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The main aim of this video article is to demonstrate the combined use of O-arm navigation and unilateral biportal endoscopy (UBE) to manage far-out syndrome (FOS). In FOS there is entrapment and compression of the fifth lumbar nerve beyond the foramen and between L5 transverse process and the sacral ala at the lumbosacral junction. Conventional microscopic decompression using a paraspinal approach had been the gold standard for its management. However, the surgery is technically challenging due to the deep location of the pathology and intricate anatomy of extraforaminal space. There have been some published reports of unsatisfactory outcomes with microscopic decompression for FOS. We decided to integrate navigation with UBE to increase precision for the management of FOS. A 70-year-old female presented to us with chief complaint of left lower limb radiculopathy since 1 year. She also complained of numbness and paresthesias in her left leg and foot. She was unable to walk for more than 10 minutes due to pain. Her magnetic resonance imaging scan revealed compression of left L5 nerve root in the extraforaminal region. UBE decompression via paraspinal approach was performed for her under O-arm navigation. She experienced immediate relief of her symptoms in the postoperative period. O-arm-navigation-guided UBE is an effective and safer alternative to microsurgical decompression for the management of FOS. This video demonstrates the step-by-step implementation of O-arm navigation with endoscopy and its precise execution. [ABSTRACT FROM AUTHOR]

Foraminal and far lateral disc herniations are rarer cause of nerve root compression. There are reports regarding the outcome, however long-term follow-up results of surgically treated patients are few. The purpose of this retrospective study is to analyze the clinical characteristics and long-term surgical outcomes of the foraminal and far lateral disc herniations. The 114 patients who underwent an operation for foraminal and far lateral disc herniaitions were reviewed. Visual analogue scale of back and leg pain, the ocurrence of motor deficit and sensory dysesthesia before and after operations were used to compare the results of early and long-term outcome. A total of 114 telephone interviews were conducted. The mean follow up was 134 months. Complete relief of symptoms were reported by 77 patients (67.1%). The average VAS of radicular leg pain was 7.5 Post-operatively the average VAS of radicular pain decreased to 2.2. Preoperatively, 9 patients (7.6%) had motor deficit and 17 (14.4%) patients had sensory dysesthesia. Post-operatively 9 (100%) of the patients showed motor, and 12 (70.6%) of the patients showed sensory improvement. In 17 patients with hypoesthesia the complaints continued during 2 weeks to 6 months. They were given gabapentin as medical treatment, however 5 of these patients still have sensory dysesthesia. The outcome was: 67.1% excellent (77 patients), 26.3% good (30 patients), 6.1% fair (7 patients). The far lateral approach is a minimally invasive and safe procedure with low complication rates. [ABSTRACT FROM AUTHOR]

Purpose: We present the paraspinal approach use for neuromuscular scoliosis with focus on deformity correction, perioperative (≤30 days) morbidity and outcome at a minimal follow-up length of 2 years. Methods: We prospectively collected data of 61 neuromuscular scoliosis patients operated using a paraspinal (Wiltse) approach between 2013 and 2019. We additionally collected data of 104 control cases, operated using a midline approach between 2005 and 2016. Fifteen Wiltse, respectively 37 control patients were excluded due to a short follow-up (<2 years), and 22 controls were excluded secondary to lacking follow-up data. Hence, 46 Wiltse and 45 control patients were compared. Results: Wiltse and control patients had comparable follow-up lengths, demographics, deformity corrections, complication rates, number of levels fused, and intensive care unit and hospital lengths of stay. Wiltse cases had a lower estimated blood loss (535 vs 1187 mL; p-value < 0.001), allogenic transfusion rate (48% vs 96%; p-value < 0.001), and operating time (ORT) (337 vs 428 min; p-value < 0.001) than controls. This was also the case when selecting for patients without pelvic fixation (p-values < 0.001). When selecting the cases with pelvic fixation (20 among 91 cases), only the number of levels fused and the ORT differed significantly according to the approach (p-value <0.015 and <0.041). Conclusion: The paraspinal approach for neuromuscular scoliosis is safe, associated with significant deformity correction, reduced estimated blood loss, and allogenic transfusion rate. These potential benefits still need to be evaluated, especially for cases with pelvic fixation, with further follow-up of larger cohorts. Level of evidence: level III. [ABSTRACT FROM AUTHOR]

