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.

Spinal dysraphism in congenital scoliosis and kyphosis: a retrospective analysis in an Indian population.

PURPOSE: Early recognition is crucial for occult spinal dysraphism associated with congenital spinal deformities. There is limited literature available on its occurrence in congenital scoliosis and kyphosis in the Indian population. METHODS: Our study involved a retrospective review of 247 children who presented at a single centre. We analyzed their demographics and clinical and radiological findings, which included the type of deformity, its location, vertebral anomaly, Cobb angle, and MRI findings. The deformities were categorized as congenital scoliosis or congenital kyphosis with failure of formation, failure of segmentation, or both. RESULTS: A total of 247 cases were examined (congenital scoliosis-229, congenital kyphosis-18). The average age was seven years (range 0.8 to 19 years, SD 4.6). The mean Cobb angle at presentation in the congenital scoliosis group was 49.4° (range 8 to 145°, SD 23.77) for those with abnormal MRI and 42.45° (range 5 to 97°, SD 20.09) for those with normal MRI. For the congenital kyphosis group, the mean K angle at presentation was 47.7° (range 14 to 110°, SD 33.33) for those with abnormal MRI and 47.36° (range 15 to 70°, SD 16.63) for those with normal MRI. Abnormal MRI results were observed in 130 of the patients (congenital scoliosis-53.7%, congenital kyphosis-38.8%). The highest incidence of abnormal MRI findings was observed in the failure of segmentation (66.6%) and mixed (65%) types. Deformities in the dorsal region had the highest incidence (61.9%). The most common dysraphism instances were diastematomyelia and tethered cord. There was a significant correlation between type of deformity and presence of dysraphism. CONCLUSION: This is the largest case series of congenital scoliosis and kyphosis reported from India. We found a high incidence of occult spinal dysraphism as compared to other published series. Occult spinal dysraphism is more common in the thoracic region. Diastematomyelia followed by tethered cord was the most common anomaly observed. We recommend MRI screening of whole spine and craniovertebral junction.

Prevalence, Features, and Predictive Factors of Spontaneous Spinal Arthrodesis in Posttraumatic Thoracolumbar Kyphosis.

OBJECTIVE: Spontaneous spinal arthrodesis (SSA) is a phenomenon of spontaneous fusion, and SSA is not rare in posttraumatic thoracolumbar kyphosis (PTK). However, few reports have focused on SSA in patients with PTK. The objective of this study was to investigate the prevalence, features, and predictive factors of SSA in patients with PTK. METHODS: In this retrospective study, 70 patients with PTK were included. Data on the clinical and radiologic parameters were obtained and evaluated. According to whether there was SSA or not, patients were divided into an SSA group (n = 45) or a non-SSA group (n = 25). A binary logistic regression analysis was used to identify the predictive factors for SSA. RESULTS: The incidence of SSA in PTK was 64%. Among 45 patients with PTK with SSA, SSA was present as a solid bridging anterior osteophyte along the vertebral bodies in 11 patients, posterior contiguous bony growth through the facet joints bilaterally in 13 patients, bony formation in both anterior and posterior elements in 18 patients, and direct contiguous bony formation from the injured vertebral body to the adjacent one in 3 patients. Patients with longer disease duration, larger local Cobb angle, and anterior wall height loss (AWHL) ratio of injured vertebral body, and less kyphosis flexibility index were significantly more likely to develop SSA. The parameter of AWHL remained significant in binary logistic regression analysis. CONCLUSIONS: SSA in PTK was common, and the SSA sign presented in various patterns, which might have implications for surgical decisions. AWHL was the independent predictor for SSA.

Increasing Cervical Kyphosis Correlates With Cervical Degenerative Disk Disease in Patients With Adolescent Idiopathic Scoliosis.

