Intraoperative Myelography in Transpsoas Lateral Lumbar Interbody Fusion for Degenerative Lumbar Spinal Stenosis: A Preliminary Prospective Study

Preoperative dorsal disc height is a predictor of indirect decompression effect through oblique lateral interbody fusion in lumbar degenerative stenosis

The extent of indirect decompression after oblique lateral interbody fusion (OLIF) is one of the most important factors in deciding the strategy. To assess the radiographical predictors of the effect of indirect decompression in patients with lumbar degenerative spondylosis by OLIF. Thirty-two consecutive patients who underwent OLIF at 58 lumbar disc levels were enrolled in this study. The radiographic measurements included central disc height (cDH), dorsal disc height (dDH), right/left foraminal height in sagittal plane computed tomography (CT), and cross-sectional dural sac antero-posterior diameter (CDSD) in axial plane CT. All patients were followed up for 1 year after surgery. All CT parameters (cDH, dDH, CDSD, right foraminal height [RFH], and left foraminal height [LFH]) significantly increased after OLIF (P < .0001). The mean raised height difference was 4.3, 3.4, 3.4, and 2.6 mm for cDH, dDH, RFH, and LFH, respectively. The mean CDSD increase was 1.4 mm. The median values of post/pre-operation (change rates) were 1.5 times in cDH, 1.9 times in dDH, and 1.2 times in CDSD, RFH, and LFH. RFH and LFH change rates were related with both cDH and dDH change rates, while the CDSD change rate was only associated with the dDH change rate (P = .0206*) but not with cDH (P = .2061). There was a significant negative relationship between the CDSD change rate and preoperative dDH (P = .0311*, R2 = 0.0817) but not with preoperative cDH (P = .4864). OLIF should be avoided for patients with preserved high dDH.

Assessing the differences in operative and patient-reported outcomes between lateral approaches for lumbar fusion: a systematic review and indirect meta-analysis

OBJECTIVE

Anterior-to-psoas lumbar interbody fusion (ATP-LIF), more commonly referred to as oblique lateral interbody fusion, and lateral transpsoas lumbar interbody fusion (LTP-LIF), also known as extreme lateral interbody fusion, are the two commonly used lateral approaches for performing a lumbar fusion procedure. These approaches help overcome some of the technical challenges associated with traditional approaches for lumbar fusion. In this systematic review and indirect meta-analysis, the authors compared operative and patient-reported outcomes between these two select approaches using available studies.

METHODS

Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach, the authors conducted an electronic search using the PubMed, EMBASE, and Scopus databases for studies published before May 1, 2019. Indirect meta-analysis was conducted on fusion rate, cage movement (subsidence plus migration), permanent deficits, and transient deficits; results were depicted as forest plots of proportions (effect size [ES]).

RESULTS

A total of 63 studies were included in this review after applying the exclusion criteria, of which 26 studies investigated the outcomes of ATP-LIF, while 37 studied the outcomes of LTP-LIF. The average fusion rate was found to be similar between the two groups (ES 0.97, 95% CI 0.84-1.00 vs ES 0.94, 95% CI 0.91-0.97; p = 0.561). The mean incidence of cage movement was significantly higher in the ATP-LIF group compared with the LTP-LIF group (stand-alone: ES 0.15, 95% CI 0.06-0.27 vs ES 0.09, 95% CI 0.04-0.16 [p = 0.317]; combined: ES 0.18, 95% CI 0.07-0.32 vs ES 0.02, 95% CI 0.00-0.05 [p = 0.002]). The mean incidence of reoperations was significantly higher in patients undergoing ATP-LIF than in those undergoing LTP-LIF (ES 0.02, 95% CI 0.01-0.03 vs ES 0.04, 95% CI 0.02-0.07; p = 0.012). The mean incidence of permanent deficits was similar between the two groups (stand-alone: ES 0.03, 95% CI 0.01-0.06 vs ES 0.05, 95% CI 0.01-0.12 [p = 0.204]; combined: ES 0.03, 95% CI 0.01-0.06 vs ES 0.03, 95% CI 0.00-0.08 [p = 0.595]). The postoperative changes in visual analog scale (VAS) and Oswestry Disability Index (ODI) scores were both found to be higher for ATP-LIF relative to LTP-LIF (VAS: weighted average 4.11 [SD 2.03] vs weighted average 3.75 [SD 1.94] [p = 0.004]; ODI: weighted average 28.3 [SD 5.33] vs weighted average 24.3 [SD 4.94] [p < 0.001]).

CONCLUSIONS

These analyses indicate that while both approaches are associated with similar fusion rates, ATP-LIF may be related to higher odds of cage movement and reoperations as compared with LTP-LIF. Furthermore, there is no difference in rates of permanent deficits between the two procedures.

WISP-1 induced by mechanical stress contributes to fibrosis and hypertrophy of the ligamentum flavum through Hedgehog-Gli1 signaling

Ongoing chronic fibrosis and hypertrophy of the ligamentum flavum (LF) is an important cause of lumbar spinal canal stenosis (LSCS). Our previous work showed that WNT1-inducible signaling pathway protein 1 (WISP-1) is a critical driver of LF fibrosis. However, the potential mechanism has not been explored. Here, we found that Gli1 was upregulated in hypertrophic LF tissues and required for fibrogenesis in fibroblasts. Moreover, mechanical stretching increased the expression of WISP-1 in LF fibroblasts. Furthermore, WISP-1 induced fibrogenesis in vitro through the Hedgehog-Gli1 pathway. This conclusion was supported by the fact that WISP-1 activated the Hedgehog-Gli1 pathway in LF fibroblasts and that cyclopamine attenuated the effect of WISP-1-induced fibrogenesis. WISP-1 also promoted the transition of fibroblasts into myofibroblasts via the Hedgehog pathway. Importantly, a hypertrophic LF rabbit model induced by mechanical stress also showed pathological changes in fibrosis and elevated expression of WISP-1, Gli1, and α-SMA. Therapeutic administration of cyclopamine reduced collagen expression, fibroblast proliferation, and myofibroblast differentiation and ameliorated fibrosis in the mechanical stress-induced rabbit model. Collectively, our findings show mechanical stress/WISP-1/Hedgehog signaling as a new fibrotic axis contributing to LF hypertrophy and identify Hedgehog signaling as a therapeutic target for the prevention and treatment of LF fibrosis.

