Disc Level Research Articles

Normative Measurements of L1-S1 Segmental Angulation, Disk Space Height, and Neuroforaminal Dimensions Using Computed Tomography.

To establish normative anatomic measurements of lumbar segmental angulation (SA) and disk space height (DSH) in relation to neuroforaminal dimensions (NFDs), and to uncover the influence of patient demographic and anthropometric characteristics on SA, DSH, and NFDs. NFDs, SA, and anterior, middle, and posterior DSH were measured using computed tomography of 969 patients. NFDs were defined as sagittal anterior-to-posterior width, foraminal height, and area. Statistical analyses were performed to assess associations among SA, DSH, NFDs, and patient height, weight, body mass index, sex, and ethnicity. SA and DSH measurements increased moving caudally from L1 to S1. Foraminal width decreased moving caudally from L1 to S1. Foraminal height and area demonstrated unimodal distribution patterns with the largest values clustered at L2-L3 on the right side and L3-L4 on the left. Significant differences in SA, DSH, and NFD measurements were observed based on the disk level. Inconsistent, marginal NFD differences were observed based on laterality. Across all disk levels, only weak-to-moderate correlations were observed between SA and DSH in relation to NFDs. Patient height, weight, and body mass index were only weakly associated with SA, DSH, and NFDs. Based on patient sex, significant differences were observed for SA, DSH, and NFD measurements from L1 to S1, with males demonstrating consistently larger values compared with females. Based on patient race and ethnicity, significant differences in SA and NFD measurements were observed from L1 to S1. This study describes 48 450 normative measurements of L1-S1 SA, DSH, and NFDs. These measurements serve as representative models of normal anatomic dimensions necessary for several applications including surgical planning and diagnosis of foraminal stenosis. Normative values of SA and DSH are not moderately or strongly associated with NFDs. SA, DSH, and NFDs are influenced by sex and ethnicity, but are not strongly or moderately influenced by patient anthropometric factors.

MRI phenotypes of herniated discs associated with adjacent disc degeneration.

Adjacent segment degeneration is commonly observed in patients after fusion surgery. Among the associated risk factors is the preoperative presence of adjacent disc degeneration (ADD). The risk factors and other spine phenotypes associated with preoperative ADD is critical to understand the pathological process and better prognosis postsurgery. Current study aims to assess and compare the magnetic resonance imaging(MRI) spinal phenotype of herniated level with and without ADD. Preoperative T2W sagittal lumbar MRI images of 155 lumbar disc herniated patients were analyzed for the presence of ADD (Pfirrmann grade III and above). The herniated disc level was assessed for the presence and absence of vertebral endplate (VEP) defects, Modic changes, and high intensity zone (HIZ). Mean age of patients was 38 ± 2 years, almost 62% were males. ADD was found in 57%, VEP defects were seen in 62% of the herniated level, 24.5% showed Modic changes, 3.8% showed spondylolishthesis, and 15.5% revealed HIZ. Age and other demographic factors did not have any significant effect on the presence of ADD, the patients with extruded andsequestered discs had more ADD (p = 0.02). VEP defects were significantly higher in levels with ADD (p = 0.02). Patients with ADD had significantly VEP defect scores (p = 0.01), Modic score (p = 0.002), HIZ score (0.02), andposterior bulge score (p < 0.001). Findings suggest that affected levels with VEP defects and severe grade of disc herniation have the greater likelihood of having ADD. Once developed this ADD may also affect the other spinal levels, and also can affect postoperative prognosis.

Utility of Zero-Echo time sequence as an adjunct for MR evaluation of degenerative disease in the cervical spine.

