Blounts Disease: Symptoms, Types, Causes and Treatment

Blount disease, also known as tibia vara, is a growth disorder of the shin bone (tibia) that can lead to leg deformity, pain, and mobility issues—especially in children and adolescents. While bowed legs are common in toddlers and often resolve on their own, Blount disease is a more serious condition where the bowing worsens with time. Understanding the symptoms, types, causes, and treatment options is crucial for early diagnosis and effective management. This article provides a comprehensive, evidence-based overview of Blount disease, synthesizing insights from current research and clinical experience.

Symptoms of Blounts Disease

Blount disease can present subtly at first, but its hallmark is progressive bowing of the legs below the knees. Recognizing the symptoms early can make a significant difference in treatment outcomes and help prevent long-term complications.

Symptom	Description	Age Group	Source
Bowed Legs	Outward bowing of lower legs	Children	1 4 9
Gait Abnormality	Limp or abnormal walking pattern	All ages	2 4 9
Knee Pain	Discomfort in or around the knee	Juvenile/Adol.	2 9
Limb Shortening	Affected leg appears shorter	All ages	9

Table 1: Key Symptoms

Bowed Legs and Limb Deformity

The most recognizable feature of Blount disease is a progressive bowing (varus deformity) of the lower legs. This bowing is typically below the knee and can affect one (unilateral) or both legs (bilateral). Unlike the physiological bowing seen in many toddlers, the curve in Blount disease worsens with time and does not resolve spontaneously as the child grows 1 4 9.

Gait Abnormality

Children with Blount disease often develop an abnormal gait. Parents may notice limping, waddling, or difficulty running. In some cases, these gait disturbances are painless; in others, they can be associated with discomfort or fatigue after physical activity 2 4.

Knee Pain

While Blount disease is not always painful in its early stages, some children and adolescents may complain of knee pain—especially as the condition progresses. This pain can be due to abnormal joint loading, cartilage wear, or associated hip and knee issues 2 9.

Limb Shortening

As the disease affects the growth of the inner (medial) part of the tibial growth plate, the affected leg may become shorter than the other, leading to a noticeable leg length discrepancy 9.

Other Features

• Tibial Torsion: The shin bone may twist inward, causing the feet to point toward each other.
• Medial Plateau Depression: In severe cases, the inside of the knee joint surface may be lower than the outside, further worsening deformity 10.
• Reduced Range of Motion: Stiffness or restricted movement in the knee joint can develop in advanced cases 1 9.

Types of Blounts Disease

Blount disease is not a single entity; it is classified based on the age at which the symptoms first appear. Understanding the types helps tailor treatment and predict prognosis.

Type	Age of Onset	Main Features	Source
Infantile	< 4 years	Often bilateral, severe progression	1 3 4 5 6 9
Juvenile	4-10 years	Less common, may be unilateral or bilateral	3 4 5 12
Adolescent	> 10 years	Usually unilateral, milder deformity	3 4 5 6 12

Table 2: Types of Blount Disease

Infantile (Early-Onset) Blount Disease

This form develops in children under four years old. It is the most common type and often affects both legs, leading to severe and progressive bowing if not treated. Infantile Blount disease can be particularly aggressive, and if left untreated, may cause permanent deformity and early joint degeneration 1 4 5 6 9.

Juvenile Blount Disease

Symptoms emerge between ages four and ten. Juvenile Blount disease is less common than the infantile form and may present as either unilateral or bilateral bowing. The deformity is typically less severe than in the infantile type, but still requires careful monitoring and treatment 3 4 5 12.

Adolescent (Late-Onset) Blount Disease

Adolescent Blount disease appears after the age of ten, often in teenagers. It usually affects only one leg and tends to present with milder deformity compared to the infantile form. Obesity is a strong risk factor in this group 3 4 5 6 12.

Differences Between Types

• Laterality: Bilateral involvement is more common in infantile Blount disease, while adolescent cases are more often unilateral 6.
• Sex and Race Predilection: Early-onset Blount disease is less likely to occur in Black children and males compared to late-onset forms 6.
• Severity and Progression: Infantile cases tend to progress more rapidly and have a worse prognosis without early intervention 4 9.

Causes of Blounts Disease

Despite decades of research, the exact cause of Blount disease remains unclear. However, a combination of biomechanical, genetic, and environmental factors appears to play a role.

Cause	Description	Evidence Level	Source
Obesity	Increases mechanical load on growth plate	Strong association	1 2 3 4 7 8 9
Early Walking	Early ambulation may increase risk	Some evidence	7
Genetics	Familial and racial predisposition observed	Probable influence	1 6 7
Mechanical Stress	Medial growth plate compression	Leading hypothesis	1 3 4 5 7 9
Nutrition	Possible but unproven link	Weak evidence	7 8
Vitamin D Deficiency	Not implicated	Refuted	8

Table 3: Proposed Causes and Risk Factors

Obesity and Mechanical Stress

Obesity is the single most consistently identified risk factor for Blount disease, especially in children from certain racial backgrounds. Excess body weight places greater compressive forces on the medial side of the proximal tibial growth plate, which is thought to suppress growth and cause bowing 1 2 3 4 7 9. This mechanical overload is particularly damaging during periods of rapid growth.

