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.

Influence of dynamic neck motion on the clinical usefulness of multi-positional MRI in cervical degenerative spondylosis.

PURPOSE: The purpose of this study was to find out additional indications for multi-positional MRI in cervical degenerative spondylosis (CDS) patients. MATERIAL AND METHODS: A total of 63 patients with cervical spondylotic myelopathy that underwent multi-positional MRI and X-ray were included. Muhle's grade, C2-7 angle, and C7 slope were measured. Patients were assigned to the stenosis group (Group S) when Muhle's grades were increased by more than two or maximum grade was reached. Other patients were assigned to the maintenance group (Group M). Receiver operating characteristic (ROC) analysis was performed. Statistical significance was accepted for p values of < 0.05. RESULTS: A total of 24 patients were assigned to the S group and 39 patients to the M group. Mean C2-7 angle difference in extension (eC27A) between S and M groups was 10.97° (p = 0.002). The mean inter-group difference between C2-7 angle in extension and neutral positions (e-nC27A) was 14.39° (p = 0.000). Mean C7 slope difference in neutral position was - 6.53° (p = 0.002). Based on areas under ROC curves (AUCs), e-nC27A, eC27A, and negative C7 slope had AUCs of 0.934 (95% CI 0.876-0.992), 0.752 (95% CI 0.624-0.880), and 0.720 (95% CI 0.588-0.851), respectively. The optimal cutoff value of e-nC27A was 15.4 degrees, which had a diagnostic accuracy of 88.9%. CONCLUSION: Multi-positional MRI helps to find dynamic cord compressive lesion in CDS patients. The higher eC27A, e-nC27A values and smaller C7 slope were found to increase the likelihood of cervical dynamic stenosis. Among other factors, we recommend multi-positional MRI before surgery especially when a patient's e-nC27A is > 15.4 degrees. LEVEL OF EVIDENCE I: Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Intraoperative surveillance of the vertebral artery using indocyanine green angiography and Doppler sonography in craniovertebral junction surgeries.

OBJECTIVE: The authors sought to evaluate the usefulness of indocyanine green (ICG) angiography and Doppler sonography for monitoring the vertebral artery (VA) during craniovertebral junction (CVJ) surgery and compare the incidence of VA injury (VAI) between the groups with and without the monitoring of VA using ICG angiography and Doppler sonography. METHODS: In total, 344 consecutive patients enrolled who underwent CVJ surgery. Surgery was performed without intraoperative VA monitoring tools in 262 cases (control group) and with VA monitoring tools in 82 cases (monitoring group). The authors compared the incidence of VAI between groups. The procedure times of ICG angiography, change of VA flow velocity measured by Doppler sonography, and complication were investigated. RESULTS: There were 4 VAI cases in the control group, and the incidence of VAI was 1.5%. Meanwhile, there were no VAI cases in the monitoring group. The procedure time of ICG angiography was less than 5 minutes (mean [± SD] 4.6 ± 2.1 minutes) and VA flow velocity was 11.2 ± 4.5 cm/sec. There were several cases in which the surgical method had to be changed depending on the VA monitoring. The combined use of ICG angiography and Doppler sonography was useful not only to monitor VA patency but also to assess the quality of blood flow during CVJ surgery, especially in the high-risk group of patients. CONCLUSIONS: The combined use of ICG angiography and Doppler sonography enables real-time intraoperative monitoring of the VA by detecting blood flow and flow velocity. As the arteries get closer, they provide auditory and visual feedback to the surgeon. This real-time image guidance could be a useful tool, especially for high-risk patients and inexperienced surgeons, to avoid iatrogenic VAI during any CVJ surgery.

Comparative Analysis of 2 Different Types of Titanium Mesh Cage for Single-level Anterior Cervical Corpectomy and Fusion in Terms of Postoperative Subsidence and Sagittal Alignment.

