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Study Design: A retrospective study., Objective: Relationship between rod and spinal shape in the sagittal plane in adult spinal deformity (ASD) surgery., Background: Corrective surgery for adult spinal deformity (ASD) involves the use of contoured rods to correct and modify the spinal curvatures. Adequate rod bending is crucial for achieving optimal correction. The correlation between rods and spinal shape in long constructs has not been reported previously., Methods: We conducted a retrospective analysis of a prospective, multicenter database of patients who underwent surgery for ASD. The inclusion criteria were patients who underwent pelvic fixation and had an upper instrumented vertebra at or above T12. Pre- and post-operative standing radiographs were used to assess lumbar lordosis at the L4S1 and L1S1 levels. The angle between the tangents to the rod at the L1, L4, and S1 pedicles was calculated to determine the L4S1 and L1S1 rod lordosis. The difference between the lumbar lordosis (LL) and the rod lordosis (RL) was calculated as ΔL = LL-RL. The correlation between this difference (ΔL) and various characteristics was analyzed using descriptive and statistical methods., Results: Eighty-three patients were included in the study, resulting in 166 analyzed differences (ΔL) between the rod and spinal lordosis. The values for rod lordosis were found to be both greater and lesser than those of the spine but were mostly lower. The range for total ΔL was -24 °-30.9 °, with a mean absolute ΔL of 7.8 ° for L1S1 (standard deviation (SD) = 6.0) and 9.1 ° for L4S1 (SD = 6.8). In 46% of patients, both rods had a ΔL of over 5 °, and over 60% had at least one rod with a ΔL difference of over 5 °. Factors found to be related to a higher ΔL included postoperative higher lumbar lordosis, presence of osteotomies, higher corrected degrees, older age, and thinner rods. Multivariate analysis correlated only higher postoperative L1S1 lordosis with higher ΔL. No correlation was found between a higher ΔL and sagittal imbalance., Conclusions: Variations between spinal and rod curvatures were observed despite the linear regression correlation. The shape of the rod does not seem to be predictive of the shape of the spine in the sagittal plane in ASD long-construct surgeries. Several factors, other than rod contouring, are involved in explaining the postoperative shape of the spine. The observed variation calls into question the fundamentals of the ideal rod concept., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: The Oswestry Disability Index (ODI) and the Core Outcome Measures Index (COMI) are two commonly used self-rating outcome instruments in patients with lumbar spinal disorders. No formal crosswalk between them exists that would otherwise allow the scores of one to be interpreted in terms of the other. We aimed to create such a mapping function., Methods: We performed a secondary analysis of ODI and COMI data previously collected from 3324 patients (57 ± 17y; 60.3% female) at baseline and 1y after surgical or conservative treatment. Correlations between scores and Cohen's kappa for agreement (κ) regarding achievement of the minimal clinically important change (MCIC) score on each instrument (ODI, 12.8 points; COMI, 2.2 points) were calculated, and regression models were built. The latter were tested for accuracy in an independent set of registry data from 634 patients (60 ± 15y; 56.8% female)., Results: All pairs of measures were significantly positively correlated (baseline, 0.73; 1y follow-up (FU), 0.84; change-scores, 0.73). MCIC for COMI was achieved in 53.9% patients and for ODI, in 52.4%, with 78% agreement on an individual basis (κ = 0.56). Standard errors for the regression slopes and intercepts were low, indicating excellent prediction at the group level, but root mean square residuals (reflecting individual error) were relatively high. ODI was predicted as COMI × 7.13-4.20 (at baseline), COMI × 6.34 + 2.67 (at FU) and COMI × 5.18 + 1.92 (for change-score); COMI was predicted as ODI × 0.075 + 3.64 (baseline), ODI × 0.113 + 0.96 (FU), and ODI × 0.102 + 1.10 (change-score). ICCs were 0.63-0.87 for derived versus actual scores., Conclusion: Predictions at the group level were very good and met standards justifying the pooling of data. However, we caution against using individual values for treatment decisions, e.g. attempting to monitor patients over time, first with one instrument and then with the other, due to the lower statistical precision at the individual level. The ability to convert scores via the developed mapping function should open up more centres/registries for collaboration and facilitate the combining of data in meta-analyses., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: To determine if responses given to each question of the Scoliosis Research Society-22 (SRS22), Oswestry disability index (ODI) and Short Form-36 (SF-36) questionnaires are influenced by the radiological parameters., Methods: Patients enrolled in a multi-centre prospectively collected adult spinal deformity database