CASE 80
By: Dr. Amna Kashgari MD,SSC-Rad
HISTORY: A 4-year-old girl presented with deformity in the lower limb noted by the parent.
What are your findings?
What is your differential diagnosis?
What is your most likely diagnosis?
What are the major types of the disease?
FINDINGS:
Standing AP view of the lower limbs show bilateral Varus position of the tibia. The epiphysis is wedge-shaped, fragmented or can appear absent. The metaphysis is depressed and has a beak-like protuberance oriented medially.
DIFFERENTIAL DIAGNOSIS:
Developmental bowing.
Congenital bowing.
Blount disease.
Rickets.
Neurofibromatosis type I.
DIAGNOSIS:
Blount disease.
TYPES OF THE DISEASE: Infantile and juvenile.
PEARLS AND DISCUSSION:
Blount disease is a disordered growth of the medial aspect of the proximal tibial physis resulting in progressive lower limb deformity.
The etiology of the disease is unknown. It results from a combination of mechanical and biological factors.
The mechanical factors include: obesity, early walking and pre-exciting varus deformity.
| Infantile (Early) | Juvenile-Adolescent (Late) | |
|---|---|---|
| Age | 2-4 y | 4-10 y |
| Site | Usually bilateral (80 %) | Unilateral (90 %) |
| Course | Progressive deformity | Less deformity |
Radiological findings: Bowing “tibia vara” deformity, fragmentation of the medial tibial epiphysis, irregular medial physeal line and beaking of the proximal tibial metaphysis with fragmentation.
Tibiofemoral angle is used for measuring varus deformity.
Metaphyseal-diaphyseal angle is used to measure the severity of the disease: lines between metaphyseal beaks and perpendicular to the longitudinal axis of the tibia; >11 degrees is abnormal.
Langenskold Classification for Blount disease
• Stage I: Irregularity of medial proximal tibial physis with varus deformity.
• Stage II: Medial tapering of epiphysis, metaphysis and slight step in the physis.
• Stage III: Sharp angular step in the medial proximal tibial metaphysis.
• Stage IV: Ossification of epiphysis into the metaphyseal step.
• Stage V: Appearance of separate medial fragment.
• Stage VI: Bony bridge formation.
Treatment: High tibial osteotomy.
Prognosis: If treatment is successful there is usually no residual disability or cosmetic abnormality.
FURTHER READING:
Ralph Weissleder, and Jack Wittenberg. Primer of Diagnostic Imaging. ISBN-10: 0323065384.
Lane F Donnelly. Fundamental of pediatric radiology. ISBN-13: 978-0721690612
