A 7-year-old boy is referred for Perthes disease. The Catterall classification of Perthes disease — in which group does involvement of the ENTIRE femoral head epiphysis fall?

• A Group I
• B Group II
• C Group III
• D Group IV ✓

Explanation

Catterall classification of Perthes disease: Group I = anterior 25% of epiphysis involved, no metaphyseal reaction, no collapse; Group II = up to 50% involvement, anterolateral involvement, sequestrum may be present; Group III = 75% involvement, large sequestrum, metaphyseal changes, subchondral collapse; Group IV = entire head involved (100%), gross collapse, metaphyseal involvement, 'mushroom' deformity. Group IV has the worst prognosis. The Herring (lateral pillar) classification is now more widely used prognostically.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.