L5-S1 Junction Research Articles

Upper limit of radiation treatment portals in rectal cancer: is it wise to keep using bony landmarks in the present era of 3D conformal treatment?

This study aimed to compare the levels of L5-S1 interspace and the bifurcation of common iliac vessels on simulation images of rectal cancer patients to evaluate the adequacy of superior borders in conventional 2D planning for covering internal iliac vessels. Simulation images of 236 rectal cancer patients who received neoadjuvant chemoradiation and surgery were analyzed. The images were retrieved from the radiation treatment database and included delineations of L5-S1 interspace and common iliac vessel bifurcation. Distances between these landmarks were measured. Among the 236 patients, the majority had the common iliac artery bifurcation positioned above the L5-S1 interspace. Specifically, 78.3% of patients had the right common iliac bifurcation above L5-S1 interspace, with an average distance of 2.02 cm. For the left common iliac artery, 77.11% of patients had the bifurcation above L5-S1 interspace, with an average distance of 1.99 cm. Notably, there were cases where the bifurcations were not at the same level. Using the L5-S1 junction as the upper border of the treatment portal may result in missing proximal nodes at risk of metastases. However, further research is needed to determine the significance of failures above the L5-S1 interspace for justifying the inclusion of the common iliac artery bifurcation in the treatment portal.

Lumbosacral Transitional Vertebra among Patients Visiting the Department of Orthopaedics in a Tertiary Care Centre: A Descriptive Cross-sectional Study.

Lumbosacral transitional vertebra is a normal anatomical variant at the L5-S1 junction with an incidence as high as 4-36%. This alteration results in incorrect identification of vertebral segments leading to wrong surgery. The aim of the study was to find out the prevalence of lumbosacral transitional vertebra among patients visiting the department of orthopaedics in a tertiary care centre. A descriptive cross-sectional study was conducted from 11 September 2021 to 31 May 2022, after receiving ethical clearance from the Institutional Review Committee (Reference number: IRC-2021-9-10-09). The patients with plain radiographs of the lumbosacral spine (anteroposterior view) were assessed and evaluated by a fellow and consultant of the orthopaedic spine and classified as per Castellvi's radiographic classification. Convenience sampling was done. Point estimate and 95% Confidence Interval were calculated. Among 1002 patients, lumbosacral transitional vertebra was detected in 95 (9.48%) patients (9.40-9.56, 95% Confidence Interval). Out of 95 (9.48%) patients with the lumbosacral transitional vertebra, 67 (70.53%) had sacralisation and 28 (29.47%) had lumbarization. The mean age of the patients at the time of the study included in the study was 41.6±15.12 years (range 18-85 years). The lumbosacral transitional vertebra was more common in females than males. According to the Castellvi classification, type IIa was the most common type 47 (49.47%). The prevalence of lumbosacral transitional vertebra was similar to other studies done in similar settings.

Lumbosacral Transitional Vertebra among Patients Visiting the Department of Orthopaedics in a Tertiary Care Centre: A Descriptive Cross-sectional Study

Lumbosacral transitional vertebra is a normal anatomical variant at the L5-S1 junction with an incidence as high as 4-36%. This alteration results in incorrect identification of vertebral segments leading to wrong surgery. The aim of the study was to find out the prevalence of lumbosacral transitional vertebra among patients visiting the department of orthopaedics in a tertiary care centre. A descriptive cross-sectional study was conducted from 11 September 2021 to 31 May 2022, after receiving ethical clearance from the Institutional Review Committee (Reference number: IRC-2021-9-10-09). The patients with plain radiographs of the lumbosacral spine (anteroposterior view) were assessed and evaluated by a fellow and consultant of the orthopaedic spine and classified as per Castellvi's radiographic classification. Convenience sampling was done. Point estimate and 95% Confidence Interval were calculated. Among 1002 patients, lumbosacral transitional vertebra was detected in 95 (9.48%) patients (9.40-9.56, 95% Confidence Interval). Out of 95 (9.48%), patients with the lumbosacral transitional vertebra, 67 (70.53%) had sacralisation and 28 (29.47%) had lumbarization. The mean age of the patients at the time of the study included in the study was 41.6±15.12 years (range 18-85 years). The lumbosacral transitional vertebra was more common in females than males. According to the Castellvi classification, type IIa was the most common type 47 (49.47%). The prevalence of lumbosacral transitional vertebra was similar to other studies done in similar settings. lumbar vertebrae; orthopedics; prevalence.

