Study DesignSingle-center, retrospective cohort review.ObjectiveThis study aims to compare the impact of robotic and imaging-only navigation modalities on radiographic parameters following minimally invasive transforaminal lumbar interbody fusion (MI-TLIF).MethodsPatients with degenerative spondylolisthesis who underwent one-level MI-TLIF using navigation or robotic modalities were included and divided into two groups: robotic-assisted (Robo) or imaging-only navigation (Nav). Radiographic parameters were assessed preoperatively and 6months postoperatively. Outcome measures were screw and cage characteristics, postoperative disc height (DH) improvements, lumbar lordosis (LL), and slip reduction rates. Statistical analyses included paired and independent samples t-tests and multivariable linear regression analysis.ResultsThe Robo group often used larger screw diameters, deeper cages, and more expandable cages, while the Nav group used wider cages. The Robo group demonstrated significantly greater DH improvement compared to the Nav group (average improvement: 71.6% vs 22.5%, P = 0.002). However, the Nav group showed significantly greater LL restoration than the Robo group (P = 0.006), and preoperative LL was independently associated with postoperative LL (β = 0.64, P < 0.001). No clear differences in slip reduction or cage subsidence were observed.ConclusionsIn MI-TLIF, robotic guidance was associated with greater DH restoration and the use of larger screws, whereas LL restoration appeared to depend mainly on preoperative sagittal alignment and was greater with image-guided navigation. These findings suggest that each modality can be leveraged to optimize different radiographic goals and underscore the need for studies integrating implant strategies with clinical outcomes.

Study DesignRetrospective Single-center propensity score-matched cohort study.ObjectiveAdjacent segment disease remains a major cause of revision surgery after multilevel lumbosacral fusion, and muscle-preserving approaches may help reduce this risk. This study compared clinical and radiographic outcomes between a muscle-preserving fusion combining standalone anterior plus lateral lumbar interbody fusion (A + LLIF) vs circumferential lateral plus posterior lumbar interbody fusion (L + PLIF).MethodsPatients who underwent multilevel lumbosacral fusion (2016-2023) with either A + LLIF or L + PLIF were included. L + PLIF patients with contraindications to standalone A + LLIF were excluded. Propensity score matching, based on age, BMI, PI-LL mismatch and stenosis severity, yielded 90 1:1-matched patients. The primary outcome was revision surgery. Secondary outcomes included spinopelvic alignment, cage subsidence, and perioperative metrics.ResultsBaseline characteristics were comparable between groups (mean age 57 ± 10 years; median fusion levels: 2 [range 2-4]). The 5-year cumulative incidence of revision surgery was significantly lower with A + LLIF (1/45 events; 2.2%) than with L + PLIF (14/45 events; 31.1%; P < .001), with superior perioperative outcomes and comparable radiographic alignment.Operative time, blood loss, and length of stay were significantly lower in the A + LLIF group (P < .001 for all). Spinopelvic parameters were largely equivalent, except for improved distal lordosis and LPA-PI mismatch in the A + LLIF group (P = .003 and P = .019, respectively). Cage subsidence rates were low and similar between groups.ConclusionsIn carefully selected patients, combined standalone anterior and lateral interbody fusion offers a paraspinal muscle-preserving alternative to circumferential fusion, with significantly lower revision rates, favorable perioperative outcomes, and comparable radiographic alignment.

Minimally invasive lumbar interbody fusion continues to evolve with advancements in navigation and endoscopic technologies aimed at reducing tissue trauma and improving safety. Conventional endoscopic fusion approaches, such as the interlaminar and trans-Kambin techniques, have inherent limitations regarding neural safety and implant positioning. We describe a novel computer-navigated transfacet uniportal endoscopic lumbar interbody fusion technique that leverages advanced navigation and endoscopic visualization to safely access the disc space via a transfacet corridor. We present an initial case series to demonstrate the clinical feasibility, safety, and effectiveness of this technique.

Cost analysis for patients with adult spinal deformity by surgical approach and technique: A systematic review of the literature.