Determine the utility of ZTE as an adjunct to routine MR for assessing degenerative disease in the cervical spine. Retrospective study on 42 patients with cervical MR performed with ZTE from 1/1/2022 to 4/30/22. Fellowship trained radiologists evaluated each cervical disc level for neural foraminal (NF) narrowing, canal stenosis (CS), facet arthritis (FA), and presence of ossification of the posterior longitudinal ligament (OPLL). When NF narrowing and CS were present, the relative contributions of bone and soft disc were determined and a confidence level for doing so was assigned. Comparisons were made between assessments on routine MR without and with ZTE. With ZTE added, bone contribution as a cause of NF narrowing increased in 47% (n = 110) of neural foramina and decreased in 12% (n = 29) (p = < 0.001). Bone contribution as a cause of CS increased in 25% (n = 33) of disc levels and decreased in 10% (n = 13) (p = 0.013). Confidence increased in identifying the cause of NF narrowing (p = < 0.001)) and CS (p = 0.009) with ZTE. The cause of NF narrowing (p = 0.007) and CS (p = 0.041) changed more frequently after ZTE was added when initial confidence in making the determination was low. There was no change in detection of FA or presence of OPLL with ZTE. Addition of ZTE to a routine cervical spine MR changes the assessment of the degree of bone involvement in degenerative cervical spine pathology.

Patients of idiopathic normal-pressure hydrocephalus have small dural sac in cervical and upper thoracic levels: A supposed causal association.

Idiopathic normal pressure hydrocephalus (iNPH) is a neurological disorder presenting a triad including dementia and ventricular enlargement. The mechanism causing excessive cerebrospinal fluid (CSF) accumulation in the ventricles in iNPH is poorly understood. We hypothesized that the age-related degradation of the spinal shock-absorbing system composed of a spinal dural sac (SDS) and surrounding soft tissue, preventing ventricular enlargement caused by wide CSF pulsation driven by heartbeats, may be involved in the ventricular enlargement observed in iNPH. Sixty-four patients with iNPH in their seventies who underwent a lumboperitoneal shunt and a control group of 79 people in the same age group who underwent brain check-ups were included in the study. We compared the sizes of the cervical and upper parts of the thoracic SDS using magnetic resonance imaging between the two groups. The anterior-posterior distances of the dural sac at C5 were shorter in patients with iNPH of both sexes than those in the control group (P = 0.0008 in men and P = 0.0047 in women). The number of disc levels with disappeared CSF space surrounding the cervical cord was more in iNPH (P = 0.0176 and P = 0.0003). The midsagittal area of the upper part of the spinal sac, C2-Th4, was smaller in iNPH (P = 0.0057 and P = 0.0290). Narrowing of the cervical dural sac and midsagittal area in the upper part of the SDS in patients with iNPH may reflect the degradation of the shock-absorbing mechanism for CSF pressure pulsations, which may cause iNPH or at least aggravate iNPH by other unknown causes.

Evidence of spinal stiffening following fusionless bipolar fixation for neuromuscular scoliosis: a shear wave elastography assessment of lumbar annulus fibrosus.

There are no established criteria for stiffness after fusionless surgery for neuromuscular scoliosis (NMS). As a result, there is no consensus regarding the surgical strategy to propose at long-term follow-up. This study reports the first use of shear wave elastography for assessing the mechanical response of lumbar intervertebral discs (IVDs) after fusionless bipolar fixation (FBF) for NMS and compares them with healthy controls. The aim was to acquire evidence from the stiffness of the spine following FBF. Nineteen NMS operated on with FBF (18 ± 2y at last follow-up, 6 ± 1 y after surgery) were included prospectively. Preoperative Cobb was 89 ± 20° and 35 ± 1° at latest follow-up. All patients had reached skeletal maturity. Eighteen healthy patients (20 ± 4 y) were also included. Shear wave speed (SWS) was measured in the annulus fibrosus of L3L4, L4L5 and L5S1 IVDs and compared between the two groups. A measurement reliability was performed. In healthy subjects, average SWS (all disc levels pooled) was 7.5 ± 2.6m/s. In NMS patients, SWS was significantly higher at 9.9 ± 1.4m/s (p < 0.05). Differences were significant between L3L4 (9.3 ± 1.8m/s vs. 7.0 ± 2.5m/s, p = 0.004) and L4L5 (10.3 ± 2.3m/s vs. 7.1 ± 1.1m/s, p = 0.0006). No difference was observed for L5S1 (p = 0.2). No correlation was found with age at surgery, Cobb angle correction and age at the SWE measurement. This study shows a significant increase in disc stiffness at the end of growth for NMS patients treated by FBF. These findings are a useful adjunct to CT-scan in assessing stiffness of the spine allowing the avoidance of surgical final fusion at skeletal maturity.

