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Are valgus knees in children normal?
When in a child standing with knees straight, with feet parallel and toes pointing straight ahead, the knees are touching and there is a gap between the ankles, we are dealing with knee valgus. However, at different ages, the limit of valgus knees considered normal is different. Knee valgus appears in children around the age of two, to increase to 8-10 degrees later by the age of about four. It then decreases over several years, reaching a stable value of 5-7 degrees by the age of 7. Symmetrical valgus knee at this period of a child's development is not pathological, it is normal.
What's different is when we deal with it above the age of 8 or the knee valgus is asymmetrical. Often parents are the first to notice worrying symptoms in their children's gait. The child walks with knees rubbing against each other and feet spread apart, at the same time often complaining of pain in the thigh and calf. Then the child's gait is not natural, with medial collapse of the ankles and feet. We wrote about this on the occasion of flat feet.
Knuckle knees - causes
The most important thing is to determine the correct cause of valgus knees through a thorough medical history, physical examination and appropriate imaging. The deformity is most often localized to the bone. Determining its nature is very important, as it implies a different treatment. Most often it affects the knee joint area - the distal part of the femur, or the proximal part of the tibia.
In symmetrical cases, the direct cause is often difficult to determine, in which case valgus is referred to as idiopathic. It can be diagnosed after differential diagnosis and exclusion of all known causes. It is most often explained as a lack of spontaneous correction of physiological valgus - such a deformity can progress with the growth of the child. Other theories link it to: asymmetric loading, obesity or foot defects. A family history is an important risk factor. The following should also be considered: bone dysplasias, multiple cartilaginous outgrowths, kidney disease or congenital bone fragility.
In the case of asymmetric deformities, the cause is often easier to determine. It can be: abnormal alignment of the fragments after a fracture, asymmetric damage to the growth zones after trauma (this type of deformity is progressive), arthritis, benign bone tumors modeling growth (most often cartilaginous and cartilaginous outgrowths). Squared deformities in children should not cause pain. If pain is present, the diagnosis should be expanded to include internal damage to the knee joint, inflammatory or proliferative diseases.
Poor posture and muscle weakness can cause apparent knee valgus
The knee joint is supported by numerous muscles that are not only responsible for movement, but also for knee stabilization. If everything is in order and the knee is properly aligned, the weight of the body is distributed evenly along an axis running from the hip through the knee to the ankle. When any muscle group, as a result of injury or overload, is weakened, misalignment can occur at the knee joint. The most common muscle imbalance, which can lead to internal rotation of the entire limb and apparent valgus knee, is likely the result of weak hip adductor muscles, while the adductors are too tight. An imbalance between these two muscle groups causes the knees to point inward.
Another element affecting the positioning of the knees in internal rotation is the anterior tilt of the pelvis, which can cause internal rotation of the hips, forcing both the left and right knee to point inward. This type of positioning can lead to knee joint overload through asymmetrical loading and adversely affects the patella's trajectory. The good news is that apparent valgus that occurs due to poor posture can be corrected with properly selected rehabilitation. However, it is important that it is detected early.
Knee valgus - examples of causes:
- idiopathic - undetermined,
- familial,
- congenital - absence of fibula,
- developmental - physiological,
- trauma - past fractures, injuries to the growth cartilage area,
- metabolic diseases,
- congenital bone fragility,
- bone dysplasia,
- rheumatoid arthritis of the knee.
How to check if we have knee valgus?
There is a very simple way to check if we have knee valgus in our case. Stand with your legs together so that both knee and ankle joints are joined. If this is not possible, because the knees are in contact, but there is more than 5 centimeters of space between the ankles, we most likely have knee valgus. We should then go to a doctor, who will show us the next course of action.
Diagnosis of valgus knees
In the medical history, it is important to ask questions about the child's development, diet and whether there is a family history of similar deformities, rickets or skeletal dysplasia. The doctor will then perform a full examination of the hip, knee and foot, and assess the length and axis of the lower extremities. The clinical examination is carried out in the supine position. Among other things, the severity of the femoral deviation and the torsional profile of the tibia are assessed. The angle is measured with a goniometer. It should be noted that the clinical examination evaluates the anatomical axis of the limb, that is, how the limb looks externally. Due to the complex structure of the femur, the anatomical axis of the limb under normal conditions shows a slight valgus. A result of more than 10 degrees is abnormal.
