Olecranon fractures are classified:

Type I:  nondisplaced or minimally displaced.

    Type IA: noncomminuted

    Type IB: comminuted

Type II: displaced proximal fragment without instability

    Type IIA: no comminution with displacement

     Type IIB: comminuted with displacement

Type III: Unstable ulnohumeral joint.

   Type IIIA: no comminution.

    Type IIIB: comminuted.