Degenerative Cervical Disc Herniation: Prevalence of Affected Cervical Level in a Hispanic Population in Puerto Rico

BackgroundIn the literature, degenerative cervical disc herniation is considered to occur more frequently at the C5-C6 and C6-C7 levels. This study aimed to evaluate the operated cervical level prevalence among patients with degenerative cervical disc herniation in a Hispanic Puerto Rico population. MethodsThe University of Puerto Rico Neurosurgery database was used to identify patients who underwent anterior cervical discectomy for degenerative cervical disc herniation during a 15-year period from January 1, 2006 until December 31, 2020. Operated cervical levels for each patient were analyzed. ResultsDuring the study period, 409 patients were operated on for degenerative cervical disc herniation. Two hundred-eight patients (50.8%) had disc herniations at more than one cervical level for 663 treated levels. The most prevalent cervical levels in this Hispanic population were C5-C6 (34.8%) and C4-C5 (28.1%). The C6-C7 level was involved in 18.9% of the operated levels, and the C3-C4 level in 17.3%. The C7-T1 level was involved in only 0.6% of the operated levels, and the C2-3 level in 0.3%. The cohort included 51.3% of men and 48.7% of women, with a men-to-women ratio of 1.05:1. The median age of females was 56.5 (range 26 - 82) and 59.0 (range 31 - 85) for males. Operated cervical discs were most common between the ages of 48 and 66 years for either sex. ConclusionIn a Hispanic Puerto Rico population, the most prevalent operated degenerative cervical disc levels were C5-C6 and C4-C5.

Role of diffusion tensor imaging in stenotic and non-stenotic spinal canal

Background and purposeCervical Spondylotic Myelopathy (CSM) is a gradually escalating spinal cord disturbance set in motion by the degenerative narrowing of the vertebral canal. Routine MRI may fail to detect the subtle early alterations of the cord. MRI Diffusion Tensor Imaging (DTI) possesses the potential to detect these changes. This study intends to estimate the potential of the DTI technique in non-stenotic & stenotic spinal canals in individuals affected with CSM. MethodologySixty-four subjects who met the requirements of the inclusion criteria were incorporated into the investigation. All subjects underwent routine MRI sequences in addition to DTI of the cervical spine region. Scalars such as Fractional Anisotropy (FA), besides Apparent Diffusion Coefficient (ADC), were computed at each cervical intervertebral fibrocartilaginous disc level for all subjects. DTI fiber tractography was then performed to qualitatively assess the microstructural integrity of the tracts. ResultsA noteworthy difference (p<0.05) was seen in the FA parameter and ADC parameter values between the stenotic and non-stenotic groups, with the non-stenotic group having a higher mean FA and a lower ADC than the stenotic group (at the level of stenosis). A significant difference in age was seen between both groups, with most of the patients in the stenotic group belonging to 40 years and above. Tractography helped in demonstrating the morphology of the fiber tracts. ConclusionDTI parameters, namely FA and ADC, are sensitive to damage to the white matter and can be used to detect microstructural changes in the cord. However, standardization of the protocol is necessary when imaging the spinal canal.

The Comparison between Herniated and Non-Herniated Disc Levels Regarding Intervertebral Disc Space Height and Disc Degeneration, A Magnetic Resonance Study.

The main purpose of this study was to evaluate the intervertebral disc height and intervertebral disc degeneration between the normal group and the group with disc herniation at the level of the L4-L5 intervertebral disc by MRI using the Pfirrmann grading system. 385 patients were included in this study. MRI images were reevaluated and intervertebral disc heights were measured from the anterior, middle and posterior segments. Researchers divided disc pathologies into two groups. In the non-herniated group; normal or bulging ones; in the herniated group, they included those with protrusion or extrusion. 385 lumbar MRI examinations meeting the study criteria were included in study. There were 56.9% (219/385) females and 43.1% (166/385) males in the study. For the whole patients in the study group, the intervertebral disc height values at the L4-5 level were measured as 12.34 mm, 11.58 mm, and 7.60 mm in the anterior, middle, and posterior localizations, respectively. At the L4-5 level, the height of the disc distances in the herniated group was lower than in the normal group. The Pfirrman score was found to be higher in the herniated group in terms of disc degeneration compared to the normal group.

