Changes in Paraspinal Muscles and Facet Joints after Minimally Invasive Posterior Lumbar Interbody Fusion Using the Cortical Bone Trajectory Technique: A Prospective Study

In this prospective cohort study, we aimed to determine the surgical and adjacent segment changes in paraspinal muscles and facet joints in patients with lumbar spinal stenosis after minimally invasive posterior lumbar interbody fusion (PLIF) using the cortical bone trajectory (CBT) technique. We enrolled 30 consecutive patients who underwent the single-level CBT technique between October 2017 and October 2018. We evaluated preoperative and 1-month, 3-month, 6-month, and 1-year postoperative clinical data including Visual Analogue Scale (VAS) scores and Oswestry Disability Index (ODI). Magnetic resonance imaging (MRI) was performed a year after surgery. The erector spinae (ES) muscle area, volume, and fat infiltration (FI) on the surgical and adjacent segments were evaluated using the thresholding method, and the degree of adjacent facet joint degeneration was calculated using the Weishaupt scale. FI rate was graded using the Kjaer method. All patients underwent a 12-month follow-up. The VAS and ODI scores significantly improved after surgery in all patients. No patient showed degeneration of the adjacent facet joints ( P > 0.05 ) during the 1-year follow-up postoperation. There was no significant difference in ES muscle volume, area, and FI on the surgical and adjacent segments ( P > 0.05 ). The FI rate of the upper ES muscles increased postoperatively ( P < 0.05 ); however, there were no significant changes in FI rate of the lower ES muscles. Patients with lumbar spinal stenosis could obtain satisfactory short-term clinical outcomes via minimally invasive PLIF using the CBT technique. Moreover, this technique may reduce the impact on the paravertebral muscles, especially the ES muscle, and the adjacent facet joints.

Comparison of Opioid Consumption Patterns of Three Interbody Fusion Surgical Techniques

Study Design Retrospective review. Objectives With increased awareness of the opioid crisis in spine surgery, the focus postoperatively has shifted to managing surgical site pain while minimizing opioid use. Numerous studies have compared outcomes and fusion status of different interbody fusion techniques; however, there is limited literature evaluating opioid consumption postoperatively between techniques. The aim of this study was to assess in-house and postoperative opioid consumption across 3 surgical techniques. Methods Patients were stratified by technique: posterior lumbar interbody fusion (PLIF), minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF), and cortical screw (CS) instrumentation with interbody fusion. Age, ASA, BMI, depression, preoperative opioid use, EBL, and OR time were recorded and compared across surgical groups using Welch’s ANOVA and chi-square analysis. Total morphine equivalent dose (MED) was tabulated for both in-house consumption and postoperative prescriptions and was compared across surgical techniques using Welch’s ANOVA analysis, Mann Whitney U tests, and linear regression. Results Two hundred and thirty nine patients underwent one- or two-level posterior lumbar interbody fusion between 2016 and 2020. One hundred and twenty one patients underwent CS instrumentation, 95 underwent PLIF, and 83 underwent MIS-TLIF. There was a significantly higher percentage of patients who had a history of depression and preoperative opioid consumption in the CS group ( P = .001, P = .009). CS instrumentation required significantly less total post-op opioids per kilogram bodyweight compared to MIS-TLIF and PLIF surgeries ( P = .029). Conclusions Patients who underwent CS instrumentation required less opioids postoperatively. CS instrumentation may be associated with less postoperative pain due to the less invasive approach, however, patient education and prescriber practice also play a role in postoperative opioid consumption.

Intraoperative Measurements of Nerve Root Tension During Posterior Lumbar Interbody Fusion

Background There is no effective standard method to evaluate whether the nerve root tension is restored, which is an important indicator for the recovery of nerve function. This study aimed to demonstrate a technique for measuring nerve root tension during surgery. Methods A total of 54 consecutive patients (average age, 52.3 years; range, 28-68 years) received posterior lumbar interbody fusion for lumbar disc herniation comprised the patient sample.The nerve root tension was measured twice before and after intraoperative decompression by the nerve root tension meter modified from the transverse gauge by author. Clinical outcome was assessed by the visual analog scale (VAS) for leg pain, provided by patients before and after surgery. Results There was a significant improvement in the VAS score for leg pain after surgery compared with that before surgery (7.0 ± 2.24 vs. 0.8 ± 0.84, respectively; P < 0.01). Nerve root tension was significantly decreased after decompression compared with that before surgery (1.32 ± 0.22 N vs. 0.64 ± 0.17 N, respectively; P < 0.01). The nerve root tension was positively correlated with the VAS score (r = 0.772, P < 0.05; r = 0.715, P < 0.05). Conclusions This study shows that the nerve root tension meter can instantly and non-invasively measure nerve root tension during an operation. It was demonstrated that the nerve root tension of the patient is significantly reduced after decompression. Meanwhile, the VAS score improved significantly, and the nerve root tension and VAS scores were positively correlated.

Revision for Cage Migration After Transforaminal/Posterior Lumbar Interbody Fusion; How to Perform Revision Surgery?