Management of severe adult spinal deformity with circumferential minimally invasive surgical strategies without posterior column osteotomies: a 13-year experience.

To evaluate the mid- to long-term clinical outcomes of circumferential minimally invasive surgery (CMIS) without posterior column osteotomies for severe adult spine deformity (ASD) correction. All patients with a minimum of 2-year follow-up undergoing staged CMIS correction of ASD from January 2007 to July 2018 were identified. All included patients had fusion of 3 or more interbody levels that spanned the L5-S1 junction. Only patients with severe deformity, Coronal Cobb > 50° or at least one SRS-Schwab ++ sagittal modifier (SVA > 95mm, or PI-LL > 20, or PT > 30) were included. All complications were noted. 136 patients met inclusion criteria; mean age of patients was 63.6years (21-85, SD 13.7). The mean follow-up was 82.8months (24-159, SD 36.6). The mean number of levels fused was 7 (3-16, SD 3). A total of 40 (29.4%) major complications were noted at final follow-ups: 2 (1.4%) intra-operative, 12 (8.9%) peri-operative (≤ 6weeks from index), 26 (19.1%) post-operative (> 6weeks from index). There was a total of 53 (40.0%) minor complications. Seven (5.1%) patients who developed radiographic proximal junctional kyphosis. Three patients (2.2%) developed proximal junctional failure. There were 8 (5.9%) cases of pseudarthrosis. Five of these occurred in patients undergoing AxiaLIF. All patients experienced improvements in patient-perceived outcomes (VAS, TIS, ODI, and SRS-22) and radiographic parameters at last follow-up when compared to pre-op (p < 0.05). Rates of complications with CMIS correction of severe ASD are lower than published rates of complications seen with open ASD correction. Specifically, the incidence of catastrophic complications is lower. Furthermore, CMIS is associated with significant improvements in clinical and functional outcomes, low rates of pseudarthrosis and proximal junctional kyphosis. Therefore, in the appropriately selected patient, CMIS may be an excellent alternative approach to addressing severe ASD.

The Feasibility of Anterior Spinal Access: The Vascular Corridor at the L5-S1 Level for Anterior Lumbar Interbody Fusion.

Cross-sectional study. To analyze the feasibility of anterior spinal access to the vascular corridor at the L5-S1 junction, by evaluating three crucial anatomical landmarks. This provides a framework for risk-stratification for the clinician during preoperative evaluation. The anterior lumbar interbody fusion (ALIF) offers many advantages for fusion at the L5-S1 junction. However, the variant iliac vasculature may preclude safe anterior access. Five hundred magnetic resonance imaging (MRI) images of the L5-S1 level were identified, with 379 meeting inclusion criteria. We graded the anterior access into three grades, namely, easy, advanced, or difficult by looking at three important anatomical landmarks-the vascular corridor (narrow if ≤25 mm, medium if 25-35 mm [inclusive], and wide if >35 mm), the left common iliac vein (LCIV) location (grades A-D based on the relative position of the LCIV to the L5-S1 disc space), and the presence or absence of a fat plane. Our results showed that 43.27% of the patients had wide corridor for the anterior access, 19.26% of patients had no fat plane, and 7.65% had a LCIV that extended past the midline of the disc (Grade C, D: >50%). By combining these three factors, 37.20% would have easy anterior access, while a minority (1.85%) would have a difficult anterior access. The ALIF at L5-S1 offers significant benefits to the patient. The surgeon should be aware of the dangers in an anterior access by looking at three crucial factors to determine whether the access is easy, advanced, or difficult. Patients with a difficult access should be attempted by experts, vascular access surgeons, or consider an alternative approach to L5-S1.Level of Evidence: 3.