Plant susceptibility to a shared herbivore is reduced by belowground competition with neighbors.

Spatial variation in plant community composition is an important driver of variation in susceptibility to herbivores. In close proximity, certain neighbors can attract or repel herbivores to a focal plant ("associational effects"). Neighboring plants may also compete for resources, modifying their phenotype in ways that affect susceptibility to herbivores. To test whether and how competition contributes to associational effects, we manipulated the sharing of belowground resources among plant neighbors (spotted Joe Pye weed and common boneset) that serve as alternate hosts for an herbivorous beetle. In the field, the beetle Ophraella notata laid more eggs and inflicted more damage on plants of both species that were released from belowground competition with neighbors. Competition also weakened the effects of neighbor identity during field trials, reducing associational susceptibility. When beetles were forced to choose between the two host species in cage trials, competition again reduced beetle use of Joe Pye weed as a secondary host. To test the role of plant traits related to herbivore defense and nutrition, we quantified leaf protein, specific leaf area, and trichomes, and conducted behavioral assays on leaf disks. Beetles did not distinguish between Joe Pye weed treatments at the leaf disk level, and competition did not impact specific leaf area and protein. Trichome density was higher in both species in the preferred treatment. Overall, our results suggest that belowground interactions between plants may mediate the strength of associational effects, as secondary hosts become more attractive when released from competition with primary host plants.

High-sensitivity tunable perfect absorber in Dirac semimetal-buffer-substrate

We demonstrate the numerical feasibility of achieving a highly sensitive tunable perfect absorber by inserting a thin buffer layer between a disk-shaped bulk Dirac semimetal (BDS) and a substrate. Our findings indicate that the insertion of a thin buffer film directly beneath the BDS disk enhances absorption intensity, resulting in perfect absorption. Conversely, without a buffer film, the same structure does not exhibit such improved absorption properties. Moreover, the absorption peaks in the proposed device can be effectively controlled and tuned by altering physical parameters such as the permittivity and thickness of the buffer layer, operation frequency, and the Fermi energy level of the BDS disk. Importantly, our proposed structure exhibits high refractive index sensitivity (S=17.74 (µm)/RIU) and a remarkable figure of merit (FOM=20.22) compared to previous works. These results demonstrate the potential of the proposed structure for use in optical devices across various fields, including terahertz sensors.

Development of normalized quantitative measures of lumbar disc degeneration.

Lumbar disc degeneration (DD) is widely regarded as a likely contributor to low back pain (LBP), but the association between DD and LBP is relatively weak. No known studies have normalized quantitative measures of DD severity relative to multiple variables such as age, height, and disc level. This study developed normalized quantitative measures (z-scores) of disc signal intensity (DSI) and disc height (DH) to rate relative severity of DD. Raw (unnormalized) quantitative measures of DSI and DH alongside potential normalization variables were acquired from MRI scans and clinical data of 76 patients. The associations between the raw quantitative measures and potential normalization variables were investigated to develop the normalized quantitative measures (z-scores) of DSI and DH. Construct validity was assessed by comparing the normalized measures to an experienced radiologist's subjective measures of relative severity of DSI and DH loss. CSF signal intensity, age, and disc level were significantly associated with raw DSI (R 2 = 0.06, 0.25, and 0.09, respectively). Lumbar height and disc level were significantly associated with raw DH (R 2 = 0.13 and 0.31). Normalizing DSI and DH by these variables resulted in stronger relationships (R 2 = 0.39 and 0.37) than raw DSI and DH (R 2 = 0.24 and 0.31) with the radiologist's subjective measures. Normalized DSI and DH were both normally distributed (p = 0.32 and 0.12). Construct validity and the distributions suggested that normalized quantitative measures of DSI and DH are better than existing measures of DSI and DH at rating relative DD severity. Determining whether normalized quantitative measures are more predictive of clinical outcomes is important future research.

