Long-Term Influence of Paraspinal Muscle Quantity in Adolescent Idiopathic Scoliosis Following Deformity Correction by Posterior Approach

Learning curve and long-term outcomes of minimally invasive correction and fusion for adolescent idiopathic scoliosis

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

This study sought to report the long-term outcomes of patients that underwent minimally invasive surgery (MIS) correction for Adolescent Idiopathic Scoliosis (AIS) in terms of radiographic, clinical, and patient-reported outcomes. Furthermore, we examined the learning curve of MIS technique over the course of 13 years. Both MIS and open techniques are used to surgically address AIS. MIS techniques are purported to preserve the midline spinal musculature and to decrease estimated blood loss (EBL) and hospital length of stay (LOS).

METHODS

Data were collected at a single tertiary care center of all consecutive AIS patients undergoing deformity surgery from January 2008 to October 2021. Demographic, clinical, and radiographic data were collected at various intervals. Descriptive and inferential analyses were conducted.

RESULTS

70 AIS patients were included in the study. Mean patient age was 16.2 years of which 95.7% were female, with a mean BMI of 21.7. The majority of the patients were Lenke type 1A (60%) followed by Lenke 1B (18.6%) with mean preop Cobb angle as 52.2°. The mean follow-up was approximately 6 years with 35.7% of our cohort meeting the long-term follow-up landmark (> 5 years, 2-11). The mean number of spinal levels treated was 9.3 with mean ASA score of 1.7. Overall, mean EBL was 151 cc with mean OR of 308 min. The mean LOS was 3.94 days with postop Day 1 as the initiation of ambulation. Overall, the percent correction at the last visit was significantly greater than preop (Cobb: 77.6%, p < 0.05). Mean loss of correction on follow-ups was less than 5º. The overall revision rate was 2.9%. At 2 years postop, 98.6% (69/70) of the patients achieved fusion with 100% (24/24) at 5 years, and 96% (24/25) beyond the 5-year mark. Surgeon's technical proficiency in performing MIS for the treatment of AIS corrections was achieved after 23 cases.

CONCLUSIONS

Based on our cohort's 2-11 year follow-up data, we conclude that MIS provides an effective treatment option for AIS reconstruction. Our study indicates that MIS can achieve adequate deformity correction and positive long-term clinical outcomes as indicated by Cobb angle, VAS, ODI, and SRS-22r scores during follow-ups. If the individual goals of AIS surgery can be achieved, consideration should be given to less-invasive techniques.

LEVEL OF EVIDENCE

IV.

The benefits of touched vertebra concept for the selection of the lowest instrumented vertebra in thoracic curves of adolescent idiopathic scoliosis

PURPOSE

To assess the benefits of using the touched vertebra (TV) rule in Lenke classification for thoracic curves of adolescent idiopathic scoliosis (AIS).

METHODS

A total of 141 AIS patients with thoracic curves determined by Suk classification were divided based on whether the lowest instrumented vertebra (LIV) matched the TV into groups of mTV (n = 84, LIV = TV), TV- (n = 21, LIV above TV), and TV+ (n = 36, LIV below TV) for 5-year follow-up. The radiological parameters were the central sacral vertical line (CSVL)-LIV distance, distal end vertebra rotation, coronal, and sagittal parameters. Complications included adding-on phenomenon, coronal imbalance, and distal junctional kyphosis.

RESULTS

Adding-on phenomenon and coronal imbalance were significantly higher in the TV- group (P = 0.006) and TV + group (P = 0.006), respectively. The distal motion segments were significantly saved in the mTV group (P < 0.001). The CSVL-LIV distance was significantly improved in the mTV group compared to the others during the 5-year follow-up (P = 0.007). The 5-year follow-up CSVL-LIV distance correlated with LIV tilt angle (r = 0.442, P = 0.021) and coronal balance (r = 0.437, P = 0.023).

CONCLUSIONS

Selecting the TV as LIV minimizes the loss of the distal mobile segment and reduces the complications in the thoracic curves of AIS, which produces a more stable LIV on the CSVL. Therefore, TV is an ideal landmark for determining the distal fusion level using the Lenke classification or Suk classification.

