The correlation of intraoperative distraction of intervertebral disc with the postoperative canal and foramen expansion following oblique lumbar interbody fusion.

PURPOSE: To examine the correlation of intraoperative distraction of intervertebral disc with the postoperative central canal and foramen expansion by oblique lumbar interbody fusion (OLIF) with indirect decompression. METHODS: Patients who underwent OLIF between October 2013 and April 2017 were included. Clinical outcomes included back and leg pain evaluated by visual analog scale (VAS) and Oswestry Disability Index (ODI). Intraoperative radiographic parameters of height ratio [(HR) = disc height/intervertebral body height)] and cage location were evaluated on intraoperative fluoroscopic images. Disc height (DH), foraminal height (FH), cross-sectional area of spinal canal (CSAC), and CSA of the foramen (CSAF) were measured. RESULTS: A total of 47 patients involving 62 levels were enrolled in this study. Mean follow-up was 43.8 ± 12.0 months. These patients reported an improvement of 61.7% in VAS back, 68.1% in VAS leg, and 46% in ODI (all p < 0.01). Radiographic parameters including HR, DH, FH, CSAC, and CSAF were also significantly increased by 32.6%, 48.2%, 21.4%, 44.0%, and 40.1% (left-side CSAF) or 45.4% (right-side CSAF), respectively (p < 0.05). HR increment was correlated with CSA (canal and foramen) increment. Slightly higher improvements of HR, DH, FH, CSAC, and CSAF (both sides) were noted when cage was located at middle rather than anterior (p > 0.05). CONCLUSIONS: The ligamentotaxis effect of OLIF is capable of supporting indirect decompression of central canal and neural foramina and clinical improvement. HR is a reliable intraoperative assessment method. In addition, intraoperative HR increment was correlated with postoperative neural elements expansion.

Decreasing thickness and remodeling of ligamentum flavum after oblique lumbar interbody fusion.

PURPOSE: Ligamentum flavum is one of the structures that could compress the spinal canal. Few studies have reported atrophy of ligamentum flavum after spinal fusion. The purpose of this study was to demonstrate the reduction of ligamentum flavum size after oblique lumbar interbody fusion (OLIF) using magnetic resonance imaging (MRI). METHOD: Seventeen patients who underwent OLIF without direct decompression were included. The MRI was obtained at the preoperative period, immediate postoperative period, and the follow-up period. Disc height (DH) was measured in plain radiograph. MRI measurements were spinal canal cross-sectional area (SCSA), ligamentum flavum thickness (LFT), ligamentum flavum area (LFA), and foraminal area (FA). RESULTS: Mean age of the patients was 68.5 ± 10.8. Mean times between postoperative MRI and follow-up MRI were 20.2 ± 11.9 months. Mean disc height increased from 7.6 ± 1.6 to 11.6 ± 1.7 mm at an immediate postoperative period but decreased to 10.1 ± 1.6 mm during follow-up (p < 0.001). SCSA increased from 96.9 ± 54.9 to 136.0 ± 72.7 mm2 and 171.4 ± 76.10 mm2 during follow-up (p < 0.001). LFT decreased from 3.9 ± 1.2 to 3.2 ± 0.8 mm (17.9%) and further decreased to 2.9 ± 0.7 mm during follow-up (9.4%) (p < 0.001). LFA decreased from 97.4 ± 36.9 to 86.1 ± 36.9 mm2 (11.6%) and further decreased to 77.2 ± 32.5 mm2 during follow-up (10.3%) (p = 0.001). FA increased from 69.2 ± 26.6 to 96.1 ± 23.0 mm2 and increased to 112.9 ± 23.0 mm2 during follow-up (p < 0.001). CONCLUSION: OLIF could decompress the spinal canal and foraminal canal indirectly. Despite the diminishing disc height during the follow-up period, the spinal canal was further increased in size from the remodeling of the ligamentum flavum.

Correction to: Decreasing thickness and remodeling of ligamentum flavum after oblique lumbar interbody fusion.

In the article "Decreasing Thickness and Remodeling of Ligamentum Flavum After Oblique Lumbar Interbody Fusion", Figure 2 captions contained mistakes as descriptions for the Figure sections were not assigned correctly.

Worldwide research productivity in the field of full-endoscopic spine surgery: a bibliometric study.

