Comparison of full-endoscopic and tubular-based microscopic decompression in patients with lumbar spinal stenosis: a randomized controlled trial.

PURPOSE: We aimed to demonstrate non-inferiority in terms of functional outcomes in patients with lumbar spinal stenosis who underwent full-endoscopic decompression compared with tubular-based microscopic decompression. METHODS: This prospective, randomized controlled, non-inferiority trial included 60 patients with single-level lumbar spinal stenosis who required decompression surgery. The patients were randomly assigned in a 1:1 ratio to the full-endoscopic group (FE group) or the tubular-based microscopic group (TM group). Based on intention-to-treat analysis, the primary outcome was the Oswestry Disability Index score at 24 months postoperative. The secondary outcomes included the visual analog scale (VAS) score for back and leg pain, European Quality of Life-5 Dimensions (EQ-5D) score, walking time, and patient satisfaction rate according to the modified MacNab criteria. Surgery-related outcomes were also analyzed. RESULTS: Of the total patients, 92% (n = 55) completed a 24-month follow-up. The primary outcomes were comparable between the two groups (p = 0.748). However, the FE group showed a statistically significant improvement in the mean VAS score for back pain at day 1 and at 6, 12, and 24 months after surgery (p < 0.05). No significant difference was observed in the VAS score for leg pain, EQ-5D score, or walking time (p > 0.05). Regarding the modified MacNab criteria, 86.7% of patients in the FE group and 83.3% in the TM group had excellent or good results at 24 months after surgery (p = 0.261). Despite the similar results in surgery-related outcomes, including operative time, radiation exposure, revision rate, and complication rate, between the two groups (p > 0.05), less blood loss and shorter length of hospital stay were observed in the FE group (p ≤ 0.001 and 0.011, respectively). CONCLUSION: This study suggests that full-endoscopic decompression is an alternative treatment for patients with lumbar spinal stenosis because it provides non-inferior clinical efficacy and safety compared with tubular-based microscopic surgery. In addition, it offers advantages in terms of less invasive surgery. Trial registration number (TRN): TCTR20191217001.

Vitamin D Inadequacy Affects Skeletal Muscle Index and Physical Performance in Lumbar Disc Degeneration.

Lumbar disc degeneration (LDD) is one of the fundamental causes of low back pain. The aims of this study were to determine serum 25-hydroxyvitamin D (25(OH)D) levels and physical performance and to investigate the relationship between serum vitamin D levels, muscle strength and physical activity in elderly patients with LDD. The participants were 200 LDD patients, including 155 females and 45 males aged 60 years and over. Data on body mass index and body composition were collected. Serum 25(OH)D and parathyroid hormone levels were measured. Serum 25(OH)D was classified into the insufficiency group: <30 ng/mL and the sufficiency group: ≥30 ng/mL. Muscle strength was assessed by grip strength, and physical performance (short physical performance battery) was evaluated by the balance test, chair stand test, gait speed, and Timed Up and Go (TUG) test. Serum 25(OH)D levels in LDD patients with vitamin D insufficiency were significantly lower than in those with vitamin D sufficiency (p < 0.0001). LDD patients with vitamin D insufficiency had a prolonged time in physical performance on gait speed (p = 0.008), chair stand test (p = 0.013), and TUG test (p = 0.014) compared to those with vitamin D sufficiency. Additionally, we found that serum 25(OH)D levels were significantly correlated with gait speed (r = -0.153, p = 0.03) and TUG test (r = -0.168, p = 0.017) in LDD patients. No significant associations with serum 25(OH)D status were observed for grip strength and balance tests among patients. These findings demonstrate that higher serum 25(OH)D levels are associated with better physical performance in LDD patients.

Neutral hip position for the oblique lumbar interbody fusion (OLIF) approach increases the retroperitoneal oblique corridor.

