Infantile Blount's disease

Ph Maré,Dm Thompson

doi:10.17159/2309-8309/2020/v19n3a8

Abstract

ABSTRACT Infantile Blount's disease results in multi-planar proximal tibial deformity consisting of varus, procurvatum, internal rotation and shortening. The deformity is attributed to disordered growth of the posteromedial proximal tibial physis. The aetiology is multifactorial. It is associated with childhood obesity and African ethnicity. The ability to differentiate between infantile Blount's disease and physiological bowing depends on the findings of focused clinical examination, X-ray appearance, tibial metaphyseal-diaphyseal angle and tibial epiphyseal-metaphyseal angle. The gold standard of treatment is proximal tibial metaphyseal corrective osteotomy before the age of 4 years. The limb should be realigned to physiological valgus. The recurrence rate after realignment osteotomy is high. Recurrence is associated with age at osteotomy, obesity, higher Langenskiöld stage and medial physeal slope >60°. The surgical management of severe, recurrent or neglected infantile Blount's disease is challenging. Comprehensive clinical examination and multi-planar deformity analysis with standing long leg X-rays are essential to identify all aspects of the deformity. Distal femur coronal malalignment and significant rotational deformity should be excluded. Knee instability due to intra-articular deformity should be corrected by elevation of the medial tibial plateau. Lateral epiphysiodesis should be done at the same time as medial plateau elevation and when medial growth arrest is certain to prevent recurrence. Level of evidence: Level 5 Keywords: Blount's disease, tibia vara, genu varum, recurrence, obesity

Highlights

Blount’s disease is an abnormality of growth of the metaphysis, epiphyseal cartilage and osseous centre of the epiphysis.[1]
In a paper presented at the Combined Meeting of the Orthopaedic Associations in 2016, Maré et al showed in a group of 20 children with 35 limbs that an medial physeal slope (MPS)≥60° was a highly significant predictor of recurrence (OR=1.4 95% CI [1.11–1.82], p=0.005) with a sensitivity of 0.79, specificity of 0.95, PPV of 0.92 and NPV of 0.87.46
The median ages were 3.2 years (±1.4) and 4.36 years (±2.16) for the groups with Langenskiöld stage ≤2 and ≥3 respectively. They reported a 100% correction rate in children with Langenskiöld stage ≤2 and a 33% recurrent deformity rate. This correction rate fell to 40% in children with Langenskiöld stage ≥3 with a 100% recurrence or incomplete correction rate

Summary

Introduction

Blount’s disease is an abnormality of growth of the metaphysis, epiphyseal cartilage and osseous centre of the epiphysis.[1]. Blount recognised knee instability in three cases that was responsible for part of the varus deformity.[1] Langenskiöld attributed this to the sloping of the medial tibial condyle in neglected cases.[3] Siffert and Katz confirmed the presence of the depression of the medial tibial plateau with direct visualisation at arthrotomy and described the pathoanatomy of this deformity in detail They advocated elevation of the medial tibial plateau as an essential part of treatment.[27] Medial articular elevation is normally combined with lateral epiphysiodesis of the proximal tibia and fibular and metaphyseal proximal tibial osteotomy to correct residual varus, procurvatum and internal rotation.

Conclusion and future direction

Findings

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