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Objective: Abdominal aortic calcification (AAC), often found incidentally on lateral lumbar radiographs, is increasingly recognized for its association with adverse outcomes in spine surgery. As a marker of advanced atherosclerosis affecting cardiovascular dynamics, this study evaluates AAC's impact on perioperative blood loss in posterior spinal fusion (PSF). Methods: Patients undergoing PSF from March 2016 to July 2023 were included. Estimated blood loss (EBL) and total blood volume (TBV) were calculated. AAC was assessed on lateral lumbar radiographs according to the Kauppila classification. Predictors of the EBL-to-TBV ratio (%EBL/TBV) were examined via univariable and multivariable regression analyses, which adjusted for parameters such as hypertension and aspirin use. Results: A total of 199 patients (47.2% female) were analyzed. AAC was present in 106 patients (53.3%). AAC independently predicted %EBL/TBV, accounting for an increase in blood loss of 4.46% of TBV (95% CI 1.17–7.74, p = 0.008). Conclusions: This is the first study to identify AAC as an independent predictor of perioperative blood loss in PSF. In addition to its link to degenerative spinal conditions and adverse postoperative outcomes, the relationship between AAC and increased blood loss warrants attention in patients undergoing PSF. [ABSTRACT FROM AUTHOR]

Purpose: Intervertebral vacuum phenomenon (IVP) and paraspinal muscular atrophy are age-related changes in the lumbar spine. The relationship between both parameters has not been investigated. We aimed to analyze the correlation between IVP and paraspinal muscular atrophy in addition to describing the lumbar vacuum severity (LVS) scale, a new parameter to estimate lumbar degeneration. Methods: We analyzed patients undergoing spine surgery between 2014 and 2016. IVP severity was assessed utilizing CT scans. The combination of vacuum severity on each lumbar level was used to define the LVS scale, which was classified into mild, moderate and severe. MRIs were used to evaluate paraspinal muscular fatty infiltration of the multifidus and erector spinae. The association of fatty infiltration with the severity of IVP at each lumbar level was assessed with a univariable and multivariable ordinal regression model. Results: Two hundred and sixty-seven patients were included in our study (128 females and 139 males) with a mean age of 62.6 years (55.1—71.2). Multivariate analysis adjusted for age, BMI and sex showed positive correlations between LVS-scale severity and fatty infiltration in the multifidus and erector spinae, whereas no correlation was observed in the psoas muscle. Conclusion: IVP severity is positively correlated with paraspinal muscular fatty infiltration. This correlation was stronger for the multifidus than the erector spinae. No correlations were observed in the psoas muscle. The lumbar vacuum severity scale was significantly correlated with advanced disc degeneration with vacuum phenomenon. [ABSTRACT FROM AUTHOR]

Background: The function of the paraspinal muscles and especially the psoas muscle in maintaining an upright posture is not fully understood. While usually considered solely as a hip flexor, the psoas muscle and its complex anatomy suggest that the muscle has other functions involved in stabilizing the lumbar spine. The aim of this study is to determine how the psoas muscle and the posterior paraspinal muscles (PPM; erector spinae and multifidus) interact with each other. Methods: A retrospective review including patients undergoing posterior lumbar fusion surgery between 2014 and 2021 at a tertiary care center was conducted. Patients with a preoperative lumbar magnetic resonance imaging (MRI) scan performed within 12 months prior to surgery were considered eligible. Exclusion criteria included previous spinal surgery at any level, lumbar scoliosis with a Cobb Angle > 20° and patients with incompatible MRIs. MRI-based quantitative assessments of the cross-sectional area (CSA), the functional cross-sectional area (fCSA) and the fat area (FAT) at L4 was conducted. The degree of fat infiltration (FI) was further calculated. FI thresholds for FIPPM were defined according to literature and patients were divided into two groups (< or ≥ 50% FIPPM). Results: One hundred ninetypatients (57.9% female) with a median age of 64.7 years and median BMI of 28.3 kg/m2 met the inclusion criteria and were analyzed. Patients with a FIPPM ≥ 50% had a significantly lower FI in the psoas muscle in both sexes. Furthermore, a significant inverse correlation was evident between FIPPM and FIPsoas for both sexes. A significant positive correlation between FATPPM and fCSAPsoas was also found for both sexes. No significant differences were found for both sexes in both FIPPM groups. Conclusion: As the FIPPM increases, the FIPsoas decreases. Increased FI is a surrogate marker for a decrease in muscular strength. Since the psoas and the PPM both segmentally stabilize the lumbar spine, these results may be indicative of a potential compensatory mechanism. Due to the weakened PPM, the psoas may compensate for a loss in strength in order to stabilize the spine segmentally. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the influence of vertebral endplate defects and subchondral bone marrow changes on the development of lumbar intervertebral disc degeneration (DD). Methods: Patients > 18 y/o without any history of lumbar fusion who had repeat lumbar magnetic resonance imaging scans primarily for low back pain (LBP) performed at a minimum of 3 years apart at a single institution, and no spinal surgery in between scans were included. Total endplate score (TEPS), Modic changes (MC), and Pfirrmann grading (PFG) per lumbar disc level were assessed. DD was defined as PFG ≥ 4. Results: Three hundred and fifty-three patients (54.4% female) were included in the final analysis, comprising 1765 lumbar intervertebral discs. The patient population was 85.6% Caucasian with a median age of 60.1 years and a body mass index (BMI) of 25.8 kg/m2. A cutoff score of 5 was identified for the TEPS above which both the prevalence of DD and the odds of developing DD increased. The probability of developing DD did not differ significantly between lumbar disc levels (P = 0.419). In the multivariable analysis with adjustments for age, sex, race, body mass index (BMI), MC, TEPS cutoff > 5, and spinal level, only age (OR = 1.020; P = 0.002) was found to be an independent risk factor for developing intervertebral DD. Conclusion: Our results suggest that TEPS does not unequivocally predict intervertebral DD in patients with LBP, since higher degrees of endplate defects might also develop secondarily to DD, and MC tend to occur late in the cascade of degeneration. [ABSTRACT FROM AUTHOR]

