Spontaneous facet joint fusion in patients following oblique lateral lumbar interbody fusion combined with lateral single screw-rod fixation: prevalence, characteristics and significance.

PURPOSE: To explore the characteristics of spontaneous facet joint fusion (SFJF) in patients after oblique lateral lumbar interbody fusion combined with lateral single screw-rod fixation (OLIF-LSRF). METHODS: We randomly selected 300 patients from 723 patients treated with OLIF-LSRF into a cross-sectional study based on the pilot study results. A novel fusion classification system was designed to evaluate the fusion status of the facet joints at three time points. Ultimately, the prevalence, characteristics, and significance of SFJF were analyzed. RESULTS: A total of 265 (333 levels) qualified cases were included in our study. The novel classification for SFJF has excellent reliability (kappa > 0.75). The rate of SFJF was 15.20% (45/296 levels) at 3 months postoperatively, 31.34% (89/284 levels) at 6 months postoperatively, and 33.63% (112/333 levels) at the last follow-up. The circumferential fusion rate was 31.53% (105/333 levels) at the last follow-up. The location of SFJF was mostly on the right facet joint (P < 0.001), and the rate of SFJF increased significantly from 3 to 6 months after the operation (P < 0.001). The average age of patients with SFJF was older than that of patients without SFJF (P < 0.001). There was no significant difference in Visual Analog Scale or Oswestry Disability Index scores between patients with and without SFJF. CONCLUSION: In the OLIF-LSRF procedure, SFJF occurs mostly at 3-6 months postoperatively, especially in elderly patients and at the right facet joint. OLIF-LSRF has the potential for circumferential fusion.

Bone mesenchymal stem cell-derived extracellular vesicles deliver microRNA-23b to alleviate spinal cord injury by targeting toll-like receptor TLR4 and inhibiting NF-κB pathway activation.

Bone mesenchymal stem cell-derived extracellular vesicles (BMSC-EVs) are known for recovery of injured tissues. We investigated the possible mechanism of BMSC-EVs in spinal cord injury (SCI). EVs were isolated from BMSCs and injected into SCI rats to evaluate the recovery of hindlimb motor function. The spinal cord tissue was stained after modeling to analyze spinal cord structure and inflammatory cell infiltration and detect microRNA (miR)-23b expression. The activity of lipopolysaccharide (LPS)-induced BV2 inflammatory cells was detected. The protein contents of interleukin (IL)-6, IL-1ß, IL-10 and tumor necrosis factor-α (TNF-α) in spinal cord and BV2 cells were measured. Western blot analysis was used to detect the level of toll-like receptor (TLR)4, p65, p-p65, iNOS, and Arg1 in spinal cord tissue and cells. TLR4 was overexpressed in rats and cells to evaluate the content of inflammatory cytokines. After EV treatment, the motor function of SCI rats was improved, SCI was relieved, and miR-23b expression was increased. After treatment with EV-miR-23b, iNOS, IL-6, IL-1ß, and TNF-α contents were decreased, while Arg1 and IL-10 were increased. The levels of TLR4 and p-p65 in spinal cord and BV2 cells were decreased. The rescue experiments verified that after overexpression of TLR4, the activity of BV2 cells was decreased, the contents of IL-6, IL-1ß, TNF-α, and p-p65 were increased, IL-10 was decreased, and SCI was aggravated. To conclude, The miR-23b delivered by BMSC-EVs targets TLR4 and inhibits the activation of NF-κB pathway, relieves the inflammatory response, so as to improve SCI in rats.

Carbon Monoxide-Saturated Polymerized Placenta Hemoglobin Optimizes Mitochondrial Function and Protects Heart Against Ischemia-Reperfusion Injury.

