Boyd Classification for Congenital Pseudoarthrosis of Tibia Epomedicine 1 year ago Tweet FB Share Pin It Mnemonic: BBCCDDE Boyd’s classification I – Bowing II – Constriction (hourlgass) III – Cyst IV – Dense (Sclerotic) V – Dysplastic fibula VI – “En-” neurofibroma or schwannoma (intraosseous)