Association between back muscle degeneration and spinal-pelvic parameters in patients with degenerative spinal kyphosis

Relationship between paraspinal muscle morphology and function in different directions in a healthy Chinese population at different ages: a cross-sectional study

BACKGROUND

Paraspinal muscle degeneration occurs with age; however, it is unknown whether strength and endurance change with muscle cross-sectional area (CSA) and fatty infiltration (FI) parameters in Chinese healthy individuals.

METHODS

A total of 94 asymptomatic Chinese volunteers were enrolled in this study. The participants were divided into three groups: young (20-39 years old, n = 27), middle-aged (40-59 years old, n = 49), and elderly (≥ 60 years old, n = 18). CSA and FI of the psoas (PS), quadratus lumborum (QL), multifidus (MF), and erector spinae (ES) were measured using magnetic resonance imaging. The Bionix Sim3 Pro was used to evaluate the maximum isometric torque and the Ito test to evaluate endurance.

RESULTS

The CSA of the PS and ES in the elderly group was smaller than those in the other groups, while the CSA of QL in the young group was larger than that in the other groups. There were differences in the MF and ES FI among the three groups. The maximum isometric torque and endurance test time decreased with increasing age; however, these differences were not statistically significant. Maximum isometric torque positively correlated with the average paraspinal muscle CSA and negatively correlated with the torque and FI of the MF and ES muscles. The endurance test was found to be positively correlated with the FCSA of the MF and to be negatively correlated with the FI of the MF and ES. PS and QL can predict the maximum isometric torque, and MF and PS can predict the endurance time.

CONCLUSION

MF and ES showed earlier degeneration than PS and QL. MF is the first paraspinal muscle to undergo functional area atrophy, and it plays an important role in the endurance test. The maximum moment of equal length in all directions of the lumbar spine is not completely symmetrical, but it is correlated with the imaging parameters of the paraspinal muscles. QL and PS were more activated in the lumbar activity.

TRIAL REGISTRATION

The study was registered in Chinese Clinical Trial Registry and the registration number is ChiCTR2000039073 on 15/10/2020 ( https://www.chictr.org.cn/showproj.html?proj=62785 ). Ethical Approval was obtained from the Peking University Third Hospital Medical Science Research Ethics Committee (IRB00006761-M2020305).

What patient parameters influence lumbar stiffness in patients with hip pathology?

Lumbar stiffness leads to greater hip dependence to achieve sagittal motion and increases instability after total hip arthroplasty (THA). We aimed to determine parameters that influence lumbar stiffness among patients with hip pathology. We hypothesized that modifiable (degenerative changes, spinal canal stenosis, facet orientation) and nonmodifiable factors (muscle condition) would be associated with lumbar spine stiffness. In this retrospective case-cohort study from a tertiary referral center, consecutive patients presenting at a hip specialist clinic underwent standing and deep-seated radiographic assessment to measure lumbar lordosis (∆LL) (stiffness: ∆LL < 20°), hip flexion (∆PFA: pelvic femoral angle), and degree of degenerative-disc-disease (DDD) (facet osteoarthritis, disc height, endplate proliferative changes). Of these, 65 patients were selected with previous lumbar spine magnetic resonance imaging, allowing to determine lumbar facet orientation, spinal canal stenosis (Schizas classification), and flexor- and extensor-muscle atrophy (Goutallier classification). Mean ∆LL was 45° (range: 11°-72°) and four patients (6%) exhibited spine stiffness. Patients with multilevel DDD (n = 22) had less ∆LL than those with no/single level (n = 43) DDD (34° [range: 11°-53°] vs. 51° [21°-72°]; p < 0.001). Number of DDD levels correlated strongly with ∆LL (ρ = -0.642; p < 0.001). Spinal stiffness was only seen in patients with ≥4 DDD levels. There was no correlation between ∆LL and facet orientation (p > 0.05). ∆LL correlated strongly with extensor atrophy at L3-L4 (ρ = -0.473), L4-L5 (ρ = -0.520), and L5-S1 (ρ = -0.473) and poorly with flexors at L4-L5 (ρ = -0.134) and L5-S1 (ρ = -0.227). Lumbar stiffness is dependent on modifiable (muscle atrophy) and nonmodifiable (extend of DDD) factors. This can guide nonoperative management of hip pathology, emphasizing the relevance of core muscle rehabilitation to improve posture and stiffness. Identification ≥4 DDD levels should alert surgeons of increased THA instability risk. Level of evidence: level IV, cohort series.

Automated assessment of pelvic radiographs using deep learning: A reliable diagnostic tool for pelvic malalignment

Pelvic malalignment leads to general imbalance and adversely affects leg length. Timely and accurate diagnosis of pelvic alignment in patients is crucial to prevent additional complications arising from delayed treatment. Currently, doctors typically assess pelvic alignment either manually or through radiography. This study aimed to develop and assess the validity of a deep learning-based system for automatically measuring 10 radiographic parameters necessary for diagnosing pelvic displacement using standing anteroposterior pelvic X-rays. Between March 2016 and June 2021, pelvic radiographs from 1215 patients were collected. After applying specific selection criteria, 550 pelvic radiographs were chosen for analysis. These data were utilized to develop a deep learning-based system capable of automatically measuring radiographic parameters relevant to pelvic displacement diagnosis. The system's diagnostic accuracy was evaluated by comparing automatically measured values with those assessed by a clinician using 200 radiographs selected from the initial 550. The results indicated that the system exhibited high reliability, accuracy, and reproducibility, with a Pearson correlation coefficient of ≥0.9, an intra-class correlation coefficient of ≥0.9, a mean absolute error of ≤1 cm, mean square error of ≤1 cm, and root mean square error of ≤1 cm. Moreover, the system's measurement time for a single radiograph was found to be 18 to 20 times faster than that required by a clinician for manual inspection. In conclusion, our proposed deep learning-based system effectively utilizes standing anteroposterior pelvic radiographs to precisely and consistently measure radiographic parameters essential for diagnosing pelvic displacement.

Erector Spinae Atrophy Correlates with Global Sagittal Imbalance and Postoperative Proximal Junctional Kyphosis Incidence in Lumbar Degenerative Kyphosis

STUDY DESIGN

Retrospective cohort study.

PURPOSE

This study aimed to investigate the relationship between lumbar erector muscle atrophy and global sagittal imbalance in lumbar degenerative kyphosis (LDK) and with postoperative proximal junctional kyphosis.

OVERVIEW OF LITERATURE

Lumbar erector muscle atrophy has been studied in LDK. However, its role in the compensatory mechanism is still under intense discussion, and the role of erector spinae (ES) muscle is always overlooked.

METHODS

This study enrolled 51 patients with LDK out of 382 patients with adult degenerative spinal deformity. Baseline information was reviewed including demographic data and complications. Sagittal spinopelvic alignments and global imbalance parameters were assessed on full-length X-ray images of the spine. Muscularity and the fatty infiltration area of the ES and multifidus (MF) were measured at the L4/5 level on preoperative magnetic resonance image to evaluate the lumbar erector muscle atrophy. Stratification by sagittal vertical axis (SVA) was performed: group 1 with SVA <100 mm and group 2 with SVA >100 mm, and these groups were compared. Spearman correlation and multivariable logistic regression analyses were performed to analyze and define risk factors of postoperative proximal junctional kyphosis (PJK).

RESULTS

Group 2 had lower ES and MF muscularity than group 1. ES muscularity correlated with SVA (r=-0.510, p<0.003), lumbar lordosis (r=-0.415, p<0.018), and postoperative PJK (r=-0.508, p<0.022). MF muscularity did not correlate with the above parameters. Multivariable logistic regression analysis verified ES muscularity (odds ratio [OR], 0.001; p<0.039) and SVA (OR, 1.034; p<0.048) as the risk factors for postoperative PJK.

CONCLUSIONS

ES atrophy, besides the MF, is an important predictor in distinguishing decompensated LDK from well-compensated ones. It plays an important role in compensatory mechanism, not only correlates with global sagittal imbalance but also ties to PJK after deformity corrective surgery.

