Disease Description (Causes and Symptoms)
- Summary of definition: Genu valgum (knock knees, X-shaped legs) is a leg alignment abnormality in which the area below the knees spreads apart when standing, increasing the distance between the ankles. In children, physiological (normal) genu valgum is common and usually improves as they grow.
- Main causes
- Physiological growth pattern (common during infancy and early childhood, usually between 2 and 10 years of age; most improve around 7–8 years of age)
- Metabolic bone disease (e.g., rickets, vitamin D deficiency)
- Growth plate injury (trauma, infection)
- Skeletal developmental abnormalities such as osteogenesis imperfecta and skeletal dysplasia
- Rarely, tumors, neuromuscular disease, etc.
- Pathophysiology (brief): An imbalance in the growth plates of the femur and tibia or deformation of the bone structure shifts the mechanical axis of the knee joint laterally, increasing medial knee compression and causing tension in the lateral soft tissues.
- Main symptoms
- Visually X-shaped legs (increased distance between the ankles)
- Abnormal gait, frequent tripping and falling
- Pain in the knees or wrists, etc. (especially with severe deformity or in adults)
- In severe cases, this may lead to growth impairment or intra-articular imbalance
- Diagnostic points
- Clinical examination (distance between the knees and ankles while standing, gait observation)
- Weight-bearing (long-leg) X-ray: mechanical axis and knee angle (plain radiographs are necessary for detailed evaluation)
- If necessary, blood tests (vitamin D, calcium, phosphorus, ALP, etc.), growth plate evaluation, and confirmation of past trauma and family history
Treatment Methods
- Observation (most children)
- Physiological genu valgum: because spontaneous improvement is highly likely depending on age, observation is generally recommended between 2 and 10 years of age
- Regular observation and follow-up with photographs/radiographs are recommended
- Conservative treatment
- Treatment of the underlying cause (e.g., rickets → vitamin D and calcium supplementation)
- Physical therapy: functional improvement through muscle strengthening (medial muscles) and exercise therapy
- Orthosis: generally ineffective for physiological genu valgum and often not recommended. Used only for pathological causes or specific cases at the discretion of a specialist.
- Surgery during growth (when bone growth remains)
- Temporary hemiepiphysiodesis, guided growth: gradually corrects the deformity by temporarily suppressing one side of the growth plate (e.g., with a plate and screws). It is relatively safe and allows rapid recovery.
- Surgery in adults or after growth has ended
- Corrective osteotomy: the bone is cut to correct its axis (rehabilitation is required)
- Joint replacement or other procedures may be considered when severe arthritis is also present
- Criteria for treatment selection
- Age, degree of deformity (angle, distance), whether it is progressing, presence of pain or functional impairment, and whether an underlying cause is present
- Precautions/self-care
- Avoid unnecessary use of orthoses during growth
- Seek early specialist consultation if pain, gait impairment, or progression is suspected
- Ensure appropriate treatment of underlying diseases such as rickets
Checklist Before an Outpatient Visit (Items to Bring and Example Questions)
- Items to bring
- List of currently used medications, including supplements for infants and young children
- Previous test results and radiographs (originals or a CD if possible)
- When symptoms began and how they have progressed (worsening or improvement), degree of pain (pain diary), and videos of walking (recorded with a smartphone from the front, back, and side)
- Family history (whether parents or siblings have similar deformities), and history of previous knee or leg trauma or infection
- Items useful to record during the consultation
- Discomfort during daily activities (exercise limitations, frequency of falls)
- Situations in which pain occurs (at rest, during exercise, at night, etc.)
- Growth and development (rate of height increase, other skeletal abnormalities)
- Possible tests to request (check in advance)
- Weight-bearing (long-leg) X-ray and plain knee X-ray
- Blood tests (vitamin D, calcium, phosphorus, ALP, etc.) — if rickets is suspected
- If necessary, consultation with an orthopedic specialist and an explanation of the surgical treatment plan
Examples of General Questions to Ask the Doctor
- "How likely is it that my (child's) legs will improve naturally?"
- "What tests do you recommend, and why?"
- "What are the risks and expected benefits of the treatments (medication, physical therapy, and surgery)?"
- "Are there any activities I should avoid or exercises you recommend in daily life?"
- "How should we prepare for the future risk of arthritis?"
Examples of Condition-Specific Questions
- "What is the angle of my child's knee (or the distance between the ankles), and is it outside the normal range for their age?"
- "If growth modulation using the growth plate (hemiepiphysiodesis) is needed, when would be the most appropriate time to perform the procedure? How much remaining growth time is required?"
(Note: Genu valgum in most children improves physiologically, but if there is pain, functional impairment, progressive deformity, or abnormal test findings, evaluation by an orthopedic specialist and additional testing such as radiographs and blood tests are necessary.)