Cone of Economy with the Chain of Balance-Historical Perspective and Proof of Concept

Long-term follow-up of adolescent idiopathic scoliosis surgery with Harrington instrumentations: a systematic review and meta-analysis

PURPOSE

In the 1960s, Harrington instrumentation (HRI) revolutionized the surgical treatment of adolescent idiopathic scoliosis (AIS). Despite the transition to more innovative techniques, concerns regarding its impact on sagittal alignment, associations with low back pain, and correction loss have consistently persisted. The aim of this meta-analysis is precisely to evaluate the clinical and radiological outcomes, as well as the complications of patients treated with HRI over an extended follow-up period. A systematic search of articles about AIS patients who underwent HRI and reported long-term outcomes (> 10 years) was conducted on electronic databases according to PRISMA guidelines. Data regarding radiographic and clinical outcomes were extracted and meta-analyses were performed. Eleven studies comprising 644 patients were included. The mean follow-up ranged from 10.8 to 51.7 years. Radiographic analysis revealed a decrease in the main curve Cobb angle from 60.6° to 38.3°, with a correction loss of - 9.49° between postoperative and last follow-up. Concerning sagittal parameters, preoperative thoracic kyphosis was 19.65° at last follow-up, and preoperative lumbar lordosis was 42.94°. Additional spine surgeries were required in 42% of patients. Clinical outcomes varied among studies, but overall, HRI patients showed comparable quality of life and function to controls, although a higher incidence of low back pain was reported. Patients who underwent HRI exhibited suboptimal correction of rib deformity and a flattened sagittal spinal alignment. However, they generally displayed favourable long-term functional outcomes. Despite the implant's tendency to reduce lumbar curvature, patients achieved good clinical outcomes and functional scores comparable to age-matched individuals, suggesting that disability is not an inevitable consequence of lumbar flattening.

Spinopelvic alignment and precise cup placement in total hip arthroplasty - A systematic review

Study Design

A systematic literature review and meta- analysis.

Objective

To extract and combine the available literature focused on normal and abnormal biomechanical principles of spine-pelvis-hip complex and to sum up the data in the application of THA both in the setting with and without spinal disorders.

Methods

An extensive search and analysis of the articles was done by 3 authors independently in 7 platforms based on PRISMA and MOOSE guidelines. Selection criteria 1. Articles that assessed spinopelvic parameters (SS, SPT, PI, and acetabular cup orientation) in patients undergoing THA, Articles that assessed balance in spinopelvic complex after THA, Randomized control studies, Systematic literature reviews, Meta-analyses, Clinical trials / original research studies, Review articles and Articles after 2015 were included. Cochrane's GRADE method was used to define the level of evidence. 2.Participants: Patients who underwent THA only (in asymptomatic spine), those who had ankylosing spondylitis and underwent THA and those who underwent THA with prior spinal arthrodesis. 3.Study parameters: Ante Inclination (AI), sacral slope (SS), pelvic Incidence (PI) and spinopelvic tilt (SPT) in both positions of standing and sitting. ΔAI, ΔSS and ΔSPT. Data were collected and analyzed, the means of the study parameters with SD were calculated and a meta-analysis is performed to evaluate the pooled means with optimal value range.

Results

From 218 abstracts extracted and after eligibility assessment and exclusion, 4 articles involving 439 patients were enrolled. The mean SS in standing and sitting calculated were 35.53±10.52 and 33.13±12.38. The mean of AI and SPT in standing /sitting positions are 29.7±12.29/34.69±12.96 (n = 242) and 19.56±8.9/21.22±12.53 (n=439) respectively. The ΔAI, ΔSS, and ΔSPT were 4.99,2.4 and 1.66 respectively.

Conclusion

There is a proportionate change between the spinopelvic tilt and the acetabular orientation in postural variations. Evaluation of spine, pelvis and hip becomes more critical in identifying these changes and thereby prompting the acetabular cup position in the functional safe zone.

A new 3D full-body scanner analyzing the sagittal and coronal balance of the adult spine: a preliminary prospective observational study

BACKGROUND

The degenerative spondylosis can cause the difficulty in maintaining sagittal and coronal alignment of spine, and X-ray parameters are the gold standard to analyze the malalignment. This study aimed to develop a new 3D full body scanner to analyze the spinal balance and compare it to X-ray parameters.

METHODS

Ninety-seven adult participants who suffer degenerative spondylosis underwent 3D full body scanning, whole spine X-rays, clinical questionnaires and body composition analyses. The 5 inflection points (ear, shoulder, hip, knee, ankle) of the 3D scanner in the sagittal plane were automatically labeled by an AI algorithm. Three concepts are created including "the angle between two points with respect to the plumb line", "the horizontal distances between two points in the sagittal plane" and "the angle between three points". For the coronal plane, the shoulder gradient was analyzed. X-ray parameters of cervical, thoracolumbar and whole spine sagittal balance and coronal balances were compared. The body composition data and clinical questionnaire scores were compared to x-ray and 3D scanner parameters.