BACKGROUND: The prepsoas lateral approach for spinal fusion, oblique lateral lumbar interbody fusion (OLIF), is considered one of the minimally invasive spinal fusion methods and is gaining popularity due to improved outcomes with copious supporting evidence. To date, no publication has studied the various positions of the left hip in actual patients which might affect the retroperitoneal oblique corridor (ROC). The study aimed to find the relevancy of the left hip position and the size of ROC. METHODS: We recruited 40 consecutive patients who needed diagnostic MRI from the out-patient clinic. MRI scan from L2 to L5 was performed in the supine, right lateral decubitus with hip flexion, and right lateral decubitus with hip in a neutral position. The retroperitoneal oblique corridor (ROC) was measured at the intervertebral disc level and compared. RESULTS: ROC of the hip in neutral position was significantly larger than hip flexion in all levels (p < 0.05); there was no significant difference in the ROC among levels (p = 0.22). ROC seems to be largest at L2/3 followed by L3/4 and L4/5 respectively in all positions. CONCLUSIONS: The retroperitoneal oblique corridors of L2 to L5 were significantly increased when the hip is in the neutral position, while the psoas cross-sectional area and anterior thickness were minimized in this position. Surgeons might benefit from a neutral position of the left hip in the oblique lateral lumbar interbody fusion (OLIF) procedure. In conclusion, the retroperitoneal oblique corridors of L2 to L5 were significantly increased when the hip is in the neutral position, while the psoas cross-sectional area and anterior thickness were minimized in this position. Surgeons might benefit from a neutral position of the left hip in the oblique lateral lumbar interbody fusion procedure.

A Network Meta-Analysis Comparing the Efficacy and Safety of Pedicle Screw Placement Techniques Using Intraoperative Conventional, Navigation, Robot-Assisted, and Augmented Reality Guiding Systems.

BACKGROUND: Studies were reviewed and collected to compare different image guidance systems for pedicle screw placement (PSP) regarding accuracy and safety outcomes. Included were conventional, navigation, robot-assisted, and recent technology such as augmented reality (AR) guiding systems. METHODS: This network meta-analysis obtained human comparative studies and randomized controlled trials (RCTs) regarding PSP found in 3 databases (Cochrane, PubMed, and Scopus). Data extraction for accuracy, safety, and clinical outcomes were collected. The network meta-analysis was analyzed, and a surface under the cumulative ranking curve (SUCRA) was used to rank the treatment for all outcomes. RESULTS: The final 61 studies, including 13 RCTs and 48 non-RCTs, were included in the meta-analysis. These studies included a total of 17,023 patients and 35,451 pedicle screws. The surface under the cumulative ranking curve ranking demonstrated the supremacy of robotics in almost all accuracy outcomes except for the facet joint violation. Regarding perfect placement, the risk difference for AR was 19.1 (95% CI: 8.1-30.1), which was significantly higher than the conventional method. The robot-assisted and navigation systems had improved outcomes but were not significantly different in accuracy vs the conventional technique. There was no statistically significant difference concerning safety or clinical outcomes. CONCLUSIONS: The accuracy of PSP achieved by robot-assisted technology was the highest, whereas the safety and clinical outcomes of the different methods were comparable. The recent AR technique provided better accuracy compared with navigation and conventional methods.

Is Direct Decompression Necessary for Lateral Lumbar Interbody Fusion (LLIF)? A Randomized Controlled Trial Comparing Direct and Indirect Decompression With LLIF in Selected Patients.

OBJECTIVE: To compare the clinical and radiographic outcomes following lateral lumbar interbody fusion (LLIF) between direct and indirect decompression in the treatment of patients with degenerative lumbar diseases. METHODS: Patients who underwent single-level LLIF were randomized into 2 groups: direct decompression (group D) and indirect decompression (group I). Clinical outcomes including the Oswestry Disability index and visual analogue scale of back and leg pain were collected. Radiographic outcomes including cross-sectional area (CSA) of thecal sac, disc height, foraminal height, foraminal area, fusion rate, segmental, and lumbar lordosis were measured. RESULTS: Twenty-eight patients who met the inclusion criteria were eligible for the analysis, with a distribution of 14 subjects in each group. The average age was 66.1 years. Postoperatively, significant improvements were observed in all clinical parameters. However, these improvements did not show significant difference between both groups at all follow-up periods. All radiographic outcomes were not different between both groups, except for the increase in CSA which was significantly greater in group D (77.73 ± 20.26 mm2 vs. 54.32 ± 35.70 mm2, p = 0.042). Group I demonstrated significantly lower blood loss (68.13 ± 32.06 mL vs. 210.00 ± 110.05 mL, p < 0.005), as well as shorter operative time (136.35 ± 28.07 minutes vs. 182.18 ± 42.67 minutes, p = 0.002). Overall complication rate was not different. CONCLUSION: Indirect decompression through LLIF results in comparable clinical improvement to LLIF with additional direct decompression over 1-year follow-up period. These findings suggest that, for an appropriate candidate, direct decompression in LLIF might not be necessary since the ligamentotaxis effect achieved through indirect decompression appears sufficient to relieve symptoms while diminishing blood loss and operative time.

