Genu Varum

Modern Study Review (AI-Generated)

High-Yield Summary

Genu varum, or bow-legged deformity, is a common pediatric lower limb alignment issue with a broad differential diagnosis including physiologic bowing, Blount’s disease, metabolic bone disorders, and skeletal dysplasias. Accurate diagnosis is critical as treatment strategies differ significantly based on etiology. Early identification of pathologic causes such as Blount’s disease or rickets is essential to prevent progression and optimize functional outcomes.

Key Diagnostic Findings

Anatomy

• Genu Varum: Medial angulation of the tibia relative to the femur causing bowing of the lower extremity.
• Physis and Metaphysis: Critical areas to assess for growth disturbances, especially the proximal tibial physis in Blount’s disease.

Clinical Presentation

• Physiologic Bowing: Presents in toddlers, typically resolves by age 2.
• Blount’s Disease (Infantile Tibia Vara): Progressive varus deformity, often in obese, early-walking children, more common in African American females.
• Hypophosphatemic Rickets: Presents with progressive bowing, short stature, and biochemical abnormalities.
• Skeletal Dysplasias: Associated with short stature and dysmorphic features; deformities are generalized and often recurrent.

Imaging

• Standing AP Long-Leg Radiographs: Essential to evaluate mechanical axis and deformity.
• Metaphyseal-Diaphyseal Angle: >16° suggests Blount’s disease.
• Physis Appearance: Widened and irregular in rickets or metaphyseal chondrodysplasia.
• Skeletal Survey: Indicated if generalized skeletal dysplasia is suspected.

Classification Systems

• Blount’s Disease: Langenskiöld classification (stages I-VI) remains standard for radiographic severity and guides treatment.
• Physiologic Bowing: No formal classification; diagnosis of exclusion.
• Rickets and Dysplasias: Diagnosed clinically and radiographically; no specific classification for genu varum deformity.

Current Gold Standard Treatment

Non-operative

• Physiologic Bowing: Observation and reassurance; spontaneous resolution by age 2.
• Blount’s Disease (Early Stage): Bracing (e.g., KAFO) may be effective in Langenskiöld stages I-II in young children.
• Rickets: Medical management with phosphate and vitamin D analogs is primary; surgery delayed until metabolic control is optimized.
• Skeletal Dysplasias: Observation and supportive care; bracing generally ineffective.

Operative

• Blount’s Disease: Indicated for Langenskiöld stages III-VI or failed bracing; proximal tibial osteotomy with or without fibular osteotomy is standard.
• Rickets and Dysplasias: Multi-level osteotomies may be required after metabolic control or growth completion; surgery is complex with higher recurrence risk.
• Post-traumatic or other causes: Tailored osteotomies based on deformity analysis.

Modern Complications & Outcomes

Complications

Outcomes

• Blount’s Disease: Early diagnosis and treatment yield good functional and cosmetic outcomes; late-stage disease has higher risk of recurrence and arthritis.
• Rickets: Optimal medical management improves bone quality; surgical correction improves function but may require multiple procedures.
• Skeletal Dysplasias: Outcomes are variable; surgery improves alignment but deformities often recur, requiring long-term follow-up.

Classic Clinical Notes

Genu Varum

Approach to Genu Varum

First thing: consider the differential diagnosis

• Physiologic bow legs
• Infantile or juvenile/adolescent tibia vara (Blount’s)
• Hypophosphatemic rickets
• Some sort of bony dysplasia – MED, SED, achondroplasia and pseudoachondroplasia, focal fibrocartilaginous dysplasia, metaphyseal chondrodysplasia, Down’s, pseudoachondroplasia
• Post-traumatic (easily ruled out)

As always, do a full history:

• What’s the time course of the problem? How old is the patient? Physiologic bow legs should be gone by 2.
• Family history? Hypophosphatemic rickets is an X-linked dominant trait.
• Overall health, weight gain, motor milestones, growth and development – short stature (rickets or one of the bony dysplasias); ARE THEY A DWARF?? DO THEY HAVE DYSMORPHIC FEATURES!
• Assess for risk factors of Blount’s – black, fat, female, early walker.

Basically, you want to have a treatment algorithm for Blount’s, so you want to make sure that the genu varum you are seeing is in fact Blount’s and not something else – the other disorders are treated differently!!!

Do a physical:

• Measure the deformity and do a knee exam looking for laxity, etc.
• Note the height of the patient (rickets patients are short!)
• Do a general physical to rule out any dysmorphic features and examine the hips.

Get standing AP x-rays, and have low threshold for getting entire femur to see hips and entire tib/fib to see ankles:

• Check the metaphyseal diaphyseal angle
• 16 – Blount’s
• Take a good long look at the physis – Does it look normal? Does it look widened and irregular (rickets or metaphyseal chondrodysplasia)?
• Take a look at both the femoral and tibial epiphysis – do they look normal? Look for epiphyseal dysplasias of some form or another.
• Look at the surrounding bone – are there any cystic lesions, or signs of old trauma?

If you’re not sure if this is part of a generalized skeletal dysplasia, get a skeletal survey!

Hypophosphatemic Rickets (vitamin D resistant rickets)

• X-linked dominant; look for increasing varus deformity, osteopenia, positive family history, short stature (below 5th percentile), and do bloodwork to confirm (low calcium, low phosphorus, high alk phos).
• The management requires optimal medical treatment and the delay of operative correction as long as possible; may require multiple-level osteotomies because of the generalized nature of the deformity.

Bony Dysplasias

• Similar to hypophosphatemic rickets: the deformities are generalized and recurrence is common if you do surgery early.
• Whether you should do surgery at all is controversial. Bracing is not appropriate.
• Try to delay operative treatment until function is affected or growth completed, but they will need osteotomy.

Notice how different the treatment algorithm is for rickets and the bony dysplasias from Blount’s – hence, you MUST seek to make this diagnosis!

Last Updated on January 25, 2026 by orthonet