Relationship between paravertebral muscle degeneration and spinal-pelvic sagittal parameters in patients with lumbar disc herniation

Lumbar disc herniation (LDH) is a clinically common degenerative disease of the spine, and spinal-pelvic sagittal balance and paravertebral muscle degeneration have been a research focus in recent years. To explore the relationship between the degeneration of paravertebral muscle and the changes in the spinal-pelvic sagittal parameters in LDH patients, 105 LDH patients (experimental group) and 63 healthy volunteers (control group) hospitalized in Ordos Central Hospital from January 2020 and January 2023 were included as study subjects. All the patients underwent lumbar magnetic resonance imaging and spinal X-ray using uniform criteria. The correlation between the paravertebral muscle and sagittal-pelvic sagittal parameters of the patients with LDH was obtained from two imaging examinations, and the data were organized and grouped to explore the correlation between these parameters. No significant difference in general data existed between the groups (P > 0.05). In the L4/5 LDH patients group, the ratio of fat infiltration (FIR) in the healthy side [multifidus (MF) and erector spinae (ES)] was negatively correlated with the lumbar lordosis (LL) (r = -0.461, r = -0.486, P < 0.05). The relative cross-sectional area (RCSA) of the bilateral MF was positively correlated with the pelvic tilt (r = 0.549, r = 0.515, P < 0.05). The bilateral ES RCSA was negatively correlated with the sagittal vertical axis (r = -0.579, r = -0.621, P < 0.05). A positive correlation existed between the RCSA and thoracic kyphosis in the healthy side ES (r = 0.614, P < 0.05). In the L5/S1 LDH patients group, a negative correlation existed between the FIR and LL in the healthy side ES (r = -0.579, P < 0.05). Thus, the paravertebral muscle parameters were correlated with the spinal-pelvic sagittal parameters in the patients with LDH.

Psoas muscle index and psoas muscle density are associated with functional status in patients with degenerative lumbar spinal stenosis

BACKGROUND

The factors affecting lumbar spinal function in patients with degenerative lumbar spinal stenosis (DLSS) are still unclear.

OBJECTIVE

This study explored psoas major muscle morphology in patients with DLSS and its association with their functional status.

METHODS

A retrospective study was conducted on 288 patients with DLSS and 260 control subjects. Psoas major muscle evaluation included three morphometric parameters at the L3/4 disc level: psoas major index (PMI), muscle attenuation, and psoas major morphological changes (MPM). The association between psoas major morphology and functional status was assessed using the Oswestry disability index (ODI).

RESULTS

Both female and male patients with DLSS had a higher PMI and lower muscle attenuation. PMI and muscle attenuation were inversely correlated with age in the DLSS group. After multivariable analyses, the PMI and psoas major muscle attenuation were positively correlated with patients' functional status.

CONCLUSION

The PMI and muscle attenuation were positively correlated with functional status in patients with DLSS. These findings have important implications for physiotherapy programs of postoperative rehabilitation and conservative management of DLSS.

The association between morphological characteristics of paraspinal muscle and spinal disorders

BACKGROUND

Spinal disorders affect millions of people worldwide, and can cause significant disability and pain. The paraspinal muscles, located on either side of the spinal column, play a crucial role in the movement, support, and stabilization of the spine. Many spinal disorders can affect paraspinal muscles, as evidenced by changes in their morphology, including hypertrophy, atrophy, and degeneration.

OBJECTIVES

The objectives of this review were to examine the current literature on the relationship between the paraspinal muscles and spinal disorders, summarize the methods used in previous studies, and identify areas for future research.

METHODS

We reviewed studies on the morphological characteristics of the paravertebral muscle and discussed their relationship with spinal disorders, as well as the current limitations and future research directions.

RESULTS

The paraspinal muscles play a critical role in spinal disorders and are important targets for the treatment and prevention of spinal disorders. Clinicians should consider the role of the paraspinal muscles in the development and progression of spinal disorders and incorporate assessments of the paraspinal muscle function in clinical practice.

CONCLUSION

The findings of this review highlight the need for further research to better understand the relationship between the paraspinal muscles and spinal disorders, and to develop effective interventions to improve spinal health and reduce the burden of spinal disorders.

Paraspinal Muscle Degeneration as an Independent Risk for Loss of Local Alignment in Degenerative Lumbar Scoliosis Patients After Corrective Surgery

STUDY DESIGN

Retrospective study.

OBJECTIVES

To investigate the effect of paraspinal muscle degeneration on the maintenance of local and global alignment among degenerative lumbar scoliosis (DLS) patients after corrective surgery.

METHODS

98 DLS patients with a mean follow-up period of 38.3 months after corrective surgery were included. The T1 pelvic angle (TPA), lumbar lordosis (LL), pelvic incidence were measured preoperatively, immediate postoperatively and at last follow-up. All patients were divided into LL maintenance group (n = 21) and LL loss group (n = 77). For patients with well-aligned correction (immediate postoperative TPA ≤ 20°, n = 73), they were divided into TPA maintenance group (last follow-up TPA ≤ 20°) and TPA loss group (last follow-up TPA > 20°). The relative gross cross-sectional area (rGCSA) and fat infiltration (FI) of multifidus (MF) and erector spinae (ES), and the relative functional CSA (rFCSA) of psoas major (PS) were measured at L3, L4 and L5 on preoperative magnetic resonance imaging.

RESULTS

MF rGCSA were significantly smaller in LL loss group than in LL maintenance group. Both MF rGCSA and PS rFCSA were significantly smaller and MF FI was significantly higher in TPA loss group than in TPA maintenance group. Binary logistic regression revealed that the MF rGCSA was an independent factor of LL loss; Large immediate postoperative TPA was an independent risk factor of TPA loss, but not the parameters of paraspinal muscles.

CONCLUSION

The effect of paraspinal muscles in lower lumbar segments might be mainly focused on the maintenance of local alignment rather than the global alignment.

Impacts of gait biomechanics of patients with thoracolumbar kyphosis secondary to Scheuermann's disease

Introduction: Thoracolumbar kyphosis (TLK) is a common feature in patients with spinal deformities. However, due to limited studies, the impacts of TLK on gait have not been reported. The objective of the study was to quantify and evaluate the impacts of gait biomechanics of patients with TLK secondary to Scheuermann's disease. Methods: Twenty cases of Scheuermann's disease patients with TLK and twenty cases of asymptomatic participants were recruited into this study. And the gait motion analysis was conducted. Results: The stride length was shorter in the TLK group compared to control group (1.24 ± 0.11 m vs. 1.36 ± 0.21 m, p = 0.04). Compared to control group, the stride time and step time were more prolonged in the TLK group (1.18 ± 0.11s vs. 1.11 ± 0.08 s, p = 0.03; 0.59 ± 0.06 s vs. 0.56 ± 0.04 s, p = 0.04). The gait speed of the TLK group was significantly slower than it of control group (1.05 ± 0.12 m/s vs. 1.17 ± 0.14 m/s, p = 0.01); In the sagittal plane, the range of motion (ROM) of the hip in the TLK group was significantly smaller than that of the control group (37.71 ± 4.35° vs. 40.05 ± 3.71°, p = 0.00). In the transverse plane, the adduction/abduction ROMs of the knee and ankle, as well as the internal and external rotation of the knee, were smaller in TLK group than ROMs in the control group (4.66 ± 2.21° vs. 5.61 ± 1.82°, p = 0.00; 11.48 ± 3.97° vs. 13.16 ± 5.6°, p = 0.02; 9.00 ± 5.14° vs. 12.95 ± 5.78°, p = 0.00). Discussion: The main finding of this study was that measurements of gait patterns and joint movement of the TLK group were significantly lower than those of the control group. And these impacts have the potential to exacerbate degenerative progress of joints in the lower extremities. These abnormal features of gait can also serve as a guideline for physicians to focus on TLK in these patients.

Isokinetic strength assessment of trunk muscle and its relationship with spinal-pelvic parameters in patients with degenerative spinal deformity

BACKGROUND

The incidence rate of degenerative spinal deformity (DSD) has gradually increased in the elderly. Currently, the relationship between the functional status of trunk muscle and the spinal-pelvic parameters of DSD patients remains unclear.

OBJECTIVE

This paper aims to explore the relationship between the two factors and provide new clues for exploring the mechanism of the occurrence and development of DSD.

METHODS

A total of 41 DSD patients treated in our hospital (DSD group) and 35 healthy volunteers (control group) were selected. Muscle strength was evaluated using an IsoMed-2000 isokinetic dynamometer, and the trunk flexor and extensor peak torque (PT) of subjects was measured at a low, medium, and high angular velocity of 30∘/s, 60∘/s, and 120∘/s, respectively. Hand grip strength (HGS) was assessed using an electronic grip dynamometer and Surgimap software was used to measure the spinal-pelvic parameters, including the sagittal vertical axis (SVA), thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence rate (PI), and PI-LL, and the relationship between trunk muscle function and various parameters was analyzed.

RESULTS

Under the three angular velocities, the flexor and extensor PT values in the DSD group were lower than those in the control group, and only the extensor PT showed a statistically significant difference (P< 0.05). There was no significant difference in HGS between the two groups (P> 0.05). In the DSD group, the extensor PT at 30∘/s was significantly negatively correlated with SVA (P< 0.05). At 60∘/s and 120∘/s, the extensor PT was significantly negatively correlated with SVA and PT (P< 0.05).