RESULTS

The correlation coefficient (C.C.) of dAB_hor (horizontal distance between ear and shoulder in the sagittal plane) and C2-C7 SVA was 0.478 (p-value < 0.001). The C.C. of aAC_sag (sagittal angle of ear-hip from the plumb line) and ODHA was 0.336 (p < 0.001). About coronal balance, the C.C. of shoulder gradient and clavicle angle from x-ray was 0.373 (p < 0.001). The C.C.s were merely affected by body composition data. But in multiple regression analysis, BMI affected 3D scanner data. Clinical symptoms showed correlations with aBCD(shoulder-hip-knee) and aCDE(hip-knee-ankle angle), which may reflect a compensatory pelvic retroversion and knee flexion for positive sagittal imbalance.

CONCLUSIONS

This new 3D scanner has some strengths like radiation-free methods, correlation with x-ray parameters and clinical symptoms, independence to body composition data, and possibility of analyzing dynamic spine balance.

Comparison of clinical and radiological outcomes of three-column lumbar osteotomies with and without interbody cages for adult spinal deformity

BACKGROUND CONTEXT

Correcting sagittal malalignment in adult spinal deformity (ASD) is a challenging task, often requiring complex surgical interventions like pedicle subtraction osteotomies (PSOs). Different types of three-column osteotomies (3COs), including Schwab 3, Schwab 4, Schwab 4 with interbody cages, and the "sandwich" technique, aim to optimize alignment and fusion outcomes. The role of interbody cages in enhancing fusion and segmental correction remains unclear.

PURPOSE

This study aimed to compare outcomes among these 4 3CO techniques, evaluating the impact of cage use at the osteotomy site on postoperative radiographic imaging and clinical outcomes.

STUDY DESIGN/SETTING

This is a multicenter retrospective study utilizing data from a prospective multicenter database of patients undergoing complex ASD surgery.

PATIENT SAMPLE

Ninety-seven patients who underwent 1 of 4 3CO techniques for thoracolumbar ASD correction with at least 2 years of follow-up were included. The sample consisted of 29 patients who underwent Schwab 3 osteotomy, 20 Schwab 4, 28 Schwab 4 with interbody cages, and 20 who underwent "sandwich" osteotomy.

OUTCOME MEASURES

The Scoliosis Research Society-22 revised (SRS22r) questionnaire evaluating pain, activity, appearance, mental health, and satisfaction was used to evaluate patient reported outcomes and radiographic measures including segmental lordosis and fusion rates determined by 3 blinded reviewers were used to evaluate physiologic outcomes.

METHODS

This study analyzed demographic data, radiographic outcomes, patient-reported outcomes, complications, and fusion rates over a 2-year follow-up period. Fusion status was determined via serial radiographs and evaluated independently by 3 blinded reviewers. Univariate and multivariate statistical analyses were performed to assess differences among the groups and the impact of interbody cage use on outcomes.

RESULTS

Patients undergoing "sandwich" osteotomy exhibited worse preoperative leg pain scores and lower SRS22r activity (p=.015), appearance (p=.007), and mental health domain scores (p=.0015). No differences in complications were found among groups (p>.05). Patients who underwent osteotomy with a cage were more likely to have had previous spine fusion (91.7% vs. 71.4%, p=.010). Additionally, these patients had lower preoperative SRS22r mental domain (2.9±1 vs. 3.5±1, p=.009), satisfaction (2.3±1 vs. 2.7±1.2, p=.034), and SRS22r total scores (2.3±0.6 vs. 2.6±0.6, p=.0026) but demonstrated the greatest improvement in the mental health domain (0.9±0.7 vs. 0.3±0.9, p=.002). Cage use was associated with a larger mean change in segmental lordosis at the osteotomy site (32.9±9.6 vs. 28.7±9.5, p=.038). Fusion rates were significantly higher in the cage group (79.2% vs. 55.1%, p=.0012). Regression analysis identified cage use as an independent predictor for fusion (odds ratio, 3.338; 95% confidence interval, 1.108-10.054, p=.032).

CONCLUSIONS

Interbody cage use at the osteotomy site during 3COs for ASD correction was associated with improved fusion rates and greater segmental lordosis without increasing complication rates. Incorporating cages may provide enhanced alignment and fusion outcomes in complex ASD surgeries.

Quantitative assessment of muscle activity of back and lower extremities, whole body sagittal alignment, body sway, and health-related quality of life in adult spinal deformity patients before and after spinopelvic correction surgery: From the standpoint of the "cone of economy"

BACKGROUND AND AIMS

Pain and muscle fatigue in the low back and lower extremity associated with adult spinal deformity (ASD) markedly limit daily activities and affect quality of life. This study aimed to clarify if spinal correction surgery decreases the muscle activity requirements in relation to alignment and balance parameters.