Hypertrophy of the ligamentum flavum in lumbar spinal canal stenosis is associated with increased bFGF expression.

PURPOSE: A prospective study was undertaken to investigate basic fibroblast growth factor (bFGF) expression in hypertrophic ligamentum flavum (LF) from patients with lumbar spinal canal stenosis (LSCS) and to determine whether there was a correlation of bFGF expression with LF thickness. METHODS: Twenty patients with lumbar spinal canal stenosis were enrolled in this study. bFGF mRNA and protein expressions in LF were analyzed using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), immunohistochemistry, and enzyme-linked immunosorbent assay (ELISA), respectively. The thickness of LF was measured by axial T1-weighted magnetic resonance imaging. RESULTS: Expression of bFGF was substantially higher in the hypertrophic LF group than in the control group (P < 0.001) as quantified by quantitative real-time PCR. In immunohistochemical study, bFGF was positively stained on the fibroblasts within hypertrophic LF compared to nonpathologic LF of controls. Subsequent ELISA analysis revealed that bFGF concentration in the hypertrophic LF group was remarkably higher than that in the control group (P = 0.003). The thickness of LF in the hypertrophic LF was significantly greater than that in the control group (P < 0.001). LSCS patients with greater severity of LF hypertrophy had significantly higher bFGF levels in the LF tissues (P < 0.001). Furthermore, the bFGF concentration exhibited a positive correlation with the LF thickness (r = 0.974, P < 0.001). CONCLUSIONS: These findings suggest that the increased expression of bFGF is associated with the hypertrophy of ligamentum flavum in patients with LSCS.

Comparative Outcome of Lidocaine Versus Bupivacaine for Cervical Medial Branch Block in Chronic Cervical Facet Arthropathy: A Randomized Double-Blind Study.

OBJECTIVE: This study evaluated the effect of prolonged concordant response and functional clinical improvement between lidocaine and bupivacaine for cervical medial branch block (CMBB) in chronic cervical facet syndrome. METHODS: Sixty-two patients diagnosed with chronic cervical facet syndrome were randomized into either lidocaine or bupivacaine groups. The therapeutic CMBB was performed under ultrasound guidance. Either 2% lidocaine or 0.5% bupivacaine with a volume of 0.5-1 mL per level was injected according to the patient's pain symptoms. The patients, pain assessor, and pain specialist were blinded. The primary outcome was the duration of pain reduction by at least 50%. The Numerical Rating Scale of 0-10 and the Neck Disability Index questionnaire were recorded. RESULTS: There was no significant difference in the duration of 50% and 75% pain reduction and Neck Disability Index between the lidocaine and bupivacaine groups. Lidocaine provided significant pain reduction up to 16 weeks (P < 0.05) and significant improvement in neck functional outcomes up to 8 weeks (P < 0.01) compared to the baseline. While bupivacaine yielded significant pain alleviation for up to 8 weeks for pain upon neck mobilization (P < 0.05) and demonstrated notable improvement in neck function up to 4 weeks (P < 0.01) compared to the baseline. CONCLUSION: CMBB using lidocaine or bupivacaine provided clinical benefits in prolonged analgesic effect and improving neck functions for chronic cervical facet syndrome. Lidocaine illustrated better performance and could be considered a local anesthetic of choice regarding the prolonged concordance response.

Lumbar Sympathetic Chain Tract and Mobility of Oblique Lumbar Interbody Fusion Approach: A Cadaveric Study.

OBJECTIVE: We sought to assess the lumbar sympathetic chain (LSC) relation to the surgical corridor for the oblique lumbar approach and the ability to mobilize the LSC. METHODS: Forty-three cadavers were included. A left-sided anterior retroperitoneal approach was performed in supine position. The distances between the great vessels and psoas muscle (oblique corridor) and distance between great vessels and LSC at the L2/3, L3/4, and L4/5 disk levels were measured. Mobilization of LSC at each disk level was done either close to or away from the psoas muscle, and each mobilization distance was measured. RESULTS: The presence rates of LSC in oblique corridor were 19.5%, 43%, and 75.7% at L2/3, L3/4, and L4/5 levels, respectively. At the L2/3 disk level, the mean distance between the psoas muscle and LSC and its mobility were 0.61 mm ± 1.31 mm and 2.72 mm ± 1.24 mm, respectively. At the L3/4 disk level, the mean distance between the psoas muscle and LSC and its mobility were 1.72 mm ± 2.53 mm and 3.11 mm ± 1.02 mm, respectively. At the L4/5 disk level, the mean distance between the psoas muscle and LSC and its mobility were 2.94 mm ± 3.52 mm and 2.53 mm ± 1.03 mm, respectively. The mean width of corridor of L2/3, L3/4, and L4/5 were 10.73 mm ± 5.82 mm, 12.63 mm ± 5.02 mm, and 15.43 mm ± 6.31 mm, respectively. CONCLUSIONS: The LSC tract usually lies in the oblique corridor in L4/5 but keeps decreasing in prevalence when approaching L3/4 and L2/3 levels. It can be mobilized a few millimeters close to or away from the psoas muscle. Care should be taken to prevent an LSC injury, particularly when the LSC needs to be retracted along with the psoas muscle.