STUDY DESIGN: This was a retrospective observatory analysis study. OBJECTIVE: The objective of this study was to compare the differences in clinical and radiologic outcomes among patients who underwent anterior cervical corpectomy and fusion (ACCF) using titanium mesh cage (TMC) with end-caps and patients who underwent ACCF using TMC without end-cap. SUMMARY OF BACKGROUND DATA: TMC has been widely used as an effective treatment option for ACCF. However, the subsidence of TMC has been observed frequently in the early postoperative period in some cases, resulting in related clinical complications. MATERIALS AND METHODS: Patients who underwent single-level ACCF using TMC from September 2008 to June 2014 at our institute were retrospectively reviewed. Patients treated with TMC with end-cap were classified as an end-cap group, while patients treated with TMC without end-cap classified as a control group. The round press-fit-type end-caps with 2.5-degree angulation were used at both ends of the cage for the end-cap group. Patients were followed postoperatively for a minimum of 36 months with radiologic evaluation. RESULTS: The subsidence was lower in the end-cap group (4.3±3.6 vs. 4.8±3.0, P<0.01), with lower rates of severe subsidence (≥3 mm) than the control group (34.2% vs. 52.1%, P<0.01). Visual analogue scale (VAS) scores for neck pain and Neck Disability Index (NDI) was reported significantly less in the study group, which showed a positive correlation with lesser severe subsidence. Also, the characteristics of subsidence differed between the 2 groups. In the end-cap group, slippage type subsidence occurred, resulting in better sagittal alignment than that in the control group. CONCLUSIONS: For patients undergoing single-level ACCF, using TMC with end-cap provided better clinical results and similar fusion rate, compared with using TMC without end-cap. The end-cap decreased the severity of postoperative subsidence and related neck pain. Also, sagittal alignment was well preserved, suggesting it may contribute to cervical lordosis.

Clinical Characteristics and Outcomes of Patients with Culture-Negative Pyogenic Spondylitis according to Empiric Glycopeptide Use.

BACKGROUND: The optimal choice of antibiotics is challenging in culture-negative pyogenic spondylitis (PS). The empiric use of glycopeptides is suggested depending on various risk factors, although clinical data are sparse. This study aimed to analyze the clinical characteristics and outcomes of patients with culture-negative PS and evaluate the effect of empiric glycopeptide use on clinical outcomes in these patients. MATERIALS AND METHODS: Data on the characteristics, treatment, and outcomes of 175 patients diagnosed with PS were retrospectively obtained from the electronic database of a tertiary referral hospital from 2009 to 2016. Patients with negative culture results were grouped by the duration of glycopeptide treatment: glycopeptide therapy <28 days (Group A) and glycopeptide therapy ≥28 days (Group B). RESULTS: Of 89 patients with negative culture results, 78 were included in the analysis (Group A, n = 66; Group B, n = 12). The mean age of patients with negative culture results was 65.5 years, and 52.6% were male. The median follow-up duration was 573 (interquartile range [IQR], 83 - 1,037) days. The duration of intravenous glycopeptide therapy was 0.0 (IQR, 0.0 - 0.0) days and 55.5 (IQR, 37.0 - 75.7) days for Groups A and B, respectively. Patients who used glycopeptide longer empirically (Group B) had more commonly undergone a previous spinal procedure, including surgery (P = 0.024). The length of hospitalization, erythrocyte sedimentation rate, and C-reactive protein level were significantly higher in Group B compared with those in Group A (P <0.001, P <0.001, and P = 0.006, respectively). Regarding treatment modalities, patients in Group B underwent surgery more frequently (P = 0.017). The duration of parenteral antibiotic treatment was longer in Group B (P <0.001). Recurrence was noted in 7 patients (9.0%), and the recurrence rate was not significantly different between the 2 groups (Group A, 5/66 [7.6%]; Group B, 2/12 [16.7%]; P = 0.293). CONCLUSION: The recurrence rate among patients with culture-negative PS was not different based on the duration of empiric glycopeptide use. However, considering the small sample size and heterogeneity of our study population, we suggest that it is reasonable to administer glycopeptide antibiotics in these patients depending on clinical risk factors. Further large-scale prospective studies are needed to obtain more evidence for appropriate antibiotic treatment.

Epidemiology of C5 Palsy after Cervical Spine Surgery: A 21-Center Study.

