Proximal junctional kyphosis is a rebalancing spinal phenomenon due to insufficient postoperative thoracic kyphosis after adolescent idiopathic scoliosis surgery

Sagittal alignment correction of adolescent idiopathic scoliosis using patient-specific rods

INTRODUCTION

Surgical treatment of the adolescent idiopathic scoliosis consists of a three-dimensional correction, involving correction of the vertebral rotation in axial plane, correction of the coronal and sagittal imbalance. Previously, most studies have considered coronal Cobb angle correction as the main objective. Currently, it is admitted that the restoration of sagittal alignment remains also a primary goal. Bending rods intraoperatively can be complicated, leading to complications such as rod notching or sagittal imbalance.

PURPOSE

The aim of this study is to analyze the restoration of sagittal balance postoperatively in AIS using patient-specific rods and compare the sagittal alignment obtained at last follow-up with the preoperative planning.

METHODS

In this study, we analyzed the radiological outcomes of 53 AIS patients treated by correction fusion surgery using patient-specific rods between 2019 and 2023. Rods bending was planned by the surgeon, based on spinopelvic parameters from the patient, according to the principles described by Kariman Abelin Genevois (KAG). Demographic data, relevant radiological parameters and classifications were carried out early preoperatively, immediate post-op, 6 weeks post-op, at 6 months, at two years and at last follow up.

RESULTS

Most of the predictions of post-operative changes in sagittal parameters were inaccurate, with only three parameters (thoracic kyphosis (TK), pelvic incidence (PI), and C7 plumb line to S1 (SVA)) showing no significant differences between the predicted values and the early postoperative values. However, thoracic hypokyphosis was corrected in 14 out of 17 (82.3%) patients with preoperative hypokyphosis (< 20°). Out of the 53 patients, only 4 (7.5%) patients had a hypokyphosis postoperatively. Adjusted multivariate logistic regression didn't show any predictive factor for a poor correction of sagittal alignment correction.

CONCLUSION

Patient-specific rods are helpful for the surgeon to restore optimal sagittal alignment and the preoperative predictions correspond to the values obtained at last follow-up.

LEVEL OF EVIDENCE

Level IV.

S1 Vertebral Bone Quality Score Independently Predicts Proximal Junctional Kyphosis After Posterior Hemivertebra Resection With Transpedicular Instrumentation

OBJECTIVE

Proximal junctional kyphosis (PJK) is a prevalent postoperative complication after posterior hemivertebra (HV) resection. Previous research has demonstrated a strong correlation between the development of PJK and reduced bone mineral density. The vertebral bone quality (VBQ) score, derived from magnetic resonance imaging, is considered a predictive and evaluative tool for bone mineral density. However, obtaining accurate magnetic resonance imaging signal intensity at the L1-L4 vertebrae is challenging in patients with HV. Consequently, a novel S1 VBQ score has been proposed, which exhibits high accuracy. This study aimed to evaluate the efficacy of S1 VBQ scores in predicting the incidence of PJK in these patients.

METHODS

We conducted a retrospective analysis of patients diagnosed with HV who underwent posterior HV resection with transpedicular instrumentation at our department from 2010 to 2020. Comprehensive demographic and radiographic data were collected. To identify potential preoperative risk factors for the incidence of PJK, we utilized the least absolute shrinkage and selection operator method. Subsequently, a multivariate logistic regression model was constructed to evaluate the risk factors identified through the least absolute shrinkage and selection operator analysis. Cutoff values were determined through receiver operating characteristic analysis to assess the predictive value of the S1 VBQ score for PJK.

RESULTS

A total of 88 patients met the inclusion criteria, with 14 patients (15.9%) developing PJK. Five potential risk factors were selected, including S1 VBQ scores, Risser sign, thoracic kyphosis, pelvic tilt, and proximal junctional angle. The multivariate logistic regression model demonstrated that the S1 VBQ score is an independent risk factor for predicting PJK. The area under the receiver operating characteristic curve (area under the curve) for S1 VBQ scores was 0.770 with an optimal threshold of 2.793 (sensitivity: 78.6%, specificity: 67.6%).