Morphological and Morphometric Analysis of the Renal Artery Using Computed Tomographic Angiography

Objective: The anatomical features of the renal arteries are important for the diagnosis of various diseases affecting the kidneys and the renal arteries (RA), as well as for preoperative planning of surgical interventions. The objective of this study was to conduct a comprehensive analysis of the morphological and morphometric parameters of renal arteries specific to the Turkish population. Methods: RA diameter, angle, and distance to other vessels were performed on computed tomography angiography images of 299 patients (156 women, 143 men), considering their branching variations and the level of origin from the abdominal aorta. Results: The frequency of RA variations was 16.5%. The right RA was observed to arise between the lower T12 level and middle L4 level, most commonly (25.39%) at the L1-2 disc level. The left RA was found to originate between the upper T12 level and lower L3 level, mostly (27.44%) at the L1-2 disc level. The mean diameter of the right RA was 5.49±1.24 mm in females and 6.01±1.69 mm in males, while the mean diameter of the left RA was 5.96±1.44 mm in females and 6.45±1.74 mm in males. The mean exit angle of the right RA from the abdominal aorta was 57.06±17.27° in females and 57.65±16.62° in males, and that of the left RA was 67.05±18.13° in females and 70.37±17.42° in males. The distance of the right RA to the celiac trunk was 3.1±1.29 cm, and its distance to the aortic bifurcation was 9.56±1.52 cm. The distance of the left RA to the celiac trunk was 3.27±1.25 cm, and its distance to the aortic bifurcation was 9.38±1.41 cm. Analysis of the relationship of the study parameters with age showed statistically significant correlations between age and the left RA diameter and between age and the distance of both the right and left renal arteries to the celiac trunk. Conclusion: This study could contribute to the literature on renal artery morphology and morphometry in the Turkish population and provide guidance to clinicians.

Quantitative multi-parameter assessment of age- and gender-related variation of back extensor muscles in healthy adults using Dixon MR imaging.

Investigate sex differences in age-related back extensor muscle degeneration using Dixon MRI and analyze the relationship between quantitative muscle parameters and back muscle strength in healthy adults. 105 healthy subjects underwent lumbar Dixon MRI. Fat fraction (FF), cross-sectional area (CSA), functional CSA (FCSA), and relative FCSA (RFCSA) of multifidus muscle (MF) and erector spinae (ES) were quantified. Back extension muscle strength was measured using an external fixation dynamometer. ANOVA with post hoc Tukey correction was used for age group comparisons. Partial and Spearman's correlation analyzed relationships between age, muscle parameters, and muscle strength. MF and ES FF significantly increased with age in both genders (r = 0.55-0.85; p < 0.001). Muscle FF increased prominently for females (40-49years, MF and 50-59years, ES) and males (60-73years, MF and ES). In females, total ES FCSA and RFCSA (r = - 0.42, - 0.37; p < 0.01) correlated with age. While in males, all MF and ES muscle size parameters, except total MF CSA, correlated with age (r = - 0.30 to - 0.58; p < 0.05). Back extension muscle strength correlated with mean FF, total CSA, and total FCAS for MF and ES individually (p < 0.001). The combined MF + ES FCSA correlation coefficient (r = 0.63) was higher than FF (r = - 0.51) and CSA (r = 0.59) (p < 0.001). Age-related back extensor muscle degeneration varies by muscle type and sex. FCSA has the highest association with back muscle strength compared to FF and CSA. The investigation of sex differences in age-related back extensor muscle degeneration utilizing Dixon imaging may hold significant implications for evaluating spine health and enabling earlier intervention. Muscles' FCSA could contribute to acquiring additional evidence for reflecting muscle function change. • The multifidus muscle (MF) and erector spinae (ES) fat fraction (FF) increased with age at all lumbar disc levels in females and males. • Age-related changes in muscle morphological quantitative parameters of healthy adults were specific by muscle type and gender. • The muscle functional cross-sectional area (FCSA) measured by Dixon imaging may better monitor back extensor muscle strength changes than muscle FF and cross-sectional area (CSA).

