It is my understanding that fusion of vertebrae cannot be seen on X-rays but that thickening/solidifying between vertebrae can be seen which MAY BE fusion, but that fusion itself can not be definitively diagnosed or decided. Fusion can be decided/diagnosed at a surgery to stress the joining of the vertebrae or in the negative sense, when someone w/ spinal surgery has sudden pain and the X-ray shows non-junction.
Degenerative Adult Onset Scoliosis @65, 25* T & 36* L scoliosis w/ 11.2 cm coronal & 3.5 cm sagittal balance, T kyphosis 90*; Severe disc degen T & L stenosis
2013: T3- S1 Fusion w/ ALIF L4-S1/XLIF L2-4, PSF T4-S1 2 surgeries
2014: Hernia @ ALIF repaired
2014: Emerg Rev surgery spinal cord injury;hardware removal T3-T5 w/reinstrumentation
2015: Replacement all T hardware due to lack fusion; tethering & replacement broken rod; infection discovered
9/2015: Broken L L4 rod