CONCLUSION

A higher S1 VBQ score is an independent risk factor for PJK, with a diagnostic accuracy of 77%. The S1 VBQ threshold of 2.793 was found to be effective in identifying PJK.

LEVEL OF EVIDENCE

Level III.

Curve progression following selective and nonselective spinal fusion for adolescent idiopathic scoliosis: are selective fusions stable?

PURPOSE

The purpose of this study is to compare postoperative outcomes between selective and non-selective fusions longitudinally over the first five postoperative years.

METHODS

Patient parameters were retrieved from a multicenter, prospective, database. Patients with Lenke 1-6, B and C deformities were included. Patients were stratified into 2 groups: selective fusion (SF), if the last instrumented vertebra (LIV) was at or cranial to the lumbar apex, or non-selective fusion (NSF). Differences in coronal and sagittal radiographic outcomes were assessed with generalized linear models (GLMs) at 1-, 2- and 5- year postoperative outcomes. Five-year postoperative categorical radiographic outcomes, flexibility, scoliosis research society scores (SRS), and reoperation rates were compared between groups. Matched cohorts were created for subgroup analysis.

RESULTS

416 (SF:261, NF:155) patients, including 353 females were included in this study. The mean preoperative thoracic and lumbar Cobb angles were 57.3 ± 8.9 and 45.3 ± 8.0, respectively. GLMs demonstrated greater postoperative coronal deformity in the SF group (p < 0.01); however, the difference between groups did not change overtime (p > 0.05) indicating a relatively stable postoperative deformity correction. The SF group had a greater incidence of lumbar Cobb ≥ 26 degrees (p < 0.01). The NSF group demonstrated worse forward and lateral flexibility at 5-year postoperative outcome (p < 0.05). There was no difference in postoperative SRS scores between the SF and NSF groups. Reoperation rates were similar between groups.

CONCLUSION

Selective fusion results in greater coronal plane deformity; however, this deformity does not progress significantly over time compared to non-selective fusion. Selective spinal fusion may be a beneficial option for a larger subset of patients than previously identified.

LEVEL OF EVIDENCE

III.

Spontaneous multilevel lumbar pediculolysis associated with spondylolysis: a rare case and review of the literature

BACKGROUND

Pediculolysis is bone hypertrophy and pseudoarthrosis caused by pedicle fracture and has often been combined with contralateral spondylolysis in previous reports. Multilevel pediculolysis with spondylolysis is extremely rare, and we report a case who underwent surgery. Cases of multisegment pediculolysis were reviewed to inspire the diagnosis and treatment of similar pathological phenomena.

CASE PRESENTATION

A 55-year-old man suffering from low back pain and sciatica was admitted to hospital after failing conservative treatment. The imaging studies revealed bilateral pediculolysis at L3 and L4 and right spondylolysis at L5. When L2-5 internal fixation and fusion surgery were performed, the symptoms improved immediately after surgery. At the 2-year postoperative follow-up, proximal junctional failure appeared and progressively worsened.

CONCLUSIONS

Multilevel pediculolysis often requires surgical intervention, and segment instability is an important consideration in the development of surgical fusion strategies. The etiology of pediculolysis is still complex and unknown, and the spondylolysis protocol can be used as a reference for treatment. Surgeons should be cautious in surgical planning to minimize the likelihood of postoperative instrumentation failure.