In general, a physical examination is sufficient to raise the suspicion of valgus knee disease
In the diagnosis, it is necessary to take an X-ray of the whole lower limbs standing AP (bilateral from the hip to the ankles). It allows you to assess the deviation of the knee joint from the mechanical axis of the limb. The mechanical axis of the limb is represented by a line running from the center of the femoral head to the center of the ankle bone. Correctly, it should pass through the center of the intercondylar notch, which defines the center of the knee joint in the frontal plane. Slight deviations in the mechanical axis of the limb of less than 1 cm are not considered pathological. In addition, on the basis of whole limb X-rays, it is possible to accurately determine the progression of the deformity, how many degrees there are and where in the limb.
When and how to treat knee valgus?
We deal with the pathological condition when the defect persists or worsens in patients over the age of 7. One should be cautious in surgical treatment of children at a younger age, especially when the defect is symmetrical. For small deformities, or symmetrical non-painful deformities in young children, observation and possibly physiotherapy is indicated. It is aimed at improving the biomechanics of movement of the knee joint and promoting spontaneous correction. For more severe deformities, surgical intervention should be considered. The indications for it are determined by the result of the radiograph.
If we are dealing with the most common form of deformity, localized around the knee joint, and the child still has growth potential (boys usually up to 14-15 years, girls usually 13-14 years), a growth modulation procedure with a figure-eight plate can be used. The procedure is minimally invasive, and allows a quick return to school and sports (most patients regain full function after 2 weeks). In this procedure, a small plate is placed on the growth zone of the bone (femur or tibia, respectively, depending on the location of the deformity), which causes the limb to grow asymmetrically for a specified period of time and straightens the deformity on its own. This is the least burdensome surgical treatment for the patient. Its main disadvantage is that once the growth potential is lost, this method can no longer be used.
For significant deformities in adolescents who already have a low growth potential, adults or located far from the joint, surgical treatment with corrective osteotomy should be considered. The procedure involves cutting the bone, positioning it correctly and reconnecting it in the manner most suited to the patient (with a special plate, intramedullary nail or external braces). This type of treatment is more taxing on the patient and resembles the treatment of a surgically treated fracture. In many cases, it requires relieving pressure on the limb, and recovery usually takes about three months and depends on the chosen method of stabilization and the course of healing.
What does knee valgus affect?
Knee valgus leads to abnormal mechanical loading of the joint surfaces, which can cause overloading of the lateral compartment, damage to the lateral meniscus and early degenerative changes. Knee valgus also affects the patellofemoral joint. It can cause lateral pinning of the patella, and in extreme cases promote patellar subluxation or dislocation. In addition, it affects the alignment of the ankle joint and the entire foot, promoting the formation of a flat foot.
Exercises for valgus knees
Knee valgus has mainly a bony cause, so rehabilitation - exercises - is designed to improve the biomechanics of knee joint movement. It is also intended to promote spontaneous correction in deformities of minor severity. A selected set of exercises for children with valgus knees:
Exercise 1. In a bent sit with knees bent outward, grasp each other's feet with the palms of your hands and alternately, once with the left and once with the right leg, touch the toes of your feet to your nose.
Exercise 2. In a bent-back supported sit with knees bent outward, try to lift the feet slightly and applaud with them.
Exercise 3. In a cross-legged sit, try to rise while keeping the legs crossed.
Exercise 4. In a bent sit with knees bent outward, grasp the feet touching with the soles of the feet with the palms of the hands, lean forward while pushing the knees apart with the elbows.
Exercise 5. In a supine position with the physiotherapy tape in a loop on the knees, with the feet aligned together, stretch the tape by bending the knees to hip width, lift the hips upward while keeping the tape taut.
Related articles:
Other possible cases of pediatric orthopedics.
Bibliography:
- White G.R., Mencio G.A.: Genu Valgum in Children: Diagnostic and Therapeutic Alternatives. „Journal of the American Academy of Orthopaedic Surgeons”, 1995
- Salenius P., Vankka E.: The development of the tibiofemoral angle in children. „The Journal of Bone and Joint Surgery”, 1975
- Kaspiris A., Zaphiropoulou C., Vasiliadis E.: Range of variation of genu valgum and association with anthropometric characteristics and physical activity: Comparison between children aged 3-9 years. „Journal of Pediatric Orthopaedics B”, 2013
- Maciałczyk-Paprocka K., Stawińska-Witoszyńska B., Kotwicki T. et al.: Prevalence of incorrect body posture in children and adolescents with overweight and obesity. „European Journal of Pediatrics”, 2017