Retrospective matched cohort study. We sought to compare circumferential minimally-invasive surgery (cMIS) to open deformity correction surgery on patients' timing of return to work. Adult spinal deformity (ASD) impacts functional ability and quality of life, often influencing patients' ability to work. Surgical correction can improve alignment and symptoms; however, recovery timelines may vary depending on surgical technique. Prospectively collected data from the International Spine Study Group (ISSG) multicenter database was queried for ASD correction. Patients were evaluated in two cohorts: cMIS or open surgery. Propensity scoring matched age, body mass index, pelvic incidence-lumbar lordosis mismatch, and sagittal vertical axis. All patients had at least two years of follow-up. The cohorts were compared at six weeks, one year, and two years. Of 173 matched patients (85 open, 88 cMIS), there were no significant differences in age, sex, or ASA classification. The average age was 68.2 years with ≥3 levels fused. The open group had significantly more direct posterior decompressions, a higher median number of transforaminal lumbar interbody fusions, longer surgery time, greater blood loss, and longer hospital stay. The cMIS group had a higher median number of lateral lumbar interbody fusions. Baseline work status did not differ significantly: disabled (4.7% vs. 6.8%), working(20.0% vs. 21.5%), retired (71.7% vs. 67.0%), not working (3.5% vs. 4.5%). At six weeks, working patients were similar (14.1% vs. 15.9%, P =0.741); at one year, significantly more cMIS patients returned to work (10.5% vs. 21.5%, P =0.049). At two years, more cMIS patients had returned to work (14.1% vs. 19.3%), but this was not significant ( P =0.277). Patients undergoing cMIS surgery returned to work at a higher rate between six weeks and one year postoperatively. At two years, return-to-work remained higher for cMIS but this difference was no longer statistically significant.

Study Design: Retrospective review of consecutively, prospectively enrolled patients. Objective: To evaluate the impact of navigation for percutaneous pedicle screw fixation (PPSF) in lateral decubitus single position surgery (L-SPS) on operative efficiency and safety. Summary of Background Data: Posterior instrumentation is increasingly being performed in the lateral decubitus position. In L-SPS, PPSF is most often performed using a fluoroscopic technique. However, the utilisation of computer-assisted navigation enables simultaneous anterior exposure to be performed and limits radiation exposure to operating staff. Methods: L-SPS patients involving anterior lumbar interbody fusion (ALIF) with or without additional lateral lumbar interbody fusion (LLIF) were divided according to the PPSF technique. “Nav” patients had PPSF utilising computer navigation with simultaneous anterior exposure. “Fluoro” patients had PPSF under fluoroscopy performed either before or following anterior exposure. Results: Two hundred seventy-three patients were included, 187 “Nav” and 86 “Fluoro” patients. In total, 1036 pedicle screws were inserted, 708 navigated, and 328 fluoroscopic. Mean posterior levels (1.89 vs . 1.91, P = 0.910) and ALIF levels fused (1.17 vs . 1.13, P = 0.435) were similar. Mean operative time was significantly reduced in the “Nav” group (116.83 vs. 148.54 min, P &lt; 0.001; 21.3% reduction). Estimated blood loss (258.28 vs . 188.53 mL, P = 0.066) and length of stay (2.33 vs. 2.24 d, P = 0.730) were not statistically significant. Patient radiation dose (91.11 vs. 46.47 mGy, P &lt; 0.001) and radiation time (132.82 vs. 117.20 seconds, P &lt; 0.001) were higher among “Nav” patients. Intraoperative complications (4.3% vs. 2.3%, P = 0.425) including vascular injury (2.1% vs. 0.0%, P = 0.172) and instrumentation-related complications (2.1% vs. 2.3%, P = 0.922) were not statistically significant. Postoperative complications (12.8% vs. 20.9%, P = 0.112) and reoperation rates within 90 days (3.2% vs. 7.0%, P = 0.158) were not statistically significant. No posterior instrumentation-related revisions were observed among “Nav” patients, compared with 2.3% of “Fluoro” patients ( P = 0.036). Conclusions: Simultaneously navigating posterior instrumentation during anterior exposure in L-SPS improves operative efficiency and may reduce instrumentation-related complications without compromising safety.

Bed break-induced attenuation of downside leg sciatic nerve sensory and motor evoked potentials during lateral lumbar interbody (LLIF) fusion surgery.

