Blount Disease (Tibia Vara) Treatment & Management


Practice Essentials

Blount disease is a developmental disorder characterized by disordered growth of the medial aspect of the proximal tibial physis resulting in progressive lower-limb deformity. [12 Although it is also referred to as tibia vara (because the varus coronal plane deformity is most distinctive), the disease usually results in a multiplanar deformity of the limb. The deformity consists of varus, procurvatum, and internal rotation of the tibia. This pattern is a result of the asymmetry of disordered physeal growth most pronounced in the posteromedial aspect of the proximal tibial physis. Blount disease can also be associated with a limb-length discrepancy and, in some patients, deformity of the distal femur as well. [34]

Erlacher was the first to describe a case of tibia vara in 1922. Walter Blount brought attention to the disease in 1937 in an article describing 13 children with tibia vara or osteochondrosis deformans. Because he was the first to identify the similar clinical, radiographic, and pathologic characteristics of the cases in the literature, the disease has become associated with Blount. Later, in 1952, Langenskiöld described a progression of radiographic changes seen with the disease in the Scandinavian population. [5 (See the image below.)

Diagram depicting the radiographic changes in the Diagram depicting the radiographic changes in the infantile form of Blount disease described by Langenskiöld.

The natural history of Blount disease leads to irreversible pathologic changes, especially at the medial portion of the proximal tibial epiphysis because of growth disturbances of the physis. The progression and characteristics of the disease are distinct in the two described forms of the disease. (See the image below.)

A 14-year-old boy with unilateral Blount disease dA 14-year-old boy with unilateral Blount disease demonstrating tibia vara on the left. Courtesy of S. Robert Rozbruch, MD.

Classically, Blount disease has been described as two distinct forms: early or infantile Blount disease and late or adolescent Blount disease. Infantile Blount disease is diagnosed at age 1-3 years, presenting when a child begins to ambulate. Infantile Blount disease is less commonly associated with obesity and is often bilateral. Late-onset Blount disease has been further subcategorized into juvenile, occurring at age 4-10 years, and adolescent, occurring at older than 10 years. Blount disease occurring in older children is more commonly seen associated with obesity and is more often unilateral. [6789]

Conservative treatment can be an option in early-onset Blount disease and consists of brace treatment. In late-onset patients and early-onset patients in whom brace management fails, operative intervention is indicated for increasing severity of symptoms or progression of deformity.

Anatomy

Relevant anatomy for this disease is that of the proximal tibia and its surrounding structures. Structures at risk in this area on the medial side include the saphenous nerve and its branches. On the lateral side, the peroneal nerve courses around the neck of the fibula before dividing into deep and superficial branches. When performing osteotomies or with pin insertion, these nerves, as well as the anterior tibial artery and its recurrent branch, are at risk. With acute correction of the varus deformity, medial-side structures are at risk for stretch injury. Compartment syndrome is a risk, particularly with acute correction of tibial deformity.

Pathophysiology

Blount disease most likely is caused by a combination of excessive compressive forces on the proximal medial metaphysis of the tibia and altered enchondral bone formation. [8It is unclear whether the deformity is caused by an intrinsic alteration of bone formation that is exacerbated by compressive forces or by compressive forces that cause a disruption in normal endochondral bone formation.

The combination of mechanical and biologic factors in tibia vara most likely influences the disease to varying extents. The mechanical forces contributing to the disease are the weight of the child, age at walking, and the varus deformity. In accordance with the Heuter-Volkmann principle, compressive force across the medial femoral physis leads to growth retardation.