STUDY DESIGN: Retrospective review. OBJECTIVE: Our goal was to investigate the incidence of cervical degenerative disk disease (DDD) in patients with adolescent idiopathic scoliosis (AIS), before surgical intervention. SUMMARY OF BACKGROUND DATA: AIS is often associated with thoracic hypokyphosis and compensatory cervical kyphosis. In adults, cervical kyphosis is associated with DDD. Although cervical kyphosis has been reported in up to 60% AIS patients, the association with cervical DDD has not been reported. MATERIALS AND METHODS: A retrospective review was conducted from January 2014 to December 2019 of all consecutive AIS patients. Inclusion criteria were AIS patients over 10 years of age with cervical magnetic resonance imaging and anterior-posterior and lateral spine radiographs within 1 year of each other. Magnetic resonance imaging were reviewed for evidence of cervical DDD. Severity of cervical changes were graded using the Pfirrmann classification and by a quantitative measure of disk degeneration, the magnetic resonance signal intensity ratio. RESULTS: Eighty consecutive patients were included (mean age: 14.1 years, SD=2.5 years). Increasing cervical kyphosis was significantly correlated to decreasing thoracic kyphosis ( r =0.49, P <0.01) and increasing major curve magnitude ( r =0.22, P =0.04). Forty-five patients (56%) had the presence of DDD (grades 2-4) with a mean cervical kyphosis of 11.1° (SD=9.5°, P <0.01). More cervical kyphosis was associated with more severe cervical DDD as graded by Pfirrmann classification level ( P <0.01). Increasing cervical kyphosis was also positively associated with increasing magnetic resonance signal intensity ratio ( P <0.01). Nine patients had ventral cord effacement secondary to DDD with a mean cervical kyphosis of 22.8° (SD=8.6°) compared with 2.6° (SD=11.2°) in those who did not ( P <0.01). CONCLUSIONS: Cervical kyphosis was significantly associated with increasing severity of cervical DDD in patients with AIS. Patients with evidence of ventral cord effacement had the largest degree of cervical kyphosis with a mean of 22.8±8.6°. This is the first study to evaluate the association between cervical kyphosis in AIS with cervical DDD.

Functional Alignment Within the Fusion in Adult Spinal Deformity (ASD) Improves Outcomes and Minimizes Mechanical Failures.

STUDY DESIGN: Retrospective review of an adult deformity database. OBJECTIVE: To identify pelvic incidence (PI) and age-appropriate physical function alignment targets using a component angle of T1-pelvic angle within the fusion to define correction and their relationship to proximal junctional kyphosis (PJK) and clinical outcomes. SUMMARY OF BACKGROUND DATA: In preoperative planning, a patient's PI is often utilized to determine the alignment target. In a trend toward more patient-specific planning, age-specific alignment has been shown to reduce the risk of mechanical failures. PI and age have not been analyzed with respect to defining a functional alignment. METHODS: A database of patients with operative adult spinal deformity was analyzed. Patients fused to the pelvis and upper-instrumented vertebrae above T11 were included. Alignment within the fusion correlated with clinical outcomes and PI. Short form 36-Physical Component Score (SF36-PCS) normative data and PI were used to compute functional alignment for each patient. Overcorrected, under-corrected, and functionally corrected groups were determined using T10-pelvic angle (T10PA). RESULTS: In all, 1052 patients met the inclusion criteria. T10PA correlated with SF36-PCS and PI (R=0.601). At six weeks, 40.7% were functionally corrected, 39.4% were overcorrected, and 20.9% were under-corrected. The PJK incidence rate was 13.6%. Overcorrected patients had the highest PJK rate (18.1%) compared with functionally (11.3%) and under-corrected (9.5%) patients ( P <0.05). Overcorrected patients had a trend toward more PJK revisions. All groups improved in HRQL; however, under-corrected patients had the worst 1-year SF36-PCS offset relative to normative patients of equivalent age (-8.1) versus functional (-6.1) and overcorrected (-4.5), P <0.05. CONCLUSIONS: T10PA was used to determine functional alignment, an alignment based on PI and age-appropriate physical function. Correcting patients to functional alignment produced improvements in clinical outcomes, with the lowest rates of PJK. This patient-specific approach to spinal alignment provides adult spinal deformity correction targets that can be used intraoperatively.

