Blount Disease Treatment & Management

Treatment depends on the age of the child and the severity of the varus deformity.

Observation or a trial of bracing is used most frequently for children aged 2-5 years. However, progressive deformity usually requires osteotomy.^{[8, 11]} Operative treatment is not recommended for children younger than 2 years because the deformity may be an exaggerated physiologic genu varum.

Nonoperative treatment

In a child older than 2 years, orthotic treatment can be used when the deformity is increasing or if the child has a tibiofemoral angle greater than 15°, a metaphyseal-diaphyseal angle of greater than 11°,^[25] and a metaphyseal-epiphyseal angle of 25-30°.^[19] Ambulatory daytime bracing using an above-the-knee brace with a free ankle may favorably alter the natural history of patients with tibia vara who are younger than 3 years and who have Langenskiöld stage I or II deformity, because the deformity is often reversible at these stages.^[26]

Nonetheless, documentation of the effectiveness of bracing is difficult because tibia vara can resolve spontaneously.

If the deformity persists or increases to stage III or IV with daytime brace treatment, osteotomy is required. If possible, it is preferable to perform the osteotomy before the child is aged 4 years to prevent recurrence.^[27] If deformity is severe (ie, Langenskiöld stage V or VI), operative correction is essential. Orthotic devices are ineffective in controlling the varus deformity in adolescents, and the treatment is surgical.

Surgical approaches for infantile Blount disease

If the deformity does not improve with orthotic treatment and the disease progresses radiographically to advanced stage II or stage III deformity, surgical correction should be performed. Furthermore, surgery is recommended for a deformity that is increasing in severity and disabling the child, or if the child has a tibiofemoral angle greater than 15°, a metaphyseal-diaphyseal angle greater than 14°, and a metaphyseal-epiphyseal angle greater than 30°. Absolute indications for surgery are depression of the tibial plateau, impending closure of the medial physis of the upper tibia (stage IV), and ligamentous laxity of the knee.^[19]

Osteotomy has been the most frequently used form of surgical management.^[7] Many different types of osteotomies have been described in the literature, including opening and closing wedge, spike, dome, and oblique osteotomies.^{[24, 28, 29]} In the more skeletally mature individual, the valgus osteotomy can be carried out through the physeal scar. However, it is important to remember that in the younger child, the osteotomy must be carried out below the insertion of the patellar ligament because the proximal tibia physis is still open.^[8]

The rate of recurrence of the varus deformity is high in individuals with infantile Blount disease treated with proximal tibial and fibular osteotomy.^{[6, 11, 18]} Doyle et al identified only 2 prognostic features for the recurrence of deformity: the patient's age and Langenskiöld stage at initial osteotomy.^[27] They recommended (1) operative treatment before age 4 years for patients with progressive clinical and radiographic findings; (2) surgical correction when radiographic findings correspond to Langenskiöld stage I or II; and (3) a single corrective osteotomy early on the affected limb that results in permanent correction. The failure to correct the tibia vara deformity early can result in permanent physeal damage, with development of symptomatic degenerative intra-articular knee pathology at maturity.

Surgical approaches for adolescent Blount disease

In individuals with adolescent tibia vara, observation is indicated when the deformity is not progressing, not causing severe deformity, and not disabling the patient, because spontaneous regression has been reported.^{[6, 18]} Surgical treatment depends on the stage of the disease and the skeletal age of the child. Many surgical procedures have been described for treating adolescent tibia vara with disease progression, including proximal tibial osteotomy, hemiepiphysiodesis, asymmetric physeal extraction, and external fixation with distraction osteogenesis.^{[10, 22, 30, 31, 32, 33, 34, 35, 36]}

As in the infantile form, osteotomy remains the most common method of treatment.^[7] If adolescent tibia vara is recognized early with a physeal bony bridge and minimal deformity, then it may be excised and spacer material, such as fat, inserted. When disease is moderate to severe, a more extensive procedure is indicated. For girls older than 11-12 years or for boys older than 13-14 years, remaining growth is minimal, and physeal bony bridge resection is meaningless.^[19]

