OBJECTIVE: In the treatment of lumbar degenerative spondylolisthesis (LDS) with Posterior lumbar interbody fusion (PLIF) surgery, interbody fusion implants play a key role in supporting the vertebral body and facilitating fusion. The objective of this study was to assess the impact of implantation depth on sagittal parameters and functional outcomes in patients undergoing PLIF surgery.
METHODS: This study reviewed 128 patients with L4-L5 LDS between January 2016 and August 2019. All patients underwent an open PLIF surgery that included intravertebral decompression, implantation of pedicle screws and cage. We grouped according to the position of the center of the cage relative to the L5 vertebral endplate. Patients with the center of the cage located at the anterior 1/2 of the upper end plate of the L5 vertebral body were divided into Anterior group, and located at the posterior 1/2 of the upper end plate of the L5 vertebral body were divided into Posterior group. The lumbar lordosis (LL), segmental lordosis (SL), sacral slope (SS), pelvic incidence (PI), pelvic tilt (PT) and slope degree (SD) was measured for radiographic outcomes. We used the visual analog scale (VAS) and the oswestry disability index (ODI) score to assess functional outcomes. Paired t-test was used to compare imaging and bedside data before and after surgery between the two groups, and independent sample t-test, χ2 test and Fisher exact test were used to compare the data between the two groups.
RESULTS: The mean follow-up of Anterior group was 44.13 ± 9.23 months, and Posterior group was 45.62 ± 10.29 months (P > 0.05). The LL, SL, PT, SS, SD and PI-LL after operation showed great improvements, relative to the corresponding preoperative values in both groups (P < 0.05). Compared to Posterior group, Anterior group exhibited far enhanced SL (15.49 ± 3.28 vs. 13.67 ± 2.53, P < 0.05), LL (53.47 ± 3.21 vs. 52.08 ± 3.15, P < 0.05) outcomes and showed depressed PI-LL (8.87 ± 5.05 vs. 10.73 ± 5.39, P < 0.05) outcomes at the final follow-up. Meanwhile, the SL in Anterior group (16.18 ± 3.99) 1 months after operation were also higher than in Posterior group (14.12 ± 3.57) (P < 0.05). We found that VAS and ODI at the final follow-up in Anterior group (3.62 ± 0.96, 25.19 ± 5.25) were significantly lower than those in Posterior group (4.12 ± 0.98, 27.68 ± 5.13) (P < 0.05).
CONCLUSIONS: For patients with LDS, the anteriorly placed cage may provide better improvement of SL after PLIF surgery. Meanwhile, the anteriorly placed cage may achieve better sagittal parameters of LL and PI-LL and functional outcomes at the final follow-up.

This was a single-centre retrospective study. Minimally invasive techniques for transforaminal lumbar interbody fusion (MIS-TLIF), oblique lumbar interbody fusion (OLIF), and percutaneous endoscopic transforaminal lumbar interbody fusion (Endo-TLIF) have been extensively used for lumbar degenerative diseases. The present study analyses the short-term and mid-term clinical effects of the above three minimally invasive techniques on L4/L5 degenerative spondylolisthesis. In this retrospective study, 98 patients with L4/L5 degenerative spondylolisthesis received MIS-TLIF, 107 received OLIF, and 114 received Endo-TLIF. All patients were followed up for at least one year. We compared patient data, including age, sex, body mass index (BMI), Oswestry disability index (ODI), visual analogue scale of low back pain (VAS-B), visual analogue scale of leg pain (VAS-L), surgical time, blood loss, drainage volume, hospital stay, complications, and neurological status. Moreover, we performed imaging evaluations, including lumbar lordosis angle (LLA), disc height (DH) and intervertebral fusion status. No significant differences were noted in age, sex, BMI, preoperative ODI, preoperative VAS-B, preoperative VAS-L, preoperative LLA, or preoperative DH. Patients who underwent OLIF had significantly decreased blood loss, a lower drainage volume, and a shorter hospital stay than those who underwent MIS-TLIF or Endo-TLIF (P < 0.05). The VAS-B in the OLIF group significantly decreased compared with in the MIS-TLIF and Endo-TLIF groups at 6 and 12 months postoperatively (P < 0.05). The VAS-L in the Endo-TLIF group significantly decreased compared with that in the MIS-TLIF and OLIF groups at 6 months postoperatively (P < 0.05). The ODI in the OLIF group was significantly better than that in the MIS-TLIF and Endo-TLIF groups at 6 months postoperatively (P < 0.05). No statistically significant differences in the incidence of complications and healthcare cost were found among the three groups. Follow-up LLA and DH changes were significantly lower in the OLIF group than in the other groups (P < 0.05). The intervertebral fusion rate was significantly higher in the OLIF group than in the other groups at 6 and 12 months postoperatively (P < 0.05). In conclusion, while MIS-TLIF, OLIF, and Endo-TLIF techniques can effectively treat patients with L4/5 degenerative spondylolisthesis, OLIF has more benefits, including less operative blood loss, a shorter hospital stay, a smaller drainage volume, efficacy for back pain, effective maintenance of lumbar lordosis angle and disc height, and a higher fusion rate. OLIF should be the preferred surgical treatment for patients with L4/5 degenerative spondylolisthesis.