OBJECTIVE: C5 palsy is a severe complication after cervical spine surgery, the pathophysiology of which remains unclear. This multicenter study investigated the incidence of C5 palsy following cervical spine surgery in Korea. METHODS: We conducted a retrospective multicenter study involving 21 centers from the Korean Cervical Spine Study Group. The inclusion criteria were cervical spine surgery patients between 2012 and 2016, excluding cases of neck surgery. In patients with C5 palsy, the operative methods, disease category, onset time of C5 palsy, recovery time, C5 manual muscle testing (MMT) grade, and post-C5 palsy management were analyzed. RESULTS: We collected 15,097 cervical spine surgery cases from 21 centers. C5 palsy occurred in 88 cases (0.58%). C5 palsy was more common in male patients (p=0.019) and after posterior approach procedures (p<0.001). C5 palsy usually occurred within 3 days after surgery (77 of 88, 87.5%) and most C5 palsy patients recovered within 6 months (51 of 88, 57.95%). Thirty C5 palsy patients (34.09%) had motor weakness, with an MMT grade≤2. Only four C5 palsy patients (4.5%) did not recover during follow-up. Posterior cervical foraminotomy was performed in 7 cases (7.95%), and steroids were used in 56 cases (63.63%). Twenty-six cases (29.55%) underwent close observation only. CONCLUSION: The overall incidence of C5 palsy was relatively low (0.58%). C5 palsy was more common after posterior cervical surgery and in male patients. C5 palsy usually developed within 3 days after surgery, and more than half of patients with C5 palsy recovered within 6 months.

Full-endoscopic interlaminar discectomy for the treatment of a dorsal migrated thoracic disc herniation: Case report.

RATIONALE: Thoracic disc herniation (TDH) is an infrequent spinal disease and difficult to treat well. Various surgical approaches and procedures were introduced in many literatures. The authors report a patient with dorsal migrated TDH compressing the spinal cord at T10-11 level. PATIENT CONCERNS: A 65-year-old male patient presented with complaints of severe paresthesia of both legs and progressive motor weakness for 1 week. DIAGNOSES: Magnetic resonance imaging (MRI) of the thoracic and lumbar spine revealed TDH and migration of dorsal side on spinal cord at T10-11 level. INTERVENTIONS: Successful decompressive surgery was performed through a posterior interlaminar approach using only endoscopic instruments. OUTCOMES: After the operation, patient's symptoms, paraparesis and paresthesia, immediately improved. LESSONS: The successful results of this case suggest that full endoscopic laminotomy and discectomy may be an attractive minimally invasive surgical technique for treating TDH with dorsal migrated fragments.

Time Course Observation of Outcomes between Minimally Invasive Transforaminal Lumbar Interbody Fusion and Posterior Lumbar Interbody Fusion.

The purpose of this study is to compare the long-term patient-outcomes, spinal fusion, and incidence of adjacent segment degeneration (ASD) between minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and open posterior lumbar interbody fusion (O-PLIF). We retrospectively reviewed 70 consecutive cases who underwent single-level MIS-TLIF or O-PLIF from March 2010 to July 2013. All the patients achieved a minimum of 5-year follow-up. Data collected for each patient included demographic data, perioperative data, and complications. Clinical outcomes were evaluated with Oswestry disability index and visual analogue scale (VAS). Radiological outcomes included fusion rate and ASD. About 34 patients of MIS-TLIF and 36 patients of O-PLIF were enrolled. Higher Charlson comorbidity index scores were noted in MIS-TLIF than in O-PLIF. Blood loss was significantly lower in MIS-TLIF than O-PLIF. There were significant improvements in clinical and radiological outcomes in both groups. At 6 months, in MIS-TLIF group had significantly lower VAS for back pain and disc height compared with in O-PLIF group. The fusion rate was similar between the two groups at 5-year follow-up. Although the total complication rates were similar between the two groups, both the incidence of ASD was significantly higher in O-PLIF group than MIS-TLIF group (P = 0.032). In conclusion, this study indicates that MIS-TLIF is comparable to O-PLIF in terms of fusion rates and clinical outcomes in single-segment degenerative lumbar diseases. In addition, compared with O-PLIF, MIS-TLIF has the advantages of lesser blood loss, faster recovery, and lower incidence of ASD.

Epidemiology of Iatrogenic Vertebral Artery Injury in Cervical Spine Surgery: 21 Multicenter Studies.