ABSTRACT: Ischemia-reperfusion (I-R) injury is detrimental to cardiovascular system. This study was designed to investigate whether carbon monoxide-saturated polymerized human placenta hemoglobin (CO-PolyPHb) attenuates cardiac I-R injury and to elucidate the underlying mechanism(s). Sixty male adult Sprague-Dawley rats were randomly divided into 6 groups: saline + sham group, PolyPHb + sham group, CO-PolyPHb + sham group, saline + I-R group, PolyPHb + I-R group, and CO-PolyPHb + I-R group. Rats were pretreated with injection of PolyPHb, CO-PolyPHb (0.5 g Hb/kg/d), or an equivalent volume of saline via caudal vein for 3 days. After pretreatment, hearts were isolated Langendorff perfused and subjected to 30-minute no-flow ischemia and 120-minute reperfusion. As compared with the saline + I-R group, pretreatment with CO-PolyPHb greatly improved the recovery of cardiac function, reduced infarct size, and suppressed the release of cardiac enzyme. Importantly, CO-PolyPHb showed more prominent cardioprotective effect than PolyPHb, exhibiting a promising therapeutic potential in cardiac I-R injury. Further study demonstrated that CO-PolyPHb activated molecular signaling toward mitophagy and significantly elevated the mitochondrial respiratory function in the heart. In addition, CO-PolyPHb upregulated the phosphorylation of the proteins in insulin signaling pathway and increased the glucose uptake rate in cardiomyocytes. Pharmacological inhibition of this pathway by wortmannin abrogated the anti-I-R effect of CO-PolyPHb. In conclusion, using an isolated rat heart model, we have demonstrated that pretreatment with CO-PolyPHb provided protective effect against cardiac I-R injury, and this protection was mediated by the improvement of mitochondrial function and activation of insulin signaling pathway in the heart.

Oral delivery of carrier-free dual-drug nanocrystal self-assembled microspheres improved NAD+ bioavailability and attenuated cardiac ischemia/reperfusion injury in mice.

Nicotinamide riboside (NR), as a dietary supplement, can be converted to nicotinamide adenine dinucleotide (NAD+) in cells to support mitochondrial energy metabolism. However, the efficacy of oral administrated NR is limited due to its quick degradation in circulation and low bioavailability in targeted organs. In this study, we fabricated nanocrystal self-assembled microspheres by Nano Spray Dryer for oral delivery of NR. The structure of NR and resveratrol (RES) nanocrystal self-assembled microspheres (NR/RESms) is confirmed by the morphology, chemical structure, and crystallization. The NR/RESms displayed restricted NR release at the gastric acid-mimic condition (<15% in the first 8 hours), while achieved accelerated NR release in an enteric-mimic environment (>46% within 8 hours). Oral administration of NR/RESms for 8 hours significantly elevated NAD+ levels in serum (169.88 nM versus 30.93 nM in the NR group, p < .01; and 66.89 nM in the NR + RES group, p < .05), and enhanced NAD+ abundance in multiple organs in mice, exhibiting an improved oral NAD+ bioavailability. In addition, without any serious adverse effects on major organs, oral delivery of NR/RESms attenuated myocardial infarction (15.82% versus 19.38% in the I/R + NR group and 20.76% in the I/R + NR + RES group) in a cardiac ischemia/reperfusion (I/R) injury mouse model. Therefore, our data supported that the NR/RESms is a promising candidate as NAD+ booster for oral administration.

SIRT4 suppresses the inflammatory response and oxidative stress in osteoarthritis.

Sirtuins have been involved in the osteoarthritis (OA) process. However, the functions of SIRT4 in the degeneration of human chondrocytes and OA are not fully understood. This study aimed to explore the role of SIRT4 during OA and mechanisms implicated. We extracted total protein and mRNA of the cartilage from OA patients and isolated the chondrocytes from the cartilage in different degenerated degrees for cell culture. Collagen II and SIRT4 levels of the tissues were analyzed by quantitative reverse-transcription polymerase chain reaction (RT-PCR) and Western blot. Chondrocytes were transferred with SIRT4-siRNA, treated with recombinant human SIRT4 protein for 24 h, respectively. Aggrecan, collagen I, collagen II, MMP-13, IL-6, TNF-α, SOD1, SOD2, and CAT expression, and ROS levels were investigated by Western blot, RT-PCR, immunofluorescence, enzyme-linked immunosorbent assay (ELISA), or flow cytometry. Collagen II decreased significantly in severely degenerated cartilage compared to the mild one, paralleling with SIRT4 expression both in protein and mRNA levels. Chondrocytes in severe OA grade were observed with a decrease in aggrecan, collagen II, SOD1, SOD2, CAT expression, nonetheless, an increase in collagen I, reactive oxygen species (ROS), MMP-13, IL-6, and TNF-α levels. However, SRIT4 protein treatment significantly upregulated aggrecan, collagen II, an antioxidant enzyme, and suppressed ROS and inflammatory response. Further analysis revealed that silencing of SIRT4 expression induced healthy chondrocytes, a decrease in aggrecan, collagen II and antioxidant enzyme expression, and an increase in ROS and inflammatory response, importantly, which can be reversed by SIRT4 protein stimuli. Our results elucidated that SIRT4 was tangled with the development of OA, and SIRT4 overexpression contributes to suppresses the inflammatory response and oxidative stress.

