# Blount Disease > Blount disease for NEET-PG Orthopaedics: infantile versus late-onset tibia vara, Langenskiold staging, metaphyseal-diaphyseal angle and treatment options. - Canonical URL: https://prepelephant.com/topics/neet-pg/orthopaedics/blount-disease - Exam / course: NEET-PG · Subject: Orthopaedics - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-14 - Last updated: 2026-10-14 - Reference basis: Maheshwari's Essential Orthopaedics; Apley's System of Orthopaedics and Fractures - How to cite: "Blount Disease", PrepElephant, https://prepelephant.com/topics/neet-pg/orthopaedics/blount-disease ## Direct answer Blount disease is a growth disorder of the medial proximal tibial physis that causes progressive bowing of the leg, termed tibia vara. It is divided by age at onset into the infantile form, presenting before about three years, and the late-onset form in older children and adolescents. The key discriminator from physiological bowing is a metaphyseal-diaphyseal angle above about 11 degrees on a standing radiograph. ## What you must remember - **Site:** the lesion lies in the medial part of the proximal tibial growth plate, which slows medial growth and drives the knee into varus. - **Infantile form:** presents before about three years, is often bilateral, and is linked with early walking and obesity. - **Metaphyseal-diaphyseal angle:** a value above about 11 degrees favours Blount disease, whereas physiological bowing gives a smaller angle. - **Langenskiold staging:** grades progressive medial physeal and metaphyseal damage in the infantile form, from mild change to a depressed, beaked medial metaphysis. - **Radiographic clue:** a beak-like medial metaphyseal projection and an irregular physeal outline on a standing long-leg film. - **Physiological contrast:** normal bowing is symmetrical, peaks around 18 months and corrects with growth without medial metaphyseal change. - **Management:** bracing or observation for early infantile disease; proximal tibial osteotomy for progressive or established deformity. - **Late-onset form:** often unilateral and progressive, and generally managed surgically. ## A staged pathway from varus to osteotomy A 2-year-old boy who began walking at nine months has a progressive varus knee on one side. The approach moves from separating normal bowing to measuring, staging and choosing treatment. 1. **Separate normal from abnormal:** physiological varus peaks around 18 months and then corrects, so a varus that persists or worsens after this age warrants review. 2. **Measure on a standing film:** a long-leg radiograph measures the metaphyseal-diaphyseal angle, with values above about 11 degrees favouring Blount disease. 3. **Inspect the medial metaphysis:** beaking, depression and physeal irregularity are sought, since these signs suggest the deformity will not correct on its own. 4. **Stage the physeal damage:** Langenskiold staging grades the medial physis, and advanced stages are unlikely to remodel without intervention. 5. **Brace or observe early:** early infantile disease may be braced or observed, although bracing does not reliably correct an established varus. 6. **Operate for progression:** a proximal tibial osteotomy realigns the limb in the child with progressive or established deformity, with attention to the risk of recurrence. ## Where the exam tries to catch you Examiners test the boundary between normal bowing and disease, and the timing of surgery. - **Trap:** calling every bowed leg in a toddler Blount disease. **Correct:** physiological varus is normal up to about 2 years, and only an angle above about 11 degrees with medial metaphyseal change points to Blount. - **Trap:** operating at once on early infantile disease. **Correct:** early disease is observed or braced, with osteotomy reserved for progression or an established deformity. - **Trap:** confusing Blount disease with rickets. **Correct:** rickets shows widened, cupped physes at several sites with low phosphate and raised alkaline phosphatase, whereas Blount disease is a localised medial lesion with normal biochemistry. ## Frequently asked questions ### Which angle distinguishes Blount disease from physiological bowing? The metaphyseal-diaphyseal angle, measured on a standing long-leg radiograph, is the commonly quoted discriminator. A value above about 11 degrees favours Blount disease, whereas physiological bowing produces a smaller angle without medial metaphyseal change. ### What does Langenskiold staging describe in Blount disease? Langenskiold staging grades progressive damage to the medial proximal tibial physis and metaphysis in the infantile form. Advanced stages, with a depressed and beaked medial metaphysis, are unlikely to remodel spontaneously and usually need surgical correction. ### Is bracing an effective treatment for infantile Blount disease? Bracing may be used in early infantile disease, but it does not reliably correct an established varus. Proximal tibial osteotomy is reserved for progressive or advanced deformity that bracing does not control. ### Which conditions must be excluded in a child with tibia vara? Rickets and skeletal dysplasias such as achondroplasia must be excluded in any child with tibia vara. Serum calcium, phosphate, alkaline phosphatase and vitamin D status help separate them from Blount disease, which has normal biochemistry. ### Which factors raise the risk of recurrence after tibial osteotomy in Blount disease? Obesity, advanced Langenskiold stage and delayed surgery (osteotomy after about 4 years of age) are commonly cited risk factors for recurrence. Incomplete correction at surgery also favours recurrence.