METHODS

Integrated electromyogram (I-EMG) studies of the low back and lower extremity in addition to whole body alignment, body sway, and health-related quality of life (HRQOL) were evaluated in 16 patients with ASD before and after surgery. Sixteen healthy volunteers were included as control subjects. Muscle activities of the bilateral lumbar paravertebral, biceps femoris, rectus femoris, gastrocnemius, and tibialis anterior were measured using surface electromyogram in both resting and working standing positions. Surgical outcomes were based on improvements in muscle fatigue using the sum of the whole muscle I-EMGs and body sway. HRQOL was evaluated by SRS-22r, which measures 4 domains (function, pain, self-image, mental health) and subtotal scores.

RESULTS

In controls, the sum of the 10 whole I-EMGs (mVms; mean ± SD) was 3316 ± 1247 in the resting standing position and 5625 ± 2065 in the working standing position. The I-EMG values were higher in ASD patients than in healthy subjects; in the resting standing position, the sum of the whole 10 I-EMGs significantly decreased from baseline (9125 ± 3529) to 3 (6088 ± 1793) and 6 (6381 ± 1776) months postoperatively (p < 0.01). In the working standing position, the sum in ASD patients also significantly decreased from baseline (14,160 ± 5474) to 3 (8085 ± 2540) and 6 (8557 ± 3025) months postoperatively (p < 0.01). I-EMG values did not differ significantly between the 3- and 6-month time points in either condition. Body sway was also improved postoperatively at 3 months and maintained at 6 months along with the amelioration of whole-body sagittal alignment, and 4 domains and subtotal SRS-22r scores significantly increased postoperatively.

CONCLUSION

Following spinopelvic correction surgery, whole body sagittal alignment was improved, and muscle activity based on I-EMG and body sway were significantly decreased. The SRS-22r scores after surgery also indicated significant improvement, suggesting that muscle fatigue in the standing position was ameliorated, i.e., the "cone of economy" was normalized.

Alignment considerations in degenerative spinal conditions: A narrative review

Background

With an aging population, degenerative spinal diseases are contributing significantly to the healthcare's burden. Spinal alignment in the context of adult spinal deformities has become an important domain of research.

Methods

We conducted a narrative review of the latest considerations in spinal alignment within the context of degenerative spinal conditions, discussed current strategies for morphological assessment and finally identified potential areas for future research.

Results

This review reported that degenerative spinal conditions lead to a complex disruption of spinal alignment. It also highlighted the importance of spino-pelvic alignment with specific attention to compensatory mechanisms that occur in response to spinal deformities. Emerging technologies including Artificial Intelligence and epigenetics are showing promises in terms of patient care.

Conclusions

Understanding spinal alignment in degenerative conditions underscores the importance of dynamic and individualized assessments. Future research should integrate emerging technologies along with traditional clinical practices in order to optimize patient outcomes and minimize complications for patients suffering from degenerative spinal diseases.

L4 Pedicle Subtraction Osteotomy in a Patient With Multiple Previous Revisions: A Case Report

Pedicle subtraction osteotomy (PSO) is a technically complex procedure that is effective at improving the sagittal profile in spinal deformity surgery. This case report describes a 64-year-old man with a history of ten previous spinal surgeries, including failed T10-pelvis posterior spinal fusion, undergoing revision with L4 PSO. The patient regained approximately 30° of lumbar lordosis. The procedure was complicated by an uneventful intraoperative durotomy and delayed postoperative surgical site infection requiring two surgical debridements and a prolonged course of antibiotics. At the 14-month follow-up, the patient was ambulating 3 miles per day and had significantly decreased pain with no sign of recurrent infection. PSOs performed in revision cases are more challenging procedures but can achieve similar degrees of correction even in patients with multiple previous revisions.

How cervical and cervicothoracic scoliosis influence the atlantoaxial joint

INTRODUCTION

Children with cervical or cervicothoracic congenital scoliosis are limited in their ability to compensate for the main curve of the deformity because there are only a few mobile segments in their cervical spine. Over the years, we have frequently observed coronal atlantoaxial dislocation (CAAD) in a lateral direction (from left to right or vice versa) in these patients. It was anticipated that CAAD might compensate for the horizontal position of the head, and it is hypothesized that CAAD depends on the degree of scoliotic deformity. Thus, the aim of our study was to investigate whether there is a correlation between CAAD and scoliosis parameters in these patients.

METHODS

Retrospective analysis was performed based on CAT scans and preoperative X-rays of patients with cervical and cervicothoracic scoliosis with an apex between C4 and T6. Seventeen patients, with a mean age of 7.25 years, who were 9 girls and 8 boys, and who were treated between 2006 and 2022 were included. Cobb`s angle of the main curve (CA-MC), Cobb`s angle of the secondary curve (CA-SC), and T1-, C2- and UEV (upper end vertebra) tilt were measured on whole-spine radiographs in the standing position. The CAAD was measured via coronal CAT scan reconstruction and defined as the difference in the distances of the lateral masses to the midline of the axis. Pearson`s linear correlation coefficients (r) were determined using SPSS to evaluate correlations between CAAD and the measured parameters. p < 0.05 indicated statistical significance.

