PMC10069913_01
Preoperative images (A, X-ray; B, 3D-CT; and C and D, CT).
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Preoperative X-ray shows lumbosacral facet abnormality at the left side (A, white arrows).
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Preoperative 3D-CT shows the left L5 inferior articular process dislocated ventrally to the S1 superior articular process, resembling facet interlocking (B; C2, white circle). Bone fragment by the tip of the left L5 inferior articular process (C1; C3, arrowhead), mild spondylosis at the left L5/S1 facet, severe spondylosis at the right L5/S1 facet, and hypoplasia of the left S1 pedicle (D, white arrow) are confirmed via preoperative CT.
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Plain X-ray films showed something abnormal at the left lumbosacral facet region, the details of which could not be confirmed by this examination (Fig. 1A). Computed tomography (CT) scan showed the left L5 inferior articular process located at the ventral side of the left S1 superior articular process, resembling "facet interlocking" (Fig. 1B). A small bone fragment at the tip of the L5 inferior articular process and hypoplasia of the left S1 pedicle were also noticed (Fig. 1C1-3, D).
Preoperative MRI CISS (A), intraoperative view (right), and the schema (left) (B).
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The left S1 nerve is compressed by the dislocated left L5 inferior articular process and bone fragment (A, white circle).
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Left L5 inferior articular process dislocated ventral to left S1 superior articular process is intraoperatively confirmed (B).
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A small bone fragment at the tip of the L5 inferior articular process and hypoplasia of the left S1 pedicle were also noticed (Fig. 1C1-3, D). MRI constructive interference in steady state (CISS) showed the left S1 nerve root compressed toward the medial side by the ventrally dislocated left L5 inferior articular process and bone fragment (Fig. 2A). Intraoperative findings revealed that the left L5 inferior articular process was located ventral to the left S1 superior articular process (Fig. 2B).
Postoperative MRI CISS (A) and 3D-CT (B).
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Postoperative MRI CISS shows decompression of the left S1 nerve (A).
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Partial facetectomy of the left L5/S1 and removal of the bone fragment are confirmed via postoperative 3D-CT (B).
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A small bone fragment at the tip of the L5 inferior articular process and hypoplasia of the left S1 pedicle were also noticed (Fig. 1C1-3, D). Postoperative images showed decompression of the left S1 nerve on MRI CISS and partial facetectomy and removal of the bone fragment on CT (Fig. 3A, B).