Perioperative Intravenous Nefopam on Pain Management and Ambulation after Open Spine Surgery: A Randomized Double-Blind Controlled Study.

STUDY DESIGN: This was a randomized double-blind controlled study. PURPOSE: This study was designed to evaluate the effects of intravenous nefopam regarding its ability to reduce morphine consumption and postoperative pain and improve recovery in patients undergoing open spine surgery. OVERVIEW OF LITERATURE: Multimodal analgesia, including nonopioid medications, is essential for pain management in spine surgery. Evidence regarding the use of intravenous nefopam in open spine surgery as part of enhanced recovery after surgery is lacking. METHODS: In this study, 100 patients undergoing lumbar decompressive laminectomy with fusion were randomized into two groups. The nefopam group received 20-mg intravenous nefopam diluted in 100-mL normal saline intraoperatively, followed by 80-mg nefopam diluted in 500-mL normal saline, administered as a continuous infusion postoperatively for 24 hours. The control group received an identical volume of normal saline. Postoperative pain was managed using intravenous morphine via patient-controlled analgesia. Morphine consumption in the first 24 hours was recorded as the primary outcome. Secondary outcomes, including postoperative pain score, postoperative function, and length of hospital stay (LOS), were assessed. RESULTS: No statistically significant differences in the total morphine consumption and postoperative pain score in the first 24 hours postoperatively between the two groups. At the post-anesthesia care unit (PACU), the nefopam group demonstrated lower pain scores while at rest (p =0.03) and upon movement (p =0.02) than the normal saline group. However, the severity of postoperative pain between the two groups was similar from postoperative day 1 to day 3. LOS was significantly shorter in the nefopam group than in the control group (p <0.01). The time to first sitting and walking and PACU discharge between the two groups were comparable. CONCLUSIONS: Perioperative intravenous nefopam demonstrated significant pain reduction during the early postoperative period and shortened LOS. Nefopam is considered safe and effective as a part of multimodal analgesia in open spine surgery.

Ultrasound-guided pulsed radiofrequency of cervical nerve root for cervical radicular pain: a prospective randomized controlled trial.

BACKGROUND CONTEXT: Pulsed radiofrequency (PRF) on cervical dorsal root ganglion (DRG) for pain management in cervical radicular pain is mainly performed via a transforaminal approach under fluoroscopic guidance. Ultrasound-guidance periradicular cervical nerve root intervention raises concern about the neuromodulatory effect. This study aims to evaluate the effectiveness and duration of pain relief between PRF treatment and steroid injection on the cervical nerve roots. PURPOSE: To evaluate the efficacy of pulsed radiofrequency for cervical radicular pain. STUDY DESIGN: A prospective, double-blinded, randomized controlled clinical trial PATIENT SAMPLE: Patients who underwent ultrasound-guided periradicular cervical nerve root PRF or steroid injection from January 2020 to May 2021 at King Chulalongkorn Memorial Hospital (KCMH), Bangkok, Thailand. OUTCOME MEASURES: The primary outcome was the pain score at 3 months postprocedure. The secondary outcomes were the duration of pain relief of at least 50%, pain scores at other time points after pain intervention, the amount of rescue pain medications, procedural time, and complications. METHOD: Forty-two patients who presented with chronic cervical radicular pain were prospectively randomized into the PRF and steroid groups. Patients in the PRF group received PRF treatment at 42°C for 4 minutes, followed by the injection of 2% lidocaine 1.5 mL and dexamethasone 10 mg to the targeted cervical nerve root. The steroid group received the same injectate. Patients and pain assessors were blinded. The numerical rating scale (NRS) and the Neck Disability Index (NDI) questionnaires were used for pain intensity and neck functional assessment before and after the procedure. Pain reduction was recorded up to a 9-month follow-up. RESULTS: Data analysis was obtained from 20 and 21 patients receiving PRF and steroid treatment, respectively. At 3-month postprocedure, there were 70% of patients in the PRF group reported 50% pain reduction compared with 23.8% of patients in the steroid group (p<.01). Moreover, patients in the PRF group had significantly less pain (NRS 2.8±2.7) compared with patients in the steroid group (NRS 5.5±2.6) (p=.01). The neck disability index demonstrated significant improvement at 3 and 6 months (p<.01) after PRF treatment compared with steroid injection alone. The duration, in which pain relief was at least 50%, was significantly longer in patients who received PRF treatment (6.0±4.1 months) compared with those in the steroid group (2.3±2.1 months) (p<.01). CONCLUSION: Ultrasound-guided periradicular cervical nerve root PRF exhibited a neuromodulatory effect and was considered effective for patients with cervical radicular pain. It provided a longer duration of pain relief and improvement of neck function for up to 6 months.

