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.

You will find here:

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


  • Some pages are accompanied by illustrations
  • All pages contain tags for easy navigation

The concept

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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    Heterotopic ossification of the hip following total hip replacement - Brooker Classification

    Brooker classification divides heterotopic ossifications that form following total hip replacement to four classes. It was published in 1973 by Brooker et al.

    Class Description
    Class I islands of bone within soft tissues around hip
    Class II bone spurs in pelvis or proximal end of femur leaving ≥1 cm between the opposing bone surfaces
    Class III bone spurs that extend from pelvis or the proximal end of femur, which reduce the space between the opposing bone surfaces to <1cm
    Class IV ankylosis of the hip on x-ray


    1. Brooker AF, Bowerman JW, Robinson RA, Riley LH Jr. Ectopic ossification following total hip replacement. Incidence and a method of classification. J Bone Joint Surg Am. 1973 Dec;55(8):1629–32.
    2. Søballe K, Christensen F, Kristensen SS. Ectopic bone formation after total hip arthroplasty. Clin. Orthop. Relat. Res. 1988 Mar;(228):57–62.

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