UNASSIGNED: This study aimed to evaluate the 10-year clinical outcomes of endoscope-assisted, minimally invasive surgical (MIS) decompression for lumbar spinal canal stenosis (LSS) with lumbar degenerative spondylolisthesis (DS) and to compare the radiographic changes in patients who underwent this procedure with those who underwent conservative therapy at 10-year follow-up.
UNASSIGNED: Between April 2007 and April 2010, 347 consecutive patients with DS and evidence of LSS underwent conservative treatment first from 2 to 4 weeks. The 114 patients who failed conservative treatment were then treated surgically by endoscope-assisted MIS decompression. Of them, 91 patients were followed for more than 10 years (group S), and 146 of the 233 patients treated conservatively were followed for more than 10 years (group C). Clinical outcomes of endoscope-assisted MIS decompression were assessed using the Short Form Health Survey-36 score (SF-36), the Roland Morris Disability Questionnaire (RDQ), and the neurological leg symptoms of the Japanese Orthopaedic Association Score (JOA score). Radiographic changes of the two groups were assessed by %slip, dynamic %slip, range of motion (ROM), and the height of the disc (DH) on plain radiographs.
UNASSIGNED: Significant improvements in clinical outcomes on the SF-36, RDQ, and neurological leg symptoms of the JOA were observed. Radiographic assessment did not show significant differences in the assessed items between the two groups at baseline and after last treatment. Both groups had significantly decreased ROM and DH.
UNASSIGNED: The 10-year clinical outcomes of endoscope-assisted MIS decompression for DS were generally good. Furthermore, on radiographic comparison, the progress of spondylolisthesis after this procedure was virtually the same as in the natural course of the disease at 10-year follow-up.

OBJECTIVE: Clinical and radiographic degenerative spondylolisthesis (CARDS) classification was proposed to differentiate homogenous lumbar degenerative spondylolisthesis (LDS) subgroups. The sitting radiograph exhibited lumbar malalignment with maximum lumbar kyphosis, intervertebral kyphosis, and spondylolisthesis.This study aimed to assess the sitting radiograph for distribution of clinical and radiographic degenerative spondylolisthesis classification, and to elucidate its significance for exhibiting kyphotic alignment (CARDS type D) and segmental instability.
METHODS: A cohort of 101 patients with symptomatic lumbar degenerative spondylolisthesis (LDS) between September 2018 and December 2020 were recruited. The distribution and relibility of CARDS classification with or without sitting radiograph was assessed. The translational and angular range of motion and segmental instability was also evaluated. Univariate analysis of variance was used for multiple groups, and the least significant difference for two groups. Kappa consistency test of intrarater and interrater was evaluated for CARDS classification with or without sitting radiograph. Chi-square test was used to compare paried categorical data.
RESULTS: Utility of sitting radiographs for CARDS classification revealed higher percentage of type D than that without the sitting radiograph (p < 0.001). The sitting radiograph revealed a larger slip distance than the flexion radiograph (p = 0.003), as well as a lower slip angle than flexion radiograph (p < 0.001). The sitting-supine modality demonstrated the largest translational range of motion compared to the sitting-extension (p < 0.001) and flexion-extension modalities (p < 0.001). The sitting-supine modality showed larger angular range of motion than the flexion-extension modality (p < 0.001). The percentage of flexion, extension, upright, supine, and sitting radiograph to identify translational instability was higher than that without sitting radiograph (p < 0.001), as well as taking angular motion ≥10° as an additional criterion for segmental instability (p < 0.001).
CONCLUSIONS: The CARDS classification was reliable for LDS. The sitting radiograph showed maximal slip distance and kyphotic slip angle. Application of the sitting radiograph was necessary for evaluating segmental instability and kyphotic alignment of LDS.