who had complete SRS22, ODI and SF-36 data at baseline and at one-year follow-up were analysed. The presence of a differential item function of each question within each score in relation to radiological parameters was analysed using a mixed Rasch model with the radiological threshold value(s) determined., Results: Of those patients analysed (n = 1745; 1406 female, average age 51.0 ± 19.8 years), 944 were surgically and 801 were non-surgically treated. For the SRS22, questions (Q) 3, 5 and 18 were sensitive to almost all radiological parameters and the overall score was found sensitive to the Cobb angle. For the ODI, Q3, 6, 9 and 10 were not sensitive to any radiologic parameters whereas Q4 and 5 were sensitive to most. In contrast, only 3 of the SF-36 items were sensitive to radiological parameters., Conclusions: 78% of the SRS-22, 60% of the ODI and 8% of the questions in the SF-36 are sensitive to radiological parameters. Sagittal imbalance is independently associated with a poor overall outcome, but affects mental status and function more than pain and self-image. The assembly of questions responsive to radiological parameters may be useful in establishing a connection between changes in radiologic parameters and HRQL., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Sagittal lumbar apex has been demonstrated to be a key parameter in sagittal plane morphology. Our aim was to understand its behavior with postural changes, analyzing two different concepts of lumbar apex., Materials and Methods: Prospective observational study with a cohort of patients presenting sagittal malalignment identified from a monocenter database of adult spinal deformities (ASD). Inclusion criteria were age > 30 years, SVA > 40 mm, and/or PT > 20. All patients had full-spine EOS radiographs in 2 different positions: (P1: natural position) and position 2 (P2: compensated position). Sagittal alignment, spinopelvic values, and two different methods of assessing lordosis apex location were analyzed in both P1 and P2 positions. Changes between P1 and P2 were compared using a paired t test with a significance level at p < 0.05., Results: Twenty-five patients were recruited (21 women and 4 men). The mean age was 64.8 years (range 21-79). The patient's main compensation was based on an increase in the femoral shaft angle, and pelvic retroversion, with a subsequent decrease in sacral slope, and therefore of the lower lumbar arc. When the lumbar apex was calculated as the most anterior point touching the vertical line in a lateral radiograph, postural compensation changes modified its location usually shifting it to a more caudal position. When the lumbar apex was assessed as the most distant point of the global lumbar lordosis, its position remained stable regardless of compensation., Conclusions: Postural changes can modify the location of the lumbar apex when understanding its location as the cornerstone of sagittal plane harmonic distribution. This concept can be useful as an additional sign to assess compensation. However, if the lumbar apex was calculated as the angular point of the global lordosis, its position remained stable regardless of postural changes. This concept can help to mold lumbar lordosis in ASD surgery., Level of Evidence Iv: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Purpose: The aim of this study was to evaluate factors that distinguish between patients with adult spinal deformity (ASD) with and without an indication for surgery, irrespective of their final treatment., Methods: Baseline variables (demographics, medical history, outcome measures, coronal, sagittal and neurologic parameters) were evaluated in a multicentre, prospective cohort of patients with ASD. Multivariable analyses were carried out for idiopathic and degenerative patients separately with the dependent variable being "indication for surgery" and baseline parameters as independent variables., Results: In total, 342 patients with degenerative ASD and 624 patients with idiopathic ASD were included in the multivariable models. In patients with degenerative ASD, the parameters associated with having an indication for surgery were greater self-rated disability on the Oswestry Disability Index [odds ratio (OR) 1.04, 95% confidence interval (CI) 1.02-1.07] and a lower thoracic kyphosis (OR 0.97 95% CI 0.95-0.99), whereas in patients with idiopathic ASD, it was lower (worse) SRS self-image scores (OR 0.45 95% CI 0.32-0.64), a higher value for the major Cobb angle (OR 1.03 95% CI 1.01-1.05), lower age (OR 0.96 95% CI 0.95-0.98), prior decompression (OR 3.76 95% CI 1.00-14.08), prior infiltration (OR 2.23 95% CI 1.12-4.43), and the presence of rotatory subluxation (OR 1.98 95% CI 1.11-3.54) and sagittal subluxation (OR 4.38 95% CI 1.61-11.95)., Conclusion: Specific sets of variables were found to be associated with an indication for surgery in patients with ASD. These should be investigated in relation to patient outcomes for their potential to guide the future development of decision aids in the treatment of ASD. These slides can be retrieved under Electronic Supplementary Material.

