Lukas Schönnagel

Background: Spinal mobility and functional strength is an integral part in the orthopaedic and rheumatologic assessment of patients with spinal disorders and chronic low back pain (cLBP), yet their relationship with health-related quality of life (QoL) remains insufficiently explored. Patients and methods: This is a retrospective cross-sectional study that recruited volunteers with (cLBP) and without chronic low back pain (nLBP) between 2022 and 2025. Lumbar mobility was assessed using a device-assisted back-scan (Idiag M360 ^® ), as well as conventional functional assessments, including Schober and finger-to-floor-distance (FFD). Functional strength was assessed via sit-to-stand test (STS). Primary outcomes were the short form 36 domains Physical Functioning (SF36-PF) and Bodily Pain (SF36-BP) as well as cLBP. The International Physical Activity Questionnaire–Short Form (IPAQ-SF) served as a secondary outcome measure. Multivariable linear regression models were performed adjusted for baseline characteristics; and in a subgroup analysis stratified by LBP; binary logistic regression was performed to evaluate the independent associations of each measure for cLBP. Results: 1,309 adults (cLBP = 562, nLBP = 747) were included. LBP groups were comparable in BMI and physical activity. The STS, FFD and Idiag M360 thoracolumbar flexion/extension were significantly associated with SF36-PF and SF36-BP in both pain-status groups (all p ≤ 0.002). Greater STS performance, higher (inverted) FFD and Idiag M360 thoracolumbar flexion/extension were associated with a lower OR of cLBP (all p ≤ 0.001). The Schober test showed weaker associations with SF-36 overall (β* = 0.085–0.120). The IPAQ showed no meaningful associations with any mobility measure. Conclusions: Lumbar functional strength and mobility were strongly associated with cLBP and QoL and when reduced, was associated with higher odds for cLBP. The findings of this study support the adoption of STS and device-assisted mobility measurements for functional assessment of the spine; whether these measures can identify early, modifiable determinants of QoL or predict outcomes remains a hypothesis for prospective studies.

Purpose: Forward head posture (FHP) is commonly assessed using isolated cervical measures, potentially overlooking its relationship with global sagittal alignment. This study introduces the Global Sagittal Deviation Index (GSDI-5), a composite measure integrating multiregional sagittal alignment with explicit inclusion of the upper cervical spine. Methods: Standing lateral EOS radiographs from 201 adults referred for evaluation of low back pain were analysed and classified into FHP and non-FHP groups. Standardized sagittal parameters across the cervical, thoracic, lumbar, and global spine were combined into a single score. Initial construct validity was examined through known-groups comparisons and convergent analyses with TPA and PI–LL. Results: Individuals with FHP demonstrated higher GSDI-5 scores. GSDI-5 showed a large effect size for differentiating FHP from non-FHP (Hedges’ g = 0.85), slightly exceeding that of TPA (g = 0.81) and PI–LL (g = 0.32), with increasing severity associated with progressive changes in global alignment measures. Conclusion: By integrating upper cervical alignment into a whole-spine framework, GSDI-5 summarizes cranio-cervical behaviour relevant to FHP and may serve as a complementary exploratory measure for global sagittal deviation in radiographic and postural assessment, alongside existing sagittal alignment metrics.

Study Design: Retrospective cohort study of prospectively enrolled patients. Objectives: To evaluate the association between postoperative slip reduction and improvement in disability and low back pain (LBP) after lumbar fusion for low-grade degenerative spondylolisthesis (DLS), and to determine whether outcomes are independently associated with slip reduction or with sagittal alignment changes. Methods: 160 patients undergoing lumbar fusion for low-grade DLS were analyzed. Slip reduction was quantified on lateral radiographs as absolute change in relative slippage normalized to vertebral body dimensions. Disability and LBP were assessed using the Oswestry Disability Index (ODI) and numeric rating scale (NRS) preoperatively and at two years. Associations between slip reduction and improvement in ODI and LBP were analyzed using multivariable linear regression adjusted for demographics, baseline symptoms, fusion length, and preoperative slippage. Results: Slip reduction was independently associated with greater improvement in ODI and LBP (both p0.05). Conclusions: Postoperative slip reduction was independently associated with greater improvement in disability and LBP among patients undergoing lumbar fusion with attempted reduction for low-grade DLS, whereas associated changes in sagittal alignment were not. However, given the moderate explanatory power of the regression models, slip reduction should be interpreted as one of several factors associated with postoperative outcomes. As this was an observational analysis, residual confounding by indication cannot be excluded, and prospective validation is warranted to further define the role of slip reduction in surgical decision-making.

