Still normal, or already pathologic? Every radiologist, surgeon, and orthopaedic surgeon are confronted with this question on a daily basis, indeed it accompanies them for their professional life. For more than 90 years, Koehler/Zimmer has been the reference for differentiating borderline findings. This standard work in diagnostic radiology is now in it’s fifth edition, and has been restructured and expanded to include: more than 4200 images; concentration on borderline findings between normal and pathologic; integration of appropriate CT and MR Imaging findings; and structuring of all possible changes in five pathologic categories: dysplasia, trauma, necroses, inflammation, and tumour. This work should help the radiologist to increase his or her certainty and confidence in describing findings in skeletal radiology, and in arriving at appropriate diagnosis.