Purpose: Lumbar fusion surgery has become a standard procedure in spine surgery and commonly includes the posterior placement of pedicle screws. Bone quality is a crucial factor that affects pedicle screw purchase. However, the relationship between paraspinal muscles and the bone quality of the pedicle is unknown. The aim of the study was to determine the relationship between paraspinal muscles and the ex vivo bony microstructure of the lumbar pedicle. Methods: Prospectively, collected data of patients undergoing posterior lumbar fusion for degenerative spinal conditions was analyzed. Pre-operative lumbar magnetic resonance imaging (MRI) scans were evaluated for a quantitative assessment of the cross-sectional area (CSA), functional cross-sectional area (fCSA), and the proportion of intramuscular fat (FI) for the psoas muscle and the posterior paraspinal muscles (PPM) at L4. Intra-operative bone biopsies of the lumbar pedicle were obtained and analyzed with microcomputed tomography (µCT) scans. The following cortical (Cort) and trabecular (Trab) bone parameters were assessed: bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), connectivity density (CD), bone-specific surface (BS/BV), apparent density (AD), and tissue mineral density (TMD). Results: A total of 26 patients with a mean age of 59.1 years and a mean BMI of 29.8 kg/m2 were analyzed. fCSAPPM showed significant positive correlations with BV/TVTrab (ρ = 0.610; p < 0.001), CDTrab (ρ = 0.679; p < 0.001), Tb.NTrab (ρ = 0.522; p = 0.006), Tb.ThTrab (ρ = 0.415; p = 0.035), and ADTrab (ρ = 0.514; p = 0.007). Cortical bone parameters also demonstrated a significant positive correlation with fCSAPPM (BV/TVCort: ρ = 0.584; p = 0.002; ADCort: ρ = 0.519; p = 0.007). FIPsoas was negatively correlated with TMDCort (ρ = − 0.622; p < 0.001). Conclusion: This study highlights the close interactions between the bone microstructure of the lumbar pedicle and the paraspinal muscle morphology. These findings give us further insights into the interaction between the lumbar pedicle microstructure and paraspinal muscles. [ABSTRACT FROM AUTHOR]

Purpose: To investigate whether (1) there is a difference between patients with normal or sagittal spinal and spinopelvic malalignment in terms of their paraspinal muscle composition and (2) if sagittal malalignment can be predicted using muscle parameters. Methods: A retrospective review of patients undergoing posterior lumbar fusion surgery was conducted. A MRI-based muscle measurement technique was used to assess the cross-sectional area, the functional cross-sectional area, the intramuscular fat and fat infiltration (FI) for the psoas and the posterior paraspinal muscles (PPM). Intervertebral disc degeneration was graded for levels L1 to S1. Sagittal vertical axis (SVA; ≥ 50 mm defined as spinal malalignment), pelvic incidence (PI) and lumbar lordosis (LL) were measured, and PI-LL mismatch (PI-LL; ≥ 10° defined as spinopelvic malalignment) was calculated. A receiver operating characteristic (ROC) analysis was conducted to determine the specificity and sensitivity of the FIPPM for predicting sagittal malalignment. Results: One hundred and fifty patients were analysed. The PI-LL and SVA malalignment groups were found to have a significantly higher FIPPM (PI-LL:47.0 vs. 42.1%; p = 0.019; SVA: 47.7 vs. 41.8%; p = 0.040). ROC analysis predicted sagittal spinal malalignment using FIPPM (cut-off value 42.69%) with a sensitivity of 73.4% and a specificity of 54.1% with an area under the curve of 0.662. Conclusion: Significant differences in the muscle composition between normal and malalignment groups with respect to FIPPM in both sagittal spinal and spinopelvic alignment were found. This work underlines the imminent impact of the paraspinal musculature on the sagittal alignment. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to determine the effect of age on the psoas and posterior paraspinal muscles (PPM; multifidus muscle and erector spinae) and to evaluate potential sex-related differences.Methods: MRI-based quantitative assessments of the cross-sectional area (CSA), the functional cross-sectional area (fCSA), the fat area (FAT) and the proportion of intramuscular fat (FI) were conducted on patients undergoing lumbar fusion surgery between 2014 and 2021. The regions of interest were the psoas muscle and the PPM at the superior endplate of L4. The left and right sides of the muscle groups were summarized and normalized by the patient's height (cm2/m2). The relationships between age and muscular parameters were analyzed stratified by sex.Results: A total of 195 patients (57.9%female) with a median age of 64.2 years and a body mass index of 28.3 kg/m2 were analyzed. The CSAPsoas was 7.7 cm2/m2 and differed significantly between females and males (p < 0.001); likewise, the fCSAPsoas differed significantly between the sexes. The CSAPPM was 18.8 cm2/m2 with no sex-specific differences. Significant differences were found in the FIPPM (males: 41.1% vs. females: 47.9%; p < 0.001), but not in the FIPsoas (males: 3.7% vs. females: 4.5%; p = 0.276). Considering the effect of age on FI, a significant positive correlation was observed for the PPMs for both sexes. Only in women, there was a negative correlation between age and CSAPsoas (ρ =  - 0.248; p = 0.008), FATPsoas (ρ =  - 0.421; p < 0.001) and FIPsoas (ρ =  - 0.371; p < 0.001).Conclusion: This study demonstrated sex-specific differences in spinal muscle morphology in relation to patient age. With increasing age there was a decrease in FIPsoas in women only, unlike in the PPMs in which there was increased FI that was significantly higher in women compared to men. [ABSTRACT FROM AUTHOR]