PURPOSE: To investigate the quantity and quality of articles in the field of full-endoscopic spine surgery (FESS) from different countries and assess characteristics of worldwide research productivity. METHODS: Articles published from 1997 to July 23, 2018, were screened using the Web of Science database. All studies were assessed for the following parameters: the number of total publications, h-index, contribution of countries, authors, journals, and institutions. RESULTS: A total of 408 articles were identified between 1997 and 2018. Between 1997 and 2017, the number of published articles tended to increase by 41 times. The largest number of articles was from China (30.15%), followed by South Korea (28.68%), the USA (13.97%), Germany (9.31%), and Japan (4.90%). The highest h-index was found for articles from South Korea (23), followed by the USA (18), Germany (16), China (11), and Japan (7). The highest number of articles was published in World Neurosurgery (12.50%), followed by Pain Physician (10.29%), Spine (6.62%), European Spine Journal (4.66%), and Journal of Neurosurgery: Spine (4.17%). Wooridul Spine Hospital published the largest number of articles (10.29%), followed by Tongji University (5.88%), University of Witten/Herdecke (5.39%), Brown University (5.15%), and Third Military Medical University (3.43%). CONCLUSIONS: The number of articles published in the field of FESS has increased rapidly in the past 20 years. In terms of quantity, China is the most contributive country based on the number of publications. High-quality papers as measured by h-index and the large quantity is from South Korea (second only to China). These slides can be retrieved under Electronic Supplementary Material.

Comparative analysis of the intervertebral disc signal and annulus changes between immediate and 1-year postoperative MRI after transforaminal endoscopic lumbar discectomy and annuloplasty.

PURPOSE: Postoperative magnetic resonance imaging (MRI) after microdiscectomy for lumbar disc herniation frequently shows spinal canal compression by the remaining annulus, which gradually decreases over time. Transforaminal endoscopic lumbar discectomy (TELD) can remove the herniation with minimal trauma to surrounding soft tissue. We aim to identify this remodeling of annulus fibrosus and the change of disc signal after TELD. METHODS: We reviewed patients who underwent TELD. Clinical data obtained were Oswestry disability index (ODI) and visual analog scale (VAS) for back and leg pain. Residual mass signal and disc protrusion size were measured in postoperative MRI. RESULTS: Thirty-one patients were reviewed. The mean age was 38.3 ± 14.4 years (range 18 to 76 years). ODI was 18.2% at the first follow-up and 12.7% at the last follow-up (p = 0.009). VAS for back and leg pain were 2.0 and 1.0 without significant change during follow-up. Disc protrusion size was reduced by 67.7% at the 1-year follow-up (p < 0.001). The residual mass signals at postoperative day 1 were high in 12 cases, intermediate in 18 cases, and low in1 case. The signal intensity was correlated with the percentage of disc protrusion reduction (p = 0.048). The percentage of disc protrusion reduction correlated with the last follow-up ODI (p = 0.018). CONCLUSION: One year after TELD, annulus remodeling was observed with an average of 67.7% of size reduction. The high signal intensity of residual mass at day 1 correlated with disc protrusion reduction at follow-up MRI. The percentage of disc protrusion reduction associated with the ODI at the final follow-up.

Artificial Intelligence in Spinal Imaging and Patient Care: A Review of Recent Advances.

Artificial intelligence (AI) is transforming spinal imaging and patient care through automated analysis and enhanced decision-making. This review presents a clinical task-based evaluation, highlighting the specific impact of AI techniques on different aspects of spinal imaging and patient care. We first discuss how AI can potentially improve image quality through techniques like denoising or artifact reduction. We then explore how AI enables efficient quantification of anatomical measurements, spinal curvature parameters, vertebral segmentation, and disc grading. This facilitates objective, accurate interpretation and diagnosis. AI models now reliably detect key spinal pathologies, achieving expert-level performance in tasks like identifying fractures, stenosis, infections, and tumors. Beyond diagnosis, AI also assists surgical planning via synthetic computed tomography generation, augmented reality systems, and robotic guidance. Furthermore, AI image analysis combined with clinical data enables personalized predictions to guide treatment decisions, such as forecasting spine surgery outcomes. However, challenges still need to be addressed in implementing AI clinically, including model interpretability, generalizability, and data limitations. Multicenter collaboration using large, diverse datasets is critical to advance the field further. While adoption barriers persist, AI presents a transformative opportunity to revolutionize spinal imaging workflows, empowering clinicians to translate data into actionable insights for improved patient care.