Long-term outcomes of spinal fusion in adolescent idiopathic scoliosis: a literature review

Adolescent idiopathic scoliosis (AIS) is the most common form of spinal deformity in the younger population. The surgical management for these patients improved constantly over the last year and might not be comparable to modern treatment strategies. However, under this aspect the present investigation updates and discusses current evidence regarding the long-term outcome of the surgical management of AIS. All the clinical studies which evaluated the long-term outcomes of spinal fusion were considered. Level of evidence, clinical and radiological data, results of health-related questionnaires and surgery-associated complications during long-term follow-up, e.g., proximal and distal junctional kyphosis (PJK/DJK), and adjacent segment degeneration (ASD), are presented. Data concerning the following patient-reported outcomes measures were collected: Oswestry Disability Index (ODI), Scoliosis Research Society (SRS) Outcome Questionnaire, visual analogue scale (VAS), and short form-12 and 36 (SF-12/SF-36). Overall, data from 1115 patients were included. Of them, 324 underwent anterior and 791 posterior spinal fusion. One study focuses on a combined anterior/posterior fusions. The mean follow-up was 22.6 years (posterior fusion: 24.6 years, anterior fusion: 18.31 years). Seven studies focus on the thoracic segments, while 12 focus on the lumbar spine. Data on imaging was reported in 13 studies and those on PROMs in 15 investigations. In conclusion, there is low quality and paucity of long-term data on AIS. However, the long-term results of the implicated studies on AIS patients in this review appear to be satisfactory, although there are limitations in the outcome compared to healthy comparison cohorts. Adjacent degenerations appear to be the most common mechanical complication after long-segment fusions, despite their influence on the outcome remains unclear. With regard to pregnancies, there are slightly increased cesarean section rates, which could be explained by deviations in the sagittal profile.

Posterior Correction and Fusion Using a 4D Anatomical Spinal Reconstruction Technique Improves Postural Stability Under the Eye-Closed Condition in Patients with Adolescent Idiopathic Scoliosis

Background: Patients with adolescent idiopathic scoliosis (AIS) has been reported to exhibit impaired postural stability. Posterior correction and fusion using four-dimensional (4D) anatomical spinal reconstruction techniques may improve postural stability to correct the spine for optimal anatomical alignment. This prospective study aimed to determine the effect of posterior correction and fusion using a 4D anatomical spinal reconstruction technique on postural stability in the eye-open and eye-closed standing position in patients with thoracic AIS. Methods: Thirty-three patients with AIS, excluding those with Lenke type 5C AIS, participated in the study. The mean and standard deviation of the minimum values of the time-to-boundary (TTB) were determined. All patients were asked to perform the quiet standing position under the eye-open and eye-closed condition on a force plate preoperatively and at 1 week and 2 years postoperatively. The TTB value was calculated from the velocity and distance to the foot boundary of the acquired center-of-pressure data. Results: Under the eye-closed condition, the mean and standard deviation of the minimum TTB were significantly higher at 2 years postoperatively than preoperatively and at 1 week postoperatively. The mean and standard deviation of the minimum TTB values were significantly lower at 1 week postoperatively than preoperatively. Conclusions: The results of this study suggest that surgery using the 4D anatomical spinal reconstruction technique reduces postural stability immediately after surgery; however, it improves postural stability at 2 years compared to the preoperative values.

Systematic review and meta-analysis for the proximal junctional kyphosis in adolescent idiopathic scoliosis

Objective

The risk factors of PJK (proximal junctional kyphosis) related to AIS (adolescent idiopathic scoliosis) are inconsistent due to heterogeneity in study design, diagnostic criteria, and population. Therefore, the meta-analysis was conducted to investigate the factors affecting PJK after posterior spinal fusion for AIS patients.

Methods

We implemented a systematic search to obtain potential literature relevant to PJK in AIS surgery. Then, a meta-analysis was performed to assess the incidence of PJK and its risk factors.

