Welcome to Classifications and Online Calculators in Radiology

This site was build along with the Atlas of Radiology Images to support your knowledge in radiology.

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that are used in radiology and related fields with free access.


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The concept of this website is based on a previous site that was founded in 2008 and is still up and running. The website is composed as a book, where all sources are properly referenced, according to a good practice in scientific publications.

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    Posterior dislocation of the hip - Thompson-Epstein classification

    Thompson-Epstein classification describes five types of posterior hip dislocation defined by associated acetabular fracture or fracture of the femoral head as depicted on plain radiographs. In general, there are three types of dislocations in the hip joint:

    • posterior: the femoral head is dislocated posteriorly, most commont type
    • anterior: the femoral head is dislocated anteriorly
    • central: impact of the femoral through the acetabular floor into the pelvis
    Type Description
    Type I posterior dislocation with no or minor fracture
    Type II posterior dislocation with large single fracture of posterior acetabular rim
    Type III posterior dislocation with comminution of acetabular rim, irrespective of the size of fragments
    Type IV posterior dislocation with fracture of the acetabular floor
    Type V posterior dislocation with fracture of the femoral head


    1. Thompson VP, Epstein HC. Traumatic dislocation of the hip; a survey of two hundred and four cases covering a period of twenty-one years. J Bone Joint Surg Am. 1951 Jul;33-A(3):746–778; passim.
    2. Epstein HC. Traumatic dislocations of the hip. Clin Orthop Relat Res. 1973 May;(92):116–42.
    3. Dwyer AJ, John B, Singh SA, Mam MK. Complications after posterior dislocation of the hip. Int Orthop. 2006 Aug;30(4):224–7

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