Global tilt angle in spinal alignment of asymptomatic older women with low bone mass

This study investigated the relationship between sagittal spinal alignment and musculoskeletal health in older women, particularly those exhibiting diminished bone density without apparent symptoms. The study assessed the impact of global tilt (GT) and the presence of coronal malalignment on spinal health. The research involved 165 asymptomatic older women with an average age of 68.91 ± 7.25 years and average body mass index of 24.26 ± 3.66 kg/m². Comprehensive standing anteroposterior and lateral spine radiographs were used for assessment. Through multivariate linear regression analysis, the study identified significant correlations between increased GT angles and various factors, including coronal malalignment, the C7 slope, and pelvic incidence. This led to the formulation of a predictive GT model: GT = -9.79 + 0.06 × menopausal period + 0.19 × body mass index (BMI)- 0.81 × average T score - 0.11 × grip strength + 3.03 × (presence of coronal malalignment) + 0.08 × sagittal vertical axis (SVA) + 0.12 × C7 slope - 0.35 × upper lumbar lordosis (ULL) - 0.43 × lower lumbar lordosis (LLL) + 0.70 × pelvic incidence (PI), with an adjusted R² of 0.816. The study findings highlight the prevalence of coronal malalignment in this demographic and its significant associations with critical spinal parameters. The proposed GT predictive model may enable development of personalized treatment plans for older women with low bone mass.

Comparison of elasticity changes in the paraspinal muscles of adolescent patients with scoliosis treated with surgery and bracing

Scoliosis is a three-dimensional spinal deformity, and paraspinal muscles play an important role as stabilizers of the spinal curve. In this prospective study, we compared elasticity changes in the paraspinal muscles of adolescent patients with scoliosis after surgery or bracing. Elasticity was measured on the concave and convex sides of the paraspinal muscles at the apex of the curve at the beginning of treatment and 6 and 12 months after treatment. Twenty-six patients with correction surgery (n = 15) or bracing (n = 11) were included. At initial evaluation, the Cobb angle was larger in the surgery group (72.3 ± 20.2° in surgery vs. 30.6 ± 5.1° in brace, p < 0.001). The estimated mean elasticity value of the paraspinal muscles was lower in the surgery group at baseline on the convex side (15.8 vs. 22.8 kPa, p = 0.037) and 6 months on both the concave (12.1 vs. 22.7 kPa, p = 0.004) and convex (13.4 vs. 23.8 kPa, p = 0.005) sides. There was a significant stiffness decrease from baseline to 6 months on the concave side in the surgery group (5.9 kPa, p = 0.025). However, the elasticity change recovered at 12 months without significant differences between the two groups.

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.

Is Lenke type V adolescent idiopathic scoliosis associated with different muscular morphometry?

The aim of the study was to evaluate the changes in psoas major (PM), erector spinae (ES), multifidus (MF), and rectus abdominis (RA) morphometry in Lenke type V adolescent idiopathic scoliosis (AIS) and control. Forty-two Lenke V AIS patients and 30 control were enrolled. The cross-sectional area (CSA) and CSA index (CI) of the PM, ES, MF, and RA at the T9-L5 levels were measured and compared between Lenke type V patients and control. The CI of the RA was significantly higher in the control group than the Lenke V group in multiple levels. On the other hand, there was no significant difference between patients with Lenke V AIS and control regarding the CI of the RA, ES, and PM. There was no significant difference between concave and convex sides of the Lenke V group regarding the CI of the RA, PM, MF, and ES. RA muscle mass is significantly affected in Lenke type 5 AIS regardless of convex or concave sides. This difference may be related to postural differences and back pain development in Lenke type 5 patients. Level of evidence: Level III.

Significance of paraspinal muscle quality in risk between single and multiple osteoporotic vertebral fractures

PURPOSE

To compare paraspinal muscle quality between patients with single and multiple osteoporotic vertebral fractures (OVFs) and evaluate the role of the paraspinal muscles in OVFs.

METHODS

A total of 262 consecutive patients with OVFs were retrospectively analyzed in two groups: those with single OVF (n = 173) and those with multiple OVFs (n = 89). The cross-sectional area (CSA) and fatty degeneration of the paraspinal muscles were calculated from axial T2-weighted magnetic resonance imaging at the level of the L4 upper endplate by manual tracing in ImageJ software. Pearson's correlation analysis was performed to analyze correlations of paraspinal muscle quality to multiple OVFs.