BACKGROUND: The overall incidence of iatrogenic vertebral artery injury (IVAI) in cervical spine surgeries (CSSs) is reported to be 0.07%-1.4%. Although IVAI occurred during C1-2 fusion, there is no accurate information regarding the surgery-specific risk of IVAI. This study aimed to stratify incidence of IVAI by surgical method and evaluate the correlation between IVAI and its sequelae. METHODS: This retrospective, multicenter study involved clinical and radiologic evaluations for IVAI. All CSSs performed between 2012 and 2016 were included; neck mass excision and pain intervention were excluded. Patient characteristics, diagnosis, surgical technique, complications, and presence of IVAI were collected. In IVAI cases, technique details, characteristics, and sequelae were investigated. RESULTS: This study included 14,722 patients with 15,582 CSSs in 21 centers. IVAIs were identified in 13 (0.08%) patients. Surgery-specific incidence of IVAI was 1.35% in cases involving C1-2 posterior fixation and 0.20% in cases involving C3-6 posterior fixation. Common injury mechanisms were screw-in (31%) and high-speed drilling (23%). Screw-related IVAI occurred in 9 (69%) patients, and IVAI of the C1 lateral mass and C2 pedicle screws occurred in 4 and 3 patients, respectively. Of 13 cases of IVAI, 3 (23%) involved cerebellar or stem infarction; the infarction had no substantial correlation with injury grade or dominancy. CONCLUSIONS: Overall incidence of IVAI in CSSs was 0.08%. C1-2 posterior fixation had the highest incidence of IVAI (1.35%). Although clinical results of IVAI can be highly variable, controlling risk factors of IVAI is important.

Accuracy and Safety in Screw Placement in the High Cervical Spine: Retrospective Analysis of O-arm-based Navigation-assisted C1 Lateral Mass and C2 Pedicle Screws.

STUDY DESIGN: This study was a retrospective analysis. OBJECTIVE: The purpose of present study was to evaluate accuracy, efficiency, and safety of intraoperative O-arm-based navigation system for the placement of C1 lateral mass screw (C1LMS) and C2 pedicle screws (C2PSs) in high cervical spine operations. SUMMARY OF BACKGROUND DATA: High screw misplacement rates, various pedicle morphometry and vertebral body size variations have led to a search of image-guided systems to improve the surgical accuracy of screw insertion in high cervical spine. The use of O-arm has been proposed for more accurate and efficient spinal instrumentation. MATERIALS AND METHODS: Between June 2009 and August 2016, a total of 48 patients with atlantoaxial instability were surgically treated using the image-guidance system. To reconstruct atlantoaxial instability, we have been using Harm's technique of C1LMS and C2PS fixations. A frameless, stereotactic O-arm-based image-guidance system was used for correct screw placement. Postoperative computed tomographic scan with multiplanar reconstructions were used to determine the accuracy of the screw placement. RESULTS: A total of 182 screws, including 90 C1LMS and 92 C2PSs were inserted using image-guidance system. In total, 4.4% (4/90) of C1LMS and 7.6% (10/92) of C2PS had cortex violation over 2 mm and considered as "significant." Among the significant cortex violations, "unexpected breech" was 3.3% of all the screws inserted. Two (2.1%) screws inserted had perforated the vertebral artery canal and iatrogenic vertebral artery stenosis was proved with postoperative computed tomography angiography. When divided into time periods, 60% of significant breech occurred during the beginning stage, 40% during adaptation stage and none during expert stage. CONCLUSIONS: In this study, the authors demonstrated that use of image-guidance system seems to be beneficial for high cervical instrumentation which requires much experience and steep learning curves. However, incidence of cortex violation does not disappear completely due to the close proximity to spinal canal and surrounding vessels.

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.

The Clinical Usefulness of Preoperative Imaging Studies to Select Pathologic Level in Cervical Spondylotic Myelopathy: Comparative Analysis of Three-Position MRI and Post-Myelographic CT.

AIM: To compare the accuracy of determining pathologic segment between three-position MRI (3P-MRI) and post-myelographic CT (PMCT) in cervical spondylotic myelopathy (CSM) by assessing the degree of inter-observer and intra-observer agreement. MATERIAL AND METHODS: We retrospectively reviewed 3P-MRI and PMCT for the diagnosis of multilevel CSM in 136 patients who underwent surgery. Using an assessment scale, 8 blind observers with various clinical experiences examined 5 parameters: spinal canal narrowing, foraminal stenosis, bony abnormality, intervertebral disc herniation, and nerve root compression. Spinal canal, neural foraminal, spinal cord and disc protrusion diameters were measured. Intra-observer and inter-observer agreement of each image was analyzed. RESULTS: Spinal canal width and foraminal diameter was found to be significantly smaller in 3P-MRI compared to PMCT. No significant differences of cervical cord diameter and the size of disc protrusion measured in 3P-MRI compared to PMCT were observed. Comparing between 3P-MRI and PMCT, disc abnormality and nerve root compression showed better agreement on 3P-MRI, whereas foraminal stenosis and bony lesion showed better agreement on PMCT. CONCLUSION: In the present study, PMCT was still useful in diagnosis of the foraminal stenosis and bony lesion compared to 3P-MRI but showed limitation in disc abnormality and nerve root compression. Even though PMCT may provide valuable additional information in difficult or ambiguous cases, universal standard of 3P-MRI showed higher reliability in detecting pathologic levels in CSM patients.

