Fractures of the scaphoid may be overlooked, thus often evolving towards nonunion. When a fracture has not healed by 3 months, it can be considered as a nonunion. One should distinguish between chronic cases of nonunion and those that have been evolving for less than 6 months because treatment options are completely different.
Herbert?s classification individualizes four stages:
Type D1: tight nonunion with interfragmentary fibrosis
Type D2: loose nonunion without bone deformity
Type D3: losse nonunion with bone deformity
Type D4: necrosis of the proximal pole
Alnot’s classification has four different stages:
Stage I: linear nonunion with no modification of the scaphoid shape and no instability or intracarpal dissociation.
Stage II: further divided in IIA when the nonunion is stable with bone resorption at the level of the fracture site and IIB when the nonunion is mobile with an anterior defect and flessum of the proximal pole towards the distal tubercle leading to an intracarpal dissociation with DISI (Dorsal Intercalated Segment Instability)
Stage III: displaced and unstable nonunion with intracarpal dissociation as in stage IIB. Stage III is further divided into stages IIIA, with stylo-scaphoid arthritis, and IIIB, with both radiocarpal and intercarpal arthritis.
The first three stages of this classification represent the natural evolution of the same individual lesion.
Stage IV is a different stage related to necrosis of the proximal fragment, divided in stages IVA, with dissociation, and IVB, with radioscaphoid and intercarpal arthritis.