Purpose: Presumed benefits of erector spinae plane blocks (ESPB) include an enhanced safety profile and few complications. There are few large series, which report the incidence of complications associated with ESPB on a procedure-specific basis. The objective of this retrospective cohort study was to estimate the incidence of complications of ESPB in a large series of patients undergoing lumbar spine surgery. Patients and Methods: We included 342 consecutive patients who underwent any primary lumbar spine surgery via posterior approach (November 2018–July 2020). All patients received bilateral ultrasound-guided ESPB. The primary study outcome was the incidence of any perioperative complication, defined a priori as sensory, motor, hematologic, hemodynamic or respiratory complication consistent with plausible contribution from the ESPB. Secondary outcomes included the incidence of numeric rating scale (NRS) pain scores ≥ 7 in the post anesthesia care unit (PACU) and risk factors associated with NRS ≥ 7 (age, sex, ASA class, BMI, opioid tolerance, surgical type, and duration). Results: We did not identify any pre-specified complications associated with ESPB. There was one unilateral pneumothorax, in one patient, deemed unlikely to have been related to ESPB. NRS ≥ 7 was found in 17/342 patients (5%) and was independent of any background differences or risk factors assessed. Conclusion: Ultrasound guided ESPB for lumbar spine surgery was associated with zero complications, no interference with intraoperative neuromonitoring or the early postoperative neurological examination, and low incidence of poorly controlled pain in the PACU. These results help to establish procedure-specific risks and benefits of ESPB for spine surgery. [ABSTRACT FROM AUTHOR]

Purpose: Anterior (ALIF) and lateral (LLIF) lumbar interbody fusion is associated with significant postoperative pain, opioid consumption and length of stay. Transversus abdominis plane (TAP) blocks improve these outcomes in other surgical subtypes but have not been applied to spine surgery. A retrospective study of 250 patients was performed to describe associations between TAP block and outcomes after ALIF/LLIF. Methods: The electronic medical records of 129 patients who underwent ALIF or LLIF with TAP block were compared to 121 patients who did not. All patients were cared for under a standardized perioperative care pathway with comprehensive multimodal analgesia. Differences in patent demographics, surgical factors, length of stay (LOS), opioid consumption, opioid-related side effects and pain scores were compared in bivariable and multivariable regression analyses. Results: In bivariable analyses, TAP block was associated with a significantly shorter LOS, less postoperative nausea/vomiting and lower opioid consumption in the post-anesthesia care unit (PACU). In multivariable analyses, TAP block was associated with significantly shorter LOS (β − 12 h, 95% CI (− 22, − 2 h); p = 0.021). Preoperative opioid use was a strong predictive factor for higher opioid consumption in the PACU, opioid use in the first 24 h after surgery and longer LOS. We did not find significant differences in pain scores at any times between the groups. Conclusion: TAP block may represent an effective addition to pain management and opioid-reducing strategies and improve outcomes after ALIF/LLIF. Prospective trials are warranted to further explore these associations. [ABSTRACT FROM AUTHOR]

Atrophy of the paraspinal musculature (PM) as well as generalized sarcopenia are increasingly reported as important parameters for clinical outcomes in the field of spine surgery. Despite growing awareness and potential similarities between both conditions, the relationship between "generalized" and "spine-specific" sarcopenia is unclear. To investigate the association between generalized and spine-specific sarcopenia. Retrospective cross-sectional study. Patients undergoing lumbar spinal fusion surgery for degenerative spinal pathologies. Generalized sarcopenia was evaluated with the short physical performance battery (SPPB), grip strength, and the psoas index, while spine-specific sarcopenia was evaluated by measuring fatty infiltration (FI) of the PM. We used custom software written in MATLAB® to calculate the FI of the PM. The correlation between FI of the PM and assessments of generalized sarcopenia was calculated using Spearman's rank correlation coefficient (rho). The strength of the correlation was evaluated according to established cut-offs: negligible: 0–0.3, low: 0.3–0.5, moderate: 0.5–0.7, high: 0.7–0.9, and very high≥0.9. In a Receiver Operating Characteristics (ROC) analysis, the Area Under the Curve (AUC) of sarcopenia assessments to predict severe multifidus atrophy (FI≥50%) was calculated. In a secondary analysis, factors associated with severe multifidus atrophy in nonsarcopenic patients were analyzed. A total of 125 (43% female) patients, with a median age of 63 (IQR 55–73) were included. The most common surgical indication was lumbar spinal stenosis (79.5%). The median FI of the multifidus was 45.5% (IQR 35.6–55.2). Grip strength demonstrated the highest correlation with FI of the multifidus and erector spinae (rho=-0.43 and -0.32, p<.001); the other correlations were significant (p<.05) but lower in strength. In the AUC analysis, the AUC was 0.61 for the SPPB, 0.71 for grip strength, and 0.72 for the psoas index. The latter two were worse in female patients, with an AUC of 0.48 and 0.49. Facet joint arthropathy (OR: 1.26, 95% CI: 1.11–1.47, p=.001) and foraminal stenosis (OR: 1.54, 95% CI: 1.10–2.23, p=.015) were independently associated with severe multifidus atrophy in our secondary analysis. Our study demonstrates a low correlation between generalized and spine-specific sarcopenia. These findings highlight the risk of misdiagnosis when relying on screening tools for general sarcopenia and suggest that general and spine-specific sarcopenia may have distinct etiologies. [ABSTRACT FROM AUTHOR]

Study Design.: A retrospective analysis of prospectively collected data. Objective.: To assess the association between intervertebral disk degeneration and hip and knee osteoarthritis (OA) in patients with degenerative lumbar spondylolisthesis. Background.: The co-occurrence of hip OA and degenerative spinal pathologies was first described as the "hip-spine syndrome" and has also been observed in knee OA. It remains unclear whether both pathologies share an underlying connection beyond demographic factors. Materials and Methods.: Intervertebral disk degeneration was classified by the Pfirrmann Classification and intervertebral vacuum phenomenon. Intervertebral vacuum phenomenon was classified into mild (1 point), moderate (2 points), and severe (3 points) at each level and combined into a lumbar vacuum score (0–15 points). Similarly, a lumbar Pfirrmann grade was calculated (5–25 points). Patients with previous hip or knee replacement surgery were classified as having an OA burden. We used multivariable regression to assess the association between OA and disk degeneration, adjusted for age, body mass index, and sex. Results.: A total of 246 patients (58.9% female) were included in the final analysis. Of these, 22.3% had OA burden. The multivariable linear regression showed an independent association between OA burden and lumbar vacuum (β = 2.1, P <0.001) and Pfirrmann grade (β = 2.6, P <0.001). Representing a 2.1 points higher lumbar vacuum and 2.6 points higher lumbar Pfirrmann grade after accounting for demographic differences. Conclusions.: Our study showed that OA burden was independently associated with the severity of the intervertebral disk degeneration of the lumbar spine. These findings give further weight to a shared pathology of OA of large joints and degenerative processes of the lumbar spine. Level of Evidence: 3. [ABSTRACT FROM AUTHOR]

