PMC6350032_01
Preoperative lumbar radiographs and magnetic resonance imaging. In the lateral lumbar (A) flexion and (B) extension radiographs, no spondylolisthesis was present and the intervertebral disc spaces were maintained at all levels; however, spondylolysis at the levels of L3 (arrowhead) and L5 (arrow) was suspected. (C) A midsagittal magnetic resonance T2-weighted image showed degeneration of the L3/4 and L5/S1 discs.
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F1
L3 and L5 was suspected (Figs. 1A and 1B). Lumbar magnetic resonance imaging (MRI) revealed degeneration of the L3/4 and L5/S1 discs (Fig. 1C).
Preoperative computed tomography (CT). (A) Right and (B) left parasagittal CT scans demonstrated bilateral L3 pars fracture with osteophyte formation (arrowhead) and L5 pars fracture (arrow) without osteophyte formation. Axial CT scans demonstrated (C) marginal sclerosis with osteophyte formation at L3 and (D) pseudarthrosis without osteophyte formation at L5. No spondylolisthesis was present, and the intervertebral disc spaces were maintained at all levels.
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F2
Additionally, osteophyte formation was observed around the L3 but not L5 pars interarticularis (Figs. 2A-2E).
Illustration of the surgical procedure. The defect of the L3 pars interarticularis was exposed and curetted, then refreshed using a diamond burr. (A) Bilateral L3 pedicle screws were inserted. (B) When the bent rod was bumped against the spinous process using a rod pusher, the loose lamina was firmly fixed.
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F3
Using anatomic landmarks and fluoroscopic guidance, a starting hole for the pedicle screw was burred, the hole was tapped, and bilateral multiaxial pedicle screws were inserted (Fig. 3A). The loose lamina was fixed more firmly after the bent rod was bumped against the spinous process using a rod pusher (Fig. 3B).
Postoperative radiographs. (A) Lateral lumbar radiograph and (B) three-dimensional computed tomography.
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Cancellous bone was implanted into the pars defects (Figs. 4A and 4B).