Severe heterotopic ossification in a seronegative spondyloarthritis patient after cervical Bryan disc arthroplasty: A case report

Figure 4 Initial X-rays at four years after the motorcycle accident. Left: Shiny corner sign, a sclerotic margin of the T-L vertebral body corner, compatible with seronegative spondyloarthropathy; Right: Bone sclerotic change in the bilateral sacroiliac joint, compatible with bilateral sacroiliitis, grade I.