Background : Although percutaneous endoscopic lumbar discectomy (PELD) has been popularized as an alternative to microscopic lumbar discectomy, it has been reported to be associated with a re-herniation rate of 5–11%. Recurrent lumbar disc herniation (RLDH) might occur not only at the same level previously operated upon but also at the annular penetration site created during PELD procedures. Method: Biportal endoscopic paraspinal approach (BE-Para) was used for revisional foraminal lumbar discectomy. Procedures and some discussions regarding indications, advantages, potential complications, and ways to avoid complications were described. Conclusion: BE-Para may be an effective modality for RLDH after PELD. [ABSTRACT FROM AUTHOR]

Background: Rarely can a herniated disc in the far-lateral extraforaminal area of the lumbar spine cause compression of a nerve root. Objective: To focus on L5-S1 foraminal/extraforaminal lumbar disc as well as to analyze the outcome of surgical management via the lateral approach. Patients and Methods: From March 2016 to July 2020, 42 patients with L5-S1 foraminal or extraforaminal disc herniations were included in this study after they received unilateral L5-S1 paraspinal decompression at Benha University Hospitals and Brüder Hospital Trier. All medical charts of the included patients were reviewed and analyzed regarding clinical presentation, complete neurological examination, operative findings, complications, and short-term outcome. MacNab scale of excellent (no pain), good (some pain), fair (moderate pain), and poor was used to assess patients' subjective levels of postoperative satisfaction (unchanged or worse). Results: Preoperative sensory and motor deficits showed obvious improvement in the majority of patients. Motor weakness showed significant improvement in 24 patients out of 30 patients (80%). Pain scoring (Visual Analogue Score; VAS) after surgery before discharge of the patients from the hospital revealed that 23 patients had no pain, 16 patients had mild to moderate pain (VAS 1-3) and 3 patients had significant pain (VAS >4). Conclusions: Orientation of the pathology, proper diagnostic imaging as well as familiarity of the approach are significant factors for patient’s improvement. We have found that our modified lateral approach is a safe, minimally invasive option with little complications. [ABSTRACT FROM AUTHOR]

Study Design: A case-control study.Objectives: The aim of this study was to evaluate the outcomes of two modified laminoplasties (LPs) based on a novel paraspinal approach for treating multilevel cervical spondylotic myelopathy.Summary Of Background Data: No laminoplasty through a natural intermuscular plane mimicking Wiltse approach to minimize intraoperative injury to extensor muscles has ever been developed and studied.Methods: Ninety-two patients were enrolled, including patients treated with either modified LP and patients treated with concurrent conventional LP. Operation time, blood loss, and complications were recorded. Clinical outcomes were evaluated by VAS, JOA scores, and recovery rate. Cervical sagittal alignment was measured on cervical radiographs. Spinal canal expansion was assessed on CT scans. Cross-sectional area (CSA) and atrophy rate (AR) of cervical deep extensors were evaluated on MRI.Results: The average follow-up duration was 33.05, 31.55, 33.02, and 32.52 months, respectively in each group. Compared to concurrent conventional procedure, unilateral muscle-preserving procedure displayed similar, whereas bilateral muscle-preserving procedure showed significantly increased operation time and blood loss; each modified procedure resulted in comparable and satisfied perioperative clinical scores, spinal canal expansion while achieving significantly lower axial pain incidence, better cervical lordosis maintenance, and better deep extensor preservation. AR of deep extensors on the open side was significantly lower than that on the hinge side. Bilateral paraspinal approach demonstrated significantly better muscle-preservation on the open side and increased operation duration, with similar clinical scores, axial pain incidence, cervical lordosis maintenance, and spinal canal expansion compared to unilateral paraspinal approach. Loss of cervical lordosis was strongly correlated with AR of deep extensors.Conclusion: Paraspinal approach is a good manner to protect deep extensor muscles; the two modified LPs have similar effects on clinical outcomes.Level of Evidence: 3. [ABSTRACT FROM AUTHOR]

