[Diagnostics and classification of non-unions]

Non-union is defined as an insufficiently consolidated fracture in which healing without a surgical intervention is no longer foreseeable. Several underlying predispositions and factors have to be taken into account in order to optimize the diagnostics, classification and surgical treatment of this complex and challenging pathology.

As the patient-specific optimized treatment sometimes pursues different goals depending on the specific subtype of non-union, an agreement on the most important parameters within the framework of a standardized classification is of crucial importance. In addition to established diagnostic algorithms, this article also describes modern radiologic diagnostic methods.

In addition to the clinical examination, the diagnostics of non-union are mainly based on radiological imaging using X‑ray or computed tomography. Complex fracture morphology or uncertainty, particularly regarding the infection status and perfusion of non-union, can be an indication for an extension of the diagnostics using contrast-enhanced ultrasound (CEUS) or dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

A practicable and precise classification of the different types of non-union can only be successful based on a focussed diagnostic procedure using radiologic and functional diagnostic tools, which guide the surgeon in establishing the optimal treatment. This also includes modern functional imaging examinations, such as CEUS and DCE-MRI.