How to determine the optimal proximal fusion level for Scheuermann kyphosis.

OBJECTIVE: To determine optimal proximal fusion levels for instrumented spinal fusion for Scheuermann kyphosis. METHODS: We reviewed 86 patients (33 women) who underwent corrective instrumented spinal fusion for Scheuermann kyphosis. All patients had long-cassette upright lateral radiographs taken preoperatively, postoperatively, and at 2 years and the last follow-up. Demographic, radiographic, and surgical parameters were compared between patients with and without PJK. RESULTS: PJK occurred in 28 patients (32%). The mean maximum Cobb angle was 85.8° ± 11.7° preoperatively, 54.8° ± 14.2° postoperatively, and 59.7° ± 16.8° at the last follow-up. Age and sex did not differ between the PJK and non-PJK groups (P > 0.05). The preoperative curve characteristics, fusion levels, and corrective ratio were similar in both groups (P > 0.05). The maximal Cobb angle at 2 years and the last follow-up significantly differed between the 2 groups (P < 0.05). The proportion of patients with the uppermost instrumented vertebra (UIV) at or above the proximal end vertebra (PEV) was similar in both groups (P > 0.05). The proportion of patients with UIV at or above T2 was significantly greater in the non-PJK group (P < 0.05). PJK was significantly associated with a C7 plumb line (C7PL)-sacrum distance ≥ 50 mm (P < 0.05). CONCLUSION: PJK is the main cause of postoperative correction loss. Proper fusion-level selection can reduce PJK occurrence. We recommend having the UIV at T2 or above, especially when the C7PL-sacrum distance ≥ 50 mm.

Can Pelvic Incidence Change After Lumbo-Pelvic Fixation for Adult Spine Deformity, and Would the Change be Affected by the Type of Pelvic Fixation?

STUDY DESIGN: Retrospective review. OBJECTIVE: To assess the change in pelvic incidence (PI) after lumbo-pelvic fixation and the differential impact of the type of pelvic fixation: S2-alar-iliac screws (S2AI) versus Iliac screws (IS) on postoperative PI. SUMMARY OF BACKGROUND DATA: Recent studies suggest that changes occur to the previously assumed fixed PI after spino-pelvic fixation. METHODS: Adult spine deformity (ASD) patients who underwent spino-pelvic fixation with≥4 levels of fusion were included. Preoperative and postoperative PI, lumbar lordosis (LL), thoracic kyphosis, pelvic tilt, sacral slope, PI-LL mismatch, and the Sagittal Vertical Axis (SVA) were analyzed on EOS imaging. A significant PI change was established at≥6°. Patients were categorized based on the type of pelvic fixation (S2AI vs. IS). RESULTS: One-hundred-forty-nine patients were included. Of these, 77(52%) had a>6° change in their PI postoperatively. In patients with high preoperative PI (>60°), 62% had a significant PI change compared with 33% of patients with normal PI (40°-60°) and 53% in patients with low PI (<40°; P =0.01). PI was likely to decrease in patients with high baseline PI (>60°) and to increase in patients with low baseline PI (<40°). Patients with a significant PI change had a higher PI-LL. Patients in the S2AI group (n=99) and those in the IS group (n=50) were comparable at baseline. In the S2AI group, 50 (51%) patients had>6° change in their PI compared with 27(54%) patients in the IS group( P =0.65). In both groups, patients with high preoperative PI were more prone to significant postoperative changes ( P =0.02 in IS, P =0.01 in S2AI). CONCLUSION: PI changed significantly in 50% of patients postoperatively, especially in those with high/low preoperative PI and those with severe baseline sagittal imbalance. This occurs similarly in patients with S2AI and those with IS screws. Surgeons should keep in mind these anticipated changes while planning ideal LL, as this impacts postoperative PI-LL mismatch. LEVEL OF EVIDENCE: 4.

Proximal Junctional Failure after Corrective Surgery: Focusing on Elderly Patients with Severe Sagittal Imbalance.