Comparing Efficacy of Lumbar Disc Space Preparation via an Anterior-to-Psoas Approach Between Intraoperative Conventional Fluoroscopy and Computed Tomographic-Based Navigation System: A Cadaveric Study.

OBJECTIVE: To compare the efficacy of intervertebral disc space preparation via an anterior-to-psoas (ATP) approach using conventional fluoroscopy (Flu) and computer tomography (CT)-based navigation by evaluating the disc remaining area. METHODS: We equally assigned 24 lumbar disc levels from 6 cadavers into Flu and CT-based navigation (Nav) groups. Two surgeons performed disc space preparation using the ATP approach in both groups. Digital images of each vertebral endplate were obtained, and the remaining disc tissue was calculated in total and in quadrants. Operative time, number of attempts at disc removal, endplate violation area, number of endplate violation segments, and access angle were recorded. RESULTS: The overall percentage of remaining disc tissue was significantly less in the Nav group than in the Flu group (32.7% vs. 43.3% respectively, P < 0.001). A significant difference was found in the posterior-ipsilateral (4.2% vs. 7.1%, P = 0.005) and posterior-contralateral (6.1% vs. 10.9%, P = 0.002) quadrants, respectively. No significant between-group difference was found concerning operative time, number of attempts at disc removal, endplate violation area, number of endplate violation segments, or access angle. CONCLUSIONS: Intraoperative CT-based navigation may improve vertebral endplate preparation quality for an ATP approach, especially in the posterior quadrants. This technique may offer an effective alternative disc space and endplate preparation methods and may help enhance the fusion rates.

Should a Narrow Corridor Be a Contraindication for Performing Oblique Lateral Interbody Fusion Procedure or Not?

STUDY DESIGN: Retrospective study. OBJECTIVES: We investigated the effect of corridor width on the postoperative outcomes of patients who underwent the OLIF procedure. METHODS: Patients who underwent OLIF surgery, which included L4-5, between 2015 and 2021 were retrospectively studied. The patients were divided into three groups by the width of the corridor: not more than 10 mm, between 10 and 20 mm, and 20 mm or more. We compared clinical and radiographic outcomes and complications between these groups. RESULTS: A total of 81 patients were included. There were no significant differences in VAS leg and back pain scores, ODI scores, or complications between each group. The radiographic findings, including cage position, anterior and posterior disc height, segmental Cobb angle, and foraminal height, also showed no significant differences between each group. The only radiographic finding that showed a significant difference between each group was the angle of the cage. We found significantly less degree of angle in the wider than 20 mm group when compared to the other two groups. (P-value = .01). There was no recorded incidence of major vascular complications. CONCLUSIONS: The width of oblique corridor does not affect clinical outcomes, complications, or radiographic findings, including position of the cage, anterior and posterior disc height, segmental angle, and foraminal height after OLIF procedure, including L4-5 level. Thus, the OLIF procedure can be performed safely even in patients with limited oblique corridors, especially at L4-5.

An Expanded Surgical Corridor of Oblique Lateral Interbody Fusion at L4-5: A Magnetic Resonance Imaging Study.