RESULTS

CAAD toward the convex region in patients with scoliosis was typically observed; the mean CAAD was 3 mm ± 3.7 mm. The mean CA-MC was 46° ± 13°, the mean CA-SC was 16° ± 9.6°, the mean T1 tilt was 17° ± 8.8°, the mean C2 tilt was 9°± 8.8°, and the mean UEV tilt was 24° ± 7.2°. There was a strong linear correlation between CAAD and CA-MC (r = 0.784, p < 0.001), C2 tilt (r = 0.745; p < 0.001), and UEV tilt (r = 0.519; p = 0.033). There was no correlation between CAAD and either CA-SC or T1 tilt.

DISCUSSION

Children with cervical or cervicothoracic scoliosis tend to have a CAAD toward the convexity of the scoliosis that correlates to CA-MC, C2-tilt, and UEV-tilt. CAAD may be seen as a compensatory mechanism to keep the head in a horizontal position. Severe or progressive CAAD may result in destruction of the atlantoaxial joint, including severe complaints, thus necessitating close follow-up and possibly early surgical treatment. Moreover, CAAD might be a useful additional radiographic parameter to be checked in future scoliosis studies.

Posterior Column Reconstruction of the Lumbar Spine Using En Bloc Resected Vertebral Arch in Spinal Tumor and Deformity Surgeries

Introduction

In high-grade spinal osteotomy involving large anterior column resection, restoration of the structural integrity of the posterior column at the osteotomy site can reduce postoperative instrumentation failure (IF). This study aimed to describe our technique of posterior strut bone grafting using an en bloc resected vertebral arch, which is useful for posterior column reconstruction after high-grade osteotomies during surgeries for spinal tumor and deformity in the lower lumbar spine.

Technical Note

Using a posterior approach, en bloc resection of the targeted vertebral arch was performed in accordance with the surgical technique for total en bloc spondylectomy (TES). The posterior elements in the upper and lower adjacent vertebrae were separated by a significant space after vertebral body resection followed by cage insertion in TES or anterior column osteotomy followed by correction in deformity surgery. To create a new posterior column, the en bloc resected vertebral arch was placed at 90° rotation to bridge the upper and lower vertebral arches. Using this technique, an abundant amount of bone chips made from the resected vertebral elements were placed over the en bloc resected posterior arch as an additional bone graft. The technique was used in three patients who underwent TES for spinal tumors and in one patient who underwent grade 4 osteotomy for adult spinal deformity in the lower lumbar spine. One year after surgery, computed tomography showed that the structural integrity of bony fusion was successfully achieved between the en bloc resected arch and the posterior elements of the adjacent vertebrae in all patients and showed no postoperative IFs.

Conclusions

This bone graft technique created new continuity of the posterior column after high-grade osteotomies in the lower lumbar spine. Bone fusion was achieved in the posterior elements to prevent IF after surgery.

Sagittal spinal alignment measurements and evaluation: Historical perspective

Spinal alignment analysis play an important role in evaluating patients and planning surgical corrections for adult spinal deformity. The history of these parameters is relatively short with the first parameter, the Cobb angle, introduced in 1948 as part of an effort to improve scoliosis evaluation. New developments in the field were limited for nearly 30 years before better imaging technology encouraged new theories and later data about spinal alignment and the relationship between the spine and pelvis. These efforts would ultimately contribute to the creation of foundational spinal alignment parameters, including pelvic incidence, pelvic tilt, and sacral slope. By the 1990s, spinal alignment had become a sustained area of investigation for spinal surgeons and researchers. Novel alignment parameters have since been introduced as our knowledge has evolved and has allowed for valuable research that demonstrates the clinical and surgical value of alignment measurement. This manuscript will explore the history of spinal alignment analysis over the decades.

Mismatch Between Pelvic Incidence and Lumbar Lordosis After Personalized Interbody Fusion: The Importance of Preoperative Planning and Alignment in Degenerative Spine Diseases

BACKGROUND

Emerging data have highlighted the significance of planning and aligning total and segmental lumbar lordosis with pelvic morphology when performing short-segment fusion with the goal of reducing the risk of adjacent segment disease while also decreasing spine-related disability. This study evaluates the impact of personalized interbody implants in restoring pelvic incidence-lumbar lordosis (PI-LL) mismatch compared with a similar study using stock interbody implants.

METHODS

This multicenter retrospective analysis assessed radiographic pre- and postoperative spinopelvic alignment (PI-LL) in patients who underwent 1- or 2-level lumbar fusions with personalized interbody implants for degenerative (nondeformity) indications. The aim was to assess the incidence of malalignment (PI-LL ≥ 10°) both before and after fusion surgery and to determine the rate of alignment preservation and/or correction in this population.