Damaged cartilage ossifies in a delayed fashion. [5As growth is selectively inhibited at the medial side of the knee due to these compressive forces, a resultant varus deformity progresses. The posteromedial aspect of the physis is most suppressed, contributing to the procurvatum deformity also seen in the disease. However, it is important to note that histologic changes are seen in the entirety of the growth plate, but the medial side is most affected. [10]

Cook et al demonstrated the degree of growth inhibition in children. They showed that in an obese 5-year-old child with 10° of varus angulation, sufficient force across the growth plate is generated to retard physeal growth. [11The relationship between obesity and deformity is more linear in the late-onset population than in early-onset Blount disease. [12]

A dynamic component to the overload also has been described, due to the large thigh girth of these patients. The resultant “fat thigh gait” has been implicated as causing a varus movement on the knee contributing to medial overload. [13The result is a progressive varus angulation below the knee and an increase in the compressive forces on the physis, which changes the direction of the weightbearing forces on the upper tibial epiphysis from perpendicular to oblique. The obliquity of this force tends to displace the tibial epiphysis laterally. In addition to the delayed growth of the physis, pressure on the adjacent epiphysis leads to delayed ossification and intra-articular anomalies.

Many authors believe that disease progression is the result of this cycle of growth disturbance, varus deformity, and further growth disturbance. [14Distal femoral valgus or varus deformity and/or distal tibial varus or valgus deformities also can occur in conjunction with tibia vara. [315Whether these occur as compensatory mechanisms or are due to intrinsic factors of Blount disease is unknown. These deformities should be corrected at the same time that the tibial vara deformity is corrected.

Whereas the mechanical etiology has been shown to contribute, it does not explain the development of unilateral disease. A number of authors have noted a positive family history of Blount disease in some affected individuals. These studies are limited but worthy of mention. An increased incidence with family history was seen by Bathfield, [6but without a clear pattern of inheritance. Sevastikoglou and Eriksson found four persons with tibia vara in the same family, of whom two were identical twins. [16Blount disease has a multifactorial etiology to which various genetic, environmental, and biomechanical factors contribute.

It is important to distinguish that there is controversy as whether the two forms of the disease have similar pathophysiology. Some literature supports their similarities, while other authors consider them separate entities. Adolescent Blount disease does not appear to be as progressive or as common as the infantile form. Factors such as injury or infection of the physis have been suspected to play an etiologic role; however, most patients have no history of trauma or infection, which has led many authors to discount these as the only possible causes. [141718]

Etiology

The cause of Blount disease remains controversial, but it is most likely secondary to a combination of hereditary and developmental factors.

The disease has an increased incidence in overweight children who walk at an early age. [19These findings have lead to theories that mechanical overloading of the proximal tibia contributes to Blount disease. The mechanical overload of the physis is attributed to obesity and varus deformity. [13However, mechanical factors in isolation cannot cause the disease, given that the infantile form is often seen in children with normal weight.

An association between vitamin D deficiency and Blount disease has been suggested, [20 but an independent association between the two, without regard to obesity, has not been proved. [21  

The disease has a genetic component as well, but a direct pattern of inheritance has not been shown. Clearly, the etiology of Blount disease is multifactorial and may differ in the early- and late-onset forms of the disease.

Epidemiology

The epidemiology of Blount disease is not well documented. Large series of patients with Blount disease indicated that the estimated prevalence is less than 1% [22in the United States. In South Africa, it was estimated by Bathfield and Beighton to be 0.03%. [6There is an increased incidence of disease in the African American population for both early- and late-onset Blount disease. [7]

Predisposition to Blount disease has been attributed to race, genetics, age at walking, and obesity. Blount disease has increased prevalence in the overweight African American population and in the Scandinavian population. Increased occurrence has been seen in South Africa. [6]

Demographics appear to differ somewhat between early-onset and late-onset forms of the disease. In a meta-analysis by Rivero et al, those patients with the early-onset form Blount disease were more likely to have bilateral involvement and were less likely to be male or African American. [23]

Prognosis

In long-term follow-up of infantile tibia vara, Doyle et al found that the outcome depended on the patient's age and the severity of deformity at the time of intervention. [24An understanding of the natural history of Blount disease is important for treatment. The prognosis in the infantile form of Blount disease must be considered separately from that in the adolescent form. Infantile tibia vara has a good prognosis, and recurrence rates of deformity are low when the condition is treated at a young age and an early stage.