Objective: The aims of this study were to describe the unilateral biportal endoscopic (UBE) technique for decompression of extraforaminal stenosis at L5-S1 and evaluate 1-year clinical outcomes. Especially, we evaluated compression factors of extraforaminal stenosis at L5-S1 and described the surgical technique for decompression in detail. Methods: Thirty-five patients who underwent UBE decompression for extraforaminal stenosis at L5-S1 between March 2018 and February 2019 were enrolled. Clinical results were analyzed using the MacNab criteria, the visual analogue scale (VAS) for back and leg pain, and the Oswestry Disability Index (ODI). Compression factors evaluated pseudoarthrosis within the transverse process of L5 and ala of sacrum, disc bulging with or without osteophytes, and the thickened lumbosacral and extraforaminal ligament. Results: The mean back VAS was 3.7 ± 1.8 before surgery, which dropped to 2.3 ± 0.8 at 1-year postoperative follow-up (p < 0.001). There was a significant drop in postoperative mean VAS for leg pain from 7.2 ± 1.1 to 2.3 ± 1.2 at 1 year (p < 0.001). The ODI was 61.5 before surgery and 28.6 (p < 0.001). Pseudoarthrosis between the transverse process and the ala was noted in all cases (35 of 35, 100%). Pure disc bulging was seen in 12 patients (34.3%), and disc bulging with osteophytes was demonstrated in 23 patients. The thickened lumbosacral and extraforaminal ligament were identified in 19 cases (51.4%). No complications occurred in any of the patients. Conclusion: In the current study, good surgical outcomes without complications were achieved after UBE decompression for extraforaminal stenosis at L5-S1. [ABSTRACT FROM AUTHOR]

Purpose: To examine the hidden blood loss (HBL) in treatment of AO type A1-A3 thoracolumbar fractures with three different approaches and to explore the influential factors of HBL among patients after the surgery of internal fixation for thoracolumbar fractures. Methods: We retrospectively studied 85 patients in treatment of thoracolumbar fractures: 25 patients via percutaneous approach (Group A), 33 patients via paraspinal approach (Group B), and 27 patients via conventional open approach (Group C). The demographic information of the patients was collected. Each patient's preoperative and postoperative hematocrit were recorded and used for calculating the blood loss according to the Gross's formula. The difference of blood loss between the three groups was measured by ANOVA. And influential factors were further analyzed by multivariate linear regression analysis in each group. Results: The average HBL was 240.0 ± 65.1 mL in Group A, 313.7 ± 138.1 mL in Group B, and 382 ± 153.8 mL in Group C. There was statistical difference in the HBL between three groups (P = 0.000). However, multivariate linear regression analysis revealed that HBL of three approaches was not associated with age, gender, body mass index (BMI), percentage of height loss, percentage of height restoration, fracture type, or operation time. Conclusion: There was a substantial HBL in the treatment of thoracolumbar fractures, which was neglected by surgeons. Further investigation is necessary to study the risk factors for surgery on HBL in treatment of thoracolumbar fractures. [ABSTRACT FROM AUTHOR]

Objective To report and describe a modified posterior-only approach (paraspinal approach) for total en bloc spondylectomy (TES) of lumbar spinal tumors. Methods From February 2013 to June 2014, 5 patients with lumbar spinal tumors who underwent TES through a posterior-only paraspinal approach were studied retrospectively; operative time, blood loss, complications, neurologic outcomes, and degree of resection were recorded to evaluate the efficacy of this surgical method. Results Patients included 3 men and 2 women with a mean age of 48.4 years (range, 46–52 years). Two lesions were located in L2, 2 lesions were located in L3, and 1 lesion was located in L4. Three patients had solitary metastatic tumors (lung cancer in 2 cases, breast cancer in 1 case), and 2 patients had primary tumors (osteosarcoma and plasma cell tumor). According to the surgical classification of spinal tumors by Tomita et al., 4 cases were type 4 and 1 case was type 1. Mean operative time was 464 minutes (range, 420–510 minutes), and mean blood loss was 1280 mL (range, 1000–1500 mL). One patient had cerebrospinal fluid leakage, and 1 had transient motor weakness because of nerve root traction. Mean follow-up time was 20.6 months (range, 12–30 months), and all patients had improved or stable neurologic function. No local recurrence was observed at last follow-up. Conclusions The posterior-only paraspinal approach is a valid alternative for TES of lumbar spinal tumors, especially for overweight or muscular patients. Highlights • TES performed at the lumbar spine by posterior-only approach is technically challenging. • TES carries high risks of injury to major vessels and lumbosacral plexus. • TES by posterior-only paraspinal approach provides a better view of the ventral aspect of the spine, including IVC. • The paraspinal approach is a valid alternative for TES of lumbar spinal tumors. [ABSTRACT FROM AUTHOR]