Dimensions of the spinous process and interspinous space: a morphometric study.

PURPOSE: To measure the morphological dimensions of the spinous process (SP) and interspinous space, and provide a basis for the development of interspinous devices for the Korean or East Asian populations. METHODS: We retrospectively analyzed the anatomical parameters of 120 patients. The parameters included height, length, and width of SP, interspinous distance (supine, standing, and dynamic), cortical thickness of SP, and spino-laminar (S-L) angle. Correlations between measurements, age, and gender were investigated. RESULTS: The largest height, length, and cortical thickness and S-L angle were noted at L3. The largest width was observed at S1. The interspinous distance decreased significantly from L2-3 to L5-S1 and was significantly larger in the supine than in standing posture for L5-S1. Cortical thickness was gradually tapered from the anterior to the posterior position. The S-L angle at L2 and L3 was similar and significantly decreased from L3 to S1. An increased trend in width with aging and a decreased trend in distance (supine) were noted. A significant increase in height, length, and distance in males compared with females was also observed. CONCLUSIONS: The interspinous space is wider at the anterior, and the cortex is thicker anteriorly. Accordingly, it appears that the optimized implant position lies in the interspinous space anteriorly. The varying interspinous space with different postures and gradually narrowing with age suggest the need for caution when sizing the device. Gender differences also need to be considered when designing implantable devices.

Time Course of Radiologic Changes After Lumbar Total Disc Replacement: Experience of Single Institute With Minimum 5-Year Follow-up.

STUDY DESIGN: This was a retrospective observatory analysis study. OBJECTIVE: The purpose of this study was to evaluate long-term safety and therapeutic effectiveness of the lumbar total disc replacement (TDR) using ProDisc-L by analyzing the radiologic changes at the index and adjacent levels in minimum 5-year follow-up. SUMMARY OF BACKGROUND DATA: Early successful clinical results of lumbar TDR have been reported. However, few reports have published its therapeutic effectiveness and radiologic degenerative changes at the index and adjacent segments in the long term. MATERIALS AND METHODS: Forty-three patients were followed-up for at least 60 months. Radiologic changes were assessed by segmental range of motion (ROM) at the index and adjacent levels, global lumbar lordosis, and disc space height (DSH). The magnetic resonance imaging and computed tomographic scans were used to determine the facet arthrosis and intervertebral disc degeneration at the index and adjacent levels. RESULTS: Gradual decrements of DSH restoration were observed until the last follow-up. Mean global and segmental ROM of index segments were significantly reduced (P=0.044, 0.00) at the last visit. There were 21 patients (48.8%) with no motion at index segment (ROM<0.5 degrees) at the last visit. Among the 56 segments operated on, progression of facet arthrosis was observed in 30.3% of index segments and 10.9% of adjacent segments. None of the postoperative radiologic parameters included in the present study presented significant correlation with clinical outcome. CONCLUSIONS: The study demonstrates that only half of the lumbar TDR patients can maintain segmental motion at the index level >5-year after surgery and TDR provides a good clinical outcome postoperatively regardless of motion preservation or DSH height preservation at the last follow-up. After TDR, the degenerative changes in the index and adjacent segments advanced as compared with our previous report of 2-year follow-up, however, these changes did not appear to exert negative influence upon clinical outcomes.

Correction to: Outcomes of oblique lateral interbody fusion for degenerative lumbar disease in patients under or over 65 years of age.

In the original publication of this article [1] is an error in the Results section in the first paragraph in regards to a patient value introduced.

Outcomes of oblique lateral interbody fusion for degenerative lumbar disease in patients under or over 65 years of age.