Preoperative low muscle mass and early postoperative outcomes in children undergoing living donor liver transplantation: A retrospective study.

Low skeletal muscle mass may develop in children with end-stage liver disease, affecting postoperative outcomes. We retrospectively investigated whether preoperative low muscle mass was associated with early postoperative outcomes in pediatric patients undergoing living donor liver transplantation (LDLT). Electronic medical records of children (age below 12y) who underwent LDLT between February 1, 2007, and January 31, 2018, were reviewed. The cross-sectional areas of psoas, quadratus lumborum, and erector spinae muscles at the level of fourth-fifth lumbar intervertebral disks were measured using abdominal CT images, divided by the square of the height and were added to obtain the total skeletal muscle index (TSMI). The patients were divided into two groups according to the median TSMI in the second quintile (1859.1mm 2 /m 2 ). Complications in the early postoperative period (within 30d after surgery) classified as Clavien-Dindo grade 3 or higher were considered major complications. Logistic regression analyses were performed to determine the association between preoperative low muscle mass and early postoperative outcomes. In the study population of 123 patients (median age, 14mo; range, 8-38mo) who underwent LDLT, 29% and 71% were classified in the low (mean TSMI, 1642.5 ± 187.0mm 2 /m 2 ) and high (mean TSMI 2188.1 ± 273.5mm 2 /m 2 ) muscle mass groups, respectively. The rates of major complications, mechanical ventilation >96 hours, intensive care unit stay >14 days, hospital stay >30 days, and in-hospital mortality were not significantly different between the 2 groups. Additionally, adverse outcomes according to pediatric end-stage liver disease scores and sex were not significantly different between the 2 groups. In conclusion, preoperative low muscle mass defined by TSMI was not associated with early postoperative outcomes in pediatric patients undergoing LDLT.

High Endplate Hounsfield Units Value Indicate Intervertebral Disc Degeneration Following Transforaminal Lumbar Interbody Fusion Surgery.

Lumbar disc degeneration (LDD) is a common cause of low back pain and disability, and its prevalence increases with age. The aim of this study is to investigate whether endplate Hounsfield unit (HU) values have an effect on lumbar disc degeneration (LDD) after transforaminal lumbar interbody fusion (TLIF) surgery in patients with degenerative lumbar stenosis. This study was a retrospective analysis of patients who underwent TLIF surgery in January 2016 to October 2019. One hundred and fifty-seven patients who underwent TLIF surgery for degenerative lumbar stenosis were enrolled in this study. Demographic data was recorded. VAS and ODI values were compared to assess the surgical outcomes in patients with or without process of LDD after TLIF surgery. Correlation analysis was performed to investigate associations between LDD and endplate HU value. Binary logistic regression analysis was carried out to study relationships between the DDD and the multiple risk factors. There was a statistically significant correlation between LDD, body mass index (BMI), age, paraspinal muscle atrophy, and total endplate scores (TEPS). Also, a strong and independent association between endplate HU value and LDD was found at every lumbar disc level (p < 0.01). After conditioning on matching factors, multivariate logistic regression analysis showed that higher endplate HU (odds ratio [OR]: 1.003, p = 0.003), higher TEPS (OR: 1.264, p = 0.002), higher BMI (odds ratio [OR]: 1.202, p = 0.002), a smaller cross-sectional area (CSA) of the paraspinal muscle preoperatively (OR: 0.096, p < 0.001) were significant predictors of LDD development after TLIF surgery. There is a significant association between LDD and endplate HU value after TLIF surgery in patients with degenerative lumbar stenosis. Beyond that, results from this study provide a mechanism by which high endplate HU value predisposes to LDD after TLIF surgery.

Rostral migration of cauda equina schwannoma: Case report and literature review

A case of mobile schwannoma of the cauda equina migrating from L3 body to L2-L3 disc level in a period of 9 months is reported

Risk of Injury to Retroperitoneal Structures in Prone and Lateral Decubitus Transpsoas Approaches to Lumbar Interbody Fusion: A Pilot Cadaveric Anatomical Study.

