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1Principles

A fracture subluxation with a palmar marginal fragment of variable size ...

Eaton type III (fracture subluxation)

A fracture subluxation with a palmar marginal fragment of variable size.

Stability of fracture dislocations (Eaton type III)
Stability of the reduction depends on the size of the avulsed palmar marginal fragment and the amount of collateral ligament remaining attached to the middle phalanx.
If less than 40% of the joint surface is avulsed, the fracture is displaced dorsally, with the dorsal portion of the collateral ligament remaining attached to the middle phalanx. This helps to keep the reduction stable.
However, if more than 40% of the joint surface has been avulsed, very little or no ligament will remain attached to the base of the middle phalanx, rendering reduction unstable.