CONCLUSION

Trunk extensor strength is significantly lower in DSD patients than in normal controls. The decline in trunk extensor strength in DSD patients is a type of local muscle dysfunction more closely related to the deformity, which is likely involved in the compensatory mechanism of DSD and may reflect the overall imbalance of the trunk.

A clinical nomogram for predicting the residual low back pain after percutaneous endoscopic surgery for lumbar disc herniation

PURPOSE

Current findings suggest that minimally percutaneous endoscopic lumbar discectomy (PELD) is a practical therapeutic approach for lumbar disc herniation (LDH). However, some patients still end up with residual low back pain, even after surgery. Our study aims to construct and validate a nomogram to predict residual low back pain after PELD.

METHODS

The medical records of 355 LDH patients admitted to the author's hospital were retrospectively analyzed between January 2019 and December 2021. The patients were randomly divided into two groups with a ratio of 7:3, namely a modelling group and a validation group. The univariable logistics and multivariable regression methods were used to screen the independent risk factors. A nomogram was then drawn using independent risk factors selected from the univariable and multivariable regression analyses. The concordance index (C-index), the receiver operating characteristic (ROC) curve, the calibration curve, and the decision curve analysis were used to evaluate the nomogram's performance. Finally, the accuracy of the nomogram was verified by a validation cohort.

RESULTS

36.6% (130/355) of patients showed low back pain after percutaneous endoscopic lumbar discectomy, while 63.4% (225/355) showed no symptoms. Multivariable logistical regression analysis showed that Modic change (p < 0.05, OR = 1.813), fatty infiltration of the paravertebral muscle (p < 0.05, OR = 2.935), and edema of lumbodorsal fascia (p = 0.049, OR = 1.611) were significant risk factors for post-operative residual back pain. Moreover, the C-index of the predictive nomogram was 0.743 (0.681-0.805), the area under the receiver operating characteristic curve (AUC) value was 0.739, and the DCA results exhibit a net benefit between 0.16 and 0.66. The above internal validation methods demonstrate the nomogram's good predictive capability.

CONCLUSION

Each variable in the model had a quantitatively corresponding risk score, which can be used in predicting residual low back pain after PELD.

Correlation between surgical segment mobility and paravertebral muscle fatty infiltration of upper adjacent segment in single-segment LDD patients: retrospective study at a minimum 2 years' follow-up

OBJECTIVE

The purpose of this study was to investigate the relationship between surgical segment mobility and fatty infiltration of the adjacent segment paravertebral muscles in patients with single-segment lumbar degenerative disease (LDD) who underwent decompression with fusion or dynamic stabilization.

METHODS

Retrospective analysis of patients who underwent lumbar decompression combined with titanium rod fixation intertransverse fusion (PITF group), Isobar TTL dynamic stabilization (TTL group) or Isobar EVO dynamic stabilization (EVO group) for single-segment lumbar degenerative disease, from March 2012 to July 2018. The preoperative and final follow-up clinical indexes C-LDSI and the measured imaging indexes (range of motion of the surgical segment and the upper adjacent segment, and Goutallier grade of the upper adjacent segment) were counted, and the differences between the preoperative and final follow-up indexes were compared.

RESULTS

According to the inclusion and exclusion criteria, 68 patients were included in this study, 21 in the PITF group, 24 in the TTL group, and 23 in the EVO group. At the final follow-up, the C-LSDI score had significantly higher in the PITF group than the TTL and EVO groups, and the C-LSDI score was a very strongly negatively correlated with ROM of surgical segment (r=-0.7968, p < 0.001). There was a strong negative correlation between surgical segment and upper adjacent segment mobility (r = -0.6959, p < 0.001). And there was a very strong negative correlation between ROM of surgical segment and upper adjacent segment paravertebral muscle Goutallier classification (r = -0.8092, p < 0.001), whereas the ROM of the upper adjacent segment was strong positive correlated with the Goutallier classification (r = 0.6703, P < 0.001).

CONCLUSION

Compared with decompression combined with rigid fusion, decompression combined with dynamic fixation for single-segment lumbar degenerative disease can significantly reduce postoperative low back stiffness. And a certain range of increased mobility of the dynamic stabilization device can effectively reduce the compensatory mobility of the upper adjacent segment and slow down the fatty infiltration of the paravertebral muscle in the adjacent segment.

Degenerative characteristics of multifidus at different vertebral levels of scoliosis in patients with degenerative lumbar scoliosis and relationship of these degenerative characteristics with surface electromyography activity

BACKGROUND

Previous studies have investigated the imaging changes of the paravertebral muscles (PVM) in patients with degenerative lumbar scoliosis (DLS); however, most of these studies focused on the apical vertebra (AV) level or compared with the average of the whole-segment measurement. In this study, magnetic resonance imaging (MRI) combined with surface electromyography (sEMG) was used to analyze the degenerative characteristics of the multifidus (MF) in patients with DLS at three levels of scoliosis (upper end vertebra [UEV], AV, and lower end vertebra [LEV]).

METHODS

This is a prospective cross-sectional study. Forty patients with DLS (DLS group) and 40 healthy individuals without lumbar scoliosis (control group) were evaluated. The percentage of fat infiltration area (%FIA) and muscle relative cross-sectional area (rCSA) of the MF at the three levels of scoliosis were measured on MRI, whereas the sEMG activity of the participants in both groups was recorded during action tasks. The imaging parameters, sEMG activity, and relationship between them were analyzed.

RESULTS

In the control group, there were no significant differences in the %FIA, rCSA, or sEMG activation of the MF between the bilateral sides at the three measured levels. In the DLS group, measurement of the MF at the UEV and AV levels showed that the %FIA was larger on the concave than convex side and that the rCSA was smaller on the concave than convex side, but there was no difference between the two parameters at the LEV level. In the standing flexion and extension tasks, the sEMG activation of the MF was higher on the concave than convex side. The coronal Cobb angle was correlated with the difference in the measurement data of the MF at the UEV and AV levels, but not with the difference at the LEV level.

CONCLUSION

The MF in patients with DLS has the same degenerative features at the UEV and AV levels, with the concave side showing greater degeneration; however, there are different degenerative manifestations at the LEV level. The MF degeneration at the UEV and AV levels is the result of spinal deformity, while the muscle changes at the LEV level are more consistent with natural degeneration.

Preoperative Association Between Quantitative Lumbar Muscle Parameters and Spinal Sagittal Alignment in Lumbar Fusion Patients

STUDY DESIGN

A retrospective cross-sectional study.

OBJECTIVE

To assess the association between spinal muscle morphology and spinopelvic parameters in lumbar fusion patients, with a special emphasis on lumbar lordosis (LL).

SUMMARY OF BACKGROUND DATA

Maintenance of sagittal alignment relies on muscle forces, but the basic association between spinal muscles and spinopelvic parameters is poorly understood.

MATERIALS AND METHODS

Patients operated between 2014 and 2017 who had both lumbar magnetic resonance imaging scan and standing whole-spine radiographs within six months before surgery were included. Muscle measurements were conducted on axial T2-weighted magnetic resonance images at the superior endplate L3-L5 for the psoas and L3-S1 for combined multifidus and erector spinae (paraspinal) muscles. A pixel intensity threshold method was used to calculate the total cross-sectional area (TCSA) and the functional cross-sectional area (FCSA). Spinopelvic parameters were measured on lateral standing whole-spine radiographs and included LL, pelvic incidence (PI), PI-LL mismatch, pelvic tilt, sacral slope, thoracic kyphosis, and sagittal vertical axis. Analyses were stratified by biological sex. Multivariable linear regression analyses with adjustments for age and body mass index (BMI) were performed.

RESULTS

A total of 104 patients (62.5% female) were included in the analysis. The patient population was 90.4% White with a median age at surgery of 69 years and a median BMI of 27.8 kg/m 2 . All muscle measurements were significantly smaller in women. PI, pelvic tilt, and thoracic kyphosis were significantly greater in women. PI-LL mismatch was 6.1° (10.6°) in men and 10.2° (13.5°) in women ( P =0.106), and sagittal vertical axis was 45.3 (40.8) mm in men and 35.7 (40.8) mm in women ( P =0.251). After adjusting for age and BMI, paraspinal TCSA at L3-L5, and paraspinal FCSA at L4 showed significant positive associations with LL in women. In men, psoas TCSA at L5 and psoas FCSA at L5 showed significant negative associations with LL, but none of the paraspinal muscle measurements.