Addition of Ketorolac to Local Anesthesia for Wound Infiltration in Multilevel Posterior Lumbar Spinal Fusion: A Randomized, Double-Blinded, Placebo-controlled Trial.

STUDY DESIGN: Randomized double-blind controlled trial. OBJECTIVE: The purpose of this study was to determine the efficacy of pain control and opioid consumption after administration of ketorolac directly to paraspinal muscle after spinal fusion. SUMMARY OF BACKGROUND DATA: Ketorolac is added to multimodal analgesia regimens to improve pain control, reduce opioid consumption following Orthopaedics and spine surgery. However, evidence of efficacy of adding ketorolac to local anesthesia for intrawound infiltration after spine surgery is still limited. MATERIALS AND METHODS: The patients who underwent multilevel lumbar decompression and posterolateral fusion were recruited and randomized to the control group which received 0.5% bupivacaine hydrochloride injected into paraspinal muscles before wound closure, and the ketorolac group which received 30 mg ketorolac in addition to 0.5% bupivacaine hydrochloride. Post-operative numerical rating scale (NRS) for back pain, leg pain, morphine consumption, and adverse events were recorded. RESULTS: A total of 47 patients were randomized (24 in the ketorolac group and 23 in the control group). The mean age was 60.9±6.9 years old. The mean NRS for back pain at 6 hours after surgery was 5.8±3.0 points for the control group and 3.3±2.1 points for the ketorolac group (P<0.01). The ketorolac group consumed lesser morphine than the control group by 9.1 mg in the first 24 hours, 13.8 mg at 48 hours, 14.3 mg at 72 hours, and 13.9 mg at 96 hours after the surgery (P<0.05). Post-operative complications were not different between the two groups. CONCLUSIONS: The addition of ketorolac to bupivacaine for wound infiltration after posterior lumbar spine decompression and fusion reduces early post-operative pain and total morphine consumption as compared to bupivacaine alone.

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.

The Role and Clinical Outcomes of Endoscopic Spine Surgery of Treating Spinal Metastases; Outcomes of 29 Cases From 8 Countries.

OBJECTIVE: We aim to report the outcomes and feasibility of endoscopic spine surgery used to treat symptomatic spinal metastases patients. This is the most extensive series of spinal metastases patients who underwent endoscopic spine surgery. METHODS: A worldwide collaborative network group of endoscopic spine surgeons, named 'ESSSORG,' was established. Patients diagnosed with spinal metastases who underwent endoscopic spine surgery from 2012 to 2022 were retrospectively reviewed. All related patient data and clinical outcomes were gathered and analyzed before the surgery and the followtime period of 2 weeks, 1 month, 3 months, and 6 months. RESULTS: A total of 29 patients from South Korea, Thailand, Taiwan, Mexico, Brazil, Argentina, Chile, and India, were included. The mean age was 59.59 years, and 11 of them were female. The total number of decompressed levels was 40. The technique was relatively equal (15 uniportal; 14 biportal). The average length of admission was 4.41 days. Of all patients with an American Spinal Injury Association Impairment Scale of D or lower before surgery, 62.06% reported having at least one recovery grade after the surgery. Almost all clinical outcomes parameters statistically significantly improved and maintained from 2 weeks to 6 months after the surgery. Few surgical-related complications (4 cases) were reported. CONCLUSION: Endoscopic spine surgery is a valid option for treating spinal metastases patients as it could yield comparable results to other minimally invasive spine surgery techniques. As the aim is to improve the quality of life, this procedure is valuable and holds value in palliative oncologic spine surgery.

A 30-Year Worldwide Research Productivity of Scientific Publication in Full-Endoscopic Decompression Spine Surgery: Quantitative and Qualitative Analysis.

OBJECTIVE: The ever-growing number of articles related to full-endoscopic spine surgery published in the last few decades presents a challenge which is perplexing and time-consuming in identifying the current research status. The study aims to identify and analyze the most cited works related to full-endoscopic decompression spine surgery, compare the articles published by different publishers and area, and show the current publication status of full-endoscopic research. METHODS: Using Bibliometrix, CiteSpace, and VOSviewer, we analyzed the bibliometric data selected from the Web of Science database between 1992 and 2022. Spine has the highest H-index with the most-cited journal in the field of full-endoscopic decompression spine surgery. China ranked as the most productive country, whereas the most cited with high H-index papers came from South Korea. For the author analysis, Yeung AT, Ruetten S, Hoogland T, Ahn Y, Choi G, and Mayer HM were the most impactful authors in the global and local citations. The most productive organization is Wooridul Spine Hospital. CONCLUSION: The bibliometric study showed a growing trend of research on full-endoscopic decompression spine surgery over the past 30 years. It has demonstrated that there is a significant increase in the number of authors, institutions, and internationally collaborated countries. However, the quality of studies is still low, and the lack of high-quality clinical evidence and the trend of general journal submissions has somewhat affected the quality of endoscopy journals in recent years.