The effect of psoas and paraspinal muscle parameters on cage subsidence after minimally invasive techniques, such as standalone lateral lumbar interbody fusion (SA-LLIF), is unknown. This study aimed to determine whether the functional cross-sectional area (FCSA) of psoas and lumbar spine extensor muscles (multifidus and erector spinae), and psoas FCSA normalized to the vertebral body area (FCSA/VBA) differ among levels with severe cage subsidence after SA-LLIF when compared to levels without severe cage subsidence. Retrospective single center cohort study. Patients who underwent SA-LLIF between 2008 and 2020 for degenerative conditions using exclusively polyetheretherketone (PEEK) cages, had a lumbar magnetic resonance imaging (MRI) scan within 12 months, a lumbar computed tomography (CT) scan within 6 months prior to surgery, and a postoperative clinical and radiographic follow-up at a minimum of 6 months were included. Severe cage subsidence. MRI measurements included psoas and combined multifidus and erector spinae (paraspinal) FCSA and FCSA/VBA at the L3-L5 pedicles. Following manual segmentation of muscles on axial T2-weighted images using ITK-SNAP (version 3.8.0), the FCSA was calculated using a custom written program on Matlab (version R2019a, The MathWorks, Inc.) that used an automated pixel intensity threshold method to differentiate between fat and muscle. Mean volumetric bone mineral density (vBMD) at L1/2 was measured by quantitative CT. The primary endpoint was severe cage subsidence per level according to the classification by Marchi et al. Multivariable logistic regression analysis was performed using generalized linear mixed models. All analyses were stratified by biological sex. 95 patients (45.3% female) with a total of 188 operated levels were included in the analysis. The patient population was 92.6% Caucasian with a median age at surgery of 65 years. Overall subsidence (Grades 0-III) was 49.5% (53/107 levels) in men versus 58.0% (47/81 levels) in women (p=.302), and severe subsidence (Grades II-III) was 22.4% (24/107 levels) in men versus 25.9% (21/81 levels) in women (p=.608). In men, median psoas FCSA and psoas FCSA/VBA at L3 and L4 were significantly greater in the severe subsidence group when compared to the non-severe subsidence group. No such difference was observed in women. Paraspinal muscle parameters did not differ significantly between non-severe and severe subsidence groups for both sexes. In the multivariable logistic regression analysis with adjustments for vBMD and cage length, psoas FCSA at L3 (OR 1.002; p=.020) and psoas FCSA/VBA at L3 (OR 8.655; p=.029) and L4 (OR 4.273; p=.043) were found to be independent risk factors for severe cage subsidence in men. Our study demonstrated that greater psoas FCSA at L3 and psoas FCSA/VBA at L3 and L4 were independent risk factors for severe cage subsidence in men after SA-LLIF with PEEK cages. The higher compressive forces the psoas exerts on lumbar segments as a potential stabilizer might explain these findings. Additional pedicle screw fixation might be warranted in these patients to avoid severe cage subsidence. [ABSTRACT FROM AUTHOR]

Purpose: The literature is scarce in exploring the role of imaging parameters like ultrasound (US) as a biomarker for surgical outcomes. The purpose of this study is to investigate the associations between skin US parameters and revision surgery following spine lumbar fusion.Posterior lumbar fusion patients with 2-years follow-up were assessed. Previous fusion or revision not due to adjacent segment disease (ASD) were excluded. Revisions were classified as cases and non-revision were classified as controls. US measurements conducted at two standardized locations on the lumbar back. Skin echogenicity of the average dermal (AD), upper 1/3 of the dermal (UD), lower 1/3 of the dermal (LD), and subcutaneous layer were measured. Echogenicity was calculated with the embedded echogenicity function of our institution’s imaging platform (PACS). Statistical significance was set at p < 0.05.A total of 128 patients (51% female, age 62 [54–72] years) were included in the final analysis. 17 patients required revision surgery. AD, UD, and LD echogenicity showed significantly higher results among revision cases 124.5 [IQR = 115.75,131.63], 128.5 [IQR = 125,131.63] and 125.5 [IQR = 107.91,136.50] compared to the control group 114.3 [IQR = 98.83,124.8], 118.5 [IQR = 109.28,127.50], 114 [IQR = 94.20,126.75] respectively.The findings of this study demonstrate a significant association between higher echogenicity values in different layers of the dermis and requiring revision surgery. The results provide insights into the potential use of skin US parameters as predictors for revision surgery. These findings may reflect underlying alterations in collagen. Further research is warranted to elucidate the mechanisms driving these associations.Methods: The literature is scarce in exploring the role of imaging parameters like ultrasound (US) as a biomarker for surgical outcomes. The purpose of this study is to investigate the associations between skin US parameters and revision surgery following spine lumbar fusion.Posterior lumbar fusion patients with 2-years follow-up were assessed. Previous fusion or revision not due to adjacent segment disease (ASD) were excluded. Revisions were classified as cases and non-revision were classified as controls. US measurements conducted at two standardized locations on the lumbar back. Skin echogenicity of the average dermal (AD), upper 1/3 of the dermal (UD), lower 1/3 of the dermal (LD), and subcutaneous layer were measured. Echogenicity was calculated with the embedded echogenicity function of our institution’s imaging platform (PACS). Statistical significance was set at p < 0.05.A total of 128 patients (51% female, age 62 [54–72] years) were included in the final analysis. 