Radiological outcomes of Lateral Lumbar Interbody Fusion (LIF) in Adult Spinal Deformity – A Systematic Review

Background Data: Adult spinal deformity (ASD) needing surgical treatment is often seen in the aging population. Radiological goals for ASD surgery have been standardized to achieve a good functional outcome. Lesser complication rates and blood loss have made MIS surgeries more popular in the current day. Trans-psoas / Pre-psoas Lateral Lumbar Interbody Fusion (LIF) has been the cornerstone of MIS surgeries for ASD. The corrective potential of conventional MIS surgeries was limited, owing to which various modifications have been described. Despite the demonstration of good clinical outcomes by various studies employing different surgical techniques, cumulative analysis of the radiological outcome of the various modifications of LIF is poorly discussed in the literature. A recommendation of an ideal MIS technique based on the type and magnitude of ASD is also lacking. Purpose: We aim to perform a qualitative systematic review of the radiological outcomes of various modifications of LIF surgeries for ASD and to decipher a treatment algorithm based on the type and severity of ASD with existing literature. Study design: Systematic review. Patients and Methods: A systematic search of two electronic databases (PubMed & Google Scholar) from its inception till December 2020 was done independently by 3 different authors. Relevant keywords and MeSH terms were used to identify articles and further filtered by applying appropriate selection criteria. Results: A total of 171 articles were selected for abstract screening, followed by full-text screening. After applying the selection criteria, 28 articles were selected for the systematic review. The methodology and radiological parameters of each study were analyzed qualitatively, and the inferences in regards to the radiological outcomes were validated. Conclusion: Circumferential MIS (cMIS) seems to be adequate in milder forms of ASD, while hybrid surgeries may be needed in higher magnitude deformities. Addressing the L5-S1 junction using LIF and anterior column realignment (ACR) are useful tools to correct more severe deformities. (2020ESJ223)

ATRT-31. SUCCESSFUL MULTIMODALITY MANAGEMENT OF ATRT OF THE LOWER DORSAL SPINE WITH SPINAL DROP METASTASIS

A 6 year old boy presented with low backache for the last 5 months. MRI of the spine showed a 1.5x1.5x4.7cm intradural mass extending from D10-D12, causing compression of the conus medullaris. With a preoperative diagnosis of intradural ependymoma, a gross total resection (GTR) of tumour was performed. Post-operative histopathology showed a markedly cellular, malignant tumour with frequent mitotic figures. Cells were round to polygonal with vesicular nuclei, prominent nucleoli and were immunopositive for CK,EMA,p53 and immunonegative for MIC2,desmin,SMA,GFAP,INI-1(MIB1 labeling index-35–40%). The overall impression was spinal atypical teratoid rhabdoid tumour(ATRT). Post-operative neuraxis MRI revealed post-operative changes(D10-D12) with a 9 mm enhancing lesion at L5-S1 junction suggesting drop metastasis. There was no brain lesion. CSF cytology did not show any malignant cell. The metastatic work-up was normal. He was started on chemotherapy with ICE regimen (Ifosfamide-2g/m2IVD1–D3,Carboplatin-500mg/m2IVD3,Etoposide-100mg/m2IVD1–D3q3weeks). Subsequently he received craniospinal irradiation (CSI)-36Gray/20fractions/4weeks→ focal boost to primary tumour bed and spinal drop metastasis-14.4Gray/8fractions/1.5 weeks. Thereafter he received 3 more cycles of ICE regimen. End-of-treatment MRI spine showed post-op changes(D10-D12) and 38.9%reduction of the L5-S1 lesion suggesting partial response. Six monthly spinal MRI showed serial reduction of the metastatic lesion leading to complete response (CR) 1 year after completion of treatment. On last follow-up (30 months from initial diagnosis), he was neurologically intact and in CR. Multimodality management comprising GTR,CSI followed by focal boost and multiagent chemotherapy(ICE) can lead to successful outcome in patients with this rare and aggressive spinal tumour.

Vascular anatomy and surgical approach in oblique lateral interbody fusion at lumbosacral transitional vertebrae