A second option is osteotomy through the growth plate to elevate the medial epiphysis, and a contralateral epiphysiodesis. This approach relies on the growth of the injured medial physis, and results have been unpredictable, with up to 40% of patients requiring additional surgery to improve alignment.^[10]

The third option is proximal tibial osteotomy below the physis so that the tibia is realigned mechanically. This option requires the presence of spontaneous bridging and early closure of the medial part of the proximal tibial physis, an opening of the lateral part of the tibial, and near completion of skeletal growth. Intervention consists of epiphysiodesis of the lateral sides of the tibia and proximal fibula, and valgus opening wedge osteotomy of the proximal tibia and fibula.^[19] Unfortunately, in some individuals with adolescent Blount disease, there is shortening of the involved extremity that cannot be resolved by simple angular correction of the deformity.^[37]

De Pablos has advocated another technique. He treated a group of adolescent patients with asymptomatic bilateral tibia vara with asymmetric physeal distraction, demonstrating improvement in limb alignment and uniform closure of their physes.^[22] The most appropriate indication for this technique is late-onset disease, or adolescent Blount disease with or without partial closure of the medial aspect of the proximal tibial growth plate (≤ 50%) and no severe deformity of the proximal tibial epiphysis. Asymmetrical physeal distraction should not be used for infantile forms of Blount disease; it is indicated only in the adolescent who is near skeletal maturity.

External fixation has provided promising results in adolescent Blount disease (see Image below).^{[31, 32, 33]} Coogan et al prefer the use of a circular external fixation device and distraction osteogenesis instead of proximal tibial osteotomy and lateral hemiepiphysiodesis.^[31]

Advantages to their approach are the ability to perform angular correction in any plane, allowing procurvatum and internal tibial torsion to be addressed, in addition to proximal tibial varus; correction of distal tibial deformities with only slight frame modification; limb lengthening; and gradual correction of deformity with distraction osteogenesis, allowing for fine tuning of the alignment.^[38] In addition, the stability of the frame allows for immediate weight bearing and a short hospital stay.

Their results demonstrate that distraction osteogenesis with an external fixator provides consistent correction of tibial deformities in these patients, with minimal morbidity. Correction was associated with significant improvement in symptoms and a high degree of patient satisfaction. They acknowledge disadvantages, which include the need for patient compliance in the operation of the device, potential pin fixation complications, and the possible need for a second anesthesia for device removal.

In the postoperative period, carefully observe the neurovascular status for compromise, as this is a potential hazard. Compartment syndromes must be recognized and treated early. Fortunately, the gradual correction of dynamic external fixators make this less likely.

In general, when osteotomy with internal fixation is performed, the osteotomy heals in 8 weeks. If enough callus is present to prevent change or loss of position, the cast is removed 5-6 weeks postoperatively. An above-the-knee cast is then applied with the knee in full extension and the foot and ankle free, allowing gradual partial to full weight bearing.^[19] Continuing follow-up care after initial surgical correction of the varus deformity is necessary because of the risk of recurrence. Infantile tibia vara has a good prognosis and recurrence of deformity is low when treated at a young age and early stage. However, older patients with advanced deformity (ie, stages IV-VI) are at increased risk of recurrence.^[27]

With the use of external fixators and distraction osteogenesis, gradual angular manipulation is begun 1 week after application of the external fixator and osteotomy. The correction takes place over the subsequent 2-3 weeks, depending on the severity of the deformity. After angular correction is achieved, the external frames are stabilized using additional threaded rods. The frames are generally removed 12 weeks postoperatively.^[31]

Complications associated with the treatment of Blount disease include loss of alignment, vascular impairment, pathologic fractures, wound infection, and malalignment.^{[31, 39]}

In long-term follow-up of infantile tibia vara, Doyle et al found that the outcome depends on the patient's age and severity of deformity at the time of intervention.^[27] An 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. Untreated infantile tibia vara is believed to be progressive. The literature has shown that partial or complete regression may occur in stages I-IV; however, stages V-VI do not show regression.^{[27, 40]}

Data on long-term follow-up of Blount disease are limited, and it is still unclear whether this limb abnormality predisposes patients to development of arthroses.^{[1, 11, 27]} With advances in treatment, retrospective studies on different treatment groups may show whether progression to arthrosis is a significant concern.