17 patients required revision surgery. AD, UD, and LD echogenicity showed significantly higher results among revision cases 124.5 [IQR = 115.75,131.63], 128.5 [IQR = 125,131.63] and 125.5 [IQR = 107.91,136.50] compared to the control group 114.3 [IQR = 98.83,124.8], 118.5 [IQR = 109.28,127.50], 114 [IQR = 94.20,126.75] respectively.The findings of this study demonstrate a significant association between higher echogenicity values in different layers of the dermis and requiring revision surgery. The results provide insights into the potential use of skin US parameters as predictors for revision surgery. These findings may reflect underlying alterations in collagen. Further research is warranted to elucidate the mechanisms driving these associations.Results: The literature is scarce in exploring the role of imaging parameters like ultrasound (US) as a biomarker for surgical outcomes. The purpose of this study is to investigate the associations between skin US parameters and revision surgery following spine lumbar fusion.Posterior lumbar fusion patients with 2-years follow-up were assessed. Previous fusion or revision not due to adjacent segment disease (ASD) were excluded. Revisions were classified as cases and non-revision were classified as controls. US measurements conducted at two standardized locations on the lumbar back. Skin echogenicity of the average dermal (AD), upper 1/3 of the dermal (UD), lower 1/3 of the dermal (LD), and subcutaneous layer were measured. Echogenicity was calculated with the embedded echogenicity function of our institution’s imaging platform (PACS). Statistical significance was set at p < 0.05.A total of 128 patients (51% female, age 62 [54–72] years) were included in the final analysis. 17 patients required revision surgery. AD, UD, and LD echogenicity showed significantly higher results among revision cases 124.5 [IQR = 115.75,131.63], 128.5 [IQR = 125,131.63] and 125.5 [IQR = 107.91,136.50] compared to the control group 114.3 [IQR = 98.83,124.8], 118.5 [IQR = 109.28,127.50], 114 [IQR = 94.20,126.75] respectively.The findings of this study demonstrate a significant association between higher echogenicity values in different layers of the dermis and requiring revision surgery. The results provide insights into the potential use of skin US parameters as predictors for revision surgery. These findings may reflect underlying alterations in collagen. Further research is warranted to elucidate the mechanisms driving these associations.Conclusion: The literature is scarce in exploring the role of imaging parameters like ultrasound (US) as a biomarker for surgical outcomes. The purpose of this study is to investigate the associations between skin US parameters and revision surgery following spine lumbar fusion.Posterior lumbar fusion patients with 2-years follow-up were assessed. Previous fusion or revision not due to adjacent segment disease (ASD) were excluded. Revisions were classified as cases and non-revision were classified as controls. US measurements conducted at two standardized locations on the lumbar back. Skin echogenicity of the average dermal (AD), upper 1/3 of the dermal (UD), lower 1/3 of the dermal (LD), and subcutaneous layer were measured. Echogenicity was calculated with the embedded echogenicity function of our institution’s imaging platform (PACS). Statistical significance was set at p < 0.05.A total of 128 patients (51% female, age 62 [54–72] years) were included in the final analysis. 17 patients required revision surgery. AD, UD, and LD echogenicity showed significantly higher results among revision cases 124.5 [IQR = 115.75,131.63], 128.5 [IQR = 125,131.63] and 125.5 [IQR = 107.91,136.50] compared to the control group 114.3 [IQR = 98.83,124.8], 118.5 [IQR = 109.28,127.50], 114 [IQR = 94.20,126.75] respectively.The findings of this study demonstrate a significant association between higher echogenicity values in different layers of the dermis and requiring revision surgery. The results provide insights into the potential use of skin US parameters as predictors for revision surgery. These findings may reflect underlying alterations in collagen. Further research is warranted to elucidate the mechanisms driving these associations. [ABSTRACT FROM AUTHOR]

Background Context: The thoracic spine is a common location for vertebral fractures as well as instrumentation failure after long spinal fusion procedures. The association between those complications and bone mineral density (BMD) are well recognized. Due to the overlying sternum and ribs in the thoracic spine, projectional BMD assessment tools such as dual energy x-ray absorptiometry (DXA) are limited to the lumbar spine. Quantitative computed tomography circumvents several shortcomings of DXA and allows for level-specific BMD measurements. Studies comprehensively quantifying BMD of the entire thoracic spine in patients undergoing spine surgery are limited.Purpose: The objective of this study was: (1) to assess the reliability of thoracic QCT measurements, (2) to determine possible level-specific BMD variation throughout the thoracic spine and (3) to assess the correlation between BMDs of the T1-T12 spinal levels.Study Design/setting: Cross-sectional observation study.Patient Sample: Patients undergoing spine surgery from 2016-2020 at a single, academic institution with available preoperative CT imaging of the thoracic spine were included in this study.Outcome Measures: The outcome measure was BMD measured by QCT.Methods: Patients undergoing spine surgery from 2016-2020 at a single, academic institution with available preoperative CT imaging of the thoracic spine were included in this study. Subjects with previous instrumentation at any thoracic level, concurrent vertebral fractures, a Cobb angle of more than 20 degrees, or incomplete thoracic spine CT imaging were excluded. Asynchronous quantitative computed tomography (QCT) measurements of T1-T12 were performed. To assess inter- and intra-observer reliability, a validation study was performed on 120 vertebrae in 10 randomly selected patients. The interclass correlation coefficient (ICC) was calculated. A pairwise comparison of BMD was conducted and correlations between each thoracic level were evaluated. The statistical significance level was set at