CONCLUSION

Our findings indicate that psoas and lumbar spine extensor muscles interact differently on LL among men and women, creating a unique mechanical environment.

LEVEL OF EVIDENCE

Level 4.

Surface electromyography study on asymmetry in paravertebral muscle degeneration in patients with degenerative lumbar scoliosis

The asymmetry of paravertebral muscle (PVM) degeneration in degenerative lumbar scoliosis (DLS) patients has been extensively studied by imaging and histological examination and has not yet been verified by surface electromyography (sEMG) techniques. To study the relationship between the surface electromyography (sEMG) and degenerative characteristics of paravertebral muscles (PVMs) in patients with degenerative lumbar scoliosis (DLS). In twenty DLS patients and fifteen healthy subjects, sEMG activity of the PVMs at the level of the upper end vertebra (UEV), apical vertebra (AV) and lower end vertebra (LEV) was measured during static standing and dynamic standing forward flexion and backward extension tasks. Action segmentation was achieved according to inertial measurement unit (IMU) data. The sEMG characteristics of the PVMs on the convex and concave sides were compared, and the relationship of these data with the Cobb angle and lumbar lordotic angle (LL) was analyzed. In the DLS group, there was no difference in sEMG activity between the convex and concave sides at the UEV or AV level, but in the motion and return phases of the standing forward flexion task (P = 0.000, P = 0.015) and the maintenance and return phases of the standing backward extension task (P = 0.001, P = 0.01), there was a significant difference in sEMG activity between the convex and concave sides at the LEV level. Asymmetrical sEMG activity at the LEV level was negatively correlated with the Cobb angle (F = 93.791, P < 0.001) and LL angle (F = 65.564, P < 0.001). In the DLS group, asymmetrical sEMG activity of the PVMs appeared at the LEV level, with the concave side being more active than the convex side. This sEMG characteristics were consistent with their imaging and histological degenerative features and correlated with bone structural parameters.

Global Alignment and Proportion (GAP) score in asymptomatic individuals: is it universal?

BACKGROUND

The global alignment and proportion (GAP) score was established based on American and European subjects, which might limit its applicability to the Chinese population due to ethnicity-related difference of sagittal alignment.

PURPOSE

To analyze the applicability of GAP score in the Chinese population and to investigate the age- and gender-associated differences of spinopelvic and GAP score parameters.

STUDY DESIGN

A prospective cross-sectional radiographic study.

PATIENTS SAMPLE

Of 692 asymptomatic Chinese volunteers aged between 20 and 79 prospectively recruited between January 2017 and June 2019, 490 subjects were eventually included in this study.

OUTCOME MEASURES

The pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), L1-S1 lordosis, L4-S1 lordosis, sagittal vertical axis (SVA), T1 pelvic angle (TPA) and global tilt (GT) were measured on lateral X-rays. The GAP scores and its parameters including relative pelvic version (RPV), relative lumbar lordosis (RLL), lordosis distribution index (LDI) and relative spinopelvic alignment (RSA) were calculated for each subject.

METHODS

Subjects were divided into four groups: Group 1M: male subjects <60 years old; Group 1F: female subjects <60 years old; Group 2M: male subjects ≥60 years old and Group 2F: female subjects ≥60 years old. The GAP scores and categories were determined and compared between groups. The results of sagittal alignment were compared with the previous studies evaluating the normative sagittal alignment in other populations. Univariate linear regression analysis was carried out between pelvic incidence (PI) and sacral slope (SS), lumbar lordosis (LL) and global tilt (GT) in each group.

RESULTS

The distributions of GAP categories and the updated Roussouly classification were statistically different from other populations. Significantly different distribution of GAP categories was observed between Group 1M and Group 2M, Group 1F and Group 2F, and Group 1M and Group 1F. Radiographic measurements and GAP parameters were significantly different between Group 1M and Group 2M, and Group 1F and Group 2F. Gender-related difference of parameters was more prominent between Group 1M and Group 1F. Linear relationship of PI with SS, LL and GT were different from the regression models of "ideal" sagittal alignment in GAP score.

CONCLUSIONS

The GAP score might be inappropriate in Chinese population due to ethnicity-related alignment difference. Worse feasibility of GAP score was observed in female and old subjects.

Correlations between paraspinal extensor muscle endurance and clinical outcomes in preoperative LSS patients and clinical value of an endurance classification

Background

Few study has investigated how paraspinal muscle endurance deteriorates in lumbar spinal stenosis (LSS) patients. In addition, little information is available on the relationship between clinical outcomes and the endurance of paraspinal muscles.

Objective

To explore the correlation between paraspinal extensor muscle endurance, quality of life (QOL) and sagittal spinopelvic alignment. Besides, we attempted to propose a paraspinal extensor muscle endurance test (PEMET) classification for identifying the severity of clinical symptoms and sagittal imbalance in LSS patients.

Methods

171 hospitalized LSS patients and 100 healthy controls from the community were prospectively enrolled in this study. The paraspinal extensor endurance test was performed at baseline according to Ito test. The LSS patients were stratified into three groups based on the performance time of endurance test: grade I (<10s); grade II (10–60s); and grade III (>60s). Clinical measures of QOL included the visual analog scale scores (VAS) for back pain and leg pain and the Oswestry Disability Index (ODI). Sagittal alignment was analysed by standing posteroanterior and lateral whole spine X-ray in LSS patients.

Results

The LSS group had a significantly shorter performance time of the endurance test than the control group. The paraspinal muscle endurance significantly correlated with VAS-back, VAS-leg, ODI, pelvic tilt, lumbar lordosis and sagittal vertical axis (SVA; all p < 0.05). In binary logistic regression, the performance time of the endurance test was an independent factor of both poor functional status (ODI >40; p = 0.005, OR = 0.985) and global sagittal imbalance (SVA >50 mm; p = 0.019, OR = 0.985). Based on PEMET classification, moving from the grade III group to the grade I group, there was progressive worsening in VAS-back and ODI (all adjusted p < 0.05). Moreover, the grade I group had significantly greater VAS- leg, less LL and greater SVA than the other two groups (all adjusted p < 0.05).

Conclusion

Paraspinal muscle endurance was associated with QOL and sagittal spinopelvic alignment in LSS patients. A PEMET classification system has been constructed and has shown a correlation with QOL and sagittal imbalance.

Translational potential statement

The PEMET classification system proposed in this study could be available for identifying the severity of clinical symptoms and sagittal imbalance during preoperative evaluation in LSS patients.

Relationships between Paraspinal Muscle and Spinopelvic Sagittal Balance in Patients with Lumbar Spinal Stenosis

OBJECTIVE

To investigate the relationships between measurements of paraspinal muscle and spinopelvic sagittal parameters and the predictive value of lumbar indentation value (LIV) on sagittal balance in patients with lumbar spinal stenosis.

METHODS

It was a retrospective study. We collected the data of 110 patients, who were diagnosed as lumbar spinal stenosis from December 2018 to May 2019. The total cross-sectional area (tCSA), functional cross-sectional area (fCSA), and fatty infiltration (FI) of paraspinal muscle were measured. The spinopelvic sagittal parameters were also measured, including sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), and PI minus LL (PI-LL). Correlations between measurements of paraspinal muscle and sagittal parameters were investigated by Pearson correlation analysis. The multiple linear regression analysis was used to investigate the LIV, age, gender, and BMI for assessing spinopelvic sagittal balance. Receiver-operating characteristic (ROC) curve was used to find out the most optimum cut-off point of LIV for evaluating SVA.

RESULTS

There were 42 males and 68 females in this study and the mean age was 59.9 ± 10.9 years old. By Pearson correlation analysis, MF tCSA showed significant association with LL (r = 0.455, P < 0.01) and PI-LL (r = -0.286, P < 0.01). MF fCSA had a significant correlation with LL (r = 0.326, P < 0.01) and PI-LL (r = -0.209, P < 0.05). LIV was also significantly correlated to spinopelvic sagittal parameters, including SVA (r = -0.226, P < 0.05), LL (r = 0.576, P < 0.01), TK (r = 0.305, P < 0.01), and PI-LL (r = -0.379, P < 0.01). By multiple linear regression analysis, LIV was independently associated with sagittal parameters, including PI-LL and SVA. The cut-off value of LIV for SVA ≤ 50 mm was 10.5 mm (AUC = 0.641). According to the best cut-off value, patients were divided into two groups. For patients with LIV ≤ 10.5 mm, the percentage of SVA ≤ 50 mm was 54.5% (18/33), while it was 83.1% (64/77) for patients with LIV >10.5 mm.

CONCLUSIONS

As a new index to evaluate paraspinal muscle atrophy, the LIV was independently correlated to spinopelvic sagittal balance. Degeneration of paraspinal muscle was associated with spinopelvic sagittal balance.