Early Walking

Some studies suggest that children who begin walking at a younger age may be at increased risk for Blount disease, possibly due to earlier exposure of the growth plate to mechanical stress 7. However, evidence remains limited.

Genetic and Racial Predisposition

Familial clustering and increased prevalence in certain populations (notably Black children in the Americas and Caribbean) point toward a genetic component 1 6 7. However, the disease can occur in all racial and ethnic groups.

Mechanical Theory

The prevailing hypothesis is that abnormal compressive forces on the medial tibial physis (growth plate) disrupt normal bone growth and remodeling. Histological studies reveal disorganization of bone and cartilage structures on the affected side 1 3 4 7 9.

Nutrition and Vitamin D

While nutritional factors have been postulated, there is no clear evidence linking vitamin D deficiency to Blount disease. Children with Blount disease have vitamin D levels similar to their healthy peers, and rickets (a vitamin D deficiency disorder) is typically excluded before making the diagnosis 8.

Multifactorial Origin

Consensus among researchers is that Blount disease is multifactorial, with obesity, mechanical loading, genetics, and perhaps other unknown factors all contributing to the development and progression of the disorder 7.

Treatment of Blounts Disease

Treatment of Blount disease is tailored according to the patient’s age, severity of deformity, and disease type. Early intervention is often key to preventing irreversible damage and improving long-term outcomes.

Treatment Option	Indication/Patient Group	Effectiveness	Source
Bracing	Early, mild infantile cases	Controversial; may help some	13
Growth Modulation (Guided Growth)	Young children, early to moderate cases	High success, especially in adolescent Blount	11 12 13
Osteotomy	Progressive, severe, or older children	Effective for realignment	4 9 10 13
Hemiepiphysiodesis	Medial/lateral growth modulation	Useful adjunct, especially in older children	4 12 13
Medial Plateau Elevation	Advanced, severe deformity	Restores joint surface	10 13
Weight Management	All ages, especially obese	Essential adjunct	1 2 4

Table 4: Main Treatment Approaches

Bracing

• Who it’s for: Very young children (<3 years) with mild, early-stage Blount disease.
• Use: Aimed at reducing varus stress and guiding bone growth.
• Effectiveness: Mixed results. Some children benefit, while others progress despite bracing. Close follow-up is necessary, and many will eventually require surgery 13.

Growth Modulation (Guided Growth / Tension Band Plating)

• Who it’s for: Children with open growth plates and correctable deformity, especially effective before growth is complete.
• How it works: Plates or staples are placed on one side of the growth plate to slow growth there, allowing the other side to “catch up” and gradually correct the angle.
• Outcomes: High success rates, particularly in adolescent and juvenile Blount disease. Slightly less effective in infantile cases 11 12.
• Considerations: Requires regular monitoring. Hardware complications (e.g., screw breakage) may occur. Some risk of recurrence after plate removal 11 12 13.

Osteotomy

• Who it’s for: Children with moderate-to-severe deformity, failed conservative management, or older children/adolescents.
• How it works: The tibia (and sometimes femur) is surgically cut and realigned. May be performed acutely or gradually using external fixation devices.
• Outcomes: Effective for correcting deformity and improving function. Risk of recurrence is higher in juvenile onset males. Incomplete correction may occur, especially if growth remains 4 9 10 13.

Hemiepiphysiodesis

• Who it’s for: Older children or as an adjunct to other procedures.
• How it works: Surgical procedure that arrests growth on one side of the growth plate to correct angular deformity.
• Outcomes: Useful in combination with other treatments, such as medial plateau elevation, particularly in advanced cases 4 12 13.

Medial Plateau Elevation

• Who it’s for: Children with severe depression of the medial knee joint surface.
• How it works: Surgical elevation of the depressed joint surface, often combined with osteotomy and/or hemiepiphysiodesis.
• Outcomes: Generally good results in restoring joint congruity and alignment 10 13.

Weight Management and Supportive Care

• Essential for all patients, especially those with obesity.
• Approach: Diet, exercise, and lifestyle modification can reduce mechanical stress on the tibia and improve outcomes. Physical therapy and counseling may also be beneficial 1 2 4.

Long-term Follow-Up

• Regardless of treatment, children with Blount disease need regular monitoring until skeletal maturity. This is due to the risk of recurrence, unpredictable growth plate activity, and the potential for early osteoarthritis 4 13.

Conclusion

Blount disease is a complex, multifactorial growth disorder that requires careful diagnosis and individualized management. Early recognition of symptoms and understanding the nuances of different types can make a significant difference in long-term outcomes. Here’s a concise summary of the key points:

• Symptoms include progressive bowing of the legs, gait abnormalities, knee pain, and possible limb shortening.
• Types are classified by age of onset: infantile (<4 years), juvenile (4-10 years), and adolescent (>10 years).
• Causes are multifactorial, with obesity and mechanical stress being the most significant contributors; genetic and racial predispositions also play a role.
• Treatment is tailored to age and severity, ranging from bracing and guided growth in early cases to osteotomy and more complex surgeries for advanced deformity. Weight management is a crucial adjunct.
• Long-term follow-up is essential to monitor for recurrence and prevent complications like early osteoarthritis.

With early intervention and a multidisciplinary approach, many children with Blount disease can achieve improved leg alignment and function, helping them lead active, healthy lives.