BackgroundOblique lateral interbody fusion (OLIF) at lumbosacral junction is typically performed on the central window between the bifurcations of iliac vessels. However, the central window of lumbosacral transitional vertebrae (LSTVs) is usually obstructed by the iliocaval venous structures. We aimed to describe the vascular anatomy and surgical approach in OLIF at LSTVs compared with those in OLIF at typical L5-S1 junction. MethodsSixty-eight consecutive patients who underwent OLIF at lumbosacral junction were included. Of these, 31 patients had LSTVs and 37 patients had typical L5-S1 junction. The position of the iliocaval junction and the configuration of the left common iliac vein were compared using the preoperative CT and MR images of the lumbar spine. The surgical approach and intraoperative vascular findings were analyzed. ResultsAlmost 70% of LSTVs had the iliocaval junction at low or very low position. Mobilization of left common iliac vein for central window was potentially difficult in almost 74% of OLIF at LSTVs while it was not required or was potentially easy in almost 80% of OLIF at typical L5-S1. Vascular injury was identified in 2 (6.5%) patients with OLIF at LSTVs and in 3 (8.1%) patients with OLIF at typical L5-S1 junction (P = 0.904). ConclusionsIn our series, OLIF at LSTVs was performed through lateral window in 93.5% of the cases. Preoperative evaluation of the iliocaval junction using CT/MR of lumbar spine was reliable and valid in the determination of OLIF approach at lumbosacral junction.

A review of lumbosacral transitional vertebrae and associated vertebral numeration.

To review the current literature on methods of accurate numeration of vertebral segments in patients with Lumbosacral transitional vertebrae (LSTVs). LSTVs are a common congenital anomaly of the L5-S1 junction. While their clinical significance has been debated, unquestionable is the need for their identification prior to spinal surgery. We hypothesize that there are no reliable landmarks by which we can accurately number transitional vertebrae, and thus a full spinal radiograph is required. A Pubmed and EMBASE search using various combinations of specific key words including "LSTV", "lumbosacral transitional vertebrae", "count", "vertebral numbering", and "number" was performed. The gold standard for spinal segment numeration in patients with LSTV remains whole spine imaging and counting caudally, starting from C2. If whole spine imaging is not available, the use of the iliac crest tangent sign on coronal magnetic resonance imaging (MRI) has fairly reliable sensitivity and specificity (81 and 64-88%, respectively) for accurate numeration of LSTV. The role of paraspinal anatomic markers such as the right renal artery, superior mesenteric artery, aortic bifurcation, and conus medullaris, for identification of vertebral levels is unreliable and should not be used. A sagittal whole spine view should be added as a scout view when patients obtain lumbar MRI to standardize the vertebral numbering technique. To date, there has been no other method for accurate numeration of a transitional vertebral segment, other than counting caudally from C2. These slides can be retrieved under Electronic Supplementary Material.

Multi-Rod Constructs Can Prevent Rod Breakage and Pseudarthrosis at the Lumbosacral Junction in Adult Spinal Deformity.

Study Design:Retrospective cohort study.Objective:To determine if patients fused with multi-rod constructs to the pelvis have a lower incidence of lumbosacral rod failure and pseudarthrosis than those fused with dual-rod constructs.Methods:We performed a retrospective review of consecutive adult spinal deformity patients who underwent long fusion to the pelvis. Inclusion criteria were >5 levels, primary fusion or revision for L5-S1 pseudarthrosis, and minimum 1-year follow-up. Revision patients with indications other than L5-S1 pseudarthrosis were excluded. One-year follow-up plain radiographs were reviewed for rod integrity, and computed tomography scan (CT) was obtained whenever rod breakage was observed. Dual-rod and multi-rod (3 or 4 rods) cohorts were statistically compared.Results:There were 31 patients with 15 in the dual-rod group and 16 in the multi-rod group, with average ages of 68 ± 9 and 63 ± 12 years, respectively. No patients in the multi-rod group experienced rod fracture, whereas 6 in the dual-rod group fractured a rod (P = .007), with 4 occurring at the lumbosacral junction (P = .04). CT scan in the 4 lumbosacral rod fracture cases, and surgical exploration in 3, confirmed pseudarthrosis and hypertrophic nonunion at the L5-S1 junction.Conclusion:Patients with dual-rod constructs had a statistically greater incidence of lumbosacral pseudarthrosis with implant failure than those with multi-rod constructs. CT and surgical exploration showed hypertrophic nonunion as opposed to oligo- or atrophic nonunion. This suggests that mechanical instability, not biology, is the main reason for failure, and could be addressed with the use of multi-rods.