BackgroundSymptomatic pseudarthrosis and cage migration/protrusion are difficult complications of transforaminal or posterior lumbar interbody fusion (TLIF/PLIF). If the patient experiences severe radicular symptoms due to cage protrusion, removal of the migrated cage is necessary. However, this procedure is sometimes very challenging because epidural adhesions and fibrous union can be present between the cage and vertebrae. We describe a novel classification and technique utilizing a navigated osteotome and the oblique lumbar interbody fusion at L5/S1 (OLIF51) technique to address this problem.MethodsThis retrospective study investigated consecutive patients with degenerative lumbar diseases who underwent TLIF/PLIF. Symptomatic cage migration was evaluated by direct examination, radiography, and/or computed tomography (CT) at 1, 3, 6, 12, and 24 months of follow-up. Cage migration/protrusion was defined as symptomatic cage protrusion >5 mm from the posterior border of the over and underlying vertebral body compared with initial CT. We evaluated patient characteristics including body mass index, smoking history, fusion level, and cage type. A total of 113 patients underwent PLIF/TLIF (PLIF n=30, TLIF n=83), with a mean age of 71.1 years (range, 28–87 years). Mean duration of follow-up was 25 months (range, 12-47 months). ResultsCage migration was identified in 5 of 113 patients (4.4%). All cases of symptomatic cage migration involved the L5/S1 level and the TLIF procedure. Risk factors for cage protrusion were age (younger), sex (male), and level (L5/S1). The mean duration to onset of cage protrusion was 3.2 months (range, 2–6 months). We applied a new classification for cage protrusion: type 1, only low back pain without new radicular symptoms; type 2, low back pain with minor radicular symptoms; or type 3, cauda equina syndrome and/or severe radicular symptoms. According to our classification, one patient was in type 1, three patients were in type 2, and one patient was in type 3. For all cases of cage migration, revision surgery was performed using a navigated high-speed burr and osteotome, and the patient in group 1 underwent additional PLIF without removal of the protruding cage. Three revision surgeries (group 2) involved removal of the protruding cage and PLIF, and one revision surgery (group 3) involved anterior removal of the cage and OLIF51 fusion.ConclusionsThe navigated high-speed burr, navigated osteotome, and OLIF51 technique appear very useful for removing a cage with fibrous union from the disc in patients with pseudarthrosis. This new technique makes revision surgery after cage migration much safer, and more effective. This technique also reduces the need for fluoroscopy.

Finite analysis of stability between modified articular fusion technique, posterior lumbar interbody fusion and posteriorlateral lumbar fusion

Background It is not clear whether modified facet fusion (MFF) is biomechanically different from traditional fusion techniques such as posterior lateral lumbar fusion (PLF) and posterior lumbar interbody fusion (PLIF). Methods In this study, a healthy adult Chinese male volunteer was selected to perform 3D reconstruction of CT image data and simulate the successful fusion of L4–5 MFF, PLF and PLIF, respectively. The motion range of L4–5 segments of the model was simulated under 6 working conditions, including forward flexion, extension, lateral flexion and rotation under normal physiological conditions, and the stability of the three fusion procedures in the pathological segments of the lumbar spine was compared. Results There was no difference in range of motion between MFF model and PLF or PLIF model (P < 0.05). Also, the stiffness of the PLFand the MFF model were comparable (P > 0.05), but were smaller than the PLIF model (P < 0.05). Conclusions MFF provides reliable stability at the lumbar fixation fusion level and does not differ significantly from PLF and PLIF in terms of range of motion.

Clinical and radiological outcomes in patients who underwent posterior lumbar interbody fusion: comparisons between unilateral and bilateral cage insertion

Background Although the original technique involves inserting two cages bilaterally, there could be situations that only allow for insertion of one cage unilaterally. However, only a few studies have compared the outcomes between unilateral and bilateral cage insertion. The purpose of this study was to compare the clinical and radiological outcomes in patients who underwent posterior lumbar interbody fusion (PLIF) between unilaterally and bilaterally inserted cages. Methods Among 206 eligible patients who underwent 1- or 2-level PLIF, 78 patients were 1:3 cohort-matched by age, sex, and operation level (group U, 19 patients with unilateral cages; and group B, 57 patients with bilateral cages). Fusion status was evaluated by computed tomography (CT) scans at postoperative 1 year. Clinical outcomes were measured by visual analog scale (VAS), Oswestry Disability Index (ODI), and EQ-5D. Radiological and clinical parameters were compared between the two groups. Risk factors for pseudarthrosis were also analyzed by multivariate analysis. Results The demographic data were not significantly different between the two groups. However, previous laminectomy, asymmetric disc collapse, and fusion at L5-S1 level were more frequently found in group U (P = 0.003, P = 0.014, and P = 0.014, respectively). Furthermore, pseudarthrosis was more frequently observed in group U (36.8%) than in group B (7.0%) (P = 0.004). Back pain VAS was higher in group U at postoperative 1 year (P = 0.033). Lower general activity function of EQ-5D was observed in group U at postoperative 1 year (P = 0.035). Older age (P = 0.028), unilateral cage (P = 0.007), and higher bone mineral density (P = 0.033) were positively correlated with pseudarthrosis. Conclusions Unilaterally inserted cage might be a possible risk factor for pseudarthrosis when performing PLIF, which could be related with the difficult working conditions such as scars due to previous laminectomy or asymmetric disc collapse. Furthermore, suboptimal clinical outcomes are expected following PLIF with unilateral cage insertion at postoperative 1 year regardless of similar clinical outcomes at postoperative 2 year. Therefore, caution is advised when inserting cages unilaterally, especially under above-mentioned conditions in terms of its possible relationship with symptomatic pseudarthrosis.