RESULTS

There were 135 patients included in this study. Of 83 patients who were aligned preoperatively, alignment was preserved in 76 (91.6%) and worsened in 7 (8.4%). Among the 52 preoperatively malaligned patients, alignment was restored in 23 (44.2%), and 29 (55.8%) were not fully corrected. Among patients who were preoperatively aligned, there was no statistically significant difference in either the "preserved" or "worsened" groups between stock devices and personalized interbody devices. In contrast, among patients who were preoperatively malaligned, there was a statistically significant increase in the "restored" group (P = 0.046) and a statistically significant decrease in the "worsened" groups in patients with personalized interbodies compared with historical stock device data (P < 0.05).

CONCLUSIONS

Compared with a historical cohort with stock implants, personalized interbody implants in short-segment fusions have shown a statistically significant improvement in restoring patients to normative PI-LL. Using 3-dimensional preoperative planning combined with personalized implants provides an important tool for planning and achieving improvement in spinopelvic parameters.

LEVEL OF EVIDENCE: 3

Quantitatively assessing the effect of cervical sagittal alignment on dynamic intervertebral kinematics by video-fluoroscopy technique

BACKGROUND

Cervical sagittal alignment is crucial for distributing the head load to lower cervical segments and maintaining normal cervical spine function, but its biomechanical effect on the cervical spine was not fully elucidated.

OBJECTIVE

To investigate the effect of cervical sagittal alignment on dynamic intervertebral kinematics.

DESIGN

Cross-sectional study.

METHODS

Healthy participants without neck pain were recruited and divided into lordosis, straight and kyphosis groups according to the C2-C7 Cobb angle at the neutral position. The anti-directional and total joint motions were extracted across 10 epochs of dynamic cervical flexion and extension movements.

RESULTS

/findings: The overall anti-directional joint motion during flexion is larger in the kyphosis group when compared with the lordosis group (p = 0.021), while the range of flexion is smaller in the kyphosis group than that in the lordosis group (p = 0.017). The C2/C3 anti-directional joint motion during extension in the straight group is larger than that in the lordosis group (p = 0016). The range of extension in the kyphosis group (p < 0.001) and the straight group (p = 0.002) are larger than that in the lordosis group. The increased range of extension in the kyphosis and straight groups were mainly from the C3/C4, C4/C5, and C5/C6 joints(p < 0.05).

CONCLUSION

Changes in cervical sagittal alignment alter both the quality and quantity of the individual joint motions. More adjustments are required by the cervical joints to complete neck movements with the loss of lordosis. The lordotic curvature is a relatively effort-saving mode for the cervical spine from a biomechanical perspective.

Modern Concepts in Sagittal Curve Measurement: Comparison of Spline-Based and Fixed Landmark Measurements in a Cohort of 1520 Healthy Subjects

STUDY DESIGN

Retrospective multicenter study.

OBJECTIVE

Our objective was to compare the spline-based measurement of sagittal spinal curvatures to fixed landmarks in a normative population.

SUMMARY OF BACKGROUND DATA

Recent research has stressed the importance of considering sagittal curvature in its entirety using a spline reconstruction. To date, no data supports the superiority of this method in comparison to classic measurement methods.

PATIENTS AND METHODS

Full-spine biplanar radiographs of subjects over 20 years old who had normal radiographs were analyzed. Thoracic kyphosis (TK) and lumbar lordosis (LL) were measured following two modalities: either using predefined landmarks (TK T1T12 , TK T5T12 , and LL L1S1 ) or spline-based measurement (TK Spline and LL spline ).

RESULTS

A total of 1520 subjects were included (mean 54yo). The mean difference between TK spline and TK T1T12 was 1.4° and between TK spline and TK T5T12 was 11.7° ( P <0.001). LL spline was significantly larger than LL L1S1 (55° vs . 54°, P<0.001 ). LL spline and LL L1S1 were correlated ( R =0.950, P <0.001). Pelvic incidence had no influence on the difference between LL spline and LL L1S1 ( R =-0.034, P= 0.184). Using LL L1S1 measurements, LL was underestimated in 17% of the cases. The comparison of outlier distributions according to age groups ( P =0.175), sex ( P =0.937), or pelvic incidence groups ( P =0.662) found no difference. There were significantly more outliers in Roussouly type 1 compared with other types (56%, P <0.001).

CONCLUSION

Our results suggest that the use of TK T1T12 and LL L1S1 is acceptable to assess spinal sagittal curvatures. However, TK T5T12 is not accurate for the thoracic curve and should be used with caution. LL L1S1 can be used to accurately assess the lumbar curve, except in Roussouly type 1.

What factors are associated with a better restoration of pelvic version after adult spinal deformity surgery?

INTRODUCTION

Poor restoration of pelvic version after adult spinal deformity (ASD) surgery is associated with an increased risk of mechanical complications and worse quality of life. We studied the factors linked to the improvement of postoperative pelvic version.