OBJECTIVE: We introduced a new preoperative method, the "expanded surgical corridor," to evaluate the actual safety corridor, which may expand the possibility of performing oblique lateral interbody fusion (OLIF). METHODS: Axial T2-weighted magnetic resonance images at the L4-5 disc level of 511 lumbar degenerative disease patients was evaluated. The distance between the medial edge of the left-sided psoas muscle and the major artery was measured as the conventional surgical corridor (CSc). The distance between the major vein and lumbar plexus was measured as the expanded surgical corridor (ESc). RESULTS: The mean CSc and ESc were 13.9 ± 8.20 and 37.43 ± 10.1 mm, respectively. No surgical corridor was found in 7.05% of CSc and 1.76% of ESc, small corridor ( ≤ 1 cm) was found in 27.40% of CSc and 0.59% of ESc, moderate corridor (1-2 cm) was found in 42.07% of CSc and 1.96% of ESc, and large corridor ( > 2 cm) was found in 23.48% of CSc and 95.69% of ESc. A total of 33.83% (45 of 133) of whom were preoperatively categorized as having a limited surgical corridor by conventional measurement, underwent OLIF L4-5 successfully. CONCLUSION: By using the ESc, only 2.35% were categorized as having a limited surgical corridor. The other 97.65% of the patients had an approachable corridor that could be successfully operated by experienced spine surgeons who employ meticulous surgical dissection and thorough understanding of the anatomical structures. The ESc may represent true accessibility to the disc space for OLIF, particularly at the L4-5 level.

Subsidence of Interbody Cage Following Oblique Lateral Interbody Fusion: An Analysis and Potential Risk Factors.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: This study aimed to report the incidence and potential risk factors of polyetheretherketone (PEEK) cage subsidence following oblique lateral interbody fusion (OLIF) for lumbar degenerative diseases. We proposed also an algorithm to minimize subsidence following OLIF surgery. METHODS: The study included a retrospective cohort of 107 consecutive patients (48 men and 59 women; mean age, 67.4 years) who had received either single- or multi-level OLIF between 2012 and 2019. Patients were classified into subsidence and non-subsidence groups. PEEK cage subsidence was defined as any violation of either endplate from the computed tomography scan in both sagittal and coronal views. Preoperative variables such as age, sex, body mass index, bone mineral density (BMD) measured by preoperative dual-energy X-ray absorptiometry, smoking status, corticosteroid use, diagnosis, operative level, multifidus muscle cross-sectional area, and multifidus muscle fatty degeneration were collected. Age-related variables (height and length) were also documented. Univariate and multivariate logistic regression analyses were used to analyze the risk factors of subsidence. RESULTS: Of the 107 patients (137 levels), 50 (46.7%) met the subsidence criteria. Higher PEEK cage height had the strongest association with subsidence (OR = 9.59, P < .001). Other factors significantly associated with cage subsistence included age >60 years (OR = 3.15, P = .018), BMD <-2.5 (OR = 2.78, P = .006), and severe multifidus muscle fatty degeneration (OR = 1.97, P = .023). CONCLUSIONS: Risk factors for subsidence in OLIF were age >60 years, BMD < -2.5, higher cage height, and severe multifidus muscle fatty degeneration. Patients who had subsidence had worse early (3 months) postoperative back and leg pain.

Biomechanical Comparison Between Posterior Long-Segment Fixation, Short-Segment Fixation, and Short-Segment Fixation With Intermediate Screws for the Treatment of Thoracolumbar Burst Fracture: A Finite Element Analysis.

BACKGROUND: Posterior long-segment (LS) fixation, short-segment (SS) fixation, and short segment fixation with intermediate screws (SI) have shown good outcomes for the treatment of thoracolumbar burst fractures. However, limited data compared the biomechanical properties between LS fixation and SI. The purpose of this study was to compare the von Mises stresses on the pedicular screw system and bone between posterior LS fixation, SS fixation, and SI for the treatment of thoracolumbar burst fracture. MATERIALS AND METHODS: The finite element model of thoracolumbar spines from T11 to L3 was created based on the computed tomography image of a patient with a burst fracture of the L1 vertebral body. The models of pedicular screws, rods, and locking nuts were constructed based on information from the manufacturer. Three models with different fixation configurations-that is, LS, SS, and SI-were established. The axial load was applied to the superior surface of the model. The inferior surface was fixed. The stress on each screw, rod, and vertebral body was analyzed. RESULTS: The motion of the spine in SS (0.5 mm) and SI (0.9 mm) was higher than in LS (0.2 mm). In all models, the lowest pedicle screws are the most stressed. The stress along the connecting rods was comparable between SI and LS (50 MPa). At the fracture level, stress was found at the pedicles and vertebral bodies in SI. There was relatively little stress around the fractured vertebral body in LS and SS. CONCLUSIONS: Posterior SI preserves more spinal motion than the LS. In addition, it provides favorable biomechanical properties than the SS. The stress that occurred around the pedicle screws in SI was the least among the 3 constructs, which might reduce complications such as implant failure. SI produces more stress in the fractured vertebral body than LS and SS, which could potentially aid in bone healing according to the Wolff law. CLINICAL RELEVANCE: SI has proved to be a biomechanically favorable construct and helps preserve the spinal motion segment. It could be an alternative surgical option for treating patients who present with thoracolumbar burst fractures.