Negative pressure pulmonary edema after percutaneous endoscopic interlaminar lumbar discectomy-a case report.

BACKGROUND: Negative pressure pulmonary edema (NPPE) is a rare complication that is more prevalent in young patients. NPPE usually results from acute upper airway obstruction, which is most commonly caused by laryngospasm during extubation. NPPE is characterized by the sudden onset of coughing, hemoptysis, tachycardia, tachypnea, and hypoxia, and is dramatically improved with supportive care, which prevents severe sequelae. To our knowledge, there is no report of a patient developing NPPE after percutaneous endoscopic interlaminar lumbar discectomy. CASE PRESENTATION: Herein, we report the case of a 22-year-old amateur basketball player with L5/S1 disc herniation who developed NPPE during extubation after general anesthesia for a minimally invasive spinal surgery (percutaneous endoscopic interlaminar lumbar discectomy). The NPPE was treated by maintaining the airway patency, applying positive-pressure ventilation, administering dexamethasone and antibiotics, and limiting the volume of fluid infused. The patient had an uneventful postoperative course, and was discharged to his home on postoperative day 3. CONCLUSIONS: Although NPPE is an infrequent complication, especially in patients undergoing percutaneous endoscopic interlaminar lumbar discectomy, this case report highlights the importance of early diagnosis and prompt treatment of NPPE to prevent the development of potentially fatal complications.

Complications of Lumbar Disc Herniation Following Full-endoscopic Interlaminar Lumbar Discectomy: A Large, Single-Center, Retrospective Study.

BACKGROUND: The new surgical procedure of full-endoscopic interlaminar lumbar discectomy (FILD) has achieved favorable effects in the treatment of lumbar disc herniation (LDH). Along with the wide range of applications of FILD, a series of complications related to the operation has gradually emerged. OBJECTIVE: To describe the types, incidences, and characteristics of complications following FILD and to explore preventative and treatment measures. STUDY DESIGN: Retrospective, observational study. SETTING: A spine center affiliated with a large general hospital. METHOD: In total, 479 patients with LDH underwent FILDs that were performed by a single experienced spine surgeon between January 2010 and April 2013. Data concerning the complications were recorded. RESULTS: All 479 cases successfully underwent the procedure. A total of 482 procedures were completed. The mean follow-up time was 44.3 months with a range of 24 to 60 months. The average patient age was 47.8 years with a range of 16 to 76 years. Twenty-nine (6.0%) related complications emerged, including 3 cases (0.6%) of incomplete decompression in which the symptoms gradually decreased following 3 - 6 weeks of conservative treatment, 2 cases (0.4%) of nerve root injury in which the patients recovered well following 1 - 3 months of neurotrophic drug and functional exercise treatment, 15 cases (3.1%) of paresthesia that gradually improved following 1 - 8 weeks of rehabilitation exercises and treatment with mecobalamin and pregabalin, and 9 cases of recurrent herniation (1.9%). The latter condition was controlled in 4 cases with a conservative method, and 5 of these cases underwent reoperations that included 3 traditional open surgeries and 2 FILDs. Furthermore, the complication rate for the first 100 cases was 18%. This rate decreased to 2.9% for cases 101 - 479. The incidence of L4-5 herniation (8.2%) was significantly greater than that of L5-S1 (4.5%). LIMITATIONS: This is a retrospective study, and some bias exists due to the single-center study design. CONCLUSION: FILD is a surgical approach that has a low complication rate. Incomplete decompression, nerve root injury, paresthesia, and recurrent herniation were observed in our study. Some effective measures can prevent and reduce the incidence of the complications including strict indications for surgery, a thorough action plan, and a high level of surgical skill. Key words: Complication, lumbar disc herniation, lumbar discectomy, endoscopic, inter-laminar discectomy, minimally invasive spine surgery.

[Effectiveness of combined Pregabalin and Celecoxib for treatment of neuropathic pain after percutaneous endoscopic lumbar discectomy].