BACKGROUND: Oblique lateral interbody fusion (OLIF) offers the solution to problems of anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF). However, OLIF technique for degenerative spinal diseases of elderly patients has been rarely reported. The objective of this study was to determine the clinical and radiological results of OLIF technique for degenerative spinal diseases in patients under or over 65 years of age. METHODS: Sixty-three patients who underwent OLIF procedure were enrolled, including 29 patients who were less than 65 years of age and 34 patients who were over 65 years of age. Fusion rate, change of disc height and lumbar lordotic angle, Numeric Rating Scale (NRS), return to daily activity, patient's satisfaction rate (PSR), and Oswestry disability index (ODI) were used to assess clinical and functional outcomes. RESULTS: The mean NRS scores for back and leg pain decreased, respectively, from 4.6 and 5.9 to 2.3 and 1.8 in the group A (less than 65 years) and from 4.5 and 6.8 to 2.6 and 2.2 in the group B (over 65 years) at the final follow-up period. The mean ODI scores improved from 48.4 to 24.0% in the group A and from 46.5 to 25.2% in the group B at the final follow-up period. In both groups, the NRS and ODI scores significantly changed preoperatively to postoperatively (p <  0.001). However, statistical analysis yielded no significant difference in postoperative NRS/ODI scores between two groups. In both groups, the changes in the disc height, segmental lordosis, and fusion rate between the preoperative and postoperative periods were significant. The amount of change between preoperative and postoperative disc height, segmental lordosis, and whole lumbar lordosis demonstrated significant intergroup differences (p <  0.05). Overall perioperative complications occurred in 8 of 29 (27.6%) patients in the group A and in 10 of 34 (29.4%) patients in the group B. In both groups, the major complication incidence was 0 and 3%, respectively. CONCLUSION: Although there was the slightly high incidence of complication associated with high rate of co-morbidities in elderly patients, OLIF for degenerative lumbar diseases in elderly patients showed favorable clinical and radiological outcomes.

Safety of Lateral Interbody Fusion Surgery without Intraoperative Monitoring.

AIM: Oblique lateral interbody fusion (OLIF) is a minimally invasive surgical method that can provide an access to the lumbar spine without direct dissection of psoas muscle and the need for intraoperative neuromonitoring (IOM) is questionable. The aim of this study was to examine and document the transient and persistent perioperative complications in patients who underwent OLIF for degenerative lumbar disease without IOM. MATERIAL AND METHODS: A total of 129 consecutive patients who were diagnosed as degenerative spinal disease from L1 to S1 and underwent mini-open OLIF were identified and retrospectively reviewed. All patients were classified as two groups; non-IOM group and IOM group. According to the relation to surgical procedure, the complications were divided into two groups; "procedurerelated" and "procedure-unrelated". Based on the effect of duration, the complications were defined as "transient" where the symptom is relieved within 30 days postoperatively, and "persistent" where the symptom remains for more than 30 days postoperatively. RESULTS: The study groups comprised 57 cases in the IOM group and 72 in the non-IOM group. The complication rate was 24.6% (transient; 17.6%, persistent; 7.0%) in the IOM group and 29.2% (transient; 25.0%, persistent; 4.2%) in the non-IOM group. The incidence of postoperative leg symptoms related to lumbar plexus and/or psoas muscle injury was 6 transient and 3 persistent in the IOM group (overall 15.3%), and 12 transient and 3 persistent in the non-IOM group (overall 20.9%). CONCLUSION: Mini-open OLIF can be safely carried out without the aid of IOM.

Comparative Study of the Difference of Perioperative Complication and Radiologic Results: MIS-DLIF (Minimally Invasive Direct Lateral Lumbar Interbody Fusion) Versus MIS-OLIF (Minimally Invasive Oblique Lateral Lumbar Interbody Fusion).

