Unstable Non-isthmic Spondylolisthesis Following Unilateral Biportal Endoscopy Assisted Unilateral Laminotomy for Bilateral Decompression: A Case Report

@#Lumbar decompressive laminectomy is a standard treatment for degenerative lumbar spinal stenosis, but in some cases, can lead to iatrogenic spondylolysis and delayed segmental instability. Iatrogenic spondylolysis occurs in most cases in pars interarticularis, but rare cases have also been reported, pediculolysis in pedicle and laminolysis in lamina. Minimally invasive spine surgery (MIS) is known to have a low risk of developing these iatrogenic spondylolyses, and unilateral biportal endoscopy is the MIS that has been drawing attention. We present a case of a 72-year-old female who was diagnosed with L4-5 unstable non-isthmic spondylolisthesis and severe right central disc extrusion 10 weeks after UBE assisted unilateral laminotomy for bilateral decompression (ULBD) at the consecutive segments of L3-4 and L4-5. Pre-operative imaging studies revealed severe central stenosis without spondylolisthesis at L3-L4 and L4- L5 along with L4-L5 facet tropism. She was managed by anterior lumbar interbody fusion and cement augmented pedicle screw fixation, which resulted in the complete resolution of her clinical and neurologic symptoms.

Zygapophyseal Joint Orientation and Facet Tropism and Their Association with Lumbar Disc Prolapse

STUDY DESIGN: Cross-sectional study. PURPOSE: To evaluate the association between zygapophyseal joint angle (ZJA), facet tropism (FT), and lumbar intervertebral disc prolapse (IVDP). OVERVIEW OF LITERATURE: Several studies have shown that FT increases the risk of IVDP and have postulated that a more sagittally oriented zygapophyseal joint provides less mechanical resistance to axial torque, thereby exerting excessive rotational strain on the intervertebral disc, resulting in an annular tear. In contrast, other studies have found no definitive association between FT and IVDP. Therefore, conclusive evidence regarding the role of FT in the pathogenesis of disc prolapse is currently lacking. METHODS: Magnetic resonance imaging scans of 426 patients with single-level lumbar IVDP were analyzed. Right and left ZJAs of the lumbar segments were measured on axial sections. The frequency and severity of FT were determined by calculating the absolute difference between the right and left ZJAs. Patients without IVDP at L4–L5 and L5–S1 served as controls for those with IVDP at L4–L5 and L5–S1, respectively. Chi-square test and t-test were used to compare the severity and frequency of FT between patients with and without IVDP. The receiver operating characteristic analysis was performed to determine the critical FT values that were predictive of IVDP. RESULTS: Patients with IVDP exhibited a higher frequency (L4–L5: 47% vs. 15.08%; L5–S1: 39.62% vs. 22.69%; p=0.001) and severity (L4–L5: 7.85°±3.5° vs. 4.05°±2.62°; L5–S1: 7.30°±3.07° vs. 4.82°±3.29°; p < 0.001) of FT than those without IVDP. Critical FT values of 5.7° at L4–L5 and 6° at L5–S1 increased the likelihood of IVDP by a factor of 2.89 and 1.75, respectively. CONCLUSIONS: Our results confirm the existence of a significant association between lumbar IVDP and FT; however, a causal relationship could not be ascertained.

Analysis of Factors Contributing to Postoperative Spinal Instability after Lumbar Decompression for Spinal Stenosis