Background/Objectives: Total en bloc spondylectomy (TES) remains one of the most invasive and selectively used procedures in spine oncology. Its role has become more selective in the modern era of stereotactic body radiotherapy, separation surgery, targeted systemic therapy, immunotherapy, and multidisciplinary cancer care. This study evaluated long-term survival, imaging-defined systemic disease burden, operative morbidity, patient-reported outcomes, and frailty-related variables after TES in a rare single-center cohort, with the goal of identifying selection-relevant survival and treatment-burden signals rather than developing a validated decision algorithm. Methods: We performed a retrospective single-center cohort study of consecutive adults who underwent TES for spinal tumors between 2011 and 2022. Of the 36 screened patients, 30 had sufficient clinical and survival data for analysis; patients without reliable survival or last-contact data were not included. Contrast-enhanced CT and PET-CT were reviewed for extraspinal metastases, lymphadenopathy, pleural effusion, and soft-tissue extension. Survival was analyzed using Kaplan–Meier methods, log-rank testing, and exploratory univariate Cox regression. Patient-reported outcomes included the Oswestry Disability Index (ODI) and SF-36 when available; frailty was summarized with the modified frailty index-5 (mFI-5) when component data were present. Results: The cohort included 13 men and 17 women with a mean age of 54.8 ± 15.2 years. At final follow-up, 18 patients had died, and 12 were alive. Five-year overall survival was approximately 76% in the full cohort. Extraspinal metastases were present in 72.2% of deceased patients compared with 8.3% of survivors and showed the clearest exploratory association with increased mortality (HR 3.46, 95% CI 1.23–9.78; p = 0.019). Metastatic disease demonstrated inferior survival compared with primary bone or soft-tissue tumors. Perioperative blood loss and transfusion burden were substantial but were not associated with survival in univariate analysis. ODI and SF-36 data were available only in small subsets and were therefore interpreted as descriptive signals of treatment burden. Conclusions: TES remains relevant in modern spine oncology, but only as an increasingly selective intervention. In this rare cohort, systemic disease burden, particularly extraspinal metastases, was the clearest selection-relevant survival signal, while blood loss, transfusion requirements, complications, and limited patient-reported outcomes illustrated substantial treatment burden. These findings do not establish a validated selection algorithm but support a contemporary decision threshold that integrates tumor biology, systemic disease status, anticipated margins, physiologic reserve, operative morbidity, and patient goals.

Background/Objectives: Sagittal spinal alignment is a key determinant of function and quality of life in degenerative spinal disorders. While age is an established determinant of sagittal balance, the independent contribution of BMI remains insufficiently characterized, particularly in degenerative scoliosis cases. This study aimed to investigate the association between BMI and sagittal alignment, quantify its effect relative to age, and explore potential sex-specific differences. Methods: This retrospective single-center study included 293 adults with degenerative scoliosis who underwent standing full-spine EOS imaging. Multivariable linear regression models assessed the association between BMI and sagittal vertical axis (SVA), adjusting for age, sex, diabetes mellitus, and osteoporosis. Secondary analyses examined associations with coronal deformity (Cobb angle) and lumbar degeneration (Wilke score). Sex-stratified analyses and Receiver Operating Characteristic (ROC) analyses for sagittal decompensation were also performed. Results: The cohort had a median BMI of 26.2 kg/m² (56% female; median age 71 years). Median SVA measured 56.4 mm (interquartile range 30.6–87.1), and 58% of patients exhibited sagittal decompensation. In sex-stratified analyses, higher BMI was independently associated with greater SVA in women (p = 0.015), whereas no significant association was observed in men (p = 0.061). ROC analysis demonstrated limited overall discrimination; however, a BMI ≥ 35 kg/m² showed high specificity and positive predictive values exceeding 80% for sagittal decompensation. Conclusions: BMI is independently associated with sagittal alignment in degenerative scoliosis and contributes to sagittal decompensation to a degree comparable to age. These findings suggest that body weight represents a clinically relevant biomechanical factor that should be considered alongside age and spinopelvic parameters when interpreting sagittal alignment, although BMI’s limited discriminatory performance for sagittal decompensation precludes its use as a standalone screening tool.

Chronic low back pain (cLBP) is a major contributor to global disability. This study examined the association between paraspinal muscle morphology and spinal mobility and alignment in individuals with and without cLBP. In this cross-sectional study, participants were prospectively recruited from the general population. Magnetic resonance imaging (MRI) was used to assess morphological characteristics, namely fatty infiltration (FI) and functional cross-sectional area (fCSA) of the multifidus (MF), erector spinae (ES), and psoas muscles at all lumbar levels individually and averaged. Lumbar mobility (flexion, extension, side-bending) was assessed with a skin surface measurement device. Associations between both parameters were evaluated using multivariable regression models adjusted for demographic, structural, and clinical confounders. 721 participants (56.9% females, 226 without cLBP, 495 with cLBP) with a mean age of 41.8 (SD 12.1) were included. Average MF FI showed the strongest association with flexion in the cLBP group (ß: -0.50, 95% CI-0.66 - -0.34, p < 0.001, η²=0.071), exceeding the influence of age, disc degeneration, and pain intensity. This association was also significant in asymptomatic participants, though weaker (ß: -0.40, 95% CI -0.66 - -0.14, p = 0.003, η²=0.041). Level-specific differences were observed, with MF fCSA at L4/5-L5/S1 and ES fCSA at upper levels showing the strongest association with lumbar mobility. MRI-based morphology of paraspinal muscles is associated with spinal mobility in both cLBP and asymptomatic individuals, independent of key confounders. Associations were level-, muscle-, and movement-specific, with the strongest effects observed for MF FI and lumbar flexion.