p<.05.Results: 60 patients (men, 51.7%) met inclusion criteria. The study population was 90% Caucasian with a mean age of 62.2 years and a mean BMI of 30.2 kg/m2. The inter- and intra-observer reliability of the thoracic QCT measurements was excellent (ICC of 0.97 and 0.97, respectively). The trabecular BMD was highest in the upper thoracic spine and decreased in the caudal direction (T1 = 182.3 mg/cm3, T2 = 168.1 mg/cm3, T3 = 163.5 mg/cm3, T4 = 164.7 mg/cm3, T5 = 161.4 mg/cm3, T6 = 152.5 mg/cm3, T7 = 143.5 mg/cm3, T8 = 141.3 mg/cm3, T9 = 143.5 mg/cm3, T10 = 145.1 mg/cm3, T11 = 145.3 mg/cm3, T12 = 133.6 mg/cm3). The BMD of all thoracic levels cranial to T6 was statistically higher than the BMD of all levels caudal to T6 (p < .001). Nonetheless, significant correlations in BMD among all measured thoracic levels were observed, with a Pearson's correlation coefficient ranging from 0.74 to 0.97.Conclusions: There is significant regional BMD variation in the thoracic spine depending on spinal level. This BMD variation might contribute to several clinically relevant phenomena. First, vertebral fractures occur most commonly at the thoracolumbar junction including T12. In addition to mechanical reasons, these fractures might be partially attributed to thoracic BMD that is lowest at T12. Second, the optimal upper instrumented vertebra (UIV) for stopping long fusions to the sacrum and pelvis is controversial. The BMD of surgically relevant upper thoracic stopping points (T2-T4) was significantly higher than the BMD of lower thoracic stopping points (T10-T12). Besides stress concentration at the relatively mobile lower thoracic segments, the low BMD at these levels might contribute to previously suggested higher rates of junctional failures with short fusions. [ABSTRACT FROM AUTHOR]

Lumbar fusion surgery has become a standard procedure in spine surgery and commonly includes posterior placement of pedicle screws. Bone quality is a critical factor that affects pedicle screw purchase, whereas the role of paraspinal musculature is less well understood. Pedicle screw loosening is a devastating complication often leading to revision surgery. However, the relationship of paraspinal muscles and the pedicle is unknown. Therefore, we aimed to determine the relationship between paraspinal muscle composition and bony microstructure of the lumbar. Lumbar fusion surgery has become a standard procedure in spine surgery and commonly includes posterior placement of pedicle screws. Bone quality is a critical factor that affects pedicle screw purchase, whereas the role of paraspinal musculature is less well understood. Pedicle screw loosening is a devastating complication often leading to revision surgery. However, the relationship of paraspinal muscles and the pedicle is unknown. The aim of the study was to determine the relationship between paraspinal muscle composition and bony microstructure of the lumbar pedicle. Prospective study. Twenty-four patients undergoing open posterior lumbar fusion at a single academic institution. Preoperative lumbar magnetic resonance imaging (MRI) scans were evaluated using a dedicated software for a quantitative assessment of the cross-sectional area (CSA), the functional cross-sectional area (fCSA), and the proportion of intramuscular fat. The regions of interest were the psoas muscle and the paraspinal muscles at the superior endplate of the L4 level. Left and right side of the muscle groups were averaged and normalized by the patient's height (cm2/m2). Intraoperative bone biopsies of the lumbar pedicle were obtained and analyzed with microscopic computed tomography (microCT) scans. Parameters of cortical (Cort) and trabecular (Trab) bone were collected and the following parameters assessed: bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), connectivity density (CD), specific bone surface (BS/BV), apparent density (AD) and total mineral density (TMD). The relationship between microCT parameters and paraspinal CSA, fCSA and fat infiltration were determined by the Spearman correlation. The relationship between microCT parameters and paraspinal CSA, fCSA and fat infiltration were determined by the Spearman correlation. Statistical significance was defined as p<0.05. Twenty-four patients (50% female) with a median age of 62.2 years (IQR: 54.7-68.2) and a mean (±SD) BMI of 29.8 (6) kg/m2 were analyzed. fCSA of the paraspinal muscles showed significant positive correlations with BV/TV Trab (r=0.582, p=0.003), CD Trab (r=0.639; p < 0.001), Tb.N Trab (r=0.469, p=0.021), Tb.Th (r=0.405, p=0.0049) and AD Trab (r=0.510, p=0.011). Cortical bone parameters also demonstrated a significant positive correlation with fCSA (BV/TVCort: r= 0.551, p=0.005; ADCort: r=0.551, p=0.005). fCSA of the psoas showed no correlation with cortical or trabecular microCT parameters, but fat infiltration of the psoas was negatively correlated with TMD Cort (r=-663, p < 0.001). This study provides evidence that the bone microstructure of the lumbar pedicle is significantly correlated with the fCSA of the paraspinal musculature. Whether this finding is related to mechanical coupling or to biochemical processes cannot be conclusively stated. However, this finding gives us further insight in the mutual interactions between lumbar vertebral bone and paraspinal muscles. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Quantitative computed tomography (QCT) is considered a standard reportable metric for the measurement of bone mineral density (BMD) of the lumbar spine. However, the sole determination of BMD is insufficient for the evaluation of overall bone health. Consequently, bone quality, apart from BMD, is increasingly recognized for its importance in the assessment of bone. Collagen cross-linking is a relevant factor for determining the tensile strength of bone. Non-enzymatic collagen cross-linking with the accumulation of advanced glycation end products (AGEs) stiffens and embrittles collagen fibers, thus increasing bone fragility and fracture risk. Despite the crucial role of AGEs in bone ageing, the relationship between AGEs and BMD is poorly understood. We hypothesized that an accumulation of AGEs, a marker of impaired bone quality, is related to decreased BMD. Prospective observational study. A total of 107 patients undergoing open posterior lumbar fusion at a single academic institution. Standardized lumbar QCT measurements were performed on preoperative CT scans using the L1/L2 average. Intraoperative bone biopsies from the posterior