Introduction The retroperitoneal approach for lateral lumbar interbody fusion (LLIF) originally described an initial posterolateral fascial incision enabling finger dissection from behind the peritoneum and guidance of instruments through a second direct-lateral fascial incision. It has since become common for single direct-lateral incisional access to the retroperitoneum. This study attempted to quantify the distance of the peritoneum from posterior landmarks in the space, assess the risk of peritoneal violation in each access trajectory (i.e., posterolateral versus direct lateral retroperitoneal dissection), and determine whether there are differences based on patient position (prone versus lateral decubitus). Methods In three prone cadaveric torsos, Steinman pins were percutaneously placed mid-disc at each level L2-5 bilaterally (for a total of 18 prone approaches). Open dissections exposed the retroperitoneum including the quadratus lumborum and psoas muscles, maintaining the natural reflection of the peritoneum. Visual assessment qualified whether any pin violated any retroperitoneal structure. Distance from the anterior border of the quadratus lumborum to the posterior-most reflection of the peritoneum was measured. For comparison, three additional torsos were positioned in lateral decubitus, and the above steps were repeated, only unilaterally (for a total of nine lateral decubitus approaches). Results In prone, no pin violated the peritoneum; three (3/18 total approaches) violated the kidney, all at L2-3 (3/6 approaches at L2-3). In lateral decubitus, all three L2-3 pins violated the kidney (3/3 approaches at L2-3); five of the six remaining pins from L3-5 violated the peritoneum (totaling eight violations in the nine total approaches). The incidence of any violation was significantly greater in lateral decubitus vs. prone (8/9 vs. 3/18, p=0.0006). The structure at risk (kidney vs. peritoneum) was significantly associated with disc level (p=0.0041): all kidney violations occurred at L2-3 and all peritoneal violations occurred at L3-4 or L4-5. Distance from the quadratus lumborum to the posterior-most reflection of the peritoneum averaged 8.7 cm (range: 6-10) in prone, and 2.9 cm (range: 2.5-3.2) in lateral decubitus (p=0.0129). Conclusion A cadaveric study of retroperitoneal anatomy demonstrates that there is an increased distance from the quadratus lumborum to the peritoneum in prone versus lateral decubitus and that the trajectory of approach to the lumbar discs risks violation of the peritoneum more frequently when accessing directly laterally versus posterolaterally. In either approach, care should be taken to identify and release the peritoneal reflection to create a safe passage to the lumbar discs.

Development of a finite element full spine model with active muscles for quantitatively analyzing sarcopenia effects on lumbar load

Background and objectiveThe musculoskeletal imbalance caused by disease is one of the most critical factors leading to spinal injuries, like sarcopenia. However, the effects of musculoskeletal imbalances on the spine are difficult to quantitatively investigate. Thus, a complete finite element spinal model was established to analyze the effects of musculoskeletal imbalance, especially concerning sarcopenia. MethodsA finite element spinal model with active muscles surrounding the vertebrae was established and validated from anatomic verification to the whole spine model in dynamic loading at multiple levels. It was then coupled with the previously developed neuromuscular model to quantitatively analyze the effects of erector spinae (ES) and multifidus (MF) sarcopenia on spinal tissues. The severity of the sarcopenia was classified into three levels by changing the physiological cross-sectional area (PCSA) of ES and MF, which were mild (60% PCSA of ES and MF), moderate (48% PCSA of ES and MF), and severe (36% PCSA of ES and MF). ResultsThe stress and strain levels of most lumbar tissues in the sarcopenia models were more significant than those of the normal model during spinal extension movement. The sarcopenia caused load concentration in several specific regions. The stress level of the L4-L5 intervertebral disc and L1 vertebra significantly increased with the severity of sarcopenia and showed relatively larger values than other segments. From the normal model to a severe sarcopenia model, the stress value of the L4-L5 intervertebral disc and L1 vertebra increased by 128% and 113%, respectively. The strain level of L5-S1 also inclined significantly with the severity of sarcopenia, and the relatively larger capsule strain values occurred at lower back segments from L3 to S1. ConclusionsIn summary, the validated spinal coupling model can be used for spinal injury risk analysis caused by musculoskeletal imbalance. The results suggested that sarcopenia can primarily lead to high injury risk of the L4-L5 intervertebral disc, L1 vertebrae, and L3-S1 joint capsule regarding significant stress or strain variance.