Paraspinal myopathy-induced intervertebral disc degeneration and thoracolumbar kyphosis in TSC1mKO mice model-a preliminary study

BACKGROUND

Increasing kyphosis of the spine in a human is a well-recognized clinical phenomenon that has been associated with back pain, poor physical performance and disability. The pathophysiology of age-related kyphosis is complex and has been associated with physiological changes in vertebrae, intervertebral disc (IVD) and paraspinal musculature, which current cross-sectional studies are unable to demonstrate. Creating an in vivo, paraspinal myopathic animal model for longitudinal study of these changes under controlled conditions is thus warranted.

PURPOSE

To confirm the TSC1 gene knockout effect on paraspinal muscle musculature; to analyze the development of spinal kyphosis, IVD degeneration and vertebra structural changes in a longitudinal manner to gain insights into the relationship between these processes.

STUDY DESIGN

A prospective cohort study of 28 female mice, divided into 4 groups-9-month-old TSC1mKO (n=7), 9-month-old control (n=4), 12-month-old TSC1mKO (n=8), and 12-month-old controls (n=9).

METHODS

High resolution micro-computed tomography was used to measure sagittal spinal alignment (Cobb's angle), vertebral height, vertebral body wedging, disc height index (DHI), disc wedge index (DWI), histomorphometry of trabecular bone and erector spinae muscle cross-sectional area. Paraspinal muscle specimens were harvested to assess for myopathic features with H&E stain, muscle fiber size, density of triangular fiber and central nucleus with WGA/DAPI stain, and percentage of fibers with PGC-1α stain. Intervertebral discs were evaluated for disc score using FAST stain.

RESULTS

Compared to controls, paraspinal muscle sections revealed features of myopathy in TSC1mKO mice similar to human sarcopenic paraspinal muscle. While there was significantly greater presence of small triangular fiber and density of central nucleus in 9-and 12-month-old TSC1mKO mice, significantly larger muscle fibers and decreased erector spinae muscle cross-sectional area were only found in 12-month-old TSC1mKO mice compared to controls. TSC1mKO mice developed accelerated thoracolumbar kyphosis, with significantly larger Cobb angles found only at 12 months old. Structural changes to the trabecular bone in terms of higher bone volume fraction and quality, as well as vertebral body wedging were observed only in 12-month-old TSC1mKO mice when compared to controls. Disc degeneration was observed as early as 9 months in TSC1mKO mice and corresponded with disc wedging. However, significant disc height loss was only observed when comparing 12-month-old TSC1mKO mice with controls.

CONCLUSIONS

This study successfully shows the TSC1 gene knockout effect on the development of paraspinal muscle myopathy in a mouse which is characteristic of sarcopenia. The TSC1mKO mice is by far the best model available to study the pathological consequence of sarcopenia on mice spine. With paraspinal muscle myopathy established as early as 9 months, TSC1mKO mice developed disc degeneration and disc wedging. This is followed by kyphosis of the spine at 12 months with concomitant disc height loss and vertebral body wedging due to bone remodeling. Age-related bone loss was not found in our study, suggesting osteoporosis and myopathy-induced vertebral body wedging are likely two independent processes.

CLINICAL SIGNIFICANCE

This is the first study to provide key insights on the early and late consequences of paraspinal myopathy on intervertebral disc degeneration, spinal kyphosis, and vertebral body changes. With this new understanding, future studies evaluating therapies for spinal degeneration may be performed to develop time-sensitive interventions.

Different degeneration patterns of paraspinal muscles in degenerative lumbar diseases: a MRI analysis of 154 patients

STUDY DESIGN

A retrospective study.

OBJECTIVE

To evaluate the different degeneration patterns of paraspinal muscles in degenerative lumbar diseases and their correlation with lumbar spine degeneration severity. The degeneration characteristics of different paraspinal muscles in degenerative lumbar diseases remain unclear.

METHODS

78 patients diagnosed with single-level degenerative lumbar spondylolisthesis (DLS) and 76 patients with degenerative lumbar kyphosis (DLK) were included as DLS and DLK groups. Paraspinal muscle parameters of psoas major (PS), erector spinae (ES) and multifidus muscle (MF) were measured, including fatty infiltration (FI) and relative cross-sectional area (rCSA), namely the ratio of the paraspinal muscle CSA to the CSA of the vertebrae of the same segment. Sagittal parameters including lumbar lordosis (LL) and sagittal vertical axis (SVA) were measured. The paraspinal muscle parameters and ES/MF rCSA ratio were compared between the two groups. Paraspinal muscles parameters including rCSA and FI were also compared between each segments from L1 to L5 in both DLS and DLK groups. In order to determine the influence of sagittal spinal alignment on paraspinal muscle parameters, correlation analysis was conducted between the MF, ES, PS rCSA and FI and the LL in DLS and DLK group.

RESULT

MF atrophy is more significant in DLS patients compared with DLK. Also, MF fatty infiltration in the lower lumbar spine of DLS patients was greater compared to DLK patients. DLK patients showed more significant atrophy of ES and heavier ES fatty infiltration. MF FI was significantly different between all adjacent segments in both DLS and DLK groups. In DLS group, ES FI was significantly different between L2/L3 to L3/L4 and L4/L5 to L5/S1, while in DLK group, the difference of ES FI between all adjacent segments was not significant, and ES FI was found negatively correlated with LL.

CONCLUSIONS

Paraspinal muscles show different degeneration patterns in degenerative lumbar diseases. MF degeneration is segmental in both DLS and DLK patients, while ES degenerated diffusely in DLK patients and correlated with the severity of kyphosis. MF degeneration is more significant in the DLS group, while ES degeneration is more significant in DLK patients. MF is the stabilizer of the lumbar spine segments, while the ES tends to maintain the spinal sagittal balance.

Sagittal imbalance of the spine is associated with poor sitting posture among primary and secondary school students in China: a cross-sectional study

Background

Long-term poor posture may affect the morphological development of the spine. However, there is no definite answer as to how writing posture affects students’ spine. This study attempted to compare the sagittal curvature of the spine between sitting and standing postures in adolescents to reveal the variation rule of spinal sagittal curvature of students with learning posture, and to discover the key factors that may affect students’ spinal health.

Methods

1138 participants (male, 604; female, 534; age range, 6–18 years) from three schools in Tianjin, China, including 570 primary school students and 568 secondary school students. This study used SpineScan and PA200 Station Posture Assessment System to assess the sagittal curvature of the spine for three postures: sitting on a chair in upright position, seated at a desk while reading/writing, and standing in natural relaxed position. Analyze the difference between spine angle of the three postures and the correlation between the sagittal plane angle of the spine and body posture.

Results

The mean sagittal angle of the spine changed when the participants were in reading/writing position compared to standing position, with the lumbar lordosis angle significantly decreased (p < 0.05) and the thoracic kyphosis angle significantly increased (p < 0.05). The TKA and LLA angles were abnormal in 33 and 52% of students in reading/writing posture respectively. There was a significant correlation between sitting posture and standing spinal Angle and were positively correlated with the height of the teenager (p < 0.05). By contrast, a higher percentage of TKA and LLA subjects in the standard reading/writing posture reference range maintained normal spinal shape while standing.

Conclusions

The angle of thoracic kyphosis significantly increased from standing posture to upright sitting, reading/writing posture, while lumbar lordosis significantly decreased or even disappeared. There was a significant correlation between sagittal angle of spine in different postures. The poor sitting posture associated with sagittal angle abnormalities impact the shape of the spine such that sagittal imbalance was also observed when students in natural standing posture. Height is an important factor affecting the sitting spine shape of students.

The difference of paraspinal muscle between patients with lumbar spinal stenosis and normal middle-aged and elderly people, studying by propensity score matching

OBJECTIVE

The purpose of this study was to elaborate the characteristics of paraspinal muscles in lower lumbar, to compare the differences of paraspinal muscle between patients with lumbar spinal stenosis and normal people and to explore the influencing factors of paraspinal muscle degeneration in patients with lumbar spinal stenosis.

METHOD

The 39 pairs of patients and normal people were selected by propensity score matching. The differences of multifidus muscle and erection spine muscle parameters between the two groups were compared by independent-samples t-test and the relationship between age, paraspinal muscle degeneration and other factors in patients with lumbar spinal stenosis was analyzed by Pearson or Spearman correlation analysis.