Untreated infantile tibia vara is believed to be progressive. Whereas partial or complete regression may occur in the early stages of disease, later stages continue to progress and eventually lead to joint degeneration. In the late-onset form of the disease, regression does not occur and the varus deformity may worsen over time. These patients may eventually develop sequelae as a result of joint malalignment.

Data on long-term follow-up of Blount disease are limited, and further studies are needed to characterize the relationship between the deformity and the development of arthroses. [24Severity of deformity has been shown to correlate with severity proximal tibial deformity, and poor outcomes appear to be related to the degree of physeal damage. [25With advances in treatment, retrospective studies on different treatment groups may show whether progression to arthrosis is a significant concern.


History and Physical Examination

The clinical presentation of Blount disease differs with early- and late-onset disease. Those with early-onset disease present at age 1-3 years. [22Children with early-onset disease often walk earlier than their peers, although this is controversial. [6They present with varus deformity of the tibia and internal tibial torsion. The presentation is more commonly bilateral but can be asymmetric. (See the images below.)

A 5-year-old girl with Blount disease. Courtesy ofA 5-year-old girl with Blount disease. Courtesy of Austin T. Fragomen, MD.
Clinical picture of a child with infantile Blount Clinical picture of a child with infantile Blount disease prior to surgery. Courtesy of Austin T. Fragomen, MD.
A 10-year-old boy with Blount disease. Marked obesA 10-year-old boy with Blount disease. Marked obesity and bilateral genu varum is present. Courtesy of S. Standard, MD.

The early stage of Blount disease can be difficult to distinguish from physiologic bowing. Genu varum is a normal finding in children younger than 2 years. After age 2 years, alignment migrates back to valgus, with peak valgus at around age 3 years. Physiologic bowing resolves, whereas Blount disease must be treated, with nonoperative management playing a role in the early stages of disease.

The infantile form is generally more prevalent in African Americans and may be associated with obesity. Children generally do not report pain, though they can present with a significant deformity. The metaphyseal prominence, or beak, may be palpable over the medial aspect of the proximal tibial condyle.

In contrast, patients with adolescent Blount disease usually present in late childhood or early adolescence. Patients often report pain at the medial aspect of the knee. These patients are typically overweight or obese. In contrast to the early-onset form of the disease, involvement is more commonly unilateral, and patients also often have abnormalities of the distal femur.



Laboratory Studies

Laboratory studies have not been shown to aid in the diagnosis of Blount disease. The diagnosis of both forms of Blount disease is based on history, physical examination, and radiography.

Imaging Studies

Radiographs of the knee are critical in assessing and staging the severity of the deformity in Blount disease. On knee radiographs, characteristic changes associated with Blount disease can be visualized. Such changes include the following (see the image below). [518:

  • Medial beaking of the epiphysis
  • Widened irregular medial physis
  • Irregular ossification
  • Medial slope of the epiphysis and metaphysis in varus
Anteroposterior radiograph of the knee and tibia iAnteroposterior radiograph of the knee and tibia in a 5-year-old demonstrating the medial plateau depression and prominent metaphyseal beaking (Langenskiöld III) typical of infantile genu varum. Courtesy of Austin T. Fragomen, MD.

This series of changes is described in the Langenskiöld classification of the disease.

Only irregular metaphyseal ossification exists in disease stages I and II. In these stages, infantile patients can potentially be managed nonoperatively; they are also difficult to distinguish from children with physiologic bowing. [18As patients progress beyond to stage III, there is significant deformity of the tibial epiphysis and physis with fragmentation. Bar formation can occur in stage IV and can progress to stage V, with disruption of the physeal cartilage. In stage VI, there is significant depression of the articular surface and bar formation.

For a full assessment of the coronal plane deformity of the limb, a standing anteroposterior (AP) radiograph is taken with the patellae facing forward. This can be difficult in obese patients or very young patients whose patellas are not yet ossified. Measurements taken on radiographs include the metaphyseal-epiphyseal angle, the metaphyseal-diaphyseal angle of the proximal tibia, and the tibiofemoral angle.

