It is sometimes very difficult to be sure about union of a fracture where internal fixation has been used. Evaluation of serial X-rays may help detect subtle angulation, non-progress of bridging callus, resorption of callus, loosening of screws and bending of the nail or plate. Excessive rotation may be the only abnormal mobility in a case with intra- medullary rod in situ. Oblique views, done under fluoroscopy may show an unhealed fracture better than conventional AP and lateral X-rays. It may be possible to demonstrate mobility at the fracture by stress X-rays or weight bearing X-rays. 3-D CT scan is sometimes helpful in differentiating between delayed and non-union.