MATERIALS AND METHODS

This is a retrospective analysis of a prospective multicenter ASD database. Selection criteria were: operated patients having preoperative severe pelvic retroversion as per GAP score (Relative Pelvic Version-RPV < - 15°); panlumbar fusions to the pelvis; 2-year follow-up. Group A comprised patients with any postoperative improvement of RPV score, and group B had no improvement. Groups were compared regarding baseline characteristics, surgical factors, and postoperative sagittal parameters. Parametric and non-parametric analyses were employed.

RESULTS

177 patients were studied, median age 67 years (61; 72.5), 83.6% female. Groups were homogeneous in baseline demographics, comorbidities, and preoperative sagittal parameters (p > 0.05). The difference in RPV improvement was 11.56º. Group A (137 patients) underwent a higher percentage of ALIF procedures (OR = 6.66; p = 0.049), and posterior osteotomies (OR = 4.96; p < 0.001) especially tricolumnar (OR = 2.31; p = 0.041). It also showed a lower percentage of TLIF procedures (OR = 0.45; p = 0.028), and posterior decompression (OR = 0.44; p = 0.024). Group A displayed better postoperative L4-S1 angle and relative lumbar lordosis (RLL), leading to improved sacral slope (and RPV), and global alignment (RSA). Group A patients had longer instrumentations (11.45 vs 10; p = 0.047) and hospitalization time (13 vs 11; p = 0.045). All postoperative sagittal parameters remained significantly better in group A through follow-up. However, differences between the groups narrowed over time.

CONCLUSIONS

ALIF procedures and posterior column osteotomies improved pelvic version postoperatively, and associated better L4-S1 and lumbar lordosis restoration, indirectly improving all other sagittal parameters. However, these improvements seemed to fade during the 2-year follow-up.

Harmony between spinopelvic mismatch and sagittal hip alignment contributes to upright standing in females: a cross-sectional study

Background

In upright standing, spinopelvic mismatch is compensated by hip extension. However, few studies have investigated the reciprocal relationship between the sagittal alignment of the hip joints and spinopelvic mismatch during upright standing in humans. Our study aims to investigate (I) the relationship between spinopelvic mismatch and hip extension and (II) whether insufficient hip extension against spinopelvic mismatch, i.e., pelvic incidence (PI)-lumbar lordosis (LL), affects trunk inclination in upright standing.

Methods

This study was a retrospective cross-sectional study. We included 398 consecutive female patients treated for osteoporosis at our outpatient department between November 2017 and June 2022. Patients with any of the following were excluded from the study: (I) those whose plain whole-spine radiographs did not cover the femurs, (II) those with fractures in the vertebrae or lower extremities, (III) those with a history of surgery of the spine or of the lower extremities, (IV) those with scoliosis with a Cobb angle ≥10° in the anteroposterior radiograph, and (V) those with transitional vertebrae. Sixty-two patients were divided into normal and malalignment groups based on their sagittal spinal alignment. The patients underwent plain whole-spine radiography as a routine examination. A linear approximation between the pelvic femoral angle (PFA), representing hip extension, and PI-LL was obtained in both groups. The optimal PFA of each patient was obtained by substituting the PI-LL into the linear approximation of the normal group. The difference between the optimal and measured PFA was defined as the ΔPFA for each patient. The correlation between the ΔPFA and sagittal vertical axis (SVA) was evaluated in both groups.

Results

The PFA and PI-LL were correlated in both groups. The malalignment group had a significantly greater ΔPFA than the normal group. ΔPFA was correlated with SVA only in the malalignment group.

Conclusions

The magnitude of the ΔPFA indicated insufficient hip extension to compensate for the spinopelvic mismatch during upright standing.

Assessment of malalignment at early stage in adolescent idiopathic scoliosis: a longitudinal cohort study

INTRODUCTION

Our objective was to assess abnormalities of the odontoid-hip axis (OD-HA) angle in a mild scoliotic population to determine whether screening for malalignment would help predict the distinction between progressive and stable adolescent idiopathic scoliosis (AIS) at early stage.

MATERIALS AND METHODS

All patients (non-scoliotic and AIS) underwent a biplanar X-ray between 2013 and 2020. In AIS, inclusion criteria were Cobb angle between 10° and 25°; Risser sign lower than 3; age higher than 10 years; and no previous treatment. A 3D spine reconstruction was performed, and the OD-HA was computed automatically. A reference corridor for OD-HA values in non-scoliotic subjects was calculated as the range [5th-95th percentiles]. A severity index, helping to distinguish stable and progressive AIS, was calculated and weighted according to the OD-HA value.

RESULTS

Eighty-three non-scoliotic and 205 AIS were included. The mean coronal and sagittal OD-HA angles in the non-scoliotic group were 0.2° and -2.5°, whereas in AIS values were 0.3° and -0.8°, respectively. For coronal and sagittal OD-HA, 27.5% and 26.8% of AIS were outside the reference corridor compared with 10.8% in non-scoliotic (OR = 3.1 and 3). Adding to the severity index a weighting factor based on coronal OD-HA, for thoracic scoliosis, improved the positive predictive value by 9% and the specificity by 13%.