Matched-pair cohort study of 1-year patient-reported outcomes following pelvic fixation

Background ContextPelvic fixation improves fusion and stability for thoracolumbar constructs that extend across the L5–S1 junction. No patient-reported outcomes have been published to evaluate patients' functional outcomes following these procedures compared with pelvis-sparing procedures. PurposeThe goal of this study is to identify the effect of pelvic fixation on both objective and patient-reported outcomes. Study Design/SettingThis was a retrospective, matched cohort study. Patient SampleThe sample comprised adult patients undergoing spine surgery at our institution who had complete 1-year postoperative follow-up. Outcome MeasuresPatient-reported outcome instruments (Oswestry Disability Index [ODI], Short-Form 12-item survey, and EuroQol-5D) and objective measures (length of hospital stay, discharge disposition, postoperative complications, and readmission rates) were considered. MethodsWe identified patients in our outcomes registry undergoing instrumented spinal fusion involving the pelvis between October 2010 and May 2014 who had 1-year follow-up data. Nearest-neighbor 1:1 matched controls were identified using propensity scoring from the cohort of patients undergoing any spinal procedure which extended caudally to the lumbar spine or sacrum. Objective and patient-reported outcomes were compared between cases and controls. ResultsThere were 44 patients who underwent spinal procedures involving the pelvis and had 1-year follow-up data. An equal number of controls were identified and had similar baseline demographic and clinical characteristics. No significant differences were found among operative variables or objective complication rates. Patients undergoing pelvic fixation had moderately greater improvement at 3 months as measured by ODI, but this difference was not present at 1 year. Other patient-reported outcome measures were equivocal between groups. ConclusionsThis matched cohort study demonstrates that inclusion of the pelvis in spinal hardware constructs is not associated with increased complications and may slightly improve patient disability at 1 year. Given that pelvic fixation may reduce L5–S1 breakdown and improve biomechanics, surgeons should more readily include the pelvis in instrumented fusion procedures.

Retrospective exploration of risk factors for L5 radiculopathy following lumbar floating fusion surgery.

BackgroundLumbar floating fusion occasionally causes postoperative adjacent segment disorder (ASD) at lumbosacral level, causing L5 spinal nerve disorder by L5-S1 foraminal stenosis. The disorder is considered to be one of the major outcomes of L5-S1 ASD, which has not been evaluated yet. The present study aimed to evaluate the incidence and risk factors of postoperative L5 spinal nerve disorder after lumbar interbody fusion extending to the L5 vertebra.MethodsWe evaluated 125 patients with a diagnosis of spondylolisthesis who underwent floating fusion surgery with transforaminal lumbar interbody fusion with average postoperative period of 25.2 months. The patients were regarded as symptomatic with postoperative L5 spinal nerve disorder such as radicular pain/numbness in the lower limbs and/or motor dysfunction. We estimated and compared the wedging angle (frontal view) and height (lateral view) of the lumbosacral junction in pre- and postoperative plain X-ray images and the foraminal ratio (ratio of the narrower foraminal diameter to the wider diameter in the craniocaudal direction) in the preoperative magnetic resonance image. Risk factors for the incidence of L5 spinal nerve disorder were explored using multivariate logistic regression.ResultsEight of the 125 patients (6.4 %) were categorized as symptomatic, an average of 13.3 months after surgery. The wedging angle was significantly higher, and the foraminal ratio was significantly decreased in the symptomatic group (both P < 0.05) compared to the asymptomatic group. Multivariate logistic regression analysis of possible risk factors revealed that the wedging angle, foraminal ratio, and multileveled fusion were statistically significant.ConclusionsHigher wedging angle and lower foraminal ratio in the lumbosacral junction were significantly predictive for the incidence of L5 nerve root disorder as well as multiple-leveled fusion. These findings indicate that lumbosacral fixation should be considered for patients with these risk factors even if they have few symptoms from the L5-S1 junction.

Posterior spinal fusion to sacrum in non-ambulatory hypotonic neuromuscular patients: sacral rod/bone graft onlay method.

