In Perthes disease, the severity of involvement determines prognosis. According to the lateral pillar classification (Herring), which class carries the worst prognosis and highest risk of femoral head deformity?

• A Lateral pillar Group C (<50% lateral pillar height or complete collapse) ✓
• B Lateral pillar Group A (no lateral pillar loss)
• C Lateral pillar Group B (>50% lateral pillar height maintained)
• D Lateral pillar Group B/C border (50% height, narrow lateral pillar)

Explanation

The lateral pillar (Herring) classification assesses the height of the lateral 15–30% of the femoral head (lateral pillar) during the fragmentation stage on AP radiograph. Group A: no involvement of lateral pillar — excellent prognosis. Group B: ≥50% lateral pillar height maintained — intermediate prognosis. Group C: <50% lateral pillar height — worst prognosis, highest risk of femoral head deformity (coxa magna, coxa plana) and subsequent osteoarthritis. A B/C border group was added as an intermediate category with significant prognosis implications. Age at onset also modifies prognosis — children >8 years with Group C have worst outcomes and most benefit from containment surgery.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.