superior iliac spine were obtained and analyzed with confocal fluorescence microscopy for fluorescent advanced glycation end products (fAGEs), both trabecular and cortical, representing non-enzymatic collagen cross-linking. Pearson's correlation coefficients were calculated to examine crude relationships between BMD at L1/L2 and fAGEs, stratified by biological sex. Multivariable linear regression analysis with adjustments for age, sex, body mass index (BMI), diabetes and HbA1c was used to investigate associations between BMD at L1/L2 and fAGEs. Statistical significance was defined as p<0.05. A total of 107 patients (51.2% female) with a mean age of 61.2 years and a BMI of 29.9 kg/m2 were included in the final analysis, excluding patients with anti-osteoporotic drug therapy. In the univariate analysis, cortical fAGEs increased with decreasing BMD at L1/L2 (r = -0.32; p = 0.021), but only in men. In the multivariate analysis, trabecular fAGEs increased with decreasing BMD at L1/L2 after adjusting for age, sex, BMI, diabetes mellitus, and HbA1c (β = 0.99; p = 0.04). This is the first study to assess BMD and in-vivo non-enzymatic collagen cross-linking as a marker of bone quality in lumbar fusion patients. QCT-derived BMD measurements were found to be significantly associated with collagen properties in bone, such as fAGEs, which embrittle bone tissue. Our results enhance our understanding of bone health by suggesting that spine surgery patients with deficits in bone quantity may also have deficits in bone quality. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Loss of paraspinal muscle mass over time can affect spinal degeneration and promote lumbar back pain. New methods to determine muscle quantity and quality have been established, including the evaluation of the functional cross-sectional area (fCSA) and fat infiltration. However, little is known about the aging processes that occur in spinal muscle groups and sex-specific differences. Aim of this study was to determine if the processes of aging are comparable in the psoas and posterior paraspinal muscles (PPM; musclus multifidus and erector spinae), and to evaluate potential sex-related differences. Retrospective cohort study. A total of 176 patients undergoing open posterior lumbar fusion surgery. MRI-based quantitative assessments of the cross-sectional area (CSA), the functional cross-sectional area (fCSA), and the proportion of intramuscular fat were conducted. The regions of interest were the psoas muscle and the PPM at the superior endplate of the L4 level. The left and right side of the muscle groups were averaged and normalized by the patient's height (cm2/m2). The relationship between age and 1) psoas CSA, fCSA and fat infiltration, and 2) PPM CSA, fCSA and fat infiltration was determined by Pearson´s correlation coefficients, stratifying all analyses by sex. Statistical significance was defined as p<0.05. A total of 176 patients (59% female) were included in the final analysis with a median age of 64.7 years (IQR: 56.6-71.5]) and a median BMI of 28.2 kg/m2 (IQR: 25.1.7-32.6). The mean normalized CSA of the psoas was 4.07±0.1cm2/m2 (mean±standard deviation) and differed significantly between females (3.5±1.2cm2/m2) and males (4.9±1.0cm2/m2) likewise, the fCSA of psoas differed significantly between the sexes. The mean CSA of the PMMs was 9.9 cm2/m2 (±0.2) with no sex specific differences and showed no correlation in both groups with age. Significant differences in the fatty infiltration between men and women in the paraspinal muscles (m:41.7%; f:47.3%; p < 0.001), and there were no differences found in the psoas regarding fatty infiltration (m:5.7%; f:6.1%; p=0.631). Considering the effect of age on the fat infiltration, a significant positive correlation was observed in the PMMs for both sexes (f: r=0.651, p < 0.001; m: r=0.429, p < 0.001). In women, there was a negative correlation between age and psoas CSA (r=-0.228; p=0.02), and fat infiltration of psoas (r=-0.297; p=0.002). This study demonstrated sex-specific differences in spinal muscle morphology in relation to patient´s age. There was a decrease in fat infiltration of the psoas in women with increasing age, unlike in the posterior paraspinal musclesin which there was increased fat infiltration. This phenomenon is controversial to the assumption that fatty infiltration increases with age. The work provides further evidence on sex differences within different paraspinal muscle groups in patients undergoing posterior lumbar fusion. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Bone quality, apart from bone mineral density, is increasingly recognized for its importance in the assessment of fracture risk. Collagen cross-linking is a relevant factor for determining the tensile strength of bone. Non-enzymatic collagen cross-linking with the accumulation of advanced glycation end products (AGEs) stiffens and embrittles collagen fibers thus increasing bone fragility and fracture risk. Echogenicity is an ultrasound parameter providing information regarding the skin collagen structure and can be determined by assigning amplitudes of echoes for each pixel on a scale and segmenting the image by pixel range. Increased echogenicity in the deep portion of the dermal layer is observed with increasing age, thought to be due to disordered collagen. We hypothesized that both skin and bone collagen are aging in the same fashion and that skin ultrasound measurements would therefore be associated with in-vivo bone quality. Prospective observational study. A total of 110 patients undergoing open posterior lumbar fusion at a single academic institution. Preoperative standardized skin ultrasound measurements were performed in the lumbar region for the assessment of dermal thickness and echogenicity. Intraoperative bone biopsies from the posterior superior iliac spine were obtained and analyzed with confocal fluorescence microscopy for fluorescent advanced glycation end products (fAGEs, trabecular and cortical), representing non-enzymatic collagen cross-linking. Pearson's correlation coefficients were calculated to examine relationships between (1) US measurements and fAGEs, and (2) age and fAGEs stratified by sex. Multivariable linear regression analysis with adjustments for age, sex, BMI, diabetes and HbA1c was used to investigate associations between ultrasound measurements and fAGEs. Statistical significance was defined as p<0.05. A total of 110 patients (51.9% female) with a mean age of 61.6 years and a