CONCLUSION

Analysis of OD-HA suggests that AIS patients are almost three times more likely to have malalignment compared with a non-scoliotic population. Furthermore, analysis of coronal OD-HA is promising to help the clinician distinguish between stable and progressive thoracic scoliosis.

Sagittal Alignment in the Degenerative Lumbar Spine: Surgical Planning

➤ Sagittal alignment of the spine has gained attention in the field of spinal deformity surgery for decades. However, emerging data support the importance of restoring segmental lumbar lordosis and lumbar spinal shape according to the pelvic morphology when surgically addressing degenerative lumbar pathologies such as degenerative disc disease and spondylolisthesis.➤ The distribution of caudal lordosis (L4-S1) and cranial lordosis (L1-L4) as a percentage of global lordosis varies by pelvic incidence (PI), with cephalad lordosis increasing its contribution to total lordosis as PI increases.➤ Spinal fusion may lead to iatrogenic deformity if performed without attention to lordosis magnitude and location in the lumbar spine.➤ A solid foundation of knowledge with regard to optimal spinal sagittal alignment is beneficial when performing lumbar spinal surgery, and thoughtful planning and execution of lumbar fusions with a focus on alignment may improve patient outcomes.

Impact of prior spinal fusion surgery on complications and functional outcomes following total hip arthroplasty: an updated systematic review and meta-analysis

PURPOSE

This study aimed to compare the complication rates and functional outcomes between patients with and without a history of spinal fusion undergoing THA.

METHODS

A systematic search was conducted across PubMed, EMBASE, Scopus, and Cochrane databases. Studies that compared adults with and without a history of spinal fusion after primary THA were included. The methodological quality of the studies was evaluated using MINORS criteria. Meta-analyses were performed utilizing mean differences (MD), standardized mean differences (SMD), and odds ratios (OR), along with 95% confidence intervals (CI).

RESULTS

Seventeen studies involving 1,789,356 patients (31,786 in the SF group and 1,757,570 in the Non-SF group) were analyzed. The spinal fusion group exhibited significantly higher rates of dislocation (OR 2.50, 95% CI 1.78-3.52), periprosthetic fracture (OR 1.96, 95% CI 1.39-2.77), overall complications (OR 1.73, 95% CI 1.10-2.71), and revision rates (OR 1.86, 95% CI 1.74-1.99). Furthermore, within the first three months, there was an increased risk of dislocation (OR 4.38, 95% CI 1.36-14.14) and revisions (OR 3.87, 95% CI 1.63-9.18). Longer spinal fusions were significantly associated with a higher risk of dislocations (OR 0.62, 95% CI 0.53-0.71). Additionally, prior spinal fusion was linked to higher levels of pain (SMD 0.11, 95% CI 0.02-0.19) and poorer functional outcomes (MD - 0.09, 95% CI - 0.18 to - 0.00).

CONCLUSIONS

Patients with a history of spinal fusion undergoing THA exhibit increased complication rates, higher levels of pain, and greater functional limitations than those without prior fusion. These findings have significant clinical implications for optimizing perioperative care in high-risk patient populations.

An appropriate method for predicting the femoral angle on whole-body X-ray images from full-spine X-ray images

INTRODUCTION

The importance of lower-limb compensation in patients with spinal malalignment due to spinal pathologies has been emphasized. The latest whole-body X-ray images (WBX) have enabled evaluations of whole-body alignment from head to toe. However, WBX is still not commonly available. Thus, the present study aimed to examine an alternative measurement method of the femoral angle on usual full-spine X-ray images (FSX) that approximates the femoral angle on WBX.

METHODS

A total of 50 patients (age, 52.8 ± 25.3 years; female, n = 26; male, n = 24) underwent WBX and FSX. The following parameters were measured on lateral view X-rays: WBX and FSX femoral angle (angle between the femoral axis and a perpendicular line); FSX femoral distance (distance from the center of femoral head to the distal femur on FSX); WBX intersection length (length between the center of the femoral head and the intersection point [the point at which the line connecting the center of the femoral head and the midpoint of the femoral condyle intersects the center line of the femur] on WBX).

RESULTS

The WBX femoral angle, and FSX femoral angle were 0.16 ± 4.2°, and -0.53 ± 4.1°, respectively. The FSX femoral distance was 102.7 ± 41.1 mm. An ROC curve analysis revealed that the cut-off value of the FSX femoral distance associated with minimal difference in the WBX and FSX femoral angles (<3°) was 73 mm (sensitivity 83.3%, specificity 87.5%, AUC 0.80). The WBX intersection length was 105.3 ± 27.3 mm.

CONCLUSION

To calculate the femoral angle on FSX that approximates the WBX femoral angle, the femoral distance on FSX ≥73 mm is preferable. We suggest using the FSX femoral distance within the range of 80 mm-130 mm as a simple numerical value that meets all criteria.