Background Foraminal disc herniation is rare. When conservative treatment fails, it is often treated with discectomy via a paraspinal or Wiltse approach. In contained foraminal disc herniation, more symptoms arise from the foraminal compression of the exiting nerve root, including the dorsal root ganglion, than from the herniation itself. We aimed to evaluate the benefits of stand-alone decompression without discectomy for patients with contained foraminal disc herniation. Methods This study included 17 patients with unilateral single-level foraminal disc herniation (14 women and 3 men; mean age, 62.8 ± 14.6 years, range, 37–86 years). Disc herniation was confirmed as contained by preoperative magnetic resonance imaging and/or computed tomography and by intraoperative exploration. All patients underwent thorough decompression without discectomy, via a paraspinal approach. Pain was evaluated preoperatively and at 3 and 12 months postoperatively using a visual analog scale (VAS). The Oswestry Disability Index (ODI) and Macnab criteria were used to evaluate final outcomes. Results The most commonly affected level was L5–S1. All 17 patients showed significant improvements in VAS and ODI scores at 3 and 12 months postoperatively. According to the Macnab criteria, outcome results were excellent in 13 patients and good in 4. The mean duration of follow-up was 18.4 ± 2.4 months, with no recurrences or lumbar instability at the final follow-up. Conclusions Stand-alone decompression without discectomy is an effective method for relieving symptoms and preserving the disc in contained foraminal disc herniation. A minimally invasive approach with thorough decompression techniques yields good results. Highlights • In contained foraminal disc herniation, most symptoms are due to nerve compression. • Discectomy is the usual approach if conservative treatment fails. • We report good outcomes of decompression without discectomy in all patients. • Improvement in VAS and ODI scores with no radiation leg pain was noted at 12 months. • Excellent and good outcomes were observed in 13 and 4 patients, respectively. [ABSTRACT FROM AUTHOR]

Background: Complications in posterior pedicle screw fixation using a conventional posterior approach for thoracolumbar fractures include vertebral height loss, kyphosis relapse and breakage, or loosening of instrumentation. The purpose of this study was to evaluate the clinical effects of transpedicular bone grafting and pedicle screw fixation in injured vertebrae using a paraspinal approach for thoracolumbar fractures. Methods: We retrospectively analyzed 50 patients with thoracolumbar fractures treated with transpedicular bone grafting and pedicle screw fixation in injured vertebrae using a paraspinal approach. Operative time, blood loss, visual analog scale (VAS) scores for back pain, and the relative height and Cobb angle of the fractured vertebrae were measured. Results: The average operative time was 71.8 min, and the blood loss was 155 ml. Postoperative VAS scores were significantly lower than preoperative scores (P = 0.08), but there was no difference between 1 week and 1 year postoperatively (P = 0.18). The postoperative relative heights of the fractured vertebrae were higher than the preoperative heights (P= 0.001, 0.005, 0.001), but there were no differences between 1 week and 1 or 2 years postoperatively (P = 0.24/0.16). The postoperative Cobb angles were larger than the preoperative angles (P = 0.002, 0. 007, 0.001), but there were no differences between 1 week and 1 or 2 years postoperatively (P= 0.19/0.23). Conclusions: Transpedicular bone grafting and pedicle screw fixation in injured vertebrae using a paraspinal approach for thoracolumbar fractures achieved satisfactory results and can restore vertebral height, increase the stability of the anterior and middle columns of injured vertebrae, and decrease the risk of back pain. [ABSTRACT FROM AUTHOR]

Objective: Lumbar foraminal or extraforaminal disc herniations (FEFDH) have unusual clinical features and higher incidence in elderly patients compared to usual intraspinal canal disc herniations. We evaluated the efficacy of microdiscectomy via paramedian approach for lumbar FEFDH in elderly patients over the age of 65. Methods: Retrospective study was performed in 68 patients over the age of 65 (23 male and 45 female patients; 71.46±3.87 years) who underwent microdiscectomy via paramedian approach for unilateral lumbar FEFDH causing sciatica. The radiological factors including degree of slippage, presence of instability, disc height, and degree of disc degeneration; pain and functional status by the means of visual analogue scale score, Oswestry Disability Index score, and Macnab classification were analyzed preoperatively and during the postoperative follow-up period of 3 years to evaluate the efficacy of the surgical treatment. Results: Pain and functional status improved according to short- and long-term follow-up evaluations after surgery. Radiological changes following surgery, which can be understood as structural deteriorations and deformations, did not represent patient condition. Nine patients underwent additional surgery due to sustained or recurring leg pain of aggravation of back pain, and fusion surgery was required for 3 patients. Degree of preoperative slippage was the only statistically significant factor related to additional surgery (p<0.05). Conclusion: Microdiscectomy via paramedian approach for FEFDH may be a good surgical alternative in elderly patients. Radiological changes after surgery did not show a concordance with patients' actual functional status. The excessive preoperative slippage tended to lead to unfavorable result after surgery and was associated with additional surgery. [ABSTRACT FROM AUTHOR]