PurposeA retrospective study involving 65 non-ambulatory patients with hypotonic neuromuscular scoliosis has assessed the effectiveness of a sacral rod/bone onlay technique for extending spinal fusion to the sacrum.MethodsTo extend posterior spinal fusion to the sacrum, we used either 1 Harrington rod and 1 Luque L rod with sublaminar wires in 14 patients (Group 1) or two rods with sublaminar wires in 51 patients (Group 2) along with abundant autograft and allograft bone covering the ends of the rods.ResultsDiagnoses were Duchenne muscular dystrophy 53, spinal muscular atrophy 4, myopathy 3, limb girdle muscular dystrophy 2, infantile FSH muscular dystrophy 1, cerebral palsy 1, and Friedreich ataxia 1. Mean age at surgery was 14.3 years (±2.2, range 10.9–25.2). Radiographic follow-up (2 years post-surgery or greater) was 6.4 years (±4.4, range 2–25.3). Using the onlay technique, all patients fused with no rod breakage or pseudarthrosis. For the entire series, the mean pre-operative scoliosis was 54.7° (±31.1, range 0°–120°) with post-operative correction to 21.8° (±21.7, range 0°–91°) and long-term follow-up 24° (±22.9, range 0°–94°). For pelvic obliquity, pre-operative deformity was 17.3° (±11.3, range 0°–51°) with post-operative correction to 8.9° (±7.8, range 0°–35°) and long-term follow-up 10.1° (±8.1, range 0°–27°). Five required revision at a mean of 3.3 years post-original surgery involving rod shortening at the distal end. One of these had associated infection.ConclusionLumbosacral stability and long-term sitting comfort have been achieved in all patients. Problems can be minimized by positioning the rods firmly against the sacrum at the time of surgery with a relatively short extension beyond the L5–S1 junction. The procedure is valuable in hypotonic non-ambulatory neuromuscular patients whose immobility enhances the success rate for fusion due to diminished stress at the lumbosacral junction. It is particularly warranted for those with osteoporosis and a small, deformed pelvis. Considerable weight loss and lengthy rods not closely apposed to the sacrum at the time of surgery played a major role in patients needing revision.

Biomechanical Effect of 4-Rod Technique on Lumbosacral Fixation

An in vitro biomechanical study of 3 lumbosacral fixation techniques in human cadaveric lumbar-pelvic spine models. To compare the in vitro biomechanical effect of a novel 4-rod lumbosacral reconstruction technique with conventional techniques in a human cadaveric lumbopelvic model, and to evaluate the benefit of adding supplementary rod fixation. Spinopelvic fixation involving the sacrum remains a difficult clinical challenge. Numerous lumbopelvic reconstruction methods based on the Galveston 2-rod technique have been proposed. Recently, a novel technique using supporting longitudinal rods across the lumbopelvic junction was reported. However, no comparative in vitro biomechanical testing was performed to evaluate the benefit of adding supplementary fixation at the L5-S1 levels. Seven fresh-frozen cadaveric lumbar-pelvic spines were prepared and tested for bone mineral density. The intact cadavers underwent a flexibility test, followed by insertion of the instrumented construct. Three constructs were tested: S1 screws alone (group 1), S1 screws plus iliac screws (group 2), and the 4-rod technique (group 3). Rotational angles of the L1-S1 and L5-S1 segments were measured to study the stability of the 3 lumbosacral fixation constructs compared with the intact spine. Nondestructive, multidirectional flexibility tests that included 4 loading methods followed by a destructive flexural load to failure were performed using an material testing machine. The lumbosacral peak range of motion (ROM) (millimeters or degrees) and ultimate failure load (Nm) of the 3 reconstruction techniques were statistically compared using a 1-way analysis of variance combined with a Student-Newman-Keuls post hoc test. The average bone mineral density of the 7 specimens was 0.81 ± 0.09 g/cm. The ROM of the 3 fixation constructs was significantly smaller than that of the intact group in all 6 directions (P < 0.05). In lateral bending, the ROM of groups 2 and 3 was significantly smaller than that of group 1 (P < 0.05), but groups 2 and 3 were not significantly different from each other (P > 0.05). In flexion-extension, the ROM of groups 1 and 3 was significantly smaller than group 2 (P < 0.05), but groups 1 and 3 were not significantly different from each other (P > 0.05). In axial rotation, the ROM of group 3 was significantly smaller than those of groups 1 and 2 (P < 0.05), but groups 1 and 2 were not significantly different from each other (P > 0.05). The 4-rod technique achieved stable biomechanical effects in lumbosacral fixation. At the L5-S1 junction, the 4-rod technique demonstrated better stability than the constructs using S1 screws or S1 screws plus iliac screws..