Case report: cauda equina syndrome associated with an interspinous device.

BACKGROUND: Although postoperative spinal epidural hematoma (SEH) is not uncommon, hematomas that require surgery are rare. Cauda equina syndrome (CES) may be associated with postoperative SEH. In these cases, early recognition and emergency decompression can prevent further damage and better neurologic recovery. CASE DESCRIPTION: A 41-year-old man underwent two-level discectomy with insertion of an interspinous spacer at L3-4 and L4-5 because of low back pain and radiculopathy. Eight hours after the operation, the patient developed CES. MRI revealed SEH compressing posteriorly at the L3-4 level. On emergency decompression and hematoma evacuation, the interspinous spacer had obstructed the laminotomy site at L3-4 completely, blocking drainage to the drain. The patient experienced complete neurologic recovery by 2 months followup. LITERATURE REVIEW: Many studies report risk factors for SEH. However, postoperative SEH can also be encountered in patients without these risks. One study reported a critical ratio (preoperative versus postoperative cross-sectional area) correlated with postoperative symptoms, especially in those with CES. The propensity to develop CES is likely dependent on a number of patient-specific factors. CLINICAL RELEVANCE: Surgeons should be aware that patients without risk factors may develop acute CES. Wider laminotomy (larger than half of the device size) may help to prevent this complication when one uses the compressible type of device, especially in patients with relatively small lamina.

Successful Criteria for Indirect Decompression With Lateral Lumbar Interbody Fusion.

OBJECTIVE: No consensus criteria have been established regarding ideal candidates for indirect decompression with lateral lumbar interbody fusion (LLIF), and contributing factors of indirect decompression failure were rarely reported. We aim to investigate the success rate of indirect decompression by LLIF with proposed selection criteria and identify risk factors associated with indirect decompression failure, defined as persistent pain requiring revision with direct decompression. METHODS: Data from 191 patients undergoing LLIF were retrospectively reviewed. All the following criteria must be fulfilled: (1) dynamic clinical symptoms (pain relief in supine position), (2) presence of reducible disc height (recovered disc height in supine position), (3) no profound weakness, and (4) no static stenosis. The success rate of indirect decompression with LLIF and results after at least 1 year of follow-up were collected. Preoperative, procedure-related, and postoperative factors were assessed for their relationship with failure. RESULTS: Of 191 patients,13 patients (6.8%) required additional direct decompression due to persistent pain, giving a criteria success rate of 93.2%. Factors associated with indirect decompression failure included low bone mineral density (T-score < 2.1), low reducible disc height (<13%), low postoperative disc height (< 10 mm), high-grade cage subsidence, and use of plate fixation. CONCLUSION: We proposed patient selection criteria for indirect decompression with LLIF which had a satisfactory success rate and identified factors associated with the need for additional direct decompression. Our proposed criteria may assist selection of patients likely to achieve good results following indirect decompression with LLIF, and optimize selection based on risk factors of failure.

Clinical and Radiographic Comparisons among Minimally Invasive Lumbar Interbody Fusion: A Comparison with Three-Way Matching.

STUDY DESIGN: Retrospective cohort study. PURPOSE: To compare clinical and radiographic outcomes among minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF), extreme lateral lumbar interbody fusion (XLIF), and oblique lateral lumbar interbody fusion (OLIF) techniques. OVERVIEW OF LITERATURE: To date, there are many reports comparing outcomes between MIS-TLIF and XLIF, MIS-TLIF and OLIF, or XLIF and OLIF procedures. However, there are no previous studies comparing clinical and radiographic outcomes among all these three techniques. METHODS: Data from patients who underwent minimally invasive (MI) fusion surgery for lumbar degenerative diseases at L4-L5 level was analyzed. Thirty patients each from MIS-TLIF, XLIF, and OLIF groups were recruited for propensity score matching. Visual Analog Scale (VAS) of the back and legs and Oswestry Disability Index (ODI) were evaluated preoperatively and at 1, 3, and 6 months and 1 year postoperatively. Radiographic outcomes were also compared. The fusion rate was evaluated at 1 year after surgeries. RESULTS: The clinical outcomes were significantly improved in all groups. The disk height was significantly restored in all groups postoperatively, which was significantly more improved in XLIF and OLIF than MIS-TLIF group (p<0.001). The axial canal area was significantly increased more in MIS-TLIF versus XLIF and OLIF (p<0.001). The correction of lumbar lordotic angle and segmental sagittal angle were similar among these techniques. OLIF and XLIF groups showed less blood loss and shorter hospital stays than MIS-TLIF group (p<0.001). There was no significant difference in fusion rate among all groups. CONCLUSIONS: MIS-TLIF, XLIF, and OLIF facilitated safe and effective MI procedures for treating lumbar degenerative diseases. XLIF and OLIF can achieve clinical outcomes equivalent to MIS-TLIF by indirect decompression. XLIF and OLIF showed less blood loss, shorter hospital stays, and better disk and foraminal height restorations. In single-level L4-5, the restoration of sagittal alignment was similar between these three techniques.