Objective : We evaluated postoperative outcomes in patients who have lumbar foraminal or extraforaminal disc herniation (FELDH) and suggested the risk factors for poor outcomes. Methods : A total of 234 patients were selected for this study. Pre- and post-operative Visual Analogue Scale (VAS) and Korean version Oswestry Disability Index (KODI) were evaluated and the changes of both score were calculated. Outcome was defined as excellent, good, fair, and poor based on Mcnab classification. The percentage of superior facetectomy was calculated by using the Maro-view 5.4 Picture Archiving Communication System (PACS). Results : Paramedian lumbar discectomy was performed in 180 patients and combined lumbar discectomy was performed in 54 patients. Paramedian lumbar discectomy group showed better outcome compared with combined discectomy group. p value of VAS change was 0.009 and KODI was 0.013. The average percentage of superior facetectomy was 33% (range, 0-79%) and it showed negative correlation with VAS and KODI changes (Pearson coefficient : -0.446 and -0.498, respectively). Excellent or good outcome cases (Group I) were 136 (58.1%) and fair or poor outcome cases (Group II) were 98 (41.9%). The percentage of superior facetectomy was 26.5% at Group I and 42.5% at Group II. There was significant difference in superior facetectomy percentage between Group I and II (p=0.000). Conclusion : This study demonstrated that paramedian lumbar discectomy with preservation of facet joints is an effective and good procedure for FELDH. At least 60% of facet should be preserved for excellent or good outcomes. [ABSTRACT FROM AUTHOR]

Thoracolumbar fracture is a common traumatic condition; however, the management remains challenging. The aim of this study is to establish criteria for selection of the anterior, posterior and posterolateral approaches for open reduction and internal fixation of thoracolumbar fracture. A group of 64 patients with Denis type A and B thoracolumbar burst fracture were treated with anterior, traditional posterior and paraspinal approach reduction with or without decompression. The fracture was fixed with titanium mesh and Z-plate by anterior approach and screw rod system by posterior approach and paraspinal approach. Clinical evaluations showed operation duration, blood loss, average length of incision and postoperative ODI in the paraspinal group were less than the traditional posterior group and anterior group. The statistical significant differences were reached ( P < 0.05). There is not statistical difference between the three approaches for relevant parameters of radiographs (Cobb angle). The anterior approach surgery should be limitedly used for severe Denis type B fracture with direct reduction. The posterior approach is familiar to the spine surgeons and is commonly applied to most Denis type A and B thoracic lumbar fractures with indirect reduction and has less complication compared to the anterior approach, but also has some shortcomings. Paraspinal muscle approach is the muscle gap approach, in line with the minimally invasive surgery , which is now advocated with the idea with indirect reduction, compared to traditional surgery can significantly relieve postoperative pain and is worthy of further research and promotion. [ABSTRACT FROM AUTHOR]

Purpose: The goal of this study was to determine which paraspinal approach provided a better transverse screw angle (TSA) for each vertebral level in lower lumbar surgery. Methods: Axial computed tomography (CT) images of 100 patients, from L3 to S1, were used to measure the angulation parameters, including transverse pedicle angle (TPA) and transverse cleavage plane angle (TCPA) of entry from the two approaches. The difference value between TCPA and TPA, defined as difference angle (DA), was calculated. Statistical differences of DA obtained by the two approaches and the angulation parameters between sexes, and the correlation between each angulation parameter and age or body mass index (BMI) were analyzed. Results: TPA ranged from about 16° at L3 to 30° at S1. TCPA through the Wiltse's and Weaver's approach ranged from about −10° and 25° at L3 to 12° and 32° at S1, respectively. The absolute values of DA through the Weaver's approach were significantly lower than those through the Wiltse's approach at each level. The angulation parameters showed no significant difference with sex and no significant correlation with age or BMI. Conclusions: In the lower lumbar vertebrae (L3-L5) and S1, pedicle screw placement through the Weaver's approach may more easily yield the preferred TSA consistent with TPA than that through the Wiltse's approach. The reference values obtained in this paper may be applied regardless of sex, age or BMI and the descriptive statistical results may be used as references for applying the two paraspinal approaches. [ABSTRACT FROM AUTHOR]