STUDY DESIGN: Retrospective observatory analysis. OBJECTIVE: The purpose of this study was to compare the incidence of perioperative complication, difference of cage location, and sagittal alignment between minimally invasive oblique lateral lumbar interbody fusion (MIS-OLIF) and MIS-direct lateral lumbar interbody fusion (DLIF) in the cases of single-level surgery at L4-L5. SUMMARY OF BACKGROUND DATA: MIS-DLIF using tubular retractor has been used for the treatment of lumbar degenerative diseases; however, blunt transpsoas dissection poses a risk of injury to the lumbar plexus. As an alternative, MIS-OLIF uses a window between the prevertebral venous structures and psoas muscle. MATERIALS AND METHODS: A total of 43 consecutive patients who underwent MIS-DLIF or MIS-OLIF for various L4/L5 level pathologies between November 2011 and April 2014 by a single surgeon were retrospectively reviewed. A complication classification based on the relation to surgical procedure and effect duration was used. Perioperative complications until 3-month postoperatively were reviewed for the patients. Radiologic results including the cage location and sagittal alignment were also assessed with plain radiography. RESULTS: There were no significant statistical differences in perioperative parameters and early clinical outcome between 2 groups. Overall, there were 13 (59.1%) approach-related complications in the DLIF group and 3 (14.3%) in the OLIF group. In the DLIF group, 3 (45.6%) were classified as persistent, however, there was no persistent complication in the OLIF group. In the OLIF group, cage is located mostly in the middle 1/3 of vertebral body, significantly increasing posterior disk space height and foraminal height compared with the DLIF group. Global and segmental lumbar lordosis was greater in the DLIF group due to anterior cage position without statistical significance. CONCLUSIONS: In our report of L4/L5 level diseases, the OLIF technique may decrease approach-related perioperative morbidities by eliminating the risk of unwanted muscle and nerve manipulations. Using orthogonal maneuver, cage could be safely placed more posteriorly, resulting in better disk and foraminal height restoration.

Minimally Invasive Transforaminal Lumbar Interbody Fusion Using Banana-Shaped and Straight Cages: Radiological and Clinical Results from a Prospective Randomized Clinical Trial.

BACKGROUND: In minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF), cage type and position play important roles in fusion achievement and sagittal alignment correction. However, no prospective randomized comparison of the results using different types of cage has been reported to date. OBJECTIVE: To compare the radiological and clinical outcomes of unilateral MIS-TLIF using 2 types of cage. METHODS: All candidates for single-level MIS-TLIF were randomized into banana-shaped cage and straight-cage groups. Plain radiographs and computed tomography scans were used for assessment of cage positions, fusion status, disc height, segmental lordotic angle, cage subsidence, and pelvic parameters. Clinical outcome was assessed using visual analog scale and Oswestry Disability Index scores. RESULTS: Forty-four and 40 consecutive patients were operated on using banana-shaped and straight cages, respectively. Cage position was more anterior and lateral in the straight-cage group and more medial and posterior in the banana-shaped cage group. Solid fusion was achieved in 95.2% and 96.6% of the 2 groups, respectively, at 12 mo. The change in disc height and segmental lordotic angle postoperatively was significantly greater in the banana-shaped cage group. The incidence of subsidence during follow-up was significantly higher in the banana-shaped cage group (P < .04). Clinically, the visual analog scale and Oswestry Disability Index scores decreased significantly after surgery in both groups, with no significant difference between the groups. CONCLUSION: Our preliminary outcomes suggest that the subsidence rate may be higher using banana-shaped cages in MIS-TLIF, possibly due to their more medial final position.

Surgical Outcomes of Anterior Cervical Fusion Using Deminaralized Bone Matrix as Stand-Alone Graft Material: Single Arm, Pilot Study.

OBJECTIVE: To investigate the safety and efficacy of demineralized bone matrix (DBM) as a bone graft substitute for anterior cervical discectomy and fusion (ACDF) surgery. METHODS: Twenty consecutive patients treated with ACDF using stand-alone polyestheretherketone (PEEK) cages (Zero-P) with DBM(CGDBM100) were prospectively evaluated with a minimum of 6 months of follow-up. Radiologic efficacy was evaluated with a 6-point scoring method for osseous fusion using plain radiograph and computed tomogrpahy scans. Clinical efficacy was evaluated using the visual analogue scale (VAS), Owestry disability index (ODI), and short-form health questionnaire-36. The safety of the bone graft substitute was assessed with vital sign monitoring and a survey measuring complications at each follow-up visit. RESULTS: There were significant improvements in VAS and ODI scores at a mean 6-month follow-up. Six months after surgery, solid fusion was achieved in all patients. Mean score on the 6-point scoring system was 5.1, and bony formation was found to score at least 4 points in all patients. There was no case with implant-related complications such as cage failure or migration, and no complications associated with the use of CGDBM100. CONCLUSION: ACDF using CGDBM100 demonstrated good clinical and radiologic outcomes. The fusion rate was comparable with the published results of traditional ACDF. Therefore, the results of this study suggest that the use of a PEEK cage packed with DBM for ACDF is a safe and effective alternative to the gold standard of autologous iliac bone graft.