Objective: To investigate the effectiveness of combined Pregabalin and Celecoxib for neuropathic pain after percutaneous endoscopic lumbar discectomy. Methods: Between January and June 2014, 178 patients with lumbar disc herniation underwent percutaneous endoscopic interlaminar discectomy (PEID). Ninety patients who met the inclusion criteria were recruited in this study. Every case in group A was recruited to match its counterpart in group B and group C according to gender, disease duration, herniated level, smoking history, preoperative Leeds assessment of neuropathic symptoms and signs (LANSS), and Oswestry disability index (ODI). Nine patients were excluded due to incomplete study or loss of follow-up. In each group, 27 cases were included in the final analysis. There was no significant difference in gender, age, height, body mass index, herniated level, disease duration, smoking history, preoperative LANSS, ODI, and visual analogue scale (VAS) between groups ( P>0.05). All patients of 3 groups received oral administration of Celecoxib from preoperative 3rd day to postoperative 14th day. Pregabalin was taken orally from preoperative 3rd day to postoperative 14th day in group A, and from postoperative 1st to 14th day in group B. Adverse drug reactions were observed during medication. The LANSS score and VAS score in rest state and active state were conducted before operation and at 1 day, 1 month, and 3 months after operation. ODI was conducted before operation and at 1, 3 months after operation. The number of neuropathic pain cases was recorded, and the effectiveness was evaluated by modified Macnab criteria at 3 months after operation. Results: During period of increasing Pregabalin dose, 1 patient of group A suffered severe dizziness, and 1 patient of group B suffered sleepiness, who were eliminated from this research. Another 2 cases (1 case of group A and 1 case of group C) suffered dry mouth, and 1 case of group B suffered muscle weakness. At 1 day after operation, the LANSS score and VAS in rest state and active state of group A were significantly lower than those of groups B and C ( P<0.05). At 1 month after operation, the LANSS score, ODI, and VAS in rest state and active state of group A and group B were significantly lower than those of group C ( P<0.05). At 3 months after operation, the LANSS score, ODI, and VAS in active state of group A and group B were significantly lower than those of group C ( P<0.05). There was no significant difference in the above indicators at the other time points between groups ( P>0.05). Neuropathic pain occurred at 3 months after operation in 1 case (3.7%) of group A and 6 cases (22.2%) of group C, showing significant differences in incidence of neuropathy pain between groups A, B and group C ( P<0.05), but no significant difference was found between group A and group B ( P>0.05). The excellent and good rate of modified Macnab criteria was 92.6% in group A, was 88.9% in group B, and was 85.2% in group C at 3 months after operation, showing no significant difference between groups ( P>0.05). Conclusion: Combined use of Pregabalin and Celecoxib during perioperative period can reduce postoperative pain and incidence of postoperative neuropathic pain. Preoperative oral Pregabalin can reduce the incidence of acute postoperative neuropathic pain.

Percutaneous Endoscopic Lumbar Discectomy for L5-S1 Disc Herniation Via an Interlaminar Approach Versus a Transforaminal Approach: A Prospective Randomized Controlled Study With 2-Year Follow Up.

STUDY DESIGN: A prospective, randomized controlled study of patients with L5-S1 lumbar disc herniations, operated with endoscopic discectomy through an interlaminar or transforaminal approach. OBJECTIVE: To compare the results of percutaneous endoscopic lumbar discectomy in L5-S1 disc herniation through an interlaminar or transforaminal approach. SUMMARY OF BACKGROUND DATA: The transforaminal and interlaminar techniques are both acceptable approaches for L5-S1 disc herniation. This is the first study to compare these two approaches in terms of their surgical effects and advantages. METHODS: From January 2010 to June 2010, 60 patients with L5-S1 disc herniation were randomly recruited into two groups; one group underwent percutaneous endoscopic interlaminar discectomy (PEID) and the other group underwent percutaneous endoscopic transforaminal discectomy (PETD). There were 30 patients in each group. The operation time, intraoperative radiation time, postoperative bed rest time, hospitalization time, and complications were compared between the groups. The surgical effectiveness was assessed according to the Oswestry Disability Index (ODI), Visual Analog Scale (VAS), and modified MacNab criteria. RESULTS: All the patients completed follow up with a mean of 27.6 months (range, 24-37 months). In the PEID group, the mean operation time was 65.0 ±â€Š14.9 minutes, and the intraoperative radiation time was 0.60 ±â€Š0.24 seconds. For the PETD group, the mean operation time was 86.0 ±â€Š15.4 minutes, and the intraoperative radiation time was 6.50 ±â€Š1.52 seconds. There were significant differences in operation time and radiation time between the two groups (P < 0.01) but not in the postoperative bed rest time, hospitalization time, or complication rate (P > 0.05). The postoperative ODI and VAS were obviously improved in both groups when compared with preoperation (P < 0.01). According to the MacNab criteria, the satisfactory rates were 93.3% and 90.0% in the two groups, without a significant difference (P > 0.05). CONCLUSION: PEID can escape the blockade of crista iliaca, and advantages include a faster puncture orientation, a shorter operation time, and less intraoperative radiation exposure. PETD requires higher punctuation skill and more intraoperative radiation exposure. LEVEL OF EVIDENCE: 4.