Results

We retrieved 542 articles, and 24 articles were included. The PJK incidence was 17.67%. The use of hooks at UIV (upper instrumented vertebrae) (p = 0.001) could prevent PJK. Before surgery, the larger TK (thoracic kyphosis) (p < 0.001), GTK (global thoracic kyphosis) (p < 0.001), and LL (lumbar lordosis) (p < 0.001) were presented in the PJK group. Immediately post-operatively, in the PJK group, the following parameters were higher: TK (p = 0.001), GTK (p < 0.001), LL (p = 0.04), PJA (proximal junctional angle) (p < 0.001), and PJA-RCA (rod contouring angle) (p = 0.001). At the final follow-up, the following parameters were higher in the PJK group: TK (p < 0.001), GTK (p < 0.001), LL (P < 0.001), and PJA (P < 0.001). Sub-group analysis detected that before surgery, the following parameters were larger in the PJK group: TK (p < 0.001), LL (p = 0.005), and PJA (p = 0.03) in Lenke type 5 AIS patients. Immediately post-operatively, in the PJK group, the following parameters were higher: TK (p < 0.001), LL (p = 0.005), and PJA (p < 0.001). At the final follow-up, the following parameters were higher in the PJK group: TK (p < 0.001), LL (p < 0.001), and PJA (p < 0.001).

Conclusion

The individuals with larger preoperative TK were more susceptible to PJK, and PJA was mainly influenced by the adjacent segments rather than the whole sagittal alignment. Using hooks or claws at UIV should prevent PJK.

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.

Can Lumbopelvic Parameters Be Used to Predict Thoracic Kyphosis at all Ages? A National Cross-Sectional Study

STUDY DESIGN

National cross-sectional study.

OBJECTIVE

Thoracic kyphosis (TK) is related to sagittal parameters as pelvic tilt (PT), lumbar lordosis (LL) and pelvic incidence (PI). The equation TK = 2 (PT+LL-PI) was validated for adolescents. The purpose of this study was to investigate if this equation correctly predicts TK regardless of age.

METHODS

Sagittal alignment parameters were assessed on full spine radiographs of 2599 individuals without spine pathology (1488 females, 1111 males). Calculated TK (CTK) = 2 (PT+LL-PI) and measured TK (MTK) were compared by calculating the gap and using a linear regression between both parameters. Subgroup analyses were performed for gender, age, TK groups (≤20°, 21°-40°, 41°-60°, >60°), and PI groups (<45°, 45°-60°, >60°).

RESULTS

Average values in the total population were: MTK 45.0°, CTK 36.9°. Average TK gap was 8.1°, 5.2° in females (intercept 11.7, slope .61) and 11.9° in males (intercept 7.1, slope .58). The mean gap was 3.6° for 15-34 years, 5.7° under 15 years and it increased progressively after 35 years with a maximum of 19.9° over 80 years. The gap also increased with the amount of MTK: -3.5° for TK<20° up to 17.3° for TK >60°. Differences in gaps were minor between PI groups. The intercept was smallest and slopes >.6 for PI <45° and TK ≤20°.

CONCLUSION

The formula TK=2 (PT+LL-PI) yielded moderate accuracy for adolescents and young adults, but did not fit for over 35 years and under 15. The amount and variance in TK increased in elderly subjects, which made the formula less accurate.

Incidence and risk factors of proximal junctional kyphosis in adolescent idiopathic scoliosis after correction surgery: a meta-analysis and systematic review

AIM

To analyze the risk factors of proximal junctional kyphosis (PJK) after correction surgery in patients with adolescent idiopathic scoliosis (AIS).

METHODS

PubMed, Medline, Embase, Cochrane Library, Web of Science, CNKI, and EMCC databases were searched for retrospective studies utilizing all AIS patients with PJK after corrective surgery to collect preoperative, postoperative, and follow-up imaging parameters, including thoracic kyphosis (TK), lumbar lordosis (LL), proximal junctional angle (PJA), the sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), pelvic incidence-lumbar lordosis (PI-LL), sacral slope (SS), rod contour angle (RCA) and upper instrumented vertebra (UIV).

