Malalignment of the legs (knock knees and bow legs)

Shortly before the completion of length growth, the leg axis of the adolescent should be almost straight, which allows an upright gait and optimal load distribution on the knee joints.

Knuckle bones (genu valgum) or bow legs (genu varum) refer to axial malalignments of the legs that can be associated with increased stress on the knee joints.

It is important to know here that deviations in children's leg axes also occur as part of natural development and do not require therapy in these cases. O-legs are typical in infancy, whereas X-legs are typical in kindergarten and elementary school.

Signs of malalignment of the legs may include:

• Visible malposition of the legs
• Impairment of the gait
• Knee pain

In childhood and adolescence, malalignment of the knee joint is mainly a cosmetic impairment for those affected. Pain and functional problems usually do not occur until adulthood. However, this can vary depending on the severity.

The displacement of the normal leg axes leads to increased stress on the knee joint in certain areas. In bow legs, the load-bearing axis is shifted inward, putting extra stress on the inner knee compartment and typically resulting in knee pain on the inner side . X-legs cause the weight-bearing axis to shift outward, putting stress on the outer knee compartment, which can result in knee pain on the outside.

A dreaded complication of axial misalignments is joint wear in the knee joint, known as osteoarthritis. Due to the loss of joint cartilage, the joint surfaces can no longer interact optimally with each other and pain and restricted movement are the result. This risk is significantly greater with bow legs than with knock-knees.

Causes of malalignment of the legs include:

• Normal development process
• Genetic
• Fractures
• Overload during sports (especially soccer)
• Overweight
• Vitamin D deficiency (rickets)

In the course of growth, typical changes occur in children's leg axes. O-legs are the norm in infancy, and X-legs are the norm in kindergarten and elementary school.

The causes of pathological leg malpositions are mostly unknown. It is assumed that in the majority of cases genetic factors can be held responsible for the leg malpositions.

In addition, bone fractures can lead to growth disorders and, in the course of time, to axial malpositions.

Certain sports or obesity can also contribute to deformation of the bones due to the additional load. A typical example is the development of bow legs in competitive soccer in children and adolescents with open growth plates. Overweight adolescents suffer from knock-knees more often than normal-weight peers.

The introduction of regular administration of vitamin D in infancy and early childhood has made vitamin D deficiency, also known as rickets, rare, but it still occurs. Vitamin D is essential for bone metabolism. A deficiency can cause bones to bend, leading to the development of knock knees or knock knees.

Our specialist for pediatric orthopedics Priv.-Doz. Dr. Pestka will interview you and your child in detail regarding any symptoms and complaints. This is followed by a careful physical examination, in which the assessment of the leg axes in standing position is particularly crucial.

An X-ray of the legs can then be taken in order to determine the exact axial malposition.

Conservative therapy:

The following conservative therapies are available:

• Watch and wait
• Physiotherapy

Depending on the age and severity of the malposition, a wait-and-see attitude can be adopted, as the malposition may correct itself in the further course of growth. Regular checks are usually indispensable.

As part of conservative therapy, physiotherapy can help strengthen the muscles. Although this does not affect the axial malposition, the increased stabilization of the knee joint can reduce pain.

Depending on the cause, specific therapy may be required, such as weight loss or vitamin D administration.

Operation:

Due to the risk of osteoarthritis in adulthood, axial malalignments should be corrected before growth is complete. In childhood, there is an elegant possibility with little effort to achieve a correction of the malalignment by means of a growth control at the knee joint. This operation is called temporary hemiepiphyseodesis.

The prerequisite for this procedure is that the growth plates in the knee joint area are still open. In this procedure, the open growth plate is blocked from the inside (in the case of knock knees) or outside (in the case of bow legs) on the upper or lower leg bone near the knee joint. Growth on the opposite side of the growth plate can then compensate for the malposition as growth continues. For this purpose, we use a special small plate (so-called "eight-plate"), which can be inserted through a small skin incision. Without damaging the growth plate, the plate is fixed in the bone with two screws above and below the joint and bridges and blocks it on one side.

Once growth is complete, such interventions are no longer possible. Instead, a more complex operation, a so-called conversion osteotomy, must be performed.

At Orthozentrum Freiburg our pediatric orthopedist Priv-Doz. Dr. Pestka will be happy to advise you further and answer any open questions.

Everything at a glance:

• Surgical time: 20 min per plate using a skin incision of approx. 2 cm in size, i.e. minimally invasive
• Anesthesia: General anesthesia
• Clinic stay: inpatient
• Fit for sports: after completion of wound healing

After the operation, the leg should be rested for the duration of wound healing, i.e. 14 days. Since the operation is minor, but still causes pain, an inpatient stay is necessary. This is usually no longer than three days. Already 14 days after the procedure, sports activities are allowed again. In the following months, the further length growth of your child will bring about the correction of the malposition. In order to determine the optimal time to remove the plate, regular clinical check-ups in our practice are necessary. These are very important to prevent overcorrection of the leg axis. The timing of metal removal depends on the growth rate and the extent of the preoperative deformity. Metal removal is a minor outpatient procedure.