RESULT

The general conditions of the two groups (patients with lumbar spinal stenosis and normal people) were well matched. There were significant differences in the relative fatty cross sectional area, fatty infiltration and relative signal intensity of multifidus muscle at L3 level. The fatty infiltration and relative signal intensity of multifidus muscle at L4 level and the relative signal intensity of multifidus muscle at L5 level were also significantly different. For male, the relative fatty cross sectional area, the fatty infiltration and relative signal intensity of multifidus muscle in patients were higher than those in healthy peers. For female, the relative signal intensity of multifidus muscle in patients was higher, too. In patients group, age was significantly correlated with the relative fatty cross sectional area, fatty infiltration and relative signal intensity of multifidus muscle and erector spinae muscle. Weight and BMI were significantly correlated with the relative total cross-sectional area of erector spinae muscle. The fatty infiltration increased more significantly with age in patients than that in normal people.

CONCLUSION

The change rules of paraspinal muscles in patients with lumbar spinal stenosis are similar to those in normal people. The degeneration of paraspinal muscle in patients with lumbar spinal stenosis was more severe than that in normal people, mostly in multifidus muscle. The paraspinal muscle degeneration was related to age in patients, and the effect of age on atrophy of paraspinal muscle was greater than that of normal people.

The Quantity and Quality of Lumbar Muscles and Lumbopelvic Parameters in Patients With Degenerative Spondylolisthesis

Introduction

Lumbar degenerative spondylolisthesis (DS) is one of the most common causes of low back pain. The lumbar muscles, such as the psoas major (PM), erector spinae (ES), and multifidus (MF) muscles, play an important role in the stability and functional movement of the lumbar spine. The quantities and qualities of these muscles may be related to the occurrence of DS and lumbopelvic parameters, such as lumbar lordosis (LL) and sacral slope (SS). However,the influence of lumbar muscles on DS and lumbopelvic alignment is not well understood.

Methods

Patients with L4 DS (DS group, n=25) and without DS (non-DS group, n=25) were included. Using sagittal reconstructed CT images of patients who visited our hospital for reasons other than low back disorders, LL, upper lumbar lordosis ([ULL] L1-L4), lower lumbar lordosis ([LLL] L4-S1), and SS were examined. To evaluate the quantity and quality of lumbar muscles, the gross cross-sectional area (GCSA), functional cross-sectional area (FCSA), and fat infiltration (FI) of the PM, ES, and MF muscles were measured by CT images. The lumbopelvic parameters, FCSA, GCSA, and FI of lumbar muscles were compared between the two groups. Then, each lumbar muscle parameter was analyzed for correlation with DS and lumbopelvic parameters.

Results

DS patients displayed significantly greater ULL and lower FI of the PM and ES muscles than non-DS patients (p=0.0078, 0.031, and 0.010, respectively). The FI of the ES muscle was significantly correlated with the presence of DS (p=0.010). The FCSA of the ES and MF muscles and the GCSA of the MF muscle showed a significant correlation with LL and SS in the non-DS group (p<0.05), but not in the DS group..

Conclusion

ULL was greater in L4 DS patients, possibly related to the better quality of the ES muscle. All DS patients showed mild (grade I) spondylolisthesis, suggesting the possibility that lumbar muscle quality is better in patients with mild DS than in those without DS. The ES and MF muscles may play an important role in maintaining the lumbar lordotic angle in non-DS patients but not in DS patients.

A Nomogram for Predicting the Residual Back Pain after Percutaneous Vertebroplasty for Osteoporotic Vertebral Compression Fractures

OBJECTIVE

Current findings suggest that percutaneous vertebroplasty (PVP) is a suitable therapeutic approach for osteoporotic vertebral compression fractures (OVCFs). However, a significant minority of patients still experience residual back pain after PVP. The present retrospective study was designed to determine the risk factors for residual back pain after PVP and provides a nomogram for predicting the residual back pain after PVP.

METHODS

We retrospectively reviewed the medical records of patients with single-segment OVCFs who underwent bilateral percutaneous vertebroplasty. Patients were divided into group N and group R according to the postoperative VAS score. Group R is described as the VAS score of residual back pain ≥ 4. Pre- and postoperative factors that may affect back pain relief were evaluated between two groups. Univariate and multivariate logistic regression analysis were performed to identify risk factors affecting residual back pain after PVP. We provided a nomogram for predicting the residual back pain and used the receiver operating characteristic curve (ROC), concordance index (C-index), calibration curve, and decision curve analyses (DCA) to evaluate the prognostic performance.

RESULTS

Among 268 patients treated with PVP, 37 (13.81%) patients were classified postoperative residual back pain. The results of the multivariate logistical regression analysis showed that the presence of an intravertebral vacuum cleft (IVC) (OR 3.790, P=0.026), posterior fascia oedema (OR 3.965, P=0.022), severe paraspinal muscle degeneration (OR 5.804, P=0.01; OR 13.767, P < 0.001), and blocky cement distribution (OR 2.225, P=0.041) were independent risk factors for residual back pain after PVP. The AUC value was 0.780, suggesting that the predictive ability was excellent. The prediction nomogram presented good discrimination, with a C-index of 0.774 (0.696∼0.852) and was validated to be 0.752 through bootstrapping validation. The calibration curve of the nomogram demonstrated a good consistency between the probabilities predicted by the nomogram and the actual probabilities. The nomogram showed net benefits in the range from 0.06 to 0.66 in DCA.

CONCLUSIONS

The presence of IVC, posterior fascia oedema, blocky cement distribution, and severe paraspinal muscle degeneration were significant risk factors for residual back pain after PVP for OVCFs. Patients with OVCFs after PVP who have these risk factors should be carefully monitored for the possible development of residual back pain. We provide a nomogram for predicting the residual back pain after PVP.

Stem Cell Therapy and Exercise for Treatment of Intervertebral Disc Degeneration

As part of the motor system, intervertebral disc (IVD) is a complicated tissue with multiple components. The degeneration of IVD may result in low back pain (LBP), which strongly impairs quality of life. Various causes are related to the degeneration of IVD, including cell senescence, hydration lost, and inflammation. Stem cells founded in different tissues have attracted the interest of the researchers and clinicians to study the implication of these cells in the treatment for tissue injury and degeneration. In this report, we will review the study of stem cells in the treatment for IVD degeneration. On the other hand, the effect of exercise on IVD degeneration and the relationship between IVD degeneration and musculoskeletal disorders like sarcopenia are discussed.

Clinical, Radiographic, and Genetic Analyses in a Population-Based Cohort of Adult Spinal Deformity in the Older Population

OBJECTIVE

This study aimed to identify the sagittal parameters associated with health-related quality of life and genetic variations that increase the risk of adult spinal deformity (ASD) onset in the older population.

METHODS

We recruited 120 participants who had a sagittal vertical axis > 50 mm in a sagittal imbalance study. Sagittal radiographic parameters, cross-sectional area, and intramuscular fatty infiltration using the Goutallier classification in the paraspinal lumbar muscles were evaluated. Functional scales included the self-reported Oswestry Disability Index (ODI), 36-item Short Form Health Survey (SF-36), and visual analogue scales (VAS) for back and leg pain. We performed whole-exome sequencing and an exome-wide association study using the 100 control subjects and 63 individuals with severe phenotypes of sagittal imbalance.

RESULTS

Pelvic incidence minus lumbar lordosis (PI-LL) mismatch was negatively associated with the SF-36 and positively correlated with ODI and VAS for back and leg pain. PI-LL was related to the quality and size of the paraspinal muscles, especially the multifidus muscle. We identified common individual variants that reached exome-wide significance using single-variant analysis. The most significant single-nucleotide polymorphism was rs78773460, situated in an exon of the SVIL gene (odds ratio, 9.61; p = 1.15 × 10-9).

CONCLUSION

Older age, higher body mass index, and a more significant PI-LL mismatch were associated with unfavorable results on functional scales. We found a genetic variation in the SVIL gene, which has been associated with the integrity of the cytoskeleton and the development of skeletal muscles, in severe ASD phenotypes. Our results help to elucidate the pathogenesis of ASD.

Assessing Fatty Infiltration of Paraspinal Muscles in Patients With Lumbar Spinal Stenosis: Goutallier Classification and Quantitative MRI Measurements

Objective: Fatty infiltration of paraspinal muscle is associated with spinal disorders. It can be assessed qualitatively (i.e., Goutallier classification) and quantitatively using image processing software. The aims of this study were to compare paraspinal muscle fatty infiltration as assessed using the Goutallier classification vs. quantitative magnetic resonance images (MRI) measurements and to investigate the association between anthropometric parameters and paraspinal muscle morphology and fatty infiltration in patients with symptomatic lumbar spinal stenosis (LSS).