RESULTS

Nineteen retrospective studies were included in this meta-analysis, including 550 patients in the intervention group and 3456 patients in the control group. Overall, sex (OR 1.40, 95% CI (1.08, 1.83), P = 0.01), larger preoperative TK (WMD 6.82, 95% CI (5.48, 8.16), P < 0.00001), larger follow-up TK (WMD 8.96, 95% CI (5.62, 12.30), P < 0.00001), larger postoperative LL (WMD 2.31, 95% CI (0.91, 3.71), P = 0.001), larger follow-up LL (WMD 2.51, 95% CI (1.19, 3.84), P = 0.0002), great change in LL (WMD - 2.72, 95% CI (- 4.69, - 0.76), P = 0.006), larger postoperative PJA (WMD 4.94, 95% CI (3.62, 6.26), P < 0.00001), larger follow-up PJA (WMD 13.39, 95% CI (11.09, 15.69), P < 0.00001), larger postoperative PI-LL (WMD - 9.57, 95% CI (- 17.42, - 1.71), P = 0.02), larger follow-up PI-LL (WMD - 12.62, 95% CI (- 17.62, - 7.62), P < 0.00001), larger preoperative SVA (WMD 0.73, 95% CI (0.26, 1.19), P = 0.002), larger preoperative SS (WMD - 3.43, 95% CI (- 4.71, - 2.14), P < 0.00001), RCA (WMD 1.66, 95% CI (0.48, 2.84), P = 0.006) were identified as risk factors for PJK in patients with AIS. For patients with Lenke 5 AIS, larger preoperative TK (WMD 7.85, 95% CI (5.69, 10.00), P < 0.00001), larger postoperative TK (WMD 9.66, 95% CI (1.06, 18.26), P = 0.03, larger follow-up TK (WMD 11.92, 95% CI (6.99, 16.86), P < 0.00001, larger preoperative PJA (WMD 0.72, 95% CI (0.03, 1.41), P = 0.04, larger postoperative PJA (WMD 5.54, 95% CI (3.57, 7.52), P < 0.00001), larger follow-up PJA (WMD 12.42, 95% CI 9.24, 15.60), P < 0.00001, larger follow-up SVA (WMD 0.07, 95% CI (- 0.46, 0.60), P = 0.04), larger preoperative PT (WMD - 3.04, 95% CI (- 5.27, - 0.81), P = 0.008, larger follow-up PT (WMD - 3.69, 95% CI (- 6.66, - 0.72), P = 0.02) were identified as risk factors for PJK.

CONCLUSION

Following corrective surgery, 19% of AIS patients experienced PJK, with Lenke 5 contributing to 25%. Prior and post-op measurements play significant roles in predicting PJK occurrence; thus, meticulous, personalized preoperative planning is crucial. This includes considering individualized treatments based on the Lenke classification as our future evaluation standard.

Sagittal Balance Parameters and Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis

Background: To review and evaluate multiple preoperative and postoperative sagittal parameters and their association with the risk of developing proximal junctional kyphosis (PJK) in patients with adolescent idiopathic scoliosis (AIS) who undergo correction surgery. Methods: A systematic search was performed in December 2022 in PubMed, Embase and the Cochrane Library to retrieve all the studies relevant to our research. After the study selection and data extraction following PRISMA guidelines, RevMan 5.3 was used for statistical analysis. All the analyzed factors were evaluated by using odds ratios and weighted mean differences with 95% confidence intervals. Moreover, the meta-analysis of proportions via MedCalc was used for analyzing quantitative data from the studies. Results: A total of 22 studies were included in our meta-analysis. All the available values of sagittal parameters were evaluated. Among all the potential risk factors, higher preoperative thoracic kyphosis (Test for overall effect Z = 11.79, p < 0.00001), higher preoperative sagittal vertical axis (SVA) (test for overall effect Z = 11.19, p < 0.00001), greater thoracic kyphosis change post-op. compared to pre-op. (test for overall effect Z = 6.02, p < 0.00001), increased postoperative lumbar lordosis (test for overall effect Z = 3.65, p = 0.0003), higher post-op. SVA (test for overall effect Z = 24.93, p < 0.00001) and a larger pelvic incidence/lumbar lordosis (PI/LL) mismatch (test for overall effect Z = 20.50, p < 0.00001) were found to be the risk factors for PJK after AIS surgery. Moreover, a decreased rod contour angle (RCA) (test for overall effect Z = 3.79, p < 0.0002) and higher proximal junctional angle-rod contour angle (PJA-RCA) (test for overall effect Z = 39.18, p < 0.00001) play a significant role in the risk of developing PJK after AIS correction. Conclusions: Sagittal balance is of great importance when considering the surgical correction of AIS. Many factors in our meta-analysis were found to increase the incidence for PJK such as higher preoperative thoracic kyphosis and pre-op. SVA. Furthermore, increased thoracic kyphosis change, increased post-operative lumbar lordosis, SVA and PI/LL mismatch are also factors that influence the possibility of post-op. PJK. Lastly, RCA and PJA-RCA are two important factors that need attention during AIS, as over-contouring of the rod could lead to PJK in AIS patients.