Periarticular Injection of Ketorolac Augmenting Intravenous Administration of Ketorolac for Postoperative Pain Control: A Randomized Controlled Trial in Simultaneous Bilateral Total Knee Arthroplasty.

Adequate postoperative pain control with minimal side effects is necessary for patients undergoing total knee arthroplasty (TKA). Ketorolac is a frequently used nonsteroidal anti-inflammatory drug due to its excellent disposition in all administration routes; however, it possesses an "analgesic ceiling," which means that higher doses of the drug have no additional analgesic effect. Alternatively, increasing the local concentration of ketorolac via periarticular injection may provide additional pain relief to parenteral administration of ketorolac, but evidence demonstrating the benefits and safety of this approach is limited. Therefore, this study assesses whether local ketorolac injection could yield additional pain reduction to intravenous administration of ketorolac. A total of 54 patients who underwent simultaneous bilateral TKA were enrolled. Randomization was performed to determine whether 50 mg of bupivacaine plus 30 mg of ketorolac (ketorolac group), or only 50 mg bupivacaine (bupivacaine group) would be periarticularly injected into the first knee operated on (more painful), and then the contralateral knee would receive another mixture. Ketorolac (30 mg) was intravenously given every 8 hours for the first 48 hours. Visual analog scales (VASs) were used to assess pain, knee recovery function, and patients' preferred knee. Postoperative VAS pain scores in the ketorolac group were lower than those in the bupivacaine group 6 to 96 hours postoperatively and reached statistical significance 12 (4.25 ± 2.38 vs. 5.06 ± 2.48, respectively; p = 0.04) and 24 hours (4.22 ± 1.94 vs. 5.30 ± 2.12, respectively; p < 0.01) postoperatively. The ketorolac group had higher degrees of knee flexion and straight leg raise. No patient experienced adverse effects of ketorolac. On the day of discharge, 61.11% of the patients favored the knee that received local ketorolac injection (p < 0.01). Adjunct local ketorolac injection to systemic administration is well tolerated and may improve its analgesic effect as determined by the patients' perception.

Do Obliquity and Position of the Oblique Lumbar Interbody Fusion Cage Influence the Degree of Indirect Decompression of Foraminal Stenosis?

OBJECTIVE: Oblique lumbar interbody fusion (OLIF) is a surgical technique that utilizes a large interbody cage to indirectly decompress neural elements. The position of the cage relative to the vertebral body could affect the degree of foraminal decompression. Previous studies determined the position of the cage using plain radiographs, with conflicting results regarding the influence of the position of the cage to the degree of neural foramen decompression. Because of the cage obliquity, computed tomography (CT) has better accuracy than plain radiograph for the measurement of the obliquely inserted cage. The objective of this study is to find the correlation between the position of the OLIF cage with the degree of indirect decompression of foraminal stenosis using CT and magnetic resonance imaging (MRI). METHODS: We review imaging of 46 patients who underwent OLIF from L2-L5 for 68 levels. Segmental lordosis (SL) was measured in a plain radiograph. The positions of the cage were measured in CT. Spinal canal cross-sectional area (SCSA), and foraminal crosssectional area (FSCA) measurements using MRI were taken into consideration. RESULTS: Patients' mean age was 69.7 years. SL increases 3.0±5.1 degrees. Significant increases in SCSA (33.3%), FCSA (43.7% on the left and 45.0% on the right foramen) were found (p<0.001). Multiple linear regression analysis shows putting the cage in the more posterior position correlated with more increase of FSCA and decreases SL correction. The position of the cage does not affect the degree of the central spinal canal decompression. Obliquity of the cage does not result in different degrees of foraminal decompression between right and left side neural foramen. CONCLUSION: Cage position near the posterior part of the vertebral body increases the decompression effect of the neural foramen while putting the cage in the more anterior position correlated with increases SL.

Endoscope-Assisted Anterior Lumbar Interbody Fusion with Computed Tomography-Guided, Image-Navigated Unilateral Cortical Bone Trajectory Screw Fixation in Managing Adjacent Segment Disease in L5/S1: Technical Note.