Purpose: Although many risk factors for surgical site infection (SSI) following spinal fusion have been described in the literature, methodologies and study cohorts vary widely. Patient- and procedure-specific risk factors for (SSI) can be identified via a meta-analysis. We sought to review the existing data and isolate significant risk factors for SSI in patients undergoing thoracolumbar spinal fusion., Methods: The literature was searched through December of 2016. Studies including adult patients undergoing thoracolumbar spinal fusion surgery (single or multilevel, anterior, posterior or combined approach) were identified. Only studies that included an odds ratio (OR) for SSI or sufficient data to calculate it were included. A meta-analysis was performed using RevMan 5.1. Depending on heterogeneity (I 2 ), OR with 95% confidence intervals was calculated using either the fixed-effects model (when I 2  < 60%) or the random-effects model (when I 2  > 60%)., Results: 6482 manuscripts were identified and reviewed. 29 manuscripts with 374,488 patients met the criteria for inclusion. Twelve risk factors were assessed by the meta-analysis and grouped into two categories (patient related and procedure related). Significant patient-related factors for SSI included obesity, diabetes, ASA score, tobacco use and revision status. Procedure-related risk factors included operative time, use of osteotomy, fusion length and extension of fusion to the sacrum or pelvis., Conclusions: This meta-analysis identified significant risk factors for SSI following spine arthrodesis. These included potentially modifiable factors such as obesity, diabetes, smoking status and procedure-related parameters. Non-modifiable risk factors were identified, including ASA score and age. These factors may prove useful for patient counseling as well as surgical planning., Level of Evidence: Level III (Meta-analysis including studies with a level of evidence of III or higher). These slides can be retrieved under Electronic Supplementary Material.

Purpose: Designed for patients with adolescent idiopathic scoliosis, the SRS-22 is now widely used as an outcome instrument in patients with adult spinal deformity (ASD). No studies have confirmed the four-factor structure (pain, function, self-image, mental health) of the SRS-22 in ASD and under different contexts. Factorial invariance of an instrument over time and in different languages is essential to allow for precise interpretations of treatment success and comparisons across studies. This study sought to evaluate the invariance of the SRS-22 structure across different languages and sub-groups of ASD patients., Methods: Confirmatory factor analysis was performed on the 20 non-management items of the SRS-22 with data from 245 American English-, 428 Spanish-, 229 Turkish-, 95 French-, and 195 German-speaking patients. Item loading invariance was compared across languages, age groups, etiologies, treatment groups, and assessment times. A separate sample of SRS-22 data from 772 American surgical patients with ASD was used for cross-validation., Results: The factor structure fitted significantly better to the proposed four-factor solution than to a unifactorial solution. However, items 14 (personal relationships), 15 (financial difficulties), and 17 (days off work) consistently showed weak item loading within their factors across all language versions and in both baseline and follow-up datasets. A trimmed SRS (16 non-management items) that used the four least problematic items in each of the four domains yielded better-fitting models across all languages, but equivalence was still not reached. With this shorter version there was equivalence of item loading with respect to treatment (surgery vs conservative), time of assessment (baseline vs 12 months follow-up), and etiology (degenerative vs idiopathic), but not age (< vs ≥50 years). All findings were confirmed in the cross-validation sample., Conclusion: We recommend removal of the worst-fitting items from each of the four domains of the SRS-instrument (items 3, 14, 15, 17), together with adaptation and standardization of other items across language versions, to provide an improved version of the instrument with just 16 non-management items.