Simplified S1 vertebral bone quality (vbq) score to assess proximal junctional kyphosis after Lenke 5 adolescent idiopathic scoliosis surgery

BACKGROUND

Proximal junctional kyphosis (PJK) is a common complication following corrective surgery for adolescent idiopathic scoliosis (AIS) with a Lenke 5 curve. Previous studies have suggested that PJK may be associated with osteopenia, which is prevalent in AIS patients. MRI-based vertebral bone quality (VBQ) scores have been proposed as a valuable tool to assess preoperative bone quality. However, accurately measuring VBQ scores in Lenke 5 AIS patients with a structural lumbar curve can be challenging. Recently, a simplified S1 VBQ score has been proposed as an alternative method when the traditional VBQ score is not applicable. This study aims to evaluate the predictive value of the simplified S1 VBQ score in predicting the occurrence of PJK after corrective surgery for Lenke 5 AIS.

METHODS

We conducted a retrospective analysis of patient data to assess the predictive utility of the S1 VBQ score for PJK in Lenke 5 AIS patients. Demographic, radiographic, and surgical data were collected, and S1 VBQ scores were calculated based on preoperative T1-weighted MRI images. Univariate analysis, linear regression, and multivariate logistic regression were performed to identify potential risk factors for PJK and to assess the correlation between other variables and the S1 VBQ score. Receiver operating characteristic analysis and area under the curve values were used to evaluate the predictive efficiency of the S1 VBQ score for PJK.

RESULTS

A total of 105 patients (aged 15.50 ± 2.36 years) were included in the analysis, of whom 24 (22.9%) developed PJK. S1 VBQ scores were significantly higher in the PJK group compared to the non-PJK group (2.83 ± 0.44 vs. 2.48 ± 0.30, P < 0.001), and there was a significant positive correlation between the S1 VBQ score and proximal junctional angle (PJA) (r = 0.46, P < 0.0001). Multivariate analysis revealed that the S1 VBQ scores and preoperative thoracic kyphosis (TK) were significant predictors of PJK.

CONCLUSION

This study provided evidence that higher S1 VBQ scores were independently associated with PJK occurrence following corrective surgery for Lenke 5 AIS. Preoperative measurement of the S1 VBQ score on MRI may serve as a valuable tool in planning surgical correction for Lenke 5 AIS.

Patient-Specific Surgical Correction of Adolescent Idiopathic Scoliosis: A Systematic Review

