Unified classification system for periprosthetic fractures

Last revised by Henry Knipe on 18 Sep 2023

The unified classification system (UCS) is used for periprosthetic fractures.

The classification is proposed to standardize the classification of periprosthetic fractures and provide a guide to the management of these fractures regardless of the broken bone or the joint affected 1-4.

The classification has been shown to have a high inter and intra-observer reproducibility for periprosthetic fractures around total hip 2 and total knee arthroplasties 3.


  • type A: fracture of an apophysis or bone protuberance to which soft-tissue structures are attached (e.g. trochanters of the femur)

  • type B: fracture of the bed supporting a prosthetic implant or adjacent to it

    • B1: the implant is still well fixed

    • B2: the implant is loose

    • B3: the implant is loose and there is poor quality of bone bed

  • type C: fracture of a bone containing a prosthetic implant, but distant from the bed of the implant

  • type D: fracture of a bone with two prosthetic implants (e.g. the femur following a hip and knee replacement)

  • type E: fracture of two bones supporting a prosthetic implant (e.g. the femur and tibia following a knee replacement)

  • type F: fracture of an articular surface that itself was not replaced (e.g. acetabulum following a hemi-arthroplasty of the hip)

See also

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