High-grade adult isthmic L5-s1 spondylolisthesis: a report of intraoperative slip progression treated with surgical reduction and posterior instrumented fusion

Abstract

Adult isthmic spondylolisthesis most commonly occurs at the L5-S1 level of the lumbar spine. Slip progression is relatively rare in adults with this condition and slippage is typically associated with advanced degeneration of the disk below the pars defect. When symptomatic, radiculopathy is the typical complaint in adults with isthmic spondylolisthesis. When considering options for surgical treatment of adult isthmic spondylolisthesis, the surgeon must consider several different options, such as decompression, fusion, instrumentation, reduction, and type of bone graft to be used. All of these decisions must be individualized as deemed appropriate for each particular patient. This report presents a case of intraoperative slip progression of a L5-S1 adult isthmic spondylolisthesis to a high-grade slip, which was treated with complete surgical reduction and posterior instrumented fusion. This case demonstrates the potential instability of this condition in adults and has not been previously reported. The case details and images are reviewed and the intraoperative decisions, treatment options, and patient outcome are discussed.

Keywords: adult isthmic spondylolisthesis; high-grade spondylolisthesis; posterior instrumented fusion; slip progression; surgical reduction.

Figure 1

Preoperative standing lateral radiograph demonstrating grade II spondylolisthesis with advanced degenerative disk disease at the L5–S1 level.

Figure 2

Preoperative sagittal (A) and axial (B) magnetic resonance images demonstrating grade II spondylolisthesis with advanced degenerative disk disease at the L5–S1 level. Note that there is no evidence of central stenosis despite the slip, but the symptoms are due to significant bilateral foraminal stenosis.

Figure 3

(A) Intraoperative lateral fluoroscopic image demonstrating slip progression of the spondylolisthesis to grade IV while on the operating room table. (B) Lines have been placed to outline the posterior margins of the vertebral bodies of L5 and S1 to help clarify the slip.

Figure 4

(A) Intraoperative lateral fluoroscopic image demonstrating reduction of the slip to a grade II spondylolisthesis following the repositioning of the patient in a more flexed position utilizing a bolster frame. Note the vacuum disk phenomenon seen at the L5–S1 disk following the reduction. (B) Lines have been placed to outline the posterior margins of the vertebral bodies of L5 and S1 to help clarify the slip.

Figure 5

Intraoperative lateral fluoroscopic image demonstrating near anatomic reduction of the L5–S1 spondylolisthesis following instrumentation from L4–S1.

Figure 6

Upright lateral radiograph of the lumbar spine taken postoperatively demonstrating maintenance of the reduction achieved during instrumentation.