Preliminary report of modified expansive laminoplasty in the treatment of thoracic ossification of the ligamentum flavum

Objective

This study was performed to evaluate the role of posterior suspension of the laminae–ossification of the ligamentum flavum complex combined with miniplate fixation (modified expansive thoracic laminoplasty) in treating thoracic ossification of the ligamentum flavum (TOLF).

Methods

Eight patients with TOLF treated by modified expansive thoracic laminoplasty were retrospectively analyzed. Their general information, operative time, intraoperative blood loss, and postoperative complications were recorded. Neurological functional recovery was evaluated by the modified Japanese Orthopaedic Association (mJOA) score and Hirabayashi recovery rate preoperatively, postoperatively, and at the final follow-up. Preoperative and postoperative imaging was performed, and the decompression range and internal fixation positioning were evaluated.

Results

The mJOA score significantly improved from 4.63 points preoperatively to 9.0 points at the final follow-up (Hirabayashi recovery rate of 77.75%). Postoperative computed tomography and magnetic resonance imaging revealed sufficient decompression of the surgical segment. At the final follow-up, the internal implants were well-placed, the lamina–ligamentum flavum complex showed no significant displacement, and neurological functional recovery was satisfactory.

Conclusion

Surgical treatment of TOLF is complicated and high-risk. Characterized by simplicity and sufficient decompression, modified expansive thoracic laminoplasty can reduce the risk of cerebrospinal fluid leakage and nerve injury with satisfactory neurological functional recovery.

Lateral Lumbar Interbody Fusion: What Is the Evidence of Indirect Neural Decompression? A Systematic Review of the Literature

BACKGROUND

In the past decade, lateral lumbar interbody fusion (LLIF) has gained in popularity. A proposed advantage is the achievement of indirect neural decompression. However, evidence of the effectiveness of LLIF in neural decompression in lumbar degenerative conditions remains unclear.

QUESTIONS/PURPOSES

We sought to extrapolate clinical and radiological results and consequently the potential benefits and limitations of LLIF in indirect neural decompression in degenerative lumbar diseases.

METHODS

We conducted a systematic review of the literature in English using the 2009 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and checklist. Scores on the Oswestry Disability Index (ODI) and visual analog scale (VAS) for back and leg pain were extracted, as were data on the following radiological measurements: disc height (DH), foraminal height (FH), foraminal area (FA), central canal area (CA).

RESULTS

In the 42 articles included, data on 2445 patients (3779 levels treated) with a mean follow-up of 14.8 ± 5.9 months were analyzed. Mean improvements in VAS back, VAS leg, and ODI scale scores were 4.1 ± 2.5, 3.9 ± 2.2, and 21.9 ± 7.2, respectively. Post-operative DH, FH, FA, and CA measurements increased by 68.6%, 21.9%, 37.7%, and 29.3%, respectively.

CONCLUSION

Clinical results indicate LLIF as an efficient technique in indirect neural decompression. Analysis of radiological data demonstrates the effectiveness of symmetrical foraminal decompression. Data regarding indirect decompression of central canal and lateral recess are inconclusive and contradictory. Bony stenosis appears as an absolute contraindication. The role of facet joint degeneration is unclear. This systematic review provides a reference for surgeons to define the potential and limitations of LLIF in indirect neural elements decompression.

Reassessment System and Staged Surgical Strategy with Minimally Invasive Techniques for Treatment of Severe Adult Spinal Deformities

OBJECTIVE

We determined the feasibility of minimally invasive surgery for severe adult spinal deformities and proposed a reassessment system and staged minimally invasive surgical strategy.

METHODS

We treated 53 patients from June 2016 to August 2017 using a reassessment system and a staged surgical strategy with minimally invasive techniques for minimally invasive spinal deformity surgery, class III. Patients with scoliotic apex vertebrae above L1-L2 or spontaneous fusion of the facet joints were excluded. The reassessment system was applied. The first stage involved multisegmental lateral lumbar interbody fusion and anterior column realignment (ACR), and the second stage involved posterior minimally invasive surgery. The pre- and postoperative visual analog scale scores, Oswestry disability index, surgical data, and radiographic images were collected. The major and minor complications were recorded.

RESULTS

All the patients were followed up for 11.5 months (range, 6-20). Lateral lumbar interbody fusion was performed in 168 segments, of which 113 had ACR. The average sagittal correction angle of each ACR segment was 15.6° ± 6.3° (range, 7°-28°). The correction rate of the Cobb angle for lumbar scoliosis after first stage was 55.4%, and the total correction rate was 75.6%. The lumbar lordosis-pelvic index mismatch was improved from -32.8° ± 14.9° to -2.5° ± 9.4°, reaching the sagittal matching state of the lumbar spine.

CONCLUSIONS

A reassessment system and minimally invasive staged surgery for severe adult spinal deformity can achieve good clinical outcomes and deformity correction and might have the advantage of decreasing unnecessary iatrogenic injury.