Review Question - QID 218231

This patient presents with Langenskiold stage II infantile Blount disease. While knee-foot-ankle orthosis (KFAO) bracing has been historically recommended for select patients, no strong evidence supports or refutes the efficacy of bracing for infantile Blount disease of lower (I, II) Langenskiold stages.

Infantile Blount disease is defined as progressive, pathologic tibia vara in children aged 2 to 5 years, which occurs more often in boys and presents bilaterally in 50% of cases. The Langenskiold classification characterizes the severity of disease, with worsening disease evidenced by increasing medial metaphyseal beaking and sloping, eventually developing transphyseal bony bars in the most severe cases. It may be difficult to differentiate between physiologic genu varum and true infantile Blount disease, especially in very young children. In younger (<3 years) children with milder (type I-II) disease, bracing has been historically recommended as a non-operative treatment modality. However, conclusive studies on the efficacy of bracing do not yet exist due to several challenges, including difficulty differentiating between physiologic varus and infantile Blount disease, occasional spontaneous correction of infantile Blount disease, and difficulty confirming compliance with brace wear. Operative management is reserved for older children, younger children with higher Langenskiold types, and those who fail initial brace treatment.

Shinohara et al. published a 2002 retrospective case series of patients with infantile tibia vara, documenting the natural history of the disease. Forty-six limbs were studied in 29 patients with infantile tibia vara and a metaphyseal-diaphyseal angle (MDA) of more than 11 degrees. In 22 limbs that were not in Langenskiold stages II to III, the condition resolved spontaneously without treatment. Of the remaining 24, which were in stages II to III, 18 patients resolved spontaneously by the age of six years, but six others showed little or no improvement at the latest follow-up. The authors advised no initial treatment, but recommended regular 6-month-interval follow-up visits until the age of 4 years, even in patients with Langenskiold stage II-III deformity. When deformity persisted or progressed, the authors performed a corrective osteotomy after the age of 4 years.

Birch published a 2013 JAAOS review on Blount disease. Regarding the infantile form, the author states that differentiating between early infantile Blount disease and physiologic genu varum can be difficult. Patients with metaphyseal-diaphyseal (Drennan) angles of ≥11 degrees on AP radiographs were more likely to progress to true infantile Blount disease, however the rigidity of this cutoff has been debated since the original definition by Levine and Drennan. The author states that while bracing may be employed to counteract the progressive varus deformity, it does not change the natural history of the disease. The author favors operative treatment for children over 4 years of age, Langenskiold stage III or greater, or cases of progressive radiographic deformity.

Sabharwal and Sabharwal published a 2017 update on the treatment of infantile Blount disease. They identified several factors that predicted failure of nonoperative management, including obesity (weight >90th percentile), varus thrust, age (>3 years at treatment initiation), bilateral involvement, and severe disease (≥ Langenskiold III). However, the authors acknowledge past studies that demonstrate considerable rates of spontaneous resolution of disease staged ≤ Langenskiold III, indicating that patients successfully treated with orthoses may have had similar outcomes without bracing. Given the limitations of small, uncontrolled, retrospective case series set atop the background of high rates of spontaneous resolution, a consensus has yet to be reached regarding the efficacy of bracing.

Figure A is a radiograph of Langenskiold type II infantile Blount disease, characterized by a sharp depression of the physeal line medially, medial beaking, and a more wedge-shaped and underdeveloped medial epiphysis. The measured Drennan angle in this patient is 18 degrees.

Illustration A is the original film with its corresponding Drennan angle. Illustration B is a depiction of the Langenskiold classification. Illustration C is a description of the radiographic findings associated with each stage.

Incorrect Answers:
Answers 1-2: There is no evidence to conclusively support or refute the efficacy of bracing in true infantile Blount disease.
Answer 3: There is no evidence to support bracing, with or without physical therapy, in the treatment of true infantile Blount disease.
Answer 5: True Blount disease is a progressive condition; counseling the mother that this is a self-resolving condition is not appropriate.