In Herring's lateral pillar classification for Legg-Calvé-Perthes disease, a Group C designation indicates which finding and carries which implication?

• A Lateral pillar height maintained >50% of the original; associated with good outcomes regardless of age at onset
• B Lateral pillar completely collapsed (0% height) or <15% original height; associated with poor outcomes, especially in children older than 8 years ✓
• C Lateral pillar height maintained 15–50% of the original; intermediate prognosis requiring careful monitoring
• D Lateral pillar lucency without collapse; radiological finding only with no clinical significance

Explanation

Herring's lateral pillar classification divides the femoral head into three zones: the central pillar (50% width), the medial pillar (25%), and the lateral pillar (25%). Group A: lateral pillar fully maintained. Group B: lateral pillar >50% maintained. Group B/C border: exactly 50%. Group C: lateral pillar <50% (or specifically <15%) maintained with complete collapse. Group C carries the worst prognosis — risk of flat head deformity and premature osteoarthritis. In children >8 years at onset with Group C involvement, containment surgery (varus derotation osteotomy or Salter innominate osteotomy) is typically recommended.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.