Trabecular bone structure in lumbosacral transitional vertebrae: distribution and densities across sagittal vertebral body segments

Background contextLumbosacral transitional vertebrae (LSTV) are associated with altered articular morphology at the L5–S1 junction. Studies related to lumbo-sacral trabecular architecture in LSTV are few. Altered lumbosacral load bearing at these anomalous junctions possibly results in changes in the number, density, and trajectory of the trabecular bone in transitional lumbosacral vertebral bodies. PurposeTo investigate the pattern, distribution, and density of trabecular bone in the terminal lumbar vertebrae and the first sacral segments in LSTV-affected spines. Measurements were compared with those obtained from normal lumbosacral specimens. Study designObservational and descriptive human cadaveric study of vertebral trabecular architecture. MethodsBlocks of tissues were obtained from normal (n=20) and LSTV cadaveric specimens (n=16) by sectioning vertically through the fifth lumbar and the first sacral vertebra on either side of the midsagittal plane. Photographs of the cut surfaces were computationally enlarged and mapped for vertical and transverse trabecular numbers and surface areas using the software Image J. All parameters including the trabecular density were computed for anterior, middle, and posterior segments of each of the vertebral elements. ResultsThe anterior and the posterior segments showed greater number of trabeculae across all LSTV subtypes in both the terminal lumbar and first sacral vertebrae in comparison with the middle segment. L5 exhibited greater number of vertical trabeculae, whereas the first sacral segments demonstrated greater number and densities of transverse trabeculae. Transition-associated vertebrae showed overall reduced number of the lumbar trabeculae but relatively compact sacral posterior segments with greater number of horizontal trabeculae. ConclusionsFindings suggest that some of these variations have overall reduced number of trabeculae across lumbo-sacral vertebrae in LSTV. Screw placements and subsequent pullouts in LSTV may be reviewed in light of different trabecular patterns as reported in this study.

L5 radiculopathy caused by L5 nerve root entrapment by an L5-S1 anterior osteophyte

BackgroundL5 radiculopathy is a common problem that has several causes. Entrapment of the L5 nerve root by anterior osteophytes at the L5-S1 junction is rarely reported. Posterior decompression of the L5 nerve root is commonly performed, but anterior decompression of the L5 nerve root is not a frequently performed procedure. The purpose of this case report is to describe an uncommon case of L5 radiculopathy caused by the entrapment of the L5 nerve root by an anterior osteophyte. MethodsWe report the case of a 79-year-old man with a right lower extremity L5 radiculopathy causing excruciating pain, worsening with transitioning between seated and standing positions. Radiologic evaluation showed a large osteophyte coming off of the right anterolateral border of L5-S1. The osteophyte was excised through a right-sided anterior retroperitoneal approach. An anterior interbody fusion was performed at L5-S1. ResultsPostoperatively, the patient's pain was completely resolved. Six months after surgery, he remained symptom free. ConclusionsOsteophytes at the L5-S1 junction can entrap the L5 nerve root. If nonoperative treatment fails, the osteophyte can be excised and the nerve can be safely decompressed through an anterior retroperitoneal approach.

Biomechanical evaluation of predictive parameters of progression in adolescent isthmic spondylolisthesis: a computer modeling and simulation study

BackgroundPelvic incidence, sacral slope and slip percentage have been shown to be important predicting factors for assessing the risk of progression of low- and high-grade spondylolisthesis. Biomechanical factors, which affect the stress distribution and the mechanisms involved in the vertebral slippage, may also influence the risk of progression, but they are still not well known. The objective was to biomechanically evaluate how geometric sacral parameters influence shear and normal stress at the lumbosacral junction in spondylolisthesis.MethodsA finite element model of a low-grade L5-S1 spondylolisthesis was constructed, including the morphology of the spine, pelvis and rib cage based on measurements from biplanar radiographs of a patient. Variations provided on this model aimed to study the effects on low grade spondylolisthesis as well as reproduce high grade spondylolisthesis. Normal and shear stresses at the lumbosacral junction were analyzed under various pelvic incidences, sacral slopes and slip percentages. Their influence on progression risk was statistically analyzed using a one-way analysis of variance.ResultsStresses were mainly concentrated on the growth plate of S1, on the intervertebral disc of L5-S1, and ahead the sacral dome for low grade spondylolisthesis. For high grade spondylolisthesis, more important compression and shear stresses were seen in the anterior part of the growth plate and disc as compared to the lateral and posterior areas. Stress magnitudes over this area increased with slip percentage, sacral slope and pelvic incidence. Strong correlations were found between pelvic incidence and the resulting compression and shear stresses in the growth plate and intervertebral disc at the L5-S1 junction.ConclusionsProgression of the slippage is mostly affected by a movement and an increase of stresses at the lumbosacral junction in accordance with spino-pelvic parameters. The statistical results provide evidence that pelvic incidence is a predictive parameter to determine progression in isthmic spondylolisthesis.