body mass index (BMI) of 29.8 kg/m2 were included in the final analysis, excluding patients with anti-osteoporotic drug therapy and non-Caucasian ethnicity In the univariate analysis, trabecular fAGEs increased with subcutaneous echogenicity (r = 0.31; p = 0.039); cortical and trabecular AGEs decreased with age, but only in women (cortical r = -0.32, p = 0.031; trabecular r = -0.32; p = 0.031). After adjusting for age, sex, BMI, diabetes and HbA1c, significant associations were found between cortical fAGEs and lower dermal echogenicity (β = 1.01; p = 0.012), cortical fAGEs and subcutaneous echogenicity (β = 1.01; p = 0.021), and trabecular fAGEs and lower dermal echogenicity (β = 1.01; p = 0.021). This is the first study to assess in-vivo bone quality and skin ultrasound measurements regarding non-enzymatic collagen cross-linking in lumbar spine fusion patients. Dermal ultrasound measurements were found to be significantly associated with collagen properties in bone such as fAGEs. As a noninvasive assessment tool, skin ultrasound measurements might be incorporated into future practice to investigate connective tissue aging and bone quality in spine surgery patients. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Low muscle volume, also called sarcopenia, is a common condition of aging with a prevalence between 1 and 29% in populations over the age of 50 years. Previous studies have demonstrated evidence that both osteoporosis and sarcopenia coexist, called osteosarcopenia, and these patients are at greater risk for falls, fractures and mortality. In osteoporotic post-menopausal female patients, the prevalence of sarcopenia is around 50%. Recent studies showed that sarcopenic subjects had a 4-fold higher risk of coexisting osteoporosis compared with nonsarcopenic individuals. However, a limited number of studies have been conducted in spine surgery patients. The aim of this study is to investigate the associations between the lean muscle volume (LMV) in paraspinal and proas muscle on MRI and quantitative computed tomography (QCT) volumetric bone mineral density (vBMD) in the lumbosacral region. A cross-sectional analysis of a prospectively maintained database at a single academic institution. Patients undergoing posterior lumbar fusion surgery between 2014-2020. Volumetric BMD measured by QCT in the lumbar spine and sacral ala. We reviewed an institutional database of posterior lumbar fusion patients. Patients who had ongoing antiosteoporotic therapy with bisphosphonate, denosumab or teriparatide were excluded. Muscle measurements were conducted utilizing a free software program (ITK-SNAP version 3.8) setting regions of interest (ROI) in the bilateral psoas and paraspinal (erector spinae and multifundus) muscles on preoperative T2-weighted axial MR images at the mid-L3 level. The area of fat-free muscle (LMV: lean muscle volume) was calculated using a custom written program on Matlab™ (MATLAB version 2019a, The MathWorks, Inc, Natick, MA, USA). QCT measurements were performed on preoperative CT scans using the Mindways QCT Pro Software (Mindways Software, Inc., Austin, TX, USA). QCT-vBMDs in the standard L1-L2 and bilateral sacral ala were analyzed. Pearson's correlation and linear regression analyses adjusting with age and BMI were performed. Since muscle volume is strongly affected by biological sex, we stratified by sex for all analyses. Statistical significance was set <0.05. Out of 144 patients, 30 patients were excluded due to QCT incompatible CTs or poor quality MRIs for muscle volume measurements. An additional 9 patients were excluded due to ongoing anti-osteoporotic drug therapy. A total of 105 patients (50 male and 55 female) were included in the final analysis. In female patients, there were statistically significant mild to moderate positive correlations between L1-L2 vBMD and LMV in paraspinal and psoas muscles, as well as sacral ala vBMD and paraspinal LMV, whereas there was no significant correlation in male patients. After the adjustment with age and BMI, high paraspinal LMV was an independent factor for high sacral ala vBMD (β=0.04 (95%CI: 0.00-0.14), p=0.040) and high psoas LMV was significantly associated with high L1-L2 vBMD (β=0.04 (95%CI: 0.01-0.14), p=0.025). Our results demonstrated that higher lean muscle volume was significantly associated with higher vBMD in the lumbosacral lesions in women. This association was not observed in men. This might indicate gender differences should be considered for the assessment of osteosarcopenia in spine surgery patients. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Anterior (ALIF) and lateral (LLIF) lumbar interbody fusion is associated with significant postoperative pain, opioid consumption and length of stay (LOS). Transversus abdominis plane (TAP) blocks improve these outcomes in other surgical subtypes but have not been applied to spine surgery. To describe associations between TAP block and outcomes after ALIF/LLIF. A retrospective analysis of patients who underwent primary ALIF or LLIF at an orthopedic specialty hospital. A total of 250 consecutive patients who underwent primary ALIF or LLIF between January 2016 and December 2019. LOS, pain scores, opioid consumption and opioid-related side effects The electronic medical records of 129 patients who underwent ALIF or LLIF with TAP block were compared to 121 patients who did not. All patients were cared for under a standardized perioperative care pathway with comprehensive multimodal analgesia. Differences in patent demographics, surgical factors, LOS, opioid consumption, opioid-related side-effects and pain scores were compared in bivariable and multivariable regression analyses. In bivariable analyses, TAP block was associated with a significantly shorter LOS, less postoperative nausea/vomiting, and lower opioid consumption in the post-anesthesia care unit (PACU). In multivariable analyses, TAP block was associated with significantly shorter LOS (β-12 hours, 95% CI (-22, -2 hours); p=0.021). Preoperative opioid use was a strong predictive factor for higher opioid consumption in the PACU, opioid use in the first 24 hours after surgery, and longer LOS. We did not find significant differences in pain scores at any times between the groups. TAP block may represent an effective addition to pain management and opioid reducing strategies and improve outcomes after ALIF/LLIF. Prospective trials are warranted to further explore these associations. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]