Genu Valgum

Modern Study Review (AI-Generated)

High-Yield Summary

Genu valgum, commonly known as “knock knees,” is a coronal plane deformity characterized by medial angulation of the knees. It is a frequent pediatric presentation with a broad differential diagnosis ranging from physiologic variants to metabolic and skeletal dysplasias. Accurate diagnosis and timely intervention are critical to prevent long-term patellofemoral dysfunction and gait abnormalities. Current management emphasizes observation in young children with physiologic genu valgum and guided surgical correction in persistent or pathological cases.

Key Diagnostic Findings

Anatomy

• Deformity: Medial angulation of the tibiofemoral joint causing knees to touch while ankles remain apart.
• Growth Plates: Distal femoral and proximal tibial physes are key sites influencing deformity progression or correction.

Clinical Presentation

• Age: Physiologic genu valgum peaks at 3-4 years, typically resolving by 7-8 years.
• Symptoms: Usually asymptomatic but may present with gait abnormalities or anterior knee pain due to patellofemoral maltracking.
• Physical Exam:
• Measure intermalleolar distance and tibiofemoral angle.
• Assess for ligamentous laxity, limb length discrepancy, and associated dysmorphic features.
• Evaluate overall growth and development for systemic causes.

Imaging

• Standing AP Long-Leg Radiographs: Essential to assess mechanical axis deviation, joint orientation angles, and to rule out physeal or bony abnormalities.
• Additional Imaging:
• Full-length femur and tibia films to evaluate hip and ankle alignment.
• Skeletal survey if a generalized skeletal dysplasia is suspected.

Classification Systems

Current Gold Standard Treatment

Non-operative Indications and Management

• Observation:
• Children <3 years with valgus <20° and no functional impairment.
• Physiologic genu valgum typically resolves by age 7-8.
• Non-surgical interventions: Limited role; bracing and physical therapy generally ineffective for structural deformities.

Operative Indications and Treatment

• Indications:
• Persistent valgus deformity >15-20° beyond 8-10 years of age.
• Intermalleolar distance >10 cm.
• Associated functional impairment or patellofemoral symptoms.
• Underlying pathologic causes requiring correction.

• Surgical Options:

– Correction Goals:

• Aim for neutral or slight valgus alignment.
• Avoid overcorrection into varus to prevent medial compartment overload.

Modern Complications & Outcomes

Complications

Outcomes

• Most children with physiologic genu valgum achieve spontaneous resolution without intervention.
• Surgical correction via guided growth techniques yields excellent functional and cosmetic results when appropriately timed.
• Early recognition and treatment of pathologic causes improve long-term joint health and gait mechanics.

Classic Clinical Notes

Genu Valgum

Approach to Genu Valgum

First thing: consider the differential diagnosis

• Physiologic knock knees – should max out at around 12+/-8° at 3-4 years of age
• Bony dysplasia – MED, SED, Morquio’s
• Hypophosphatemic rickets – usually varus, but can be valgus
• Proximal tibial fracture – often develop valgus deformity once healed
• Pseudoachondroplasia

As always, do a full history:

• What’s the time course of the problem? How old is the patient? – valgus should be turning around at 3-4 yrs
• 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)

The key is to be looking for hints that this is something other than simple physiologic knock knees

• On the exam, you fuckin’ better be thinking that this is not simple physiologic knock knees!

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.

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

Management

• In general, genu valgum is associated with more patellofemoral problems than genu varum
• If they are 30-36 months old and otherwise completely normal – observe; even if they are >20 degrees, they may resolve.
• Non-surgical management is not practical for these patients.

For physiologic knock knees:

• Wait until they’re 10 years of age, have >10 cm intermalleolar distance, or >15-20 degrees of valgus – then consider a hemi-epiphyseodesis if you are confident you know how much length they are going to gain on that other side; or medial physeal stapling if unsure (you can take out the staple – but you are not guaranteed that it will continue to grow once you take out the staple)

• i.e., use a hemi-epiphyseodesis when you’re fairly certain that overcorrection will not occur, but use staples when you aren’t sure or when the growth parameters are a bit weird.

Note: in general, if you are operating on a genu varus – you want to correct them big time (basically OVERcorrect them.) But in genu valgum, you want to just get them about neutral, maybe slight valgus. Do not overcorrect the valgus knee.

Last Updated on January 25, 2026 by orthonet