigh leg angle: The doctor will now calculate the clinical thigh angle, which is defined as the angle formed between the thigh and leg of the person. If the angle measurement is more than 20 degrees, the doctor will ask for an X-ray in the following cases:

• If there is the persistence of bow legs after two years of age.
• When there occurs an aggravation of bow legs after the age of one year.
• When the intercondylar distance is found to be greater than 6 cm.
• If the clinical thigh angle is greater than 20 degrees.

Measurement: The doctor also sketches the straight line from the anterior superior iliac spine passing via the patella centre to the medial malleolus. In normal conditions, all the structure lies in the identical line; however, in reference to bow legs, medial malleolus lies medially to the line. The line has possibly been drawn on the body; however, for effective outcomes, it needs to be drawn in full-length lower limb x-ray.

Bow legs correction techniques?

The mild cases of bow legs may initially be carefully identified over time by the paediatric orthopedist. The technique of bracing will possibly be tried to gradually correct the leg angles. If the bracing technique doesn’t provide an effective result, it is recommended to have surgery for the bow legs treatment. The practice of physical therapy also plays a significant role, especially when surgery has been performed.

Surgical bow leg correction technique for children and mature adolescents

In the growing child, minimal-incision surgery can be employed to support the limb to gradually develop straight. In skeletally mature adolescents, osteotomy treatment is recommended that helps in straightening the legs. X-rays are used to determine the position of the deformity and its magnitude. In most cases, the tibia is treated; however, there are some events where the femur of both tibia and femur are being treated. When the deformity is moderate, osteotomy has been typically stabilised with internal fixation; however, if the deformity is severe, gradual realignment of the limb through osteotomy is carried out with an external fixator.

Using the external fixators, pins are inserted into the bone and protrude out of the body to attach it to an external stabilising structure. In some conditions, the underlying bow leg condition makes one leg shorter than the other leg and can be corrected using limb strengthening surgery.

Conclusion

We have provided a detailed description of the bow legs deformity along with bow legs treatment procedures. It can be concluded that if the bow leg deformity persists, a patient needs to undergo surgery or other bow leg corrections technique recommended by the doctor.