The metaphyseal-diaphyseal angle (see the image below) has been shown to be predictive of progression, [26with an angle greater than 16° being a risk for progression of deformity. If the angle is less than 10°, it is likely physiologic and resolve spontaneously. This angle is formed by the intersection of a line drawn through the most distal point on the medial and lateral beaks of the tibial metaphysis to a line perpendicular to the long axis of the tibial diaphysis.

Anteroposterior radiograph of the knee and tibia dAnteroposterior radiograph of the knee and tibia demonstrating the metaphyseal-diaphyseal angle in a child with infantile Blount disease. Courtesy of Austin T. Fragomen, MD.

The severity of the varus deformity is based on the tibiofemoral angle as measured on standing hip-to-ankle AP radiographs.

The metaphyseal-epiphyseal angle is the angle formed by the intersection of a line through the transverse plane of the proximal tibia epiphysis with a line through the transverse plane of the metaphysis.

Magnetic resonance imaging (MRI) has also been used to assess tibial and extratibial abnormalities in children with infantile Blount disease. [27]

Histologic Findings

In the infantile form, bone changes include delayed ossification of the medial epiphysis and metaphysis of the proximal tibia. [14In all stages of the disease, histologic specimens from the zone of resting cartilage in the medial part of the proximal tibial physis have well-defined pathologic changes. Bradway et al described the histology seen in physis specimens in patients with Blount disease. [7These changes include cell hypertrophy and dense cellularity, fibrocartilage islands, and abnormally large groups of capillaries.

Staging

Langenskiöld classified infantile tibia vara into six progressive stages, based on the degree of metaphyseal-epiphyseal changes observed on the radiograph. Severity of disease is based on the Langenskiöld stage and the age of the child. 



Approach Considerations

Nonoperative treatment is an option in a select group of infantile Blount disease patients. If they are diagnosed before age 4 years, knee-ankle-foot orthoses (KAFOs) have a role in Langenskiöld stage I or II disease, especially with unilateral involvement. [28Patient characteristics that predispose to failure of conservative treatment include the following [8:

  • Varus thrust
  • Age older than 3 years
  • Weight greater than 90th percentile
  • Bilateral disease
  • Langenskiöld grade higher than 3

In late-onset patients and early-onset patients in whom brace management fails, operative intervention is indicated for increasing severity of symptoms or progression of deformity.

Surgical intervention is contraindicated in children younger than 2 years because it is difficult at this age to differentiate between Blount disease and excessive physiologic bowing that may resolve spontaneously.

Medical Therapy

Conservative treatment can be an option in early-onset Blount disease and consists of bracing. Brace therapy should be attempted in all children younger than 2.5 years with stage I or II disease. [29Ambulatory bracing with an above-the-knee orthosis has been shown to prevent progression of disease. Bracing has been shown to correct both the varus deformity and the pathologic proximal-medial tibial growth disturbance. [2830If the disease continues to progress to stage III with bracing, brace treatment will no longer be effective.

Other risk factors for failure of brace treatment include the following:

  • Obesity
  • Varus thrust
  • Age older than 3 years at initial treatment
  • Bilateral disease

Surgical Therapy

The obesity associated with Blount disease leads to additional risk factors for surgery. Owing to their obesity, patients are at higher risk for obstructive sleep apnea (OSA) and should be screened during their preoperative workup so that they can be adequately treated postoperatively. [31]

Infantile Blount disease

Surgical intervention is indicated in early-onset patients who develop Blount disease changes consistent with Langenskiöld stage III or IV. Bracing has not been shown to be effective past these stages, and the disease will continue to progress. Surgical options include corrective proximal tibial osteotomies with various fixation methods used sometimes in concert with guided growth or hemiepiphysiodesis. (See the images below.)