Methods: Patients affected by symptomatic LSS scheduled for surgery with available MRI of the lumbar spine were included in this retrospective cross-sectional study. Fatty infiltration at each lumbar level was rated qualitatively according to the Goutallier classification and quantified based on the cross-sectional area (CSA) of the paraspinal muscle, of its lean fraction (LeanCSA), and the ratio between LeanCSA and CSA and the CSA relative to the CSA of vertebral body (RCSA). Considering the muscle as a single unit, overall fatty infiltration according to Goutallier, overall CSA, LeanCSA, LeanCSA/CSA, and RCSA were computed as averages (aGoutallier, aCSA, aLeanCSA, aLeanCSA/aCSA, and aRCSA). Associations among parameters were assessed using Spearman's respective Pearson's correlation coefficients.

Results: Eighteen patients, with a mean age of 71.3 years, were included. aGoutallier correlated strongly with aLeanCSA and aLeanCSA/aCSA (R = −0.673 and R = −0.754, both P < 0.001). There was a very strong correlation between values of the left and right sides for CSA (R = 0.956, P < 0.001), LeanCSA (R = 0.900, P < 0.001), and LeanCSA/CSA (R = 0.827, P < 0.001) at all levels. Among all anthropometric measurements, paraspinal muscle CSA correlated the most with height (left: R = 0.737, P < 0.001; right: R = 0.700, P < 0.001), while there was a moderate correlation between vertebral body CSA and paraspinal muscle CSA (left: R = 0.448, P < 0.001; right: R = 0.454, P < 0.001). Paraspinal muscle CSA correlated moderately with body mass index (BMI; left: R = 0.423, P < 0.001; right: R = 0.436, P < 0.001), and there was no significant correlation between aLeanCSA or aLeanCSA/CSA and BMI.

Conclusions: The Goutallier classification is a reliable yet efficient tool for assessing fatty infiltration of paraspinal muscles in patients with symptomatic LSS. We suggest taking body height as a reference for normalization in future studies assessing paraspinal muscle atrophy and fatty infiltration.

Radiographic and clinical outcomes of surgical treatment of Kümmell's disease with thoracolumbar kyphosis: a minimal two-year follow-up

BACKGROUND

Up to now in the surgical treatment of Kümmell's disease combined with thoracolumbar kyphosis, little research has focused on the evaluation of the imaging and clinical outcomes of restoring the normal alignment and sagittal balance of the spine. This study aimed to evaluate the short to mid-term radiographic and clinical outcomes in the treatment of Kümmell's disease with thoracolumbar kyphosis.

METHODS

From February 2016 to May 2018, 30 cases of Kümmell's disease with thoracolumbar kyphosis were divided into group A and B according to whether the kyphosis was combined with neurological deficits. All of the cases underwent surgical treatment to regain the normal spinal alignment and sagittal balance. The radiographic outcomes and clinical outcomes of the cases were retrospectively evaluated. The sagittal imaging parameters including sagittal vertebral axis (SVA),thoracic kyphosis (TK),thoracolumbar kyphosis (TLK),lumbar lordosis (LL),pelvic incidence (PI),pelvic tilt (PT),and sacral slope (SS) before operation,immediately after operation,and the last follow-up of each case were measured and evaluated. The clinical results included the Oswestry Disability Index (ODI) and the Numerical Rating Scale (NRS) of the two groups. Statistical software SPSS21.0 was used to analyze the data.

RESULTS

In group A: Mean SVA before operation was 75 mm and 26.7 mm at the final postoperative evaluation (P = 0.000); Mean TLK before operation was 39°, and 7.1° at the final postoperative evaluation (P = 0.000); Mean NRS before operation was 4.7, compared with 0.9 at the final postoperative evaluation (P = 0.000). In group B: Mean preoperative SVA was 62.5 mm and decreases to 30.7 mm at the final postoperative evaluation (P = 0.000); Mean TLK before operation was 33°, and 9.7° 2 years post-operation (P = 0.000); Mean NRS prior to surgery was 4.0, and 0.8 at the last follow-up evaluation (P = 0.000). The improvement of the NRS scores of groups A and B was related to the improvement of the cobb angle (P = 0.020); (P = 0.009) respectively.

CONCLUSION

In the treatment of Kümmell's disease with thoracolumbar kyphosis,to restore the normal alignment and sagittal balance can obtain a satisfactory radiographic and clinical short and medium-term effects.

The compensatory mechanisms for global sagittal balance in degenerative spinal kyphosis patients: a radiological analysis of muscle-skeletal associations

BACKGROUND

The position of the head relative to the spine can be used to evaluate the true global balance in patients with degenerative spinal kyphosis (DSK). However, it is still not clear how the position of the head is related to the spinal-pelvic parameters and lumbar muscles, which are most commonly considered.

METHODS

Sixty-seven patients with DSK admitted in the hospital from January 2017 to January 2019 were retrospectively analyzed. All patients had whole spine X-ray and lumbar MRI. The head position parameters include: the angles of both lines joining the center of acoustic meati (CAM) to the center of the bi-coxofemoral axis (BA) (CAM-BA) and the most superior point of dentiform apophyse of C2 odontoid (OD) to BA (OD-BA) with the vertical line; the distance between the vertical line passing CAM and the posterior upper edge of the S1 (CAM-SVA). The spinal parameters include: C7 sagittal vertical axis (C7-SVA), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), and lumbar lordosis (LL). The pelvic parameters include: pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS). The relative cross-sectional area (RCSA) of bilateral multifidus, erector spinae and psoas muscle at L3/4 and L4/5 segments were measured. The correlations between head position parameters and the spinal-pelvic parameters and RCSA of lumbar muscles were analyzed, respectively.

RESULTS

Significant positive correlations were found between each two of CAM-SVA, C7-SVA, CAM-BA and OD-BA (p < 0.001). SS was found to be significantly positively correlated with CAM-BA (r = 0.377, p = 0.034) and OD-BA (r = 0.402, p = 0.023). CAM-BA was found to be significantly negatively correlated with TK (r = - 0.367, p = 0.039). Significant positive correlations were found between RCSA of multifidus at L3/4 level and CAM-SVA (r = 0.413, p = 0.021), CAM-BA (r = 0.412, p = 0.019) and OD-BA (r = 0.366, p = 0.04).

CONCLUSIONS

Our study showed that the head position relative to the spine were significantly correlated to some spinal-pelvic parameters, and the lower lumbar multifidus muscle. The compensatory mechanisms of the global sagittal balance status should also involve the head position area.

The effect of minimally invasive lumbar decompression surgery on sagittal spinopelvic alignment in patients with lumbar spinal stenosis: a 5-year follow-up study

OBJECTIVE

Several studies have examined the relationship between sagittal spinopelvic alignment and clinical outcomes after spinal surgery. However, the long-term reciprocal changes in sagittal spinopelvic alignment in patients with lumbar spinal stenosis after decompression surgery remain unclear. The aim of this study was to investigate radiographic changes in sagittal spinopelvic alignment and clinical outcomes at the 2-year and 5-year follow-ups after minimally invasive lumbar decompression surgery.

METHODS

The authors retrospectively studied the medical records of 110 patients who underwent bilateral decompression via a unilateral approach for lumbar spinal stenosis. Japanese Orthopaedic Association (JOA) and visual analog scale (VAS) scores for low-back pain (LBP), leg pain, leg numbness, and spinopelvic parameters were evaluated before surgery and at the 2-year and 5-year follow-ups. Sagittal malalignment was defined as a sagittal vertical axis (SVA) ≥ 50 mm.

RESULTS

Compared with baseline, lumbar lordosis significantly increased after decompression surgery at the 2-year (30.2° vs 38.5°, respectively; p < 0.001) and 5-year (30.2° vs 35.7°, respectively; p < 0.001) follow-ups. SVA significantly decreased at the 2-year follow-up compared with baseline (36.1 mm vs 51.5 mm, respectively; p < 0.001). However, there was no difference in SVA at the 5-year follow-up compared with baseline (50.6 mm vs 51.5 mm, respectively; p = 0.812). At the 5-year follow-up, 82.5% of patients with preoperative normal alignment maintained normal alignment, whereas 42.6% of patients with preoperative malalignment developed normal alignment. Preoperative sagittal malalignment was associated with the VAS score for LBP at baseline and 2-year and 5-year follow-ups and the JOA score at the 5-year follow-up. Postoperative sagittal malalignment was associated with the VAS score for LBP at the 2-year and 5-year follow-ups and the VAS score for leg pain at the 5-year follow-up. There was a trend toward deterioration in clinical outcomes in patients with persistent postural malalignment compared with other patients.

CONCLUSIONS

After minimally invasive surgery, spinal sagittal malalignment can convert to normal alignment at both short-term and long-term follow-ups. Sagittal malalignment has a negative impact on the VAS score for LBP and a weakly negative impact on the JOA score after decompression surgery.