Purpose: Spinal surgery for adult spinal deformity (ASD) may require the use of osteotomies, which may have high complication rates (up to 80 %). These may be expected to affect health-related quality of life (HRQOL) in the early postoperative phase but little is known about the clinical course of these patients in the first year following surgery. The aim of the study is to evaluate the radiological results and HRQOL in patients undergoing a spinal osteotomy for ASD within the first year following surgery with special reference to the effect of complications., Methods: From a prospective multicenter ASD database, patients who had undergone a Smith-Petersen osteotomy (SPO), pedicle substraction osteotomy (PSO), vertebral column resection (VCR) or any combination of these were reviewed for radiological sagittal alignment parameters [sagittal vertical axis (SVA), global tilt, lumbar lordosis, T2-sagittal tilt (ST)] as well as HRQOL [Oswestry Disability Index (ODI), short form-36 items (SF-36) Physical Component Score (PCS), SF-36 mental CS (MCS), Scoliosis Research Society (SRS)-22 questionnaire (SRS-22) subtotal] preoperatively and at the 6th- and 12th-month follow-ups with special reference to complications classified as major (life threatening or requiring additional surgery) and minor and their effects on HRQOL., Results: 121 patients (85 F, 36 M) with a total of 71 SPOs, 45 PSOs and 13 VCRs were evaluated. Osteotomy resulted in correction of the major coronal Cobb angle from 43.0 ± 3.7° to 24.8 ± 2.8° (p < 0.001) and the SVA from 69.0 ± 10.3 to 52.4 ± 6.6 mm (p = 0.001). Other radiological parameters showed no significant changes. Remarkable improvements in HRQOL scores with a strong age effect (p ≤ 0.01), for all instruments except SF-36 MCS, were found. Most of these HRQOL improvements have been achieved within the first 6 months. A total of 114 complications (59 major, 55 minor) that had a lesser effect on the age-adjusted HRQOL scores (p < 0.05) (except for the SF-36 PCS) and 1 death were observed., Conclusions: Osteotomies were moderately effective in radiological improvement but resulted in a significant increase in HRQOL. They were associated with a high rate of complications but these had no/minimal effect on the clinical outcome. Contrary to the general perception, the greatest improvements in HRQOL were seen to take place during the first 6 months after surgery, even in the presence of complications.

Purpose: Adult spinal deformity (ASD) may be classified as idiopathic (ID) or degenerative (DD) (or other) based on classifier's perception, the reliability of and factors inherent to which remain unknown. The aim of this study is to evaluate the inter- and intra-observer reliability of surgeons' perception in differentiating ID from DD and to identify the determinants of this differentiation., Methods: From a multicentric prospective database of ASD, 179 patients were identified with the diagnosis of ID (n = 103) or DD (n = 76); without previous surgery; and a lumbar coronal curve larger than 20°. Standing antero-posterior and lateral X-rays of these patients were sent to five experienced spine surgeons to be identified as DD or ID (or other); followed by a second round after reshuffling. Weighted kappa statistics were used, the strength of agreement for the kappa coefficient was considered as; 0.81-1 = almost perfect, 0.61-0.8 = substantial, 0.41-0.60 = moderate, 0.21-0.40 = fair, 0.01-0.20 = slight, and ≤0 = poor. Patients were then stratified based on the number of agreements on a total of 10 rounds as excellent (10 out of 10), good (more than 7 out of 10) and fair/poor (7 and less). These excellent and good agreements were further compared for additional radiological parameters., Results: Agreement levels were moderate to substantial for intra but mostly fair for inter-observer comparisons. For ID patients, there were 42 cases with excellent and 38 with very good agreement whereas for DD, there were no excellent and only 17 cases with very good agreement. Upon comparison of these (ID vs DD for at least very good cases), it was seen that they were different for some coronal parameters such as lumbar Cobb angle (larger in ID, p < 0.001), central sacral vertical line (CSVL) modifier (C more common in ID, p = 0.007) and presence of rotatory subluxation (less common in DD, p = 0.017), but very different for sagittal parameters (lumbar lordosis, sagittal vertical axis, T2 sagittal tilt, pelvic tilt, sacral slope, and global tilt; increased sagittal imbalance in DD, all p ≤ 0.001)., Conclusion: Surgeons in this study demonstrated reasonable (moderate to substantial) intra-observer agreement, but only fair agreement amongst them. Alarming as it may appear, we should be cautious in interpreting these results based on only radiology and no clinical information. In patients with good agreement, the most consistent radiologic determinant of degenerative ASD appeared to be the presence of sagittal imbalance.