UNASSIGNED: Various indicators of vertebral instability in patients with lumbar degenerative disease can be identified in myelo-computed tomography (CT) studies.
UNASSIGNED: Of 120 patients, 45 with lumbar degenerative spondylolisthesis (LDS; 53 lumbar lesions) and 75 with lumbar spinal stenosis alone (LSS; 105 lesions) (2015-2019) myelo-CT studies and surgery confirmed the presence of lumbar instability. Myelo-CT findings indicative of instability included facet joint thickness (FJT), fluid in the facet joint, facet tropism, and air in the facet and/or disc.
UNASSIGNED: For the 120 study patients, FJT was significantly elevated in both the LDS and LSS groups.
UNASSIGNED: FJT on myelo-CT is more specific for lumbar instability than other imaging parameters when evaluating LDS. An increase in FJT suggests vertebral instability likely warranting fusion.

UNASSIGNED: Degenerative lumbar spondylolisthesis affects approximately 10% of adults over 40. Although decompression has been the treatment of choice, some surgeons note possible instability development after decompression alone (D). Previous studies show that decompression with fusion (DF) has similar complication rates but is better at preventing slip progression and reducing pain. However, others stated the additional instrumentation does not result in superior functional outcomes and has higher costs and complication rates. This study aims to provide an objective, two-arm comparison of the two treatments using systematic review and meta-analysis.
UNASSIGNED: The study design was a systematic review and meta-analysis of relevant randomized controlled trials and nonrandomized comparative studies. A systematic search was conducted from April 2021 to September 2021 to identify relevant studies using PubMed, Google Scholar, EMBASE, and Cochrane databases based on PRISMA guidelines.
UNASSIGNED: This systematic review included 8 studies (6,669 patients); 7 (6,569 patients) were included in the meta-analysis, with a follow-up period of up to 143 months. The most commonly affected level was L4-5, with females being more affected than males. Visual Analog Scale improvement on back pain was significantly better in DF group (Heterogeneity, I2=32%; WMD -0.72; 95% Confidence Interval (CI), -1.35 to -0.08; P=0.03), as well as postoperative back pain (I2=96%; WMD 0.87; 95% CI, 0.19 to 1.55; P=0.01). The leg pain, Oswestry Disability Index (ODI), satisfaction rate, complication rate, and revision rate were comparable between the two procedures.
UNASSIGNED: Current systematic review and meta-analysis proved that DF is better than D in terms of back pain improvement, and the two procedures are comparable in terms of leg pain, ODI, satisfaction rate, complication rate, and revision rate.

UNASSIGNED: Vertebral slip reduction has been recommended in arthrodesis for lumbar degenerative spondylolisthesis (LDS) to achieve balanced spinal alignment and bone fusion. However, what determines the degree of slip reduction using cortical bone trajectory technique for lumbar pedicle screw insertion is yet to be determined. Thus, in this study, we aim to investigate the slip reduction capacity using cortical bone trajectory (CBT) technique and to identify factors affecting the slip reduction rate.
UNASSIGNED: This is a retrospective radiological evaluation of prospectively collected patients. In total, 49 consecutive patients who underwent single-level transforaminal lumbar interbody fusion for LDS using the CBT technique were included (mean follow-up: 28.9 months). Firstly, radiological parameters of fused segment including the percentage of anterior vertebral slip (%slip), lordotic angle, and disk height were measured. Then, patient and procedure-related parameters were examined to determine factors related to the slip reduction rate using multiple regression analysis.
UNASSIGNED: The %slip was reduced from 15.0±4.8 to 1.6±2.3% immediately after surgery and 2.2±2.9% at the last follow-up (p<0.01), with a slip reduction rate of 87.5±15.7% and correction loss of 0.6±2.1%. As per multivariate regression analysis, it was found that preoperative %slip (standardized regression coefficient [β]=-0.55, p=0.003) and the depth of screw insertion in the caudal vertebra (β=0.38, p=0.03) were significant independent factors affecting slip reduction rate (adjusted R2=0.29, p=0.008).
UNASSIGNED: To the best of our knowledge, this study is the first to investigate the capacity for and factors affecting slip reduction using the CBT technique for LDS. The CBT technique may be a useful option for achieving slip reduction, and the depth of screw insertion in the caudal vertebra was identified as a significant technical factor to obtain a more significant reduction of slipped vertebra.