Clinical picture of a child with infantile Blount Clinical picture of a child with infantile Blount disease prior to surgery. Courtesy of Austin T. Fragomen, MD.
Anteroposterior radiograph of tibia of a child witAnteroposterior radiograph of tibia of a child with infantile Blount disease at the time of distal femoral 8 plate application tibial osteotomy and Taylor spatial frame. Courtesy of Austin T. Fragomen, MD.
Subsequent standing hip-to-ankle anteroposterior rSubsequent standing hip-to-ankle anteroposterior radiograph of the lower extremities demonstrating improved alignment after gradual correction. Courtesy of Austin T. Fragomen, MD.
Clinical picture of a child with infantile Blount Clinical picture of a child with infantile Blount disease at the completion of treatment. Courtesy of Austin T. Fragomen, MD.
Clinical picture and anteroposterior radiograph ofClinical picture and anteroposterior radiograph of the tibia of a child with infantile Blount disease at the time of distal femoral 8 plate application tibial osteotomy and Taylor spatial frame. Bilateral lower extremity films demonstrating overcorrection into valgus. Subsequent standing hip–to-ankle anteroposterior radiograph of the lower extremities demonstrating improved alignment after gradual correction with monitoring by clinical pictures and radiographs at most recent visit. Courtesy of Austin T. Fragomen, MD.

In early-onset Blount disease, the risk of recurrence of the deformity is significant; accordingly, osteotomies are often overcorrected to anticipate this. Poor results and high rates of recurrence have been shown in the population with progressive Langenskiöld stage, older age at time of surgical intervention, and lack of overcorrection. [32Between 5º and 15° of valgus overcorrection has been recommended. Lower overall rates of recurrence have been seen in patients who undergo corrective osteotomies before age 4 years. [33]

Osteotomy has been the most frequently used form of surgical management. [7Many different types of osteotomies have been described in the literature, including opening and closing wedge, opening wedge, serrated, dome, and inclined osteotomies. [343536372238In the infantile population, performance of the osteotomy must spare both the tibial physis and the apophysis of the tibial tubercle.

Regardless of the technique for valgus corrective osteotomy chosen, the correction can be performed acutely or gradually corrected with external fixation. For an acute correction, the multitude of fixation options include casting, plates and screws, pins, screws alone, wires, and external fixation. [3639404142The decision to correct acutely is based on the degree and dimensions of the deformity and the safety of the structures at risk with an acute correction.

Gradual osteotomies allow for correction of multiplanar deformities by fixation with either an Ilizarov device or a Taylor spatial frame. [43Some series have shown a lower incidence of neurovascular injury and compartment syndrome with a gradual versus an acute correction. The current consensus is that gradual correction leads to a more accurate result in the correction of multiplanar deformities as compared with acute correction. [26]

When the depression of the medial plateau is severe, this deformity may have to be corrected in isolation with a medial hemiplateau elevation osteotomy. [44This osteotomy only addresses the medial plateau depression, and an additional proximal metaphyseal tibial osteotomy is needed to correct the multiplanar deformity. This proximal tibial osteotomy is performed below the tibial tubercle to realign the mechanical axis of the leg. Intervention consists of epiphysiodesis of the lateral sides of the tibia and proximal fibula and valgus opening wedge osteotomy of the proximal tibia and fibular osteotomy.

Other described techniques include asymmetric physeal distraction and physeal bar resections; however, these are not commonly used.

Adolescent Blount disease

In individuals with adolescent tibia vara, observation is indicated only with painless, nonprogressive, mild deformities. In contrast to infantile Blount disease, which can be corrected in the earlier stages with bracing, the adolescent form of the disease has not been shown to respond to nonoperative treatment. [45Surgical treatment depends on the stage of the disease and the skeletal age of the child. As with the infantile form of the disease, there are multiple surgical approaches to correction, which include proximal tibial osteotomy, hemiepiphysiodesis, guided growth, and external fixation with distraction osteogenesis. [8]