Background: Adult spinal deformity (ASD) is a major public health problem. There are pros and cons of the available treatment alternatives (surgical or non-surgical) and it had been difficult to identify the best treatment modality., Aim: To construct a statistical DA model to identify the optimum overall treatment in ASD., Methods: From an international multicentre database of ASD patients (968 pts), 535 who had completed 1 year follow-up (371 non-surgical-NS, 164 surgical-S), constitute the population of this study. DA was structured in two main steps of: (1) baseline analysis (assessing the probabilities of outcomes, assessing the values of preference-utilities-, combining information on probability and utility and assigning the quality adjusted life expectancy (QALE) for each treatment) and (2) sensitivity analysis., Results: Four hundred and thirty-two patients (309 NS, 123 S) had baseline and 1 year follow-up ODI measurements. Overall, 104 (24.1 %) were found to be improved (a decrease in ODI > 8 points), 225 (52.1 %) unchanged (-8 > ODI > 8) and 65 deteriorated. Surgery presented with a higher chance of improvement (54.2 %) versus NS (9.7 %). The overall QALE ranged from 56 to 69 (of 100 years) and demonstrated better final QALE in the NS group (60 vs. 65, P = 0.0038), this group having started with higher QALE as well (56 vs. 65 years, P < 0.0001). There were improvements in overall QALE in both groups but this was significant only in the surgical group (S from 56 to 60 years, P < 0.0001; NS from 65 to 65 years, P = 0.27). In addition, in the subgroup of patients with significant baseline disability (ODI > 25) surgery appeared to yield marginally better final QALE (58 vs. 56 years, P = 0.1) despite very a similar baseline (54 vs. 54 years, P = 0.93)., Discussion and Conclusions: This study demonstrated that a single best treatment modality for ASD may not exist. Conservative treatment appears to yield higher (up to 6 %) QALE compared to surgery, most probably secondary to a higher baseline QALE. On the other hand, surgery provides a significantly higher increase in QALE. Especially in patients with significant disability at baseline, the final QALE tended higher in the S group (although not significant). Finally, chances of a relevant improvement at first year turned out to be significantly lower with NS treatment.

Purpose: Alignment of the cervical spine (CS) in adolescent idiopathic scoliosis (IS) as well as in asymptomatic adult populations has recently been studied and described as being less lordotic in the adolescent IS population. However, few studies have examined the sagittal alignment of the CS in adult IS or its association with other radiological variables and clinical relevance. The aim of this study is to analyse the sagittal alignment of CS in adult IS and its association with age, alignment of the thoracic, lumbar and global spinal column as well as health-related quality of life (HRQOL) parameters., Methods: A retrospective review of prospectively collected data from a multicenter database was performed. Of 468 consecutive adult IS patients, 213 were included in the study; the remainder were excluded due to poor quality X-rays where the CS was not properly visible, or previous surgery. X-rays were measured for the following CS parameters: [Cranial base-C2 (C0-C2) lordosis, C2-C7 lordosis, thoracic (T1) slope, thoracic inlet angle (TIA) and odontoid (Od)-T1 offset using a measurement software]. These measurements were then evaluated for possible associations with patient age and with pre-existing alignment parameters and HRQOL scores using Pearson correlation tests., Results: The average and standard deviations for CS alignment parameters were 32.3° ± 10.2° for C0-C2; 5.7° ± 14.1° for C2-C7; 23.9° ± 11.3° for T1 slope, 70.5° ± 14.7° for TIA and 20.8° ± 16.5° for Od-T1 offset. CS alignment showed a significant (p < 0.05) correlation with age, T kyphosis and several other sagittal alignment parameters such as sagittal vertical axis (SVA), global tilt and T1 sagittal tilt, but not with the HRQOL parameters., Conclusion: The sagittal alignment of the CS in adult IS is less lordotic than the normal average while less kyphotic than that of IS of a younger age. It correlates with age, thoracic kyphosis and some global sagittal alignment parameters. These findings suggest that CS alignment is likely a component of the global sagittal alignment strongly affected by thoracic kyphosis, and most probably does not affect HRQOL by itself.