Imaging Evaluation of Fat Infiltration in Paraspinal Muscles on MRI: A Systematic Review with a Focus on Methodology

Purpose

Numerous studies have applied a variety of methods to assess paraspinal muscle degeneration. However, the methodological differences in imaging evaluation may lead to imprecise or inconsistent results. This article aimed to provide a pragmatic summary review of the current imaging modalities, measurement protocols, and imaging parameters in the evaluation of paraspinal muscle fat infiltration (FI) in MRI studies.

Methods

Web of Science, EMBASE, and PubMed were searched from January 2005 to March 2020 to identify studies that examined the FI of paraspinal muscles on MRI among patients with lumbar degenerative diseases.

Results

Intramyocellular lipids measured by magnetic resonance spectroscopy and FI measured by chemical‐shift MRI were both correlated to low back pain and several degenerative lumbar diseases, whereas results on the relationship between FI and degenerative lumbar pathologies using conventional MRI were conflicting. Multi‐segment measurement of FI at the lesion segment and adjacent segments could be a prognostic indicator for lumbar surgery. Most studies adopted the center of the intervertebral disc or endplate as the level of slice to evaluate the FI. Compared with visual semiquantitative assessment, quantitative parameters appeared to be precise for eliminating individual or modality differences. It has been demonstrated that fat CSA/total CSA (based on area) and muscle–fat index (based on signal intensity) as quantitative FI parameters are associated with multiple lumbar diseases and clinical outcomes after surgery.

Conclusion

Having a good command of the methodology of paraspinal muscle FI on MRI was effective for diagnosis and prognosis in clinical practice.

Association between fatty infiltration of paraspinal muscle, sagittal spinopelvic alignment and stenosis grade in patients with degenerative lumbar spinal stenosis

Introduction

Sagittal balance and fatty infiltration of paraspinal muscle are important factors in patients with lumbar spinal stenosis (LSS) that may affect patients’ quality of life. Sagittal spinopelvic parameters and fatty infiltration may be associated with the severity of LSS. The purpose of this study was to test the hypothesis that severity of fatty infiltration correlates with severity of LSS and with sagittal pelvic alignment independent of age.

Methods

Age and body mass index (BMI) were extracted. Fatty infiltration was rated according to Goutallier classification and the severity of LSS was graded according to Schizas at five intervertebral disc levels. Overall fatty infiltration was computed as average fatty infiltration (aFI) and severity of LSS was defined as the highest severity of LSS of all segments. The sagittal spinopelvic parameters pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL) and PI-LL were measured. Associations among parameters were assessed using Spearman correlation coefficients adjusted for age (α = 0.05).

Results

165 LSS patients with a median age of 69 years were included. All parameters correlated with age (R>0.162, P<0.05) except BMI and LL (R<0.007, P>0.05). aFI correlated with PI, PT and PI-LL before (R>0.371, P<0.05) and after (R>0.180, P<0.05) adjusting for age. Severity of LSS correlated with PI, PT and PI-LL before (R>0.187, P<0.05) but not after (R<0.130, P>0.05) adjusting for age. aFI correlated with severity of LSS before (R=0.349, P<0.05) but not (R=0.114, P>0.05) after adjusting for age.

Conclusions

The correlation of aFI with sagittal spinopelvic parameters indicates that there might be a relationship between muscle characteristics and the sagittal alignment. Sagittal spinopelvic parameters and fatty infiltration of paraspinal muscles are not associated with radiological severity of LSS. Whether they are associated with clinical manifestation of LSS remains to be investigated.

Relationship of back muscle and knee extensors with the compensatory mechanism of sagittal alignment in a community-dwelling elderly population

Compensatory mechanisms, such as a decrease in thoracic spine kyphosis and posterior tilting or rotation of the pelvis, aim to achieve optimal alignment of the spine. However, the effect of muscle strength on these compensatory mechanisms has not been elucidated. This study aimed to investigate the impact of back muscle and lower extremity strength on compensatory mechanisms in elderly people. Overall, 409 community-dwelling elderly participants (164 men, 245 women) were included. Age, disc degeneration, and 2 or more vertebral fractures showed a significant increase of risk for sagittal vertical axis (SVA) deterioration. Conversely, stronger back, hip flexor, and knee extensor muscles reduced the risk for SVA deterioration. To investigate the association of each muscle's strength with compensatory mechanisms, 162 subjects with pelvic incidence-lumbar lordosis > 10° were selected. The linear regression model for thoracic kyphosis demonstrated a negative correlation with back muscle strength and positive correlation with vertebral fracture. The regression analysis for pelvic tilt demonstrated a positive correlation with knee extensor strength. Back, hip flexor, and knee extensor muscle strength were associated with sagittal spinal alignment. Back muscle strength was important for the decrease in thoracic kyphosis, and knee extensor strength was associated with pelvic tilt.

Lumbar degenerative disease after oblique lateral interbody fusion: sagittal spinopelvic alignment and its impact on low back pain

Background

We determined the incidence and risk factors of low back pain (LBP) in patients with lumbar degenerative disease after single-level oblique lateral interbody fusion (OLIF).

Methods

We retrospectively reviewed 120 lumbar degenerative disease patients who underwent single-level OLIF. We compared preoperative and postoperative radiographic parameters, including segmental lordosis (SL), lumbar lordosis (LL), disk height (DH), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), thoracic kyphosis (TK), and C7-sagittal vertical axis (SVA). Clinical outcomes were evaluated using the Oswestry Disability Index (ODI) scores and visual analog scale (VAS) scores for back and leg pain. All patients were followed up for at least 2 years.

Results

Thirty-eight patients had postoperative LBP (VAS score for back pain ≥3; LBP group); the remaining 82 patients were in the non-LBP group. Age (P = 0.082), gender (P = 0.425), body mass index (P = 0.138), diagnosis (degenerative spondylolisthesis vs. lumbar spinal stenosis; P = 0.529), surgical level (P = 0.651), blood loss (P = 0.889), and operative time (P = 0.731) did not differ between the groups. In both groups, the ODI and VAS scores for back pain and leg pain significantly improved at the final follow-up compared with the preoperative scores (P = 0.003). Except for the VAS score for back pain (P = 0.000), none of the scores significantly differed between the two groups at the final follow-up (P > 0.05). In the non-LBP group, LL, SL, DH, TK, and SS significantly improved, while PT and C7-SVA significantly decreased at the final follow-up as compared with the preoperative values. In both groups, DH significantly improved postoperatively, with no significant between-group difference (P = 0.325). At the final follow-up, LL, PI-LL mismatch, PT, and C7-SVA showed significantly greater improvement in the non-LBP group than in the LBP group (P < 0.05). Multivariate analysis identified PT, PI-LL mismatch, and C7-SVA as significant risk factors for LBP after OLIF.

Conclusion

OLIF for single-level lumbar degenerative disease had satisfactory clinical outcomes. PT, PI-LL mismatch, and C7-SVA were significant risk factors for postoperative LBP. Patients with appropriately decreased PT, improved C7-SVA, and PI-LL match experienced less LBP.

The effect of paraspinal muscle on functional status and recovery in patients with lumbar spinal stenosis

Purpose

To investigate the association of paraspinal muscle quantity and quality with functional status in patients with lumbar spinal stenosis (LSS) and explore whether degeneration of paraspinal muscle could predict patients’ functional recovery.

Methods

The data of 69 patients (26 males, 43 females; mean age 60.6 ± 9.4 years) with LSS was reviewed. The total cross-sectional area (tCSA), functional cross-sectional area (fCSA), and fatty infiltration (FI) of paraspinal muscle were measured. The Oswestry Disability Index (ODI) scores were used to reflect patients’ functional status. Correlations between measurements of paraspinal muscle and ODI scores were investigated by the Pearson correlation analysis. The multiple linear regression analysis was used to explore the correlation between change of ODI and other potential influence factors. Receiver operating characteristic curve was used to find out the most optimum cut-off value for predicting functional recovery.

Results

The pre-operation ODI was significantly associated with multifidus muscle (MF) fCSA (r = − 0.304, p = 0.012), while the post-operation ODI was significantly correlated to MF FI (r = 0.407, p < 0.01). Preoperative MF FI was an independent influence factor for change of ODI. The best cut-off value of preoperative MF FI to predict improvement of functional status (change of ODI > 50%) was 33%.

Conclusion

The preoperative degeneration of MF was significantly associated with patients’ functional status. Preoperative MF FI was a good predictor for assessing improvement of patients’ functional status. Evaluation of paraspinal muscle before operation could be helpful for surgeons to predict patients’ functional status and recovery.