Study Design: Retrospective cohort study. Objective: To evaluate the predisposing factors to pseudoarthrosis in patients undergoing one-level L5–S1 TLIF. Background: Transforaminal lumbar interbody fusion (TLIF) at the lumbosacral junction is frequently performed for degenerative pathology, yet pseudarthrosis remains a clinically significant complication. The role of preoperative segmental alignment in predicting pseudoarthrosis at L5–S1 has not been well established. Materials and Methods: We conducted a retrospective cohort study of 151 patients undergoing single-level L5–S1 TLIF between 2018 and 2022 at a single academic center, with ≥2 years of follow-up. Patients were stratified by the presence of pseudarthrosis, defined radiographically. Demographics, preoperative sagittal parameters, and complications were analyzed. Multivariate regression identified independent predictors, and Kaplan–Meier and Cox proportional hazards modeling evaluated reoperation risk. Results: Pseudarthrosis occurred in 13 patients (8.6%). While age, sex, BMI, smoking status, and comorbidity index were not associated with pseudoarthrosis, patients with pseudarthrosis had significantly greater preoperative L5–S1 segmental lordosis (24.4° vs . 17.3°, P &lt; 0.001) and reduced L4–L5 anterior disc height (9.0 vs . 12.2 mm, P = 0.015). Both remained independent predictors on adjusted analysis (lordosis OR: 1.28, P = 0.001; disc height OR: 0.78, P = 0.012). Pseudarthrosis was associated with increased reoperation (53.8% vs . 15.9%, P = 0.002). Survival analysis demonstrated a &gt;4-fold increased hazard of reoperation (HR: 4.49; 95% CI: 1.87–10.76; P &lt; 0.001). Conclusions: Pseudarthrosis following single-level L5–S1 TLIF was associated with hyperlordotic preoperative alignment and reduced adjacent-level disc height, and carried substantially higher risks of overall and earlier reoperation. Careful evaluation of segmental morphology and adjacent-level degeneration may aid in identifying patients at greatest risk and optimizing surgical planning. Level of Evidence: Level IV.

In anterior lumbar interbody fusion, implant subsidence remains a major complication, influenced by both patient- and implant-related factors. Cage sizing has been shown to influence the subsidence load and is dependent on both the surgical approach and the patient's anatomic characteristics. Larger cage footprints have been shown to increase axial stability by allowing for a greater area of contact, but their limited sizes and footprints are not always able to accommodate the significant variance in vertebral body shape, endplate dimensions, and epiphysial rim depth. Therefore, the current study aims to quantify the incremental resistance to subsidence conferred by the use of novel endplate-specific expandable implants over conventional, static implants. Fifteen cadaveric spines were reconstructed via computed tomography (CT) scans of the L5 vertebra, and the endplates and cortical shell were isolated from the inner trabecular core to recreate bone surrogates. The novel implant was positioned on each bone surrogate in the unexpanded (control) or expanded (endplate-specific expandable) configuration and compressed at a rate of 5mm/min. The subsidence load and construct stiffness were evaluated for each group. The subsidence load of the expandable implants quantified in 3478 N ± 588 was 20% greater than that of the control group (p < 0.05). No difference was found in construct stiffness (p > 0.05). There was no correlation (r = 0.260, p = 0.350) between the stiffness and epiphyseal rim contact, whereas a positive correlation (r = 0.796, p < 0.001) was found between the subsidence load and increased epiphyseal rim contact in the expandable implant group only. In our study, endplate-specific expandable ALIF implants have shown higher resistance to subsidence than static implants. While, these results must be corroborated by clinical data, the superiority here identified indicates the potential for these implants to be advantageous over static implants. The linear correlation between the epiphyseal rim cross-sectional area of the endplate and the subsidence load, as found in the current study, highlights the potential for estimating the subsidence load during preoperative planning.