The Prevalence of Lumbosacral Transitional Vertebrae in an American Population

Lumbosacral transitional vertebrae (LSTV) is a congenital vertebral anomaly of the L5-S1 junction in the spine. This alteration may contribute to incorrect identification of a vertebral segment, leading to wrong-level spine surgery and poor correlation with clinical symptoms. Though several studies describe the occurrence of this anomaly in back pain populations, investigation of the prevalence in an American non-back pain population is lacking.

The prevalence of transitional vertebrae in the lumbar spine

Lumbosacral transitional vertebrae (LSTVs) are a congenital vertebral anomaly of the L5-S1 junction in the spine. This alteration may contribute to incorrect identification of a vertebral segment, leading to wrong-level spine surgery and poor correlation with clinical symptoms. Although several studies describe the occurrence of this anomaly in back pain populations, investigation of the prevalence in the American general population is lacking. To establish the prevalence rates for LSTVs in the general population. Retrospective review. Consecutive kidney-urinary bladder (KUB) radiographs of subjects from the past 2 years (2008-2009). Clinical demographics, number of lumbar vertebrae, L5-S1 transverse process (TP) height, and rib length. Consecutive adult KUB studies of adult subjects were queried with clear visibility of the last rib's vertebral body articulation, all lumbar TPs, and complete sacral wings. Exclusion criteria consisted of any radiologic evidence of previous lumbosacral surgery that would obstruct our measurements. A total of 1,100 abdominal films were reviewed, and 211 were identified as being adequate for the measurement of the desired parameters. Two hundred eleven subjects were identified as eligible for the study, and 75 (35.6%) were classified as positive for a transitional lumbosacral vertebra. The most common anatomical variant was the Castellvi Type IA (14.7%). The average age at the time of the KUB study was 59.8 years (18-95 years). One hundred ninety-seven subjects (93.4%) presented five lumbar (nonribbed) vertebrae, and only 14 (6.6%) had six lumbar vertebrae. The significance of lumbosacral transitional level changes to the establishment of pain, degenerative changes, stenosis, and disc disease have been well documented in symptomatic patients. Although LSTV's role in low back pain remains controversial, our study has shown that, when the same criteria are used for classification, prevalence among the general population and symptomatic patients may be similar.

Disc spaces, vertebral dimensions, and angle values at the lumbar region: a radioanatomical perspective in spines with L5–S1 transitions

Low-back pain (LBP) has been associated with lumbar spines of normal morphology as well as those with L5-S1 "transitional" vertebrae. It is hard to find literature that quantifies the overall morphological changes in lumbar spines as related to transitional states. The object of this study was to investigate lumbar spine changes resulting from the presence of these transitional states. The author quantified dimensions and angles and statistically compared the morphology of lumbar spines with or without L5-S1 transitions in the context of LBP. Anteroposterior and lateral radiographs were obtained from 50 patients suffering from LBP without transitional anomalies at the L5-S1 junction. These radiographs were compared with anteroposterior and lateral radiographs from patients suffering from LBP with L5-S1 transitional states involving accessory L5-S1 articulations, and with anteroposterior and lateral radiographs from patients with L5-S1 unilateral or bilateral fusions. Twelve linear dimensions from the anteroposterior views and 8 angles from the lateral radiographs were measured. The mean values of linear dimensions differed in 1) disc heights, 2) vertebral heights and widths, 3) pedicles and interpedicular distances, 4) angle values, and 5) overall configuration of the lumbar curvatures. The L5-S1 accessory articulations led to increased lordotic curves, L-5 vertebral heights, and pedicle and angular dimensions. The L5-S1 fusions were related to smaller disc heights at all spaces, short and wide L-5 pedicles, taller and less wide transverse processes, and overall straighter spines with the least measures for all lumbar angles. Dimensional differences provided in this study may help in placing instrumentation at the lumbar vertebrae and working on intervertebral disc replacements in spines with specific L5-S1 transitional anomalies.