The restoration of sagittal alignment is fundamental to the surgical correction of adolescent idiopathic scoliosis (AIS). Despite established techniques, some patients present with inadequate postoperative thoracic kyphosis (TK), which may increase the risk of proximal junctional kyphosis (PJK) and imbalance. There is a lack of knowledge concerning the effectiveness of patient-specific rods (PSR) with measured sagittal curves in achieving a TK similar to that planned in AIS surgery, the factors influencing this congruence, and the incidence of PJK after PSR use. This is a systematic review of all types of studies reporting on the PSR surgical correction of AIS, including research articles, proceedings, and gray literature between 2013 and December 2023. From the 28,459 titles identified in the literature search, 81 were assessed for full-text reading, and 7 studies were selected. These included six cohort studies and a comparative study versus standard rods, six monocentric and one multicentric, three prospective and four retrospective studies, all with a scientific evidence level of 4 or 3. They reported a combined total of 355 AIS patients treated with PSR. The minimum follow-up was between 4 and 24 months. These studies all reported a good match between predicted and achieved TK, with the main difference ranging from 0 to 5 degrees, p > 0.05, despite the variability in surgical techniques and the rods' properties. There was no proximal junctional kyphosis, whereas the current rate from the literature is between 15 and 46% with standard rods. There are no specific complications related to PSR. The exact role of the type of implants is still unknown. The preliminary results are, therefore, encouraging and support the use of PSR in AIS surgery.

Vertebral bone quality score as a novel predictor of proximal junctional kyphosis after thoracic adolescent idiopathic scoliosis surgery

INTRODUCTION

Proximal junctional kyphosis (PJK) is one of the most common complications after thoracic AIS surgery. Previous studies reported that the etiology of PJK was associated with osteopenia and meanwhile the AIS patients were found osteopenia which could persist into adulthood. Recently, an MRI-based vertebral bone quality score (VBQ) was reported to be a promising tool which can assess preoperative bone quality.

OBJECTIVE

This study aims to evaluate the utility of VBQ score in predicting PJK after corrective surgery for thoracic AIS (Lenke 1 and 2).

METHODS

We conducted a retrospective study to identify the predictive efficiency of VBQ score for PJK in thoracic AIS patients. Demographic, radiographic parameters, and surgical variables were collected. VBQ score was calculated using preoperative T1-weighted MRI. Univariate analysis, linear regression, and multivariate logistic regression were performed to determine potential risk factors of PJK and correlation between other parameters and VBQ score. Receiver operating characteristic analysis and area under the curve values were utilized to evaluate the predictive efficiency of VBQ score for PJK.

RESULTS

A total of 206 patients (aged 14.4 ± 2.3 years) were included, of which 33 (16.0%) developed PJK. VBQ scores were significantly different between the PJK and non-PJK groups (2.8 ± 0.2 vs 2.5 ± 0.2, P < 0.01). A significant positive correlation was found between VBQ score and PJA (R2 = 0.1728, P < 0.01).On multivariate analysis, VBQ score was the only significant predictor of PJK (odds ratio = 2.178, 95% CI = 1.644-2.885, P < 0.001), with a predictive accuracy of 83%.

CONCLUSION

Higher VBQ scores were independently associated with PJK occurrence after corrective surgery for thoracic AIS. Preoperative measurement of VBQ score on MRI may serve as a valuable tool in planning thoracic AIS surgery.

How Does Gravity Influence the Distribution of Lordosis in Patients With Sagittal Malalignment?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Compare the supine vs standing radiographs of patients with adult spinal deformity against ideals defined by healthy standing alignment.

METHODS

56 patients with primary sagittal ASD (SRS-Schwab Type N) and 119 asymptomatic volunteers were included. Standing alignment of asymptomatic volunteers was used to calculate PI-based formulas for normative age-adjusted standing PI-LL, L4-S1, and L1-L4. These formulas were applied to the supine and standing alignment of ASD cohort. Analyses were repeated on a cohort of 25 patients with at least 5 degrees of lumbar flexibility (difference between supine and standing lordosis).

RESULTS

The asymptomatic cohort yielded the following PI-based formulas: PI-LL = -38.3 + .41*PI + .21*Age, L4-S1 = 45.3-.18*Age, L1-L4 = -3 + .48*PI). PI-LL improved with supine positioning (mean 8.9 ± 18.7°, P < .001), though not enough to correct to age-matched norms (mean offset 12.2 ± 16.9°). Compared with mean normative alignment at L1-L4 (22.1 ± 6.2°), L1-L4 was flatter on standing (7.2 ± 17.0°, P < .001) and supine imaging (8.5 ± 15.0°, P < .001). L4-S1 lordosis of subjects with L1-S1 flexibility >5° corrected on supine imaging (33.9 ± 11.1°, P = 1.000), but L1-L4 did not (23.0 ± 6.2° norm vs 2.2 ± 14.4° standing, P < .001; vs 7.3 ± 12.9° supine, P < .001).