Retrospective cohort study. To determine whether multilevel L1-S1 paraspinal muscle fatty infiltration (FI) and a posterior paraspinal radiomics signature improve prediction of prolonged length of stay (LOS) after lumbar spine surgery in geriatric patients. We retrospectively included 248 patients aged ≥75 years undergoing open posterior Transforaminal Lumbar Interbody Fusion (TLIF) with preoperative axial T2-weighted MRI covering L1-S1. Paraspinal muscles were segmented (MuscleMap) to derive global L1-S1 fatty infiltration (All muscle FI) and CSA/BMI. A posterior paraspinal radiomics score (RadScore) was developed from multifidus+erector spinae radiomics features using L1-penalized logistic regression within leakage-free nested cross-validation (outer 5-fold; inner 5-fold). Prolonged LOS was defined as LOS ≥16 days (75th percentile). Discrimination (AUC), calibration, and clinical utility (DCA) were assessed using out-of-fold predictions; bootstrap 95% CIs were reported. Prolonged LOS occurred in 62/248 (25.0%). Patients with prolonged LOS had lower BMI and a markedly higher prevalence of frailty (Fried ≥3: 87.1% vs. 22.6%). All muscle FI was strongly associated with prolonged LOS after adjustment for clinical and operative factors, and RadScore remained independently associated in radiomics-augmented models; in the combined model, the association for All muscle FI was attenuated, suggesting shared prognostic information between conventional FI and radiomics-derived muscle heterogeneity. In leakage-free nested cross-validation, the clinical model achieved AUC 0.848, which improved to 0.922 after adding All muscle FI, and to 0.933 with RadScore; the combined model yielded the highest AUC (0.936). In older adults undergoing lumbar fusion, global multilevel paraspinal degeneration measured by conventional FI provides major incremental value for predicting prolonged LOS beyond clinical and geriatric factors, while posterior paraspinal radiomics offers an additional but more modest improvement. Leakage-free validation supports the robustness and clinical relevance of integrating automated muscle quantification with imaging-based risk stratification.

Feasibility and Early Safety of Single-Position Lateral Lumbar Interbody Fusion With Posterior Pedicle Screw Instrumentation and Fusion at the Ambulatory Surgery Center: A Preliminary Case Series.

This study aimed to identify predictors of cage subsidence following stand-alone oblique interbody fusion (SA-OLIF) in non-osteoporotic patients. A retrospective analysis was performed on 98 patients who underwent SA-OLIF. Cage subsidence was defined to have occured when a cage was subsided into the adjacent endplate by more than 2 mm on the last follow up radiographs. Patients were categorized into subsidence and non-subsidence groups accordingly. Patient characteristics, radiographic parameters, and clinical outcomes were recorded. Sarcopenia was assessed using the L3 skeletal muscle index on axial computed tomography images. Multivariate logistic regression analysis was conducted to identify the predictors of cage subsidence following SA-OLIF. Of the 98 patients who underwent SA-OLIF, subsidence occurred in 32 (32.7%). The subsidence group had a higher mean age (P = 0.005) and lower bone mineral density (BMD) (P < 0.001). The prevalence of sarcopenia was significantly greater in the subsidence group compared with the non-subsidence group (P = 0.003). Multivariate logistic regression identified sarcopenia (P = 0.021), age (P = 0.011), and BMD (P < 0.001) as predictors of cage subsidence. The areas under the curve for age and BMD in predicting cage subsidence were 0.676 and 0.783, respectively. Cage subsidence following SA-OLIF was a common complication in non-osteoporotic patients, with an incidence rate of 32.7%. Preoperative sarcopenia, age of >59.5 years, and T-score < -1.9 were predictors of cage subsidence following SA-OLIF in non-osteoporotic patients. Patients with sarcopenia had nearly 4-fold increased odds of subsidence. OLIF with instruments might be considered an alternative surgical method for patients with these predictor factors to decrease the incidence of cage subsidence.

Cage retropulsion is a severe complication of lumbar spinal fusion, causing neurological deficits and spinal instability. Current evidence on revision strategies is limited by small sample sizes, with no consensus on surgical planning. This retrospective study analyzed 14 patients (11 males, 3 females; mean age 57.2 ± 11.2 years) who underwent revision surgery for cage retropulsion (> 3mm posterior displacement) after lumbar fusion between 2013 and 2023. A novel 5-grade classification system (I-V) based on migration severity was proposed. Surgical approaches (anterior, n = 5; posterior, n = 9) were selected by revision timing, segment, and migration grade. Outcomes were assessed via VAS, ODI, and imaging; operative time, blood loss, and complications were recorded. 85.7% (12/14) patients showed clinical improvement: VAS decreased from 7.3 ± 1.2 to 2.3 ± 1.1, ODI from 69.5 ± 12.4% to 15.2 ± 8.7%. The average operation time for anterior approach was 215.0 ± 44.5min, and the average blood loss was 190.0 ± 156.2ml. The average operation time for posterior approach was 281.9 ± 90.9min, and the average blood loss was 387.5 ± 92.7ml. 50% (7/14) had complications, mainly transient abdominal distension (n = 5). 85.7% (12/14) achieved fusion at 78.9-month follow-up. This study proposes a practical classification system with preliminary feasibility in surgical approach selection for cage retropulsion. For symptomatic cases, early revision may yield better outcomes. Anterior surgery is recommended for L5-above segments with mild retropulsion, and posterior surgery is suggested for L5/S1 with severe retropulsion. In addition, anterior lumbar interbody fusion (ALIF) is a good option for L5/S1 with low-grade retropulsion when performed by experienced surgeon. Surgical success depends on tailored strategies considering revision timing, segments, and migration grade. But additional data are needed to confirm long-term safety and inform optimal management.

