Fig. 1
From: Characteristics of lumbar spondylolysis: L5 versus non-L5
Computed tomography images of L5 and non-L5 spondylolysis. L5 spondylolysis (a, b). Bilateral lesions are present, the right lesion is a pseudarthrosis with osteosclerosis (arrowhead) and the left lesion is a progressive stage with a clear gap (arrow). Non-L5 spondylolysis (c, d). Unilateral lesion in L4. Early-stage lesion with hairline (arrow) on the left side only