[EFFECTIVENESS OF PERCUTANEOUS ENDOSCOPIC TRANSFORAMINAL DISCECTOMY FOR RECURRENT LUMBAR DISC HERNIATION].

OBJECTIVE: To determine the feasibility and effectiveness of percutaneous endoscopic transforaminal discectomy (PETD) for recurrent lumbar disc herniation (RLDH). METHODS: Between June 2009 and December 2011, 56 patients with RLDH underwent PETD after local anesthesia, including 30 males and 26 females, with a mean age of 50 years (range, 24-70 years). The involved segments were L3, 4 in 3 cases, L4, 5 in 34 cases, and L5-S1 in 19 cases. Of 56 patients, 48 suffered from ipsilateral re-herniation, and 8 suffered from contralateral re-herniation. All the patients had a mean pain-free interval of 5.5 years (range, 6 months to 27 years). The visual analogue scale (VAS) score for back pain was 6.18 ± 1.44 and the VAS score for leg pain was 7.66 ± 1.03. Postoperative effectiveness was assessed based on the VAS score and modified MacNab criteria. RESULTS: The mean operation time was 60.4 minutes (range, 30-100 minutes) and the mean duration of hospital stay was 5.1 days (range, 3-6 days). All patients were followed up 28.2 months on average (range, 24-56 months). Patients obtained immediate pain relief postoperatively. The postoperative VAS scores of back and leg pain at 1 month, 3 months, 12 months, and last follow-up were significantly decreased when compared with preoperative score (P < 0.05). Based on the modified MacNab criteria, the results were excellent in 39 cases, good in 9 cases, fair in 5 cases, and poor in 3 cases at 12 months after operation, and the excellent and good rate was 85.7%. Surgery-related complications were found in 5 cases (8.9%); one patient (1.8%) suffered from recurrence at 18 months postoperatively, and the symptom was relieved after open lumbar discectomy and intervertebral fusion surgery. CONCLUSION: PETD has several advantages in treating RLDH, such as avoiding from the old scar tissue, decreasing operation-related complications, shortening operation time, reducing trauma, and obtaining rapid postoperative recovery. This technique is feasible and effective for RLDH.

Comparison of Total Disc Replacement with lumbar fusion: a meta-analysis of randomized controlled trials.

A meta-analysis was performed to evaluate whether a beneficial clinical effect of the Total Disc Replacement (TDR) over lumbar fusion for the treatment of patients with Degenerative Disc Disease (DDD). An electronic search of PubMed, Cochrane Central Register of Controlled Trials, and EMBASE from their inception to 2012 was completed, and we assessed risk bias and retrieved relevant data, and meta-analysis was performed, if appropriate. Oswestry Disability Index (ODI), Visual Analog Score (VAS), patient satisfaction or VAS patient satisfaction, narcotic use, overall success rate, reoperation rate, work status, "surgery again?", complications and radiographic outcomes were evaluated. Six RCTs were included in this meta-analysis. At 2 years, TDR was demonstrated to be more beneficial for patients compared to lumbar fusion in the following outcomes, including ODI scores (MD:-4.87, 95% CI: -7.77 to -1.97, p=0.001), patient satisfaction (OR:1.91, 95% CI: 1.27 to 2.86, p=0.002) and VAS patient satisfaction (MD:9.10, 95% CI: 3.20 to 14.99, p=0.002), the percentage of using narcotics (OR=0.54, 95%CI: 0.31 to 0.96, p=0.03), overall success rate (OR:1.68, 95% CI: 1.26 to 2.25, p=0.005), the rate of patients to chose the same surgical treatment again (OR:2.38, 95% CI: 1.72 to 3.28, p < 0.001), and complications (OR=0.50, 95%CI: 0.29 to 0.84, p=0.008). Other outcomes, including re-operation rate (OR:0.62, 95% CI: 0.36 to 1.06, p=0.08) and work status (OR=1.05, 95% CI: 0.75 to 1.47, p=0.80), were demonstrated to be no differences between the two groups. In a long-term of follow-up (2 years), TDR shows a significant superiority for the treatment of lumbar DDD compared with fusion.