OBJECTIVE: We sought to describe a novel technique in managing a patient with adjacent segment disease at the L5/S1 level. METHODS: We performed an endoscope-assisted anterior lumbar interbody fusion with computed tomography-guided, image-navigated unilateral cortical bone trajectory screw fixation to treat L5/S1 intervertebral disk pathology. RESULTS: Patient was successfully treated by a direct endoscopic decompression through the anterior access, interbody fusion using an anterior lumbar interbody fusion cage, unilateral cortical bone trajectory instrumentation under computed tomography-guided image navigation. CONCLUSIONS: This minimally invasive technique is effective in terms of decompression and fixation. It could be used as an alternative method to treat patients with L5/S1 adjacent segment disease.

A longitudinal investigation of the endplate cystic lesion effect on oblique lumbar interbody fusion.

OBJECTIVE: To determine longitudinal effects of changes in endplate cystic lesions on oblique lumbar interbody fusion (OLIF), the relationship between bone healing and endplate cystic lesion changes, and clinical significance of cyst formation. PATIENTS AND METHODS: A total of 107 segments in 67 patients who underwent OLIF between January 2013 and July 2016 were examined in this retrospective study. Using computed tomography, radiographic examinations of endplate cystic lesion, positive or negative cyst formation, cage subsidence, and fusion status were performed. Clinical outcomes were measured using visual analogue scale (VAS) pain scores, Oswestry disability index (ODI), and modified Macnab criteria. Outcomes were compared with preoperatively and postoperatively. A logistic regression analysis was performed to evaluate the relationship between measurements for endplate cysts. RESULTS: The fusion rate after OLIF was 94.4% at 2-year follow-up, with 86% of cases reporting satisfactory outcome (based on modified Macnab criteria). A significantly higher (P <  0.01) VAS score for back pain was observed in the cystic lesion group than non-cystic lesion group at 6-month follow-up. Cage subsidence significantly increased the risk of non-union (odds ratio [OR]: 17.24; 95% confidence interval [CI]: 1.67-178.09). Positive cyst sign was a significant risk factor for cage subsidence (OR: 8.52; 95% CI: 2.73-26.62) while cage subsidence was also a significant risk factor for positive cyst formation (OR: 8.37; 95% CI: 2.71-25.89). CONCLUSIONS: Cystic lesion may increase back pain in the early postoperative period. However, the preoperative cystic lesion does not aggravate a positive cyst formation or affect the final clinical result. Positive cyst formation was a significant risk factor for cage subsidence. In addition, cage subsidence was a significant predictor of non-union. Thus, the authors can speculate that positive cyst sign was potentially an indirect predictor of non-union.

Clinical and Radiologic Outcomes of Direct Versus Indirect Decompression with Lumbar Interbody Fusion: A Matched-Pair Comparison Analysis.

OBJECTIVE: To compare the radiologic and clinical outcomes between oblique lumbar interbody fusion (OLIF) without laminectomy and minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). METHODS: This was a retrospective study. Between April 2012 and January 2017, 25 patients in each of the MI-TLIF and OLIF groups were recruited as matched pairs. Clinical outcomes included visual analogue scale, Oswestry Disability Index, and satisfaction rates. Radiographic outcomes comprised disc height (DH) and fusion status. Intraoperative data and complications were collected. All patients completed the clinical and radiologic outcomes. Outcomes were compared preoperatively and postoperatively. RESULTS: Matched pairs were compared between 2 groups in terms of demographic data and preoperative measurements; less blood loss and shorter operative time were found in OLIF versus MI-TLIF (P < 0.001). The total complication rate was 36% in OLIF and 32% in MI-TLIF (P = 0.77). The outcomes of visual analogue scale and Oswestry Disability Index were significantly improved in both groups, and there was no significant difference between 2 groups. Satisfaction rates of the both groups were more than 90%. OLIF was superior to MI-TLIF with respect its capability to restore DH (P < 0.001). Earlier time of fusion was observed in OLIF (80%) compared with MI-TLIF (52%) at 6 months (P = 0.04). CONCLUSIONS: OLIF may achieve equivalent clinical and radiologic outcomes compared with MI-TLIF when the stenosis is minimal because the decompression performed is indirect. Furthermore, the OLIF shows less blood loss and shorter operative time, better restoration of DH, and earlier time to fusion than the MI-TLIF.