RESULTS

FD in all the paraspinal muscles was significantly higher in the multiple OVF group than the single OVF group (all p < 0.005). The functional CSA (fCSA) of the paraspinal muscles was significantly lower in the multiple OVF group than the single OVF group (all Ps < 0.001), except for the erector spine (p = 0.304). The Pearson's correlation analysis showed significant positive inter-correlations for the fCSAs of all the paraspinal muscles and the occurrence of multiple OVFs.

CONCLUSIONS

The pure muscle volumes of the multifidus, psoas major, and quadratus lumborum were lower in patients with multiple OVFs than in those with a single OVF. Furthermore, the inter-correlation among all the paraspinal muscles indicate that the muscle-bone crosstalk profoundly existed in vertebral fracture cascade. Therefore, special attention to paraspinal muscle quality is needed to prevent progression to multiple OVFs.

Elasticity change of the paravertebral fascia and muscle in adolescent idiopathic scoliosis after posterior selective fusion surgery

BACKGROUND

We sought to assess the elasticity change of the paravertebral fascia and muscle in adolescent idiopathic scoliosis patients with Lenke Type 1, 2, or 3 curves after posterior selective fusion surgery.

METHODS

The shear wave elasticity imaging system was used to assess the elasticity of the thoracic paravertebral muscles and fascia both on the concave and convex sides. Three regions of interest, including the apex, upper end, and lower end of the main curve, were tested.

FINDINGS

Ten female patients, with an average age of 16.6 ± 2.7 years old, were included. The average post-operation follow-up period was 9.0 ± 2.4 months. The Cobb angle was significantly corrected from 63.6 ± 12.0° to 10.7 ± 5.4° (p < 0.05). The length of the trunk increased from 40.4 ± 2.5 cm to 46.0 ± 2.8 cm (p < 0.05). The elasticity of deep fascia didn't show a significant change post-operation (p > 0.05). The elasticity of the paravertebral muscle on the concave side had a significant increase at the final follow-up (p < 0.05). The elasticity of the paravertebral muscle on the convex side also increased at the upper end (p < 0.05). The elasticity asymmetry of the deep fascia decreased, but the elasticity asymmetry of the paravertebral muscle increased at the upper end of the curve (p < 0.05).

INTERPRETATION

The paravertebral muscle on the concave side is stiffer after surgery. Elastic asymmetry of paravertebral muscle increased and elastic asymmetry of the deep fascia decreased at the upper end of the curvature. Further study is needed to elucidate the mechanism by which the paravertebral soft tissue responds after surgery.

Incidence and Radiological Risk Factors of Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis Following Pedicle Screw Instrumentation with Rod Derotation and Direct Vertebral Rotation: A Minimum 5-Year Follow-Up Study

Several studies have reported incidence and risk factors for the development of proximal junctional kyphosis (PJK) in patients with adolescent idiopathic scoliosis (AIS). However, there is little information regarding long-term follow-up after pedicle screw instrumentation (PSI) with rod derotation (RD) and direct vertebral rotation (DVR). Sixty-nine AIS patients who underwent deformity correction using PSI with RD and DVR were retrospectively analyzed in two groups according to the occurrence of PJK, with a minimum five-year follow-up, including a non-PJK group (n = 62) and PJK group (n = 7). Radiological parameters were evaluated at preoperative, postoperative, and last follow-up. Incidence for PJK was 10.1% (7/69 patients), with a mean 9.4-year follow-up period. The thoracolumbar/lumbar curve (TL/L curve) was proportionally higher in the PJK group. The proximal compensatory curve was significantly lower in the PJK group than in the non-PJK group preoperatively (p = 0.027), postoperatively (p = 0.001), and at last follow-up (p = 0.041). The development of PJK was associated with the TL/L curve pattern, lower preoperative proximal compensatory curve, and over-correction of the proximal curve for PSI with RD and DVR. Therefore, careful evaluation of compensatory curves as well as of the main curve is important to prevent the development of PJK in the treatment of AIS.