CONCLUSIONS

When the effects of gravity are removed, the distal portion of the lumbar spine (i.e., below the apex of lordosis) corrects, suggesting that structural lumbar deformity is primarily proximal.

Postoperative proximal junctional kyphosis correlated with thoracic inlet angle in Lenke 5c adolescent idiopathic scoliosis patients following posterior surgery

Background

Proximal junctional kyphosis is a common complication after posterior fusion in patients with adolescent idiopathic scoliosis and is correlated with postoperative changes of thoracic kyphosis. In lenke 5c patients, higher postoperative LL and spontaneous change of TK may produce an effect on final PJK. However, no studies has been performed to evaluate the correlation of PJK with thoracocervical parameters in patients with AIS.

Methods

Data from 98 patients who underwent posterior fusion for Lenke 5C AIS with 2 years of follow-up were retrospectively reviewed. Patients in the extended fusion group underwent fusion at levels higher than upper-end vertebra + 2 (n = 38), and those in the thoracolumbar/lumbar (TL/L) fusion group underwent fusion at UEV + 2 or lower (n = 60).

Results

During an average follow-up of 38.1 months, 23 of 98 patients developed PJK. The extended fusion group had a higher incidence of PJK than the TL/L fusion group (14/38 vs. 9/60, respectively; P = 0.01) and a significantly greater decrease in thoracic kyphosis than the TL/L group (P < 0.01). Patients with PJK had a significantly larger preoperative thoracic inlet angle (TIA) than those without PJK (P < 0.01). Multivariate analysis showed that a greater preoperative TIA and extended fusion were associated with PJK. The Scoliosis Research Society 22-item questionnaire score did not significantly differ between the PJK and non-PJK groups.

Conclusions

The preoperative TIA could be a predictor of PJK. Among patients with Lenke 5C AIS, those with a TIA of > 71° are more likely to develop PJK. Additionally, extended fusion in patients with Lenke 5C may increase the risk of PJK.

Risk factors for proximal junctional kyphosis after pediatric spinal deformity surgery with halo gravity traction

PURPOSE

To determine risk factors for proximal junctional kyphosis (PJK) in pediatric patients with scoliosis undergoing halo gravity traction (HGT) prior to posterior spinal fusion (PSF).

METHODS

Data from consecutive patients who underwent PSF after HGT with 2-year follow-up were retrospectively collected from a single center. Patients were divided into two groups: PJK vs. no PJK.

RESULTS

Twenty-five patients (age 13.6 ± 3.1 years) underwent HGT for a mean of 42 ± 37 days. Eight patients (32%) developed radiographic PJK and 1 (4%) developed proximal junctional failure. PJK patients had greater loss of cervical lordosis (-17.4 ± 23.2 vs. 2.7 ± 16.2°, p < 0.05), greater increase in lumbar lordosis (9.3 ± 19.5 vs. -2.8 ± 12.8°; p = 0.034) during traction, and smaller overall major coronal curve angle correction (-16.8 ± 30.6 vs. -36.6 ± 16.4°; p = 0.026). From postoperative to last follow-up, PJK patients had a greater increase in upper end vertebrae (UEV) slope (3.3 ± 7.8 vs. -4.0 ± 7.7°; p = 0.004). Selection of UIV based on which vertebra was most level either pre-traction or in-traction was not associated with PJK development (p > 0.05).

CONCLUSION

In-traction radiographic changes of decreased cervical lordosis, decreased major coronal curve, increased lumbar lordosis, and disruption of cervical sagittal balance at last follow-up may have implications for level selection and risk of PJK.