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CT scans of the degenerative change of sacroiliac joint (SIJ) obtained at 5 years after instrumented posterolateral lumbar/lumbosacral fusion.
A, Normal SIJ of the fusion group.
B, Sclerosis at the left SIJ and joint space narrowing at the right SIJ.
C, Subchondral cyst.
E, Intra-articular bone fragment.
F, Osteophyte formation.