Percutaneous endoscopic interlaminar discectomy for pediatric lumbar disc herniation.

PURPOSE: Percutaneous endoscopic interlaminar discectomy (PEID) is a widely used minimally invasive procedure which shows satisfying outcomes in the adult population. However, pediatric lumbar disc herniations (PLDH) occur in growing spines and are less related to degeneration, which makes them different from the adult disc herniations. This study evaluates the clinical outcomes of PEID in treating PLDH. METHODS: A prospect study was done in the period from June 2010 to December 2012, which included 29 consecutive pediatric patients with a mean age of 16.4 years (range, 13 to 18 years) who underwent PEID for single level lumbar disc herniation. The following measuring tools were used: visual analog scale (VAS) for back and leg pain, Oswestry Disability Index (ODI), and Macnab criteria. RESULTS: There were no severe complications such as dural tear or nerve root damage found in our study. The mean follow-up period was 19.7 months. The VAS score for leg and back pain decreased dramatically at 1 day postoperatively and kept decreasing until the follow-up visit at 3 months postoperatively, when it became stable at a low level. ODI kept improving until the follow-up visit at 6 months postoperatively when it reached a stable low level. Of the patients, 91% reported no longer having leg pain and 9% had occasional leg pain at last follow-up. CONCLUSIONS: PEID shows a satisfying outcome with a minimal rate of complications. It has the advantages of minimal traumatization and scar formation and is a safe and effective treatment for PLDH.

Endoscopic transforaminal thoracic foraminotomy and discectomy for the treatment of thoracic disc herniation.

Thoracic disc herniation is a relatively rare yet challenging-to-diagnose condition. Currently there is no universally accepted optimal surgical treatment for symptomatic thoracic disc herniation. Previously reported surgical approaches are often associated with high complication rates. Here we describe our minimally invasive technique of removing thoracic disc herniation, and report the primary results of a series of cases. Between January 2009 and March 2012, 13 patients with symptomatic thoracic disc herniation were treated with endoscopic thoracic foraminotomy and discectomy under local anesthesia. A bone shaver was used to undercut the facet and rib head for foraminotomy. Discectomy was achieved by using grasper, radiofrequency, and the Holmium-YAG laser. We analyzed the clinical outcomes of the patients using the visual analogue scale (VAS), MacNab classification, and Oswestry disability index (ODI). At the final follow up (mean: 17 months; range: 6-41 months), patient self-reported satisfactory rate was 76.9%. The mean VAS for mid back pain was improved from 9.1 to 4.2, and the mean ODI was improved from 61.0 to 43.8. One complication of postoperative spinal headache occurred during the surgery and the patient was successfully treated with epidural blood patch. No other complications were observed or reported during and after the surgery.

A simple technique of accessing the L5-S1 disc space for transforaminal endoscopic spine surgery.

Transforaminal endoscopic spine surgery is increasingly used to treat a range of spinal conditions. The success of the surgery requires an accurate insertion of the guide needle and a precise placement of the working cannula and endoscope. However, such a precise placement is challenging for many surgeons to achieve when the pathology is located at the L5-S1 level. On the basis of our years of experience with performing transforaminal endoscopic spine surgery, we have developed a simple technique to help surgeons safely access the L5-S1 level. The technique has been proven intuitive and easy for experienced as well as inexperienced surgeons to learn. The key steps of the technique involve identifying an appropriate entry point on the skin and choosing an accurate trajectory angle for insertion. The purpose of this chapter is to report how to easily identify the entry point and choose a trajectory angle depending on the patient's anatomic characteristics.