Background: Sacropelvic fixation (SPF) is an integral part of ASD surgery. Literature suggests that combination of S1 and iliac screws may be associated with lowest rate of complications., Aim: To analyze the rate and potential factors of mechanical failure associated with SPF in adult spinal deformity surgery., Materials and Methods: Of 504 patients enrolled in a prospective multicentric database, 239 were treated conservatively and 265 were treated surgically. Forty-five of those who had sacroiliac fixations and with >6 months (or to failure) f/up constitute the population. Type of iliac fixation was S2 alar/iliac (S2AI) screws in 20 (44.4%) and iliac screws with lateral connectors (IwL) in 25 (55.6%). Diagnoses were degenerative in 20, failed back in 11 and other in 14. Average instrumentation length was 11.6 ± 4.0 levels. Cases with failure were compared to those without using Fisher's Exact and Mann-Whitney U tests., Results: A total of 16 implant related complications were identified (35.6%). Failures were identified on an average of 224.1 days (8-709) following index surgery. Failure rate of S2AI screws was 35 vs. 12% for IwL screws (p > 0.05). All broken screws were associated with S2AI technique with polyaxial screws. Comparison of failed cases to others revealed that failed cases had inadequate restoration of Lumbar Lordosis but this was not statistically insignificant. Only age was a significantly different, patient with failure being older., Discussion: Pelvic fixation is still associated with a very high rate of mechanical failure. Major risk factors appear to be age and type of fixation. Although could not be shown to be statistically significant, failure to restore the optimal sagittal balance may be a contributing factor as well. So in conclusion, in cases with suboptimal sagittal plane correction, S2AI with polyaxial screws seem to have higher risk of short-term acute failure compared to IwL.

Introduction: The minimum detectable change (MDC) of the SRS-22 subtotal score is 6.8 points. With the use of this value, patients who have undergone surgery for idiopathic scoliosis can be dichotomized into two groups: the successful (S) group (those who have reached or exceeded this limit) and the unsuccessful (Un-S) group (those in whom the change was smaller). The aim of this study was to analyze the clinical and radiological differences between these patient groups, as well as those related to the surgical technique., Material and Methods: The study included 91 patients (77 women and 14 men, mean age 18.1 years). All patients completed the SRS-22 questionnaire preoperatively and at follow-up (mean 45.6 months). In addition, radiological and surgical data were collected: levels instrumented, number of fused vertebrae, and use of thoracoplasty., Results: Based on the MDC of the SRS-22 subtotal score, patients were assigned to the Un-S group (44 cases, 48.4%) or S group (47 cases). Groups were similar in age, sex, number of fused vertebrae, percentage of patients who underwent thoracoplasty, and the upper and lower instrumented levels. The magnitude of the major curve and percentage of correction after surgery were also similar (Un-S group 62.3º, 53.2%; S group 64.3º, 49.9%). As compared to Un-S group, S patients had a poorer preop score in all the SRS-22 domains, and a clinically significant postop improvement in pain, perceived body image, mental health, and subtotal score. In contrast, the Un-S group showed a worsening of pain, function, mental health, and subtotal score, and a clinically nonsignificant improvement in perceived body image on the follow-up questionnaire. There were no significant differences in the satisfaction domain score between groups (4.36 vs. 4.62). On ROC curve analysis, a preop subtotal score of 74 points predicted allocation to the S or Un-S group at follow-up with 79% sensitivity and 76% specificity., Conclusion: The preop subtotal score of the SRS-22 is a good predictor of the clinical response to surgery.