synonyms: Genu Varum, Genu Varus, infantile Blounts disease, adolescent Blounts disease
Blount’s Disease ICD-9
Blount’s Disease Etiology / Epidemiology / Natural History
- Infantile Blounts may develop from extreme physiologic varus which progresses due to growth disturbance in the posterior medial tibial physis.
- African American > whites.
- Natural history unknown, up to 50% of patients may improve with time.
Blount’s Disease Anatomy
Blount’s Disease Clinical Evaluation
- Typically large for age and early walkers.
Blount’s Disease Xray / Diagnositc Tests
- A/P and lateral Knee, A/P and lateral tibia, long-leg views. Demonstrate medial metaphyseal sloping and epiphyseal fragmentation.
Blount’s Disease Classification / Treatment
- Physiologic bowing is common in children who are less than 3 years old whereas Blount disease is reported to be less than 1% at this age. Corrective bracing is initiated for presumed early Blount disease only if the metaphyseal-diaphyseal angle is more than 16 degrees. If the angle is less than 9 degrees the patient is observed. Between 9 and 16 degrees, bracing is considered only if there is instability on walking. The patient is then evaluated on 4 month intervals. (Raney EM, JPO 1998;18:670).
- Infantile Blounts = onset prior to 3y/o. Lanenskiold Classification(1-6). Metaphyseal diaphyseal angle (of Drennan) >13 degrees, Rx=KAFO stages I-IV, Stages V-VI(have metaphyseal bar) osteotomy over correcting to valgus.. (Raney J Pediatr Orthop 18:670;1998) Xray=orthogram with patellas facing forward.--metaphyseal beaking.
- Adolescent Blounts, usually overweight, black, RX=lateral hemiepiphysiodesis vs proximal tibial osteotomy
Blount’s Disease Associated Injuries / Differential Diagnosis
Blount’s Disease Complications
Blount’s Disease Follow-up Care
Blount’s Disease Review References
- Feldman MD, Schoenecker PL; Use of metaphyseal-diaphyseal angle in the evaluation of bowed legs. JBJS 1993;75A:1602-1609.