Efficacy of Fenestration Technique for Lumbar Disc Excision in Pain Relief

Objective: To determine the outcomes of lumbar disc excision by fenestration technique for pain relief in lumbar radiculopathy due to prolapsed intervertebral disc. Methodology: This is a descriptive study conducted in a joint venture of orthopedic and neurosurgeons in a private hospital of Lahore. Study was completed in six months duration from July to December 2022. All patients presenting with lower back pain, straight leg raise test positive on &lt;60 degrees and prolapsed disc at the level of L4/L5 or L5/S1 L discs on MRI. Those with multilevel disc prolapse, previous history of spinal surgery, cauda equine syndrome and patients with lumbar stenosis were excluded from the study. All study patients were operated under general anesthesia in knee chest position. Efficacy of the procedure was determined using Dennis Pain Scale. Important findings were documented when patient was discharged. SPSS version 20 was used for statistical analysis. Results: 125 patients were studied including 73(58.4%) males and 52(41.6%) females. Patients with the age of 20-60 years were included in this study with the mean age of 47.3 ± 5.2 years. Most commonly involved disc level was L4-L5 in 77(61.6%) and L5-S1 in 48(38.4%) cases. Unilateral radicular pain was present in 94(75.2%) cases and bilateral pain was present in 31(24.8%) cases. According to Dennis Pain Scale out of 125 cases 78(62.4%) patients presented in Dennis pain scale P4 and among them complete recovery achieved in 70(89.7%) cases. Conclusion: Surgical intervention is necessary in selected patients with prolapsed intervertebral disc with chronic unilateral or bilateral radicular pain. Fenestration technique for disc excision is a very good procedure for prolapsed disc. Keywords: Sciatica, Disc Excision, Prolapsed Disc, Radiculopathy

Outpatient minimally invasive spine surgeries during the COVID-19 pandemic – A retrospective analysis of 164 consecutive cases

ObjectiveTo share our surgical experiences of minimally invasive cervical and lumbar procedures for patients who suffered from non-fatal motor vehicle accidents (MVAs) in the ambulatory surgery centers (ASCs) during the coronavirus disease 2019 (COVID-19) pandemic. MethodsAnterior cervical discectomy and fusion (ACDF), anterior lumbar interbody fusion (ALIF), minimally invasive laminotomy and discectomy (MILD), percutaneous endoscopic laser-assisted discectomy (PELD) and percutaneous kyphoplasty (PK) were performed on carefully selected patients. ResultsFrom January 2020 to December 2021, our group performed 164 cases on 153 patients involving 249 intervertebral disc (IVD) levels. Of these, 116 cases (70.73%) on 114 patients (74.51%) were cervical, 48 cases (29.27%) were lumbar (including 8 PK cases). Eight patients had both cervical and lumbar procedures in a single anesthetic session (SAS) and were discharged on the same day. One hundred and six ACDF cases (92.17%) were at the C4–C5 and C5–C6 levels, which comprised of 146 (76.04%) IVDs. Of the 40 non-PK lumbar cases, 38 (95.0%) were at L4 to S1 lumbar levels. Six of these cases (15.0%) involved 2 lumbar levels. In contrast, 6 out of 8 kyphoplasties (75.0%) involved lower thoracic/higher lumbar vertebral columns (T11 to L2) and 2 were at the lower lumbar L4 level. ConclusionsWe successfully and safely performed various cervical and lumbar spine surgeries in the ASCs amid COVID-19 pandemic and all patients achieved the same-day discharge (SDD). In the non-fatal MVAs, mid-lower cervical (C4 to C6) and lower lumbar (L4 to S1) IVDs were the most affected levels.