OBJECTIVE: Decompressive laminectomy is one of the most commonly used surgical methods for the treatment of spinal stenosis. We retrospectively examined the risk factors that induce spinal instability, including slippage (spondylolisthesis) and/or segmental angulation after decompressive laminectomy on the lumbar spine. METHODS: From January 1, 2006 to June 30, 2010, 94 consecutive patients underwent first-time single level decompressive laminectomy without fusion and discectomy. Of these 94 patients, 42 with a follow-up period of at least 2 years were selected. We measured the segmental angulation and slippage in flexion and extension dynamic lumbar radiographs. We analyzed the following contributing factors to spinal instability: age/sex, smoking history, disc space narrowing, body mass index (kg/m2), facet joint tropism, effect of the lordotic angle on lumbar spine, asymmetrical paraspinal muscle volume, and surgical method and level. RESULTS: Female patients, normal lordotic angle, and asymmetrical paraspinal muscle volume were factors more significantly associated with spondylolisthesis (p-value=0.026, 0.015, <0.01). Statistical results indicated that patients with facet tropism were more likely to have segmental angulation (p-value=0.046). Facet tropism and asymmetry of paraspinal muscle volume were predisposing factors to spinal instability (p-value=0.012, <0.01). CONCLUSION: Facet joint tropism and asymmetry of paraspinal muscle volume are the most important factors associated with spinal instability; therefore, careful follow-up after decompressive laminectomy in affected patients is necessary.

Relationship of Facet Tropism with Degeneration and Stability of Functional Spinal Unit

PURPOSE: The authors investigated the effect of lumbar facet tropism (FT) on intervertebral disc degeneration (DD), facet joint degeneration (FJD), and segmental translational motion. MATERIALS AND METHODS: Using kinetic MRI (KMRI), lumbar FT, which was defined as a difference in symmetry of more than 7degrees between the orientations of the facet joints, was investigated in 900 functional spinal units (300 subjects) in flexion, neutral, and extension postures. Each segment at L3-L4, L4-L5, and L5-S1 was assessed based on the extent of DD (grade I-V) and FJD (grade 1-4). According to the presence of FT, they were classified into two groups; one with FT and one with facet symmetry. For each group, demographics, DD, FJD and translational segmental motion were compared. RESULTS: The incidence of FT was 34.5% at L3-L4, 35.1% at L4-L5, and 35.2% at L5-S1. Age and gender did not show any significant relationship with FT. Additionally, no correlation was observed between DD and FT. FT, however, wasfound to be associated with a higher incidence of highly degenerated facet joints at L4-L5 when compared to patients without FT (p < 0.01). Finally, FT was not observed to have any effects upon translational segmental motion. CONCLUSION: No significant correlation was observed between lumbar FT and DD or translational segmental motion. However, FT was shown to be associated significantly with the presence of high grades of FJD at L4-L5. This suggests that at active sites of segmental motion, FT may predispose to the development of facet joint degeneration.

Predictable Risk Factors for Adjacent Segment Degeneration After Lumbar Fusion

OBJECTIVE: The aim of this study is to investigate predictable risk factors for radiologic degeneration of adjacent segment after lumbar fusion and preoperative radiologic features of patients who underwent additional surgery with adjacent segment degeneration. METHODS: Between January 1995 and December 2002, 201 patients who underwent lumbar fusion for degenerative conditions of lumbar spine were evaluated. We studied radiologic features, the method of operation, the length of fusion, age, sex, osteoporosis, and body mass index. Special attention was focused on, preoperative radiologic features of patients who required additional surgery were studied to detect risk factors for clinical deterioration. RESULTS: Follow-up period ranged from 3 to 11 years. In our study, 61 (30%) patients developed adjacent segment degeneration, and 15 (7%) patients required additional surgery for neurologic deterioration. Age, the postoperative delay, facet volume, motion range, laminar inclination, facet tropism, and preexisting disc degeneration of adjacent segment considered as possible risk factors. Among these, laminar inclination and preexisting disc degeneration of adjacent segment were significantly correlated with clinical deterioration. CONCLUSION: The radiologic degeneration of adjacent segment after lumbar fusion can be predicted in terms of each preoperative radiologic factor, age and the postoperative delay. Laminar inclination and preexisting disc degeneration of adjacent segment have shown as strong risk factors for neurologic deterioration. Thus, careful consideration is warranted when these risk factors are present.