Design: Retrospective study. Objective: To evaluate the predictive performance of a simplified, MRI-derived vertebral bone quality score (VBQ) using measurements at L1/2 (VBQ _L1/2 ) for opportunistic bone quality screening, compared to the established VBQ _L1-4. Methods: In patients undergoing lumbar surgery for degenerative spondylolisthesis, VBQ _L1/2 was assessed using circular regions of interest on sagittal T1-weighted sequences in L1 and L2, while VBQ _L1-4 included measurements from L1 through L4. Measurements were normalized to cerebrospinal fluid intensity at L2/3. Bone mineral density (BMD) was measured by opportunistic qCT, with osteoporosis defined as BMD < 80 mg/cm ³ and impaired bone quality (osteoporosis or osteopenia) as BMD < 120 mg/cm ³ . Agreement between VBQ _L1/2 and VBQ _L1-4 was determined using the intraclass correlation coefficient (ICC), and predictive performance was evaluated using receiver operating characteristic analysis with Youden’s index optimization. Results: Among 144 patients included ((39% male, n = 56) the median age was 69 years (interquartile range 64-67). Osteopenia was present in 47% and osteoporosis in 22%, yielding 69% impaired bone quality. VBQ _L1/2 and VBQ _L1-4 showed excellent agreement (ICC: 0.988, 95% CI: 0.982–0.991). Predictive performance was comparable for osteoporosis (AUC: VBQ _L1/2 0.71 vs. VBQ _L1-4 0.69) and impaired bone quality (AUC: 0.68 vs. 0.67). For osteoporosis detection, VBQ _L1/2 showed a higher sensitivity (94% vs 71%) but a lower specificity (45% vs 64%), as well as for detecting impaired bone quality (sensitivity 77% vs. 47%, 56%, vs 82%). Conclusions: VBQ _L1/2 offers a simplified alternative to VBQ _L1-4 for MRI-based bone quality assessment. Further validation and threshold refinement are warranted.

Even though adult degenerative scoliosis (ADS) is an increasingly relevant pathology in the aging spine, its pathophysiology has yet to be fully understood. As some previous studies have shown degeneration of the paraspinal muscles to be associated with ADS, this study aimed to examine side-specific degeneration of the erector spinae (ES), multifidus (MF), and psoas (PS) along the concave and convex aspects of the curvature. This retrospective study included patients with adult degenerative scoliosis (Cobb > 10°) and a defined apex at L3 who underwent spinal fusion surgery of at least 2 levels at a tertiary academic center. Paraspinal muscle morphology was assessed on preoperative axial T2-weighted MRIs, including fatty infiltration (FI) and height-adjusted functional cross-sectional area (fCSA). Measurements were performed bilaterally from L1/2 to L5/S1 using standardized segmentation and Otsu thresholding. Spinopelvic parameters, including Cobb angle, sagittal vertical axis (SVA), lumbar lordosis (LL), and sacral slope (SS), were measured on standing radiographs. Differences between the concave and convex sides were assessed using Wilcoxon signed-rank tests. Associations with spinopelvic alignment were analyzed using multivariable linear regression adjusted for age, sex, and BMI. A total of 51 patients with median age of 82 (IQR 72 - 85) and 70.6% posterior-only surgery were included. Marked asymmetries in paraspinal muscle composition were observed, particularly at and around the apex. The mean Cobb angle was 18.4° (15.1° - 24.3°). FI was higher and fCSA lower on the concave side, with the strongest differences in the MF at L2/3 and L3/4 (15.53, IQR 4.71-26.65, p < 0.001). Greater asymmetry in MF FI (β: 0.22, 95% CI: - 0.40- - 0.05, p = 0.014, η² = 0.147) and ES FI (β: 0.45, 95% CI: - 0.69- - 0.21, p < 0.001, η² = 0.268) was significantly associated with an increased Cobb angle. In contrast, increased erector spinae fCSA on both sides was significantly associated with greater SVA (β: 11.52, 95% CI: 3.28-19.77, p = 0.008, η² = 0.193). Our results show a significant asymmetry in muscle degeneration with more pronounced changes on the concave curve side, as well as an association of increased asymmetry with an increasing Cobb angle. In contrast, greater sagittal imbalance was linked to increased muscle mass, indicating a potential hypertrophic adaptation rather than muscle atrophy as the principal contributor to sagittal decompensation. Although our cohort is predominantly geriatric and limited to patients with moderate Cobb angles, our results should be taken into consideration for further research and when developing novel treatment strategies for these patients.