Retrospective clinical study. To study the differences in effectiveness of unilateral biportal endoscopic lumbar interbody fusion (ULIF) and percutaneous endoscopic posterolateral transforaminal lumbar interbody fusion (PE-PTLIF) in the treatment of lumbar degenerative diseases (LDD). While minimally invasive spine surgeries are gaining popularity, research on the comparative effectiveness of ULIF and PE-PTLIF remains limited. From January 2021 to January 2022, 52 patients with LDD were retrospectively recruited into the PE-PTLIF and ULIF groups. The operation time, true total blood loss, length of hospital stay, postoperative incision and drainage, postoperative complications, hospitalization cost, perioperative blood biochemical indexes, visual analog scale (VAS) score, Oswestry Disability Index (ODI), modified MacNab criteria, intervertebral disc height (DH), segmental lordosis (SL), lumbar lordosis (LL), dural sac cross-sectional area (DSCA), multifidus muscle fat infiltration score (MAIS) and multifidus muscle atrophy rate (MAR) were used as the evaluation indices. The surgical time, bleeding, and postoperative drainage volume in the PE-PTLIF group were less than those in the ULIF group. The average serum creatine kinase (CK), C-reactive protein (CRP), and hemoglobin (Hb) differences in the PE-PTLIF group were lower than those in the ULIF group on the first and third day after surgery. The VAS score of lower back pain and ODI (%) at 3 days and 1 month after surgery in the PE-PTLIF group were much lower than those in the ULIF group. At the last follow-up, the MAR and MAIS in the ULIF group were higher than in the PE-PTLIF group. PE-PTLIF has less damage to muscle and other soft tissues, faster recovery, but longer operation time. The incidence of complications of the 2 endoscopic-assisted lumbar fusions is less, and both are safe and effective surgical methods.

Retrospective cohort study. To compare the functional cross-sectional area (FCSA) of paraspinal muscles in patients undergoing single-level open transforaminal lumbar interbody fusion (Open-TLIF) versus minimally invasive TLIF (MIS-TLIF) and to assess correlations between muscle changes and clinical outcomes, including lumbar Visual Analogue Scale (VAS), leg VAS, and Oswestry Disability Index (ODI). Paraspinal muscle atrophy is linked to poorer outcomes after lumbar spine surgery. Minimally invasive techniques may reduce muscle damage. Understanding the degree of muscle preservation and its relationship to recovery can guide surgical decision-making. This study included 129 patients (Open-TLIF: 60; MIS-TLIF: 69) who underwent single-level TLIF between September 2020 and December 2024, with at least 1 year of follow-up. Computed tomography (CT) measured FCSA of the multifidus, erector spinae, and psoas muscles at index and adjacent levels. Correlation and regression analyses evaluated relationships between FCSA changes, surgical method, and clinical outcomes (lumbar VAS, leg VAS, ODI). Open-TLIF patients had significantly greater reductions in FCSA of the index and adjacent multifidus and index erector spinae muscles. MIS-TLIF patients showed lower lumbar VAS and ODI scores at final follow-up. Index multifidus FCSA loss correlated with worse lumbar VAS (r=-0.253, P=0.004) and ODI (r=-0.477, P<0.001). MIS-TLIF was significantly associated with multifidus preservation (r=0.837, P<0.001). Increased psoas FCSA correlated positively with ODI improvement (r=0.229, P=0.009) but negatively with erector spinae FCSA (r=-0.221, P=0.033). MIS-TLIF is associated with significantly less paraspinal muscle atrophy and better lumbar VAS and ODI outcomes compared with Open-TLIF. Preservation of the multifidus muscle is strongly linked to clinical improvement, and increased psoas FCSA contributes to better disability outcomes. Level II.