Current Concepts of Cervical Spine Alignment, Sagittal Deformity, and Cervical Spine Surgery

There are not many reports on cervical spine alignment, and only a few analyze ideal surgical approaches and optimal amounts of correction needed for the various types of deformity. We comprehensively reviewed the present literature on cervical spinal deformities (with or without myelopathy) and their surgical management to provide a framework for surgical planning. A general assessment of the parameters actually in use and correlations between cervical and thoracolumbar spine alignment are provided. We also analyzed posterior, anterior, and combined cervical surgical approaches and indications for the associated techniques of laminoplasty, laminectomy and fusion, and anterior cervical discectomy and fusion. Finally, on the basis of the NDI, SF-36, VAS, and mJOA questionnaires, we fully evaluated the outcomes and measures of postoperative health-related quality of life. We found the need for additional prospective studies to further enhance our understanding of the importance of cervical alignment when assessing and treating cervical deformities with or without myelopathy. Future studies need to focus on correlations between cervical alignment parameters, disability scores, and myelopathy outcomes. Through this comprehensive literature review, we offer guidance on practical and important points of surgical technique, cervical alignment, and goals surgeons can meet to improve symptoms in all patients.

Lumbar reconstruction with hyperlordotic cages: Prediction of neuroforaminal height in comparison to established age and sex dependent reference values

Interbody cages are routinely used in lumbar reconstruction surgery of deformity cases for restoration of lordosis and sagittal balance of the spine. However, if hyperlordotic implants are inserted into the intervertebral space, special consideration has to be taken concerning the height of the neural foramen during cage implantation. The greater the lordotic angle of the cage is, the higher the posterior size of the cage needs to be in order to avoid neuroforaminal nerve root impingement. In this technical communication, we propose and clinically validate a stepwise mathematic model to predict neuroforaminal height in patients undergoing lumbar reconstruction with hyperlordotic cages. The length of the superior and inferior vertebral end plates including the height of the neural foramen are measured before implantation of the cage in standing sagittal view x-rays. By assumption of an isosceles triangle in combination with the posterior height and the lordotic angle of the cage, the neuroforaminal height after cage implantation can be estimated. By comparison of the predicted neuroforaminal height with age and sex dependent reference values, nerve root impingement can be avoided by selection of the necessary posterior height of the hyperlordotic cage while still gaining sufficient lumbar lordosis.

From the Spinopelvic Parameters to Global Alignment and Proportion Scores in Adult Spinal Deformity

In the last 20 years, sagittal alignment and balance of the spine have become one of the most important issues in the field of spine surgery. Recent studies emphasize that sagittal balance and alignment are more important for health-related quality of life. The understanding of normal and abnormal sagittal alignment of the spine is necessary for the diagnosis and appropriate treatment of adult spinal deformity (ASD), and we will discuss the currently used classification of ASD, the parameters of sagittal alignment that are essential for the diagnosis of spinal deformity, compensatory actions to maintain sagittal balance, and the relationship between sagittal alignment and clinical symptoms. Furthermore, we will also discuss the recently introduced Global Alignment and Proportion scores. The Korean Spinal Deformity Society is publishing a series of review articles on spinal deformities to help spine surgeons better understand spinal deformities.

Scoliosis Research Society-22r score is affected by standing whole body sagittal alignment, age, and sex, but not by standing balance or skeletal muscle mass in healthy volunteers

PURPOSE

Aging and spinal disease impair standing whole body sagittal alignment (WBS alignment), which leads to stooping. When WBS alignment deteriorates, compensatory mechanisms are activated to maintain standing posture. Increase of the compensation impairs health-related quality of life (HRQOL). The purpose of this research was to determine whether postural factors, age, and sex affect HRQOL.

METHODS

This cross-sectional study evaluated the influence of WBS alignment, standing body sway (balance), skeletal muscle mass (SMM), aging, and sex on HRQOL in healthy volunteers (n = 150; mean age 40.9 years [20-76], 96 women). Age, sex, weight, height, and body mass index (BMI) were obtained. HRQOL was assessed with Scoliosis Research Society-22 (SRS-22r). WBS alignment and balance were measured by EOS imaging with simultaneous force plate measurement. SMM was measured using a medical body composition analyzer. Based on the bivariate analysis between the SRS-22r subtotal and all parameters, selected ten parameters were used for multivariate logistic regression analysis to identify affecting factors to SRS-22r.

RESULTS

Men had significantly higher weight, height, BMI, and SRS-22r score in all domains. The L4-S1 lumbar lordosis angle was greater in men, and pelvic tilt and knee hyperextension were greater in women. Women had a more stable standing posture, whereas men had significantly higher SMM values. Multivariate logistic regression analysis revealed that age, sex, and TPA were identified as significant factors affecting SRS-22r.

CONCLUSIONS

In healthy volunteers, SRS-22r is affected by aging, sex (woman had a lower score), and sagittal malalignment. Neither Standing balance nor SMM, however, affect SRS-22r.4.