Background: Quantitative computed tomography (qCT) efficiently measures 3-dimensional vertebral bone mineral density (BMD), but its utility in measuring BMD at various vertebral levels in patients with lumbar degenerative spondylolisthesis (LDS) is unclear. Purpose: We sought to determine whether qCT could differentiate BMD at different levels of LDS, particularly at L4-L5, the most common single level for LDS. In addition, we sought to describe patterns of BMD for single-level and multiple-level LDS. Methods: We conducted a study of patients undergoing surgery for LDS who were part of a larger longitudinal study comparing preoperative and intraoperative images. Preoperative patients were grouped as single-level or multiple-level LDS, and qCT BMD was obtained for L1-S1 vertebrae. Mean BMD was compared with literature reports; in multivariable analyses, BMD of each vertebra was assessed according to the level of LDS, controlling for covariates and for BMD of other vertebrae. Results: Of 250 patients (mean age: 67 years, 64% women), 22 had LDS at L3-L4 only, 170 at L4-L5 only, 13 at L5-S1 only, and 45 at multiple levels. Compared with other disorders reported in the literature, BMD in our sample similarly decreased from L1 to L3 then increased from L4 to S1, but mean BMD per vertebra in our sample was lower. Nearly half of our sample met criteria for osteopenia. In multivariable analysis controlling for BMD at other vertebrae, lower L4 BMD was associated with LDS at L4-L5, greater pelvic incidence minus lumbar lordosis, and not having diabetes. In contrast, in similar multivariable analysis, greater L4 BMD was associated with LDS at L3-L4. Bone mineral density of L3 and L5 was not associated with LDS levels. Conclusion: In our sample of preoperative patients with LDS, we observed lower BMD for LDS than for other lumbar disorders. L4 BMD varied according to the level of LDS after controlling for covariates and BMD of other vertebrae. Given that BMD can be obtained from routine imaging, our findings suggest that qCT data may be useful in the comprehensive assessment of and strategy for LDS surgery. More research is needed to elucidate the cause-effect relationships among spinopelvic alignment, LDS, and BMD.

Although several studies have recently shown that spinous process-splitting laminectomy (SPSL) maintains lumbar spinal stability by preserving posterior ligament components and paraspinal muscles as compared with conventional laminectomy, evidence is scarce on the treatment outcomes of SPSL limited to lumbar degenerative spondylolisthesis. We herein compare the surgical results and global alignment changes for SPSL versus posterolateral lumbar fusion (PLF) without instrumentation for lumbar degenerative spondylolisthesis.
A total of 110 patients with Grade 1 lumbar degenerative spondylolisthesis who had undergone SPSL (47 patients) or PLF (63 patients) with minimum 1-year follow-up were retrospectively enrolled from a single institutional database.
Mean operating time per intervertebral level and intraoperative blood loss per intervertebral level were comparable between the SPSL group and PLF group. Japanese Orthopaedic Association scores, Oswestry disability index, and visual analog scale scores were significantly and comparably improved at 1 year postoperatively in both groups as compared with preoperative levels. The numbers of vertebrae with slip progression to Grade 2 and slip progression of 5% or more at 1 year postoperatively were similar between the groups. In the SPSL group, mean pelvic tilt (PT) was significantly decreased at 1 year postoperatively. In the PLF group, mean lumbar lordosis (LL) was significantly increased, while mean sagittal vertical axis, PT, and pelvic incidence-LL were significantly decreased at 1 year after surgery.
Compared with PLF without instrumentation, SPSL for Grade 1 lumbar degenerative spondylolisthesis displayed comparable results for slip progression and clinical outcomes at 1 year postoperatively.

METHODS: Retrospective case series.
OBJECTIVE: To investigate the influence of screw size on achieving bone fusion in posterior lumbar interbody fusion (PLIF).
METHODS: In total, 137 consecutive patients with L4 degenerative spondylolisthesis who underwent single-level PLIF at L4-L5 were evaluated. Factors investigated for their contribution to bone fusion included: 1) age, 2) sex, 3) body mass index, 4) bone mineral density, 5) intervertebral mobility, 6) screw diameter, 7) screw length, 8) screw fitness in the pedicle (%fill), 9) screw depth in the vertebra (%depth), 10) screw angle, 11) facetectomy, 12) crosslink connector, and 13) cage material.
RESULTS: Bone fusion was confirmed in 88.2% of patients. The comparison between fusion (+) and fusion (-) groups showed no significant differences in screw size. The %fill and %length were significantly greater in the fusion (+) group than in the fusion (-) group (%fill: 58.5% ± 7.5% vs 52.3% ± 7.3%, respectively, P = .005; %depth: 59.8% ± 9.7% vs 50.3% ± 13.8%, respectively, P = .025). Multivariate logistic regression analysis revealed that %fill (odds ratio [OR]= 1.11, P = .025) and %depth (OR = 1.09, P = .003) were significant independent factors affecting bone fusion. Receiver operating characteristic curve analyses identified a %fill of 60.0% and a %depth of 54.2% as optimal cutoff values for achieving bone fusion.
CONCLUSIONS: Screw size should be determined based on the screw fitness in the pedicle (%fill > 60%) and screw insertion depth in the vertebral body (%depth > 54.2%) according to individual vertebral anatomy in L4-L5 PLIF.