Hidden blood loss in robot-assisted vs. conventional midline lumbar interbody fusion: a single-center propensity-score-matched cohort study.

Anterior lumbar interbody fusion (ALIF) is an effective treatment for lumbar degenerative diseases, but it usually requires combined posterior fixation. Currently, Currently, there is no high-strength fixation technique for single-position anterior approach. This study aimed to introduce L5 vertebral body screws combined with S1 vertebral body-pedicle screw fixation (BPSF) as a novel single-position anterior fixation technique for ALIF, and to evaluate its clinical and biomechanical outcomes. Sixty-three patients with L5/S1 degenerative disease undergoing ALIF were divided into BPSF (n = 22) and posterior pedicle screw fixation (PPSF, n = 41) groups. Clinical outcomes, radiographic parameters, and complications were collected and compared between groups. Biomechanically, an adult lumbar spine model was used to simulate two ALIF fixation configurations under normal and osteoporotic conditions. Each construct was loaded with 500N compression and 10N·m torque to simulate flexion/extension, lateral bending, and axial rotation. Kinematic analyses included ROM, interbody cage stress, and fixation device strain. The BPSF group showed significantly shorter operative duration (152.5min (127.5, 173.1) vs. 165.0min (140.0, 262.5), less intraoperative blood loss (115.0 ± 56.9ml vs. 160.0ml (110.0, 222.5) mL), and lower postoperative low back pain scores (1.6 ± 0.8 vs. 2.2 ± 0.7) compared to the PPSF group. And there were no statistically significant differences between the two groups in JOA improvement rate (49.9 ± 14.2% vs. 54.7 ± 18.1%), lumbar lordosis correction (6.9 ± 7.3° vs. 7.6 ± 7.1°), fusion rate (90.9% vs. 92.7%), or complication rate (27.3% vs. 19.5%). Biomechanically, BPSF reduced ROM during flexion (12% reduction) and axial rotation (63% reduction) compared to PPSF, with higher interbody cage stress but lower posterior fixation device stress under most loading conditions. BPSF provides safe anterior fixation for ALIF, reducing operative time and early postoperative pain. Its biomechanical stability, especially in rotational resistance, supports it as an alternative to PPSF for L5/S1 fusion.

Abdominal aortic calcification and functional recovery in patients undergoing posterior lumbar interbody fusion: a retrospective cohort study.

To evaluate the accuracy and agreement of three widely used blood-loss estimation methods-visual estimation, gravimetric measurement, and the Gross formula method-against the reference HbMass method in patients undergoing posterior lumbar interbody fusion (PLIF). A single-center retrospective cohort study included 1000 consecutive elective PLIF patients (2021-2024). Intra-operative blood loss was quantified intra-procedurally by visual, gravimetric, and Gross formula method approaches; HbMass was calculated from pre- and post-operative hemoglobin with patient blood volume estimated by the Nadler equation. Agreement was assessed with Bland-Altman 95% limits of agreement (LoA) and Spearman correlation; sensitivity analyses examined fusion extent, irrigation volume, and sampling timing. Mean blood loss was 663.8 ± 155.6mL by HbMass. Visual, gravimetric, and Gross estimates averaged 456.5 ± 175.0mL, 599.8 ± 167.5mL, and 608.0 ± 115.0mL, respectively (all P < 0.001). Correlation with HbMass was negligible (ρ = 0.185), weak (ρ = 0.424), and moderate-to-strong (ρ = 0.742). Bland-Altman biases (95% LoA) were - 238.85mL (- 631.46, 153.76), - 45.33mL (- 377.55, 286.90), and - 28.57mL (- 216.66, 159.52). Sensitivity analyses confirmed robustness. Among routine methods, the Gross formula method offers the smallest bias and narrowest agreement limits versus HbMass, whereas visual estimation is clinically unreliable. PLIF-enhanced recovery pathways should replace sole reliance on visual assessment with the Gross formula method, supplemented by HbMass in high-risk cases, to optimize peri-operative volume therapy and reduce transfusion-related complications.

S1 vertebral Hounsfield Unit value independently predicts pedicle screw loosening after posterior lumbar interbody fusion in patients with lumbar degenerative diseases.