Purpose: Far-lateral extraforaminal lumbar disc herniation is an uncommon cause of nerve root entrapment, and studies addressing the long-term outcome of surgically treated patients are few. The purpose of this study was to analyze the ultra-long-term outcome of patients who were treated via a lateral approach. Methods: The medical reports of 138 consecutive patients were analyzed with regard to signs and symptoms, operative findings, complications, and short-term outcome (6 weeks). To assess long-term results, standardized telephone interviews were performed using a structured questionnaire. The patients were questioned about pain using the verbal rating scale and persisting symptoms, if any. Other queries were related to the Oswestry Disability Index. Subjective satisfaction with the result of surgery was classified as excellent (no pain), good (some pain), fair (moderate pain), and poor (unchanged or worse) based on MacNab classification. Results: At short-term follow-up, major and moderate leg pain had decreased from 99.3 to 5.1% and low back pain from 97.8 to 2.8%. Sensory and motor deficits, however, were still present in the majority of patients. A total of 87 telephone interviews were conducted, and the mean follow-up was 146 months. As many as 49 patients (56.3%) reported complete relief of symptoms, 14 patients (16.1%) had minor ailments under physical stress, and 24 patients (27.6%) had permanent residual symptoms. The most common complaint was remaining sensory disturbance. Despite residual symptoms, the vast majority of patients expressed satisfaction with the result of surgery. The outcome was subjectively rated as follows: 75.9% excellent (66 patients), 18.4% good (16 patients), 4.6% fair (4 patients), and 1.1% poor (1 patient). Conclusions: The lateral approach is a minimally invasive and safe procedure with low complication rates. The profit from surgery is maintained beyond the usual postoperative observation periods. Thus, ultimate outcome at ultra-long-term follow-up is very gratifying in the vast majority of patients. [ABSTRACT FROM AUTHOR]

The article discusses the medical advantage of using a multilevel Magnetic Resonance Imaging (MRI) in the study of Multifidus and Longissimus cleavage planes when adapting Wiltse's paraspinal approach in treating lumbar patients. Factors why MRI or Computerized Tomography (CT) scan is not available to some patients include claustrophobia, pacemaker and spinal cord stimulator. The 1988 revision of Wiltse's paraspinal approach is also discussed.

The original description of the paraspinal posterior approach to the lumbar spine was for spinal fusion, especially regarding lumbosacral spondylolisthesis treatment. In spite of the technical details described by Wiltse, exact location of the area where the sacrospinalis muscle has to be split remains somewhat unclear. The goal of this study was to provide topographic landmarks to facilitate this surgical approach. Thirty cadavers were dissected in order to precisely describe the anatomy of the trans-muscular paraspinal approach. The level of the natural cleavage plane between the multifidus and the longissimus part of the sacrospinalis muscle was noted and measurements were done between this level and the midline at the level of the spinous process of L4. A natural cleavage plane between the multifidus and the longissimus part of the sacrospinalis muscle was present in all cases. There was a fibrous separation between the two muscular parts in 55 out of 60 cases. The mean distance between the level of the cleavage plane and the midline was 4 cm (2.4–5.5 cm). In all cases, small arteries and veins were present, precisely at the level of the cleavage plane. We found it possible to easily localize the anatomical cleavage plane between the multifidus part and the longissimus part of the sacrospinalis muscle. First the superficial muscular fascia is opened near the midline, exposing the posterior aspect of the sacrospinalis muscle. Then, the location of the muscular cleft can be found by identifying the perforating vessels leaving the anatomical inter-muscular space. [ABSTRACT FROM AUTHOR]

Objective: To determine the anatomic location of the multifidus-longissimus intermuscular cleavage plane in a Chinese population and thereby to aid surgery by Wiltse's approach. Methodology: Two hundred patients (100 males, 100 females) were enrolled. The distance between the midline and the intermuscular plane at each disc level between L1 and S1 was measured on axial T2-weighted magnetic resonance images (MRI). Age, sex and body mass index (BMI) were also recorded. Results: The mean measured distance differed significantly between disc levels (P<0.05). At L5-S1, it was 33.56 mm; at L4-L5, 29.85 mm; at L3-L4, 24.97 mm; at L2-L3, 19.91 mm; and at L1-L2, 16.17 mm. Mean distances were significantly greater in males than in females (1 mm) at L1-L2, L2-L3 and L3-L4. There was no significant relationship between distance and height, weight or age. Conclusions: The location of the intermuscular cleavage plane was related to disc level and not correlated with age, height or weight. Mean distances were slightly greater in males than in females at L1-L2, L2-L3 and L3-4, which was not consistent with a previous report. These findings may aid surgery by Wiltse's approach. [ABSTRACT FROM AUTHOR]