How Prone Position Affects the Anatomy of Lumbar Nerve Roots and Psoas Morphology for Prone Transpsoas Lumbar Interbody Fusion.

BACKGROUND: Lumbar nerve root injury is a serious complication of transpsoas lumbar interbody fusion. Researchers have reported lumbar nerve roots and psoas muscle anatomy in the supine position, but no previous studies have used prone position magnetic resonance imaging to evaluate these structures. OBJECTIVE: The purpose of this study was to show the changes in the lumbar nerve roots and psoas muscle related to the lumbar intervertebral disc using supine and prone magnetic resonance imaging. METHODS: Thirty volunteers without spinal or hip abnormalities were included in this observational study. Each volunteer underwent supine and prone lumbosacral magnetic resonance imaging without abdominal compression. The lumbar nerve roots, psoas muscle, aorta, superior vena cava, common iliac artery, and vein were identified at each lumbar disc level. The lumbar plexus position relative to the transpsoas working channel, psoas muscle morphology, and great vessels relative to the anterior and posterior aspects of the annulus fibrosus in the axial plane were measured by 1 observer, and intraobserver reliability was calculated. RESULTS: Fifteen men and 15 women were included in this study. There were no significant differences in the axial image distance of the lumbar nerve roots, psoas/disc ratio, and location of other related anatomy between the supine and prone positions. More lordosis (both upper and lower arc lordosis) was noted in the prone position (51.98° ± 10.54°) than in the supine position (42.12° ± 10.13°). CONCLUSIONS: Lumbar nerve roots, psoas morphology, and great vessel position were not affected by the prone position compared with the supine position.

Trajectory of Lumbar Translaminar Facet Screw Under Navigation: A Cadaveric Study.

STUDY DESIGN: Anatomic cadaver study. OBJECTIVE: Translaminar facet screw fixation supplements unilateral pedicle screw-rod fixation in minimally invasive transforaminal lumbar interbody fusion (TLIF). Various screw diameters, lengths, trajectories, and insertion points are used; however, they do not represent true screw trajectory. We aimed to evaluate lumbar laminar anatomy and suggest a safe and effective insertion point and trajectory during lumbar-translaminar facet screw fixation in an anatomic cadaver study. METHODS: O-arm navigation simulating the true translaminar facet screw trajectory was used to evaluate L1-S1 in cadaveric spines. The inner and outer diameters, length, and trajectory of the screw pathway were measured along the trajectory from the spinous process base through the contralateral lamina, crossing the facet joint to the transverse process base using 2 starting points: cephalad one-third (1/3SL) and one-half (1/2SL) of the spinolaminar junction. RESULTS: Using the 1/2SL starting point, the outer and inner lamina diameters did not differ significantly from L1-L5 (7.47 ± 1.38 to 6.7 ± 1.84 mm and 4.73 ± 1.04 to 3.86 ± 1.46 mm, respectively). Screw length (36.16 ± 4.02 to 49.29 ± 10.07 mm) and lateral angle increased (50.28° ± 8.78° to 60.77° ± 8.88°), but caudal angle decreased (16.19° ± 9.01° to 1.13° ± 11.31°). Lamina diameter and screw length did not differ with different starting points. L2-L3 caudal angles were lower in the 1/2SL starting point. CONCLUSION: A 36- to 50-mm translaminar facet screw-with 5.0-mm diameter for L1-L2 and 4.5-mm diameter for L3-L5-can be inserted at the middle of the spinolamina, especially during minimally invasive TLIF, with a 50° to 60° lateral angle relative to the spinous process, and a caudal angle of 16° to 1° relative to the spinolamina from L1-L5.