Journal Logo

Supplement Article

Unified Classification System for Periprosthetic Fractures (UCPF)

Journal of Orthopaedic Trauma: January 2018 - Volume 32 - Issue - p S141-S144
doi: 10.1097/BOT.0000000000001068
  • Free


The UCPF is based upon the following factors:

  1. The fracture location may involve either the bone supporting the implant or distant to it.
  2. The stability of the components must be assessed to determine if the bone implant surface is stable prior to fracture and after fracture.
  3. The adequacy of the bone stock and bone strength supporting the implant must be sufficient to support internal fixation or a revision without additional major reconstruction.
  4. For clinical use, the definitions and terminology of the UCPF are used. In order to maintain consistency in coding and allow easy data retrieval for data collection, the UCPF has been modified so that the AO/OTA bone code appears first.
  5. The UCPF code follows as a qualification in square brackets.
  6. Fractures about or in a bone with a nonarthroplasty implant are coded using the universal modifier [12] following the AO/OTA fracture code.

Classification and coding process

  1. The bone is identified by the AO/OTA code (see Fig 1). The fracture morphology maybe classified in as much detail as needed.
  2. The UCPF for the joint involved is added as a modifier in square brackets [ _ ] after the bone code (see Fig 1).
  3. The fracture type is based on the location of the fracture in relation to the implant as follows:
    • • Apophysis adjacent implant with no effect on implant stability—Type A
      • – Tuberosities of the humerus
      • – Epicondyles or olecranon of distal humerus
      • – Trochanters and epicondyles of femur
      • – Spines of the pelvis
      • – Poles or tips of the patella
      • – Tibial tuberosity and malleoli
    • • Bed of the implant or around the implant—Type B
      • – Good bone no implant loosening—Type B1
      • – Good bone but implant loose—Type B2
      • – Poor bone or defect, implant loose—Type B3
    • • Clear of the implant—Type C
    • • Dividing the bone between two implants—Type D
    • • Each of the two bones supporting the implant—Type E
    • • Facing and articulating with a hemiarthroplasty—Type F

Fig 1
Fig 1:
AO/OTA bone codes and UCPF joint codes.

The table provides the unified codes that follow the fracture classification.

Example: A spiral fracture about a femoral prosthesis of a total hip, which on x-rays shows loosening of the implant but good bone stock = 32A1[IVB2]


Duncan CP, Haddad FS. Classification. In: Schütz M, Perka C, ed. Periprosthetic Fracture Management. Stuttgart: Georg Thieme; 2013:47–90.
    Copyright © 2017 by AO Foundation, Davos, Switzerland; Orthopaedic Trauma Association, IL, US