As in the infantile form, osteotomy remains the most common method of treatment. The same considerations are relevant as in the infantile form, with the options of acute versus gradual correction. With significant remaining growth, hemiepiphysiodesis of the lateral proximal tibial physis has been described. A drawback of this technique is the unpredictable growth from the diseased medial tibial physis and therefore unpredictable correction. This technique has been shown to be less effective in obese patients and more severe deformity. [8 The use of a titanium tension-band plate appears also to be a risk factor for failure. [46]

Guided growth with compressive plating across the convexity of the growth plate is an option in those with significant growth remaining. [4748Guided growth can also be used concomitantly to correct less severe deformities of the distal femur while correcting the proximal tibia. However, both guided growth and hemiepiphysiodesis fail to address sagittal-plane deformity or limb-length discrepancy.

Gradual correction distraction osteogenesis with an external fixator provides consistent correction of multiplanar tibial deformities in these patients, with minimal morbidity. Correction is associated with significant improvement in symptoms and a high degree of patient satisfaction. (See the images below.)

Sachs et al compared two groups of adolescent patients, one treated with osteotomy and one without. They concluded that in patients with no growth remaining, tibia vara might be safely treated by using the Taylor spatial frame without osteotomy and fixation of the fibula. [49]

Standing hip-to-ankle anteroposterior radiograph oStanding hip-to-ankle anteroposterior radiograph of the lower extremities of a patient before osteotomy and Taylor spatial frame for the treatment of adolescent Blount disease. The patient also had distal femoral malalignment managed with a distal femoral osteotomy. Courtesy of S. Robert Rozbruch, MD.
Clinical photograph of a patient before osteotomy Clinical photograph of a patient before osteotomy and Taylor spatial frame for the treatment of adolescent Blount disease. The patient also had distal femoral malalignment managed with a distal femoral osteotomy. Courtesy of S. Robert Rozbruch, MD.
Standing hip-to-ankle anteroposterior radiograph oStanding hip-to-ankle anteroposterior radiograph of the lower extremities of a patient after osteotomy and Taylor spatial frame for the treatment of adolescent Blount disease. The patient also had distal femoral malalignment managed with a distal femoral osteotomy. Courtesy of S. Robert Rozbruch, MD.
Clinical photographs of a patient after osteotomy Clinical photographs of a patient after osteotomy and Taylor spatial frame for the treatment of adolescent Blount disease. The patient also had distal femoral malalignment managed with a distal femoral osteotomy. Courtesy of S. Robert Rozbruch, MD.
Standing hip-to-ankle anteroposterior radiograph oStanding hip-to-ankle anteroposterior radiograph of the lower extremities of a patient after osteotomy and Taylor spatial frame for the treatment of adolescent Blount disease. The patient also had distal femoral malalignment managed with a distal femoral osteotomy. Courtesy of S. Robert Rozbruch, MD.

Postoperative Care

In the postoperative period, it is important to carefully monitor the neurovascular status because patients who undergo corrective proximal tibial osteotomies are at risk for compartment syndrome. Compartment syndrome must be recognized and treated early. Owing to the increased incidence of obesity, patients with Blount disease are at significant risk for deep venous thrombosis (DVT), especially in the adolescent population, and patients therefore should be on chemoprophylaxis postoperatively.

Complications

Complications associated with the treatment of Blount disease can be distinguished on the basis of whether they are complications of operative treatment or complications associated with the disease itself. Operative complications include the following:

  • Vascular impairment
  • Pathologic fractures
  • Wound infection
  • Malalignment

Complications of the disease include the following [24:

  • Recurrence of deformity
  • Joint degeneration, in the long term

Long-Term Monitoring

Follow-up and postoperative weightbearing are specific to the procedure performed. In general, osteotomies heal in approximately 6-8 weeks, and, if the method of fixation is temporary, it should be maintained until evidence of healing is seen. In patients undergoing gradual correction, the timeline of external fixation depends on the degree of correction and length of distraction osteogenesis. In general, external fixation remains in place for 12 weeks postoperatively.

Continuing follow-up care after initial surgical correction of the varus deformity is necessary because of the risk of recurrence.


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