Surgical Treatment of Lumbar Spondylolisthesis in the Elderly

The Reliability of CT Scan Measurements of Pelvic Incidence in the Evaluation of Adult Spondylolisthesis

Background: Pelvic incidence (PI) has been described as a parameter that may be a risk factor for lumbar spondylolisthesis (SPL). Studies have reported PI measurement is more precise in CT scans. Very limited studies have measured PI using CT scans to evaluate SPL. We analyzed the reliability of CT scans to measure PI to evaluate SPL and compared it to patients without SPL.

Methods: A retrospective, cross-sectional study of PI in a consecutive cohort of patients’ pelvic/abdominal CT scans from an emergency room visit at a Level 1 trauma center between 2013 and 2016. Inclusion criteria was >18 years and had no lumbar or pelvis fracture. A total of 361 patients met the criteria for our study. We documented age, average PI, and SPL (type, grading, and location). Sagittal CT scans were used to measure PI (between hip axis to an orthogonal line originating at the center of superior end plate axis of first sacral vertebra). Patients were categorized: with SPL (n=45) and without SPL (n=316). Subgroups were comprised based on the location of SPL (L4/L5 and L5/S1) and type of SPL. Analysis of variance (ANOVA) and chi-square tests used; p≤0.05 considered statistically significant.

Results: Patients with SPL were significantly older versus patients without SPL, p=0.006. There were no statistical differences in PI between patients with and without SPL (p=0.29); between subgroups of patients with SPL at L4/L5 and without SPL (p=0.52); between subgroups with type of SPL at L4/L5 and without SPL (p=0.47); and between SPL patients at L5/S1 and without SPL (p=0.40). Patients with isthmic SPL at L5/S1 had nearly significant higher PIs (p=0.06) compared to those without SPL or with degenerative SPL at L5/S1. There was a trend towards higher PI in Grade 2 SPL patients at L5/S1, p=0.18.

Conclusions: Patients with SPL were significantly older than patients without SPL. The two trends observed were that PI was higher in patients with isthmic SPL at L5/S1 and an increased PI with Grade 2 isthmic SPL at L5/S1. Our reported CT PI measurements correlated with reported PI measured using standard radiographs in patients with SPL. CT scans may be a reliable modality to evaluate adult SPL.

Ipsilateral Pedicle Stress Fracture After Endoscopic Foraminal Decompression for Patient with Isthmic Spondylolisthesis

BACKGROUND

Minimally invasive endoscopic spine surgery is useful for the treatment of various spinal conditions. Although surgery-related complications such as dural injury, exiting nerve root injury, incomplete decompression, and hematoma have been reported, there are few reports of late complications after endoscopic surgery.

CASE DESCRIPTION

A 51-year-old man complained of radiating pain to the right leg. The patient underwent endoscopic foraminal decompression under the diagnosis of foraminal stenosis with isthmic type spondylolisthesis (L5-S1). The lower extremity radiating pain was improved after surgery. Six weeks after surgery, the patient's symptoms recurred. The patient experienced a sudden onset of severe low back pain, which was aggravated by any motion of the lumbar spine. Computed tomography scan and magnetic resonance imaging revealed a fracture line with a sclerotic margin at the base of the right pedicle at the L5 level. Because the symptoms significantly interfered with his normal activities of daily living, the patient was treated with a total laminectomy, followed by posterior instrumented fusion. As the indication for endoscopic spinal surgery is widening, endoscopic decompression surgery is being performed for patients with low-grade lumbar spondylolisthesis, regardless of the presence of advanced spinal instability. However, endoscopic decompression surgery may cause damage to the posterior facet joint, which may have worsened the instability and lead to late complications such as progression of spondylolisthesis and pedicle stress fracture.

CONCLUSIONS

The surgeon should carefully review risk factors such as isthmic type spondylolisthesis before planning spine surgery and minimize facet joint damage during endoscopic decompression.