Table 2. Multipledetector CT Findings in Cases of Acquired Spondylolysis or Spondylolisthesis after Posterior Lumbar Laminectomy.

Group	Case	Level and Width of Laminectomy		Spondylolysis		Spondylolisthesis		Facet Joint Changes	Fatty Grade of Paraspinal Muscles
		Level	Width (%)	Level	Location	Level	Degree (%)
1	1	Both L3	70.2	Both L3	F	L3–4	8.4	-	Grade 1
	2	Both L4	68.2	Both L4	F	L4–5	2.5	-	Grade 0
	3	Right L3	55.1	Right L3	F	-	-	-	Grade 0
	4	Left L4	22.6	Left L4	F	L4–5	7.4	Subluxation and OA	Grade 0
2	5	Both L4	75.9	-	-	-	-	-	Grade 2
		Left L5	34.8	Right L5	I	-	-	-	Grade 2
	6	Left L4	49.1	-	-	L3–4	6.4	Subluxation	Grade 2

Group 1 was included patients who have had posterior lumbar laminectomy without fusion, and Group 2 was included patients who have had posterior lumbar laminectomy with fusion.

F = below the pars interarticularis and adjacent to the facet joint, I = isthmic portion at pars interarticularis, L = lumbar, OA = osteoarthritis