Background: Previous reports with proximal junctional failure (PJF) included relatively young patients or deformity without sagittal imbalance. The present study focused on the two well-known risk factors for PJF, old age and severe sagittal imbalance. With these high-risk patients, the present study aimed to identify a strategy that could prevent PJF and to investigate whether the degree of correction would really affect the PJF occurrence. Methods: Patients who were ≥ 60 years of age and underwent long fusion (≥ 4) to the sacrum for severe sagittal imbalance (defined as pelvic incidence minus lumbar lordosis [PI-LL] ≥ 30°) were included. PJF was defined as a vertebral fracture at the uppermost instrumented vertebra (UIV) or UIV+1, failure of UIV fixation, myelopathy, or any need for proximal extension of fusion. Presumed risk factors were compared between the patients with and without PJF. Results: Total 146 patients (mean age, 68.4 years) with preoperative mean PI-LL of 46.8° were included. PJF developed in 39 patients (26.7%) at a mean of 18.1 months after surgery. Multivariate analysis showed that osteoporosis (odds ratio [OR], 2.812; p = 0.019) and UIV located below T10 (OR, 3.773; p = 0.010) were significant risk factors for developing PJF. However, the degree of correction did not affect PJF occurrence. Conclusions: The present study indicates that osteoporosis should be well corrected preoperatively and extending the fusion above T10 should be considered for severe imbalance in old patients. However, the amount of correction was not associated with PJF development.

Is the pelvic incidence a determinant factor for kyphosis curve patterns of ankylosing spondylitis patients?

To investigate the influence of pelvic incidence (PI) on the kyphosis curve patterns and clinical outcomes in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis and to construct a classification of AS according to the PI value for surgical decision-making. 107 AS patients underwent single-level lumbar pedicle subtraction osteotomy (PSO) and finished a minimal of 2-year follow-up. All patients were divided into three groups: low PI (PI ≤ 40°), moderate PI (40° < PI ≤ 60°), and high PI (PI > 60°). Standing lateral radiographs were taken to evaluate the location of kyphotic apex, thoracic kyphosis (TK), lumbar lordosis (LL), C7 sagittal vertical axis (SVA), spino-sacral angle (SSA), global kyphosis (GK), PI, sacral slope (SS), and pelvic tilt (PT). Visual Analogue Scale (VAS) score, Oswestry Disability Index (ODI) and Bath Ankylosing Spondylitis Functional Index (BASFI) were used to evaluate quality of life. Before surgery, a significant difference was shown in the average LL and the mean GK in high PI group was the largest among the three groups. Correction of SVA, GK and LL in high PI group was the smallest among the three group. No significant difference in clinical outcomes was found among the three groups before surgery and at the final follow-up. Regarding the preoperative sagittal profile, the kyphosis curve pattern of moderate PI group is similar to that of low PI group. For AS patients in these two groups, harmonious sagittal alignment can be restored by a single-level PSO. However, the sagittal imbalance is insufficiently realigned by a single-level PSO in a patient with high PI.

Can placement of hook at the upper instrumented level decrease the proximal junctional kyphosis risk in adolescent idiopathic scoliosis?

OBJECTIVE: Proximal junctional kyphosis is a commonly encountered clinical and radiographic phenomenon after pediatric and adolescent spinal deformity surgery that may lead to postoperative deformity, pain, and dissatisfaction. The purpose of the study was to identify whether the placement of transverse process hooks is an effective way to prevent PJK. METHODS: Adolescent idiopathic scoliosis patients who underwent posterior spinal fusion between November 2015 and May 2019 were retrospectively analyzed. A minimum 2-year follow-up was required. Demographic and surgical data included UIV level type of instrumentation (hook vs screw) were reported. Radiologic parameters included main curve Cobb angle, thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), and proximal junctional angle (PJA) were assessed. Patients were divided into two groups based on the type of instrumentation at the UIV level whether placement of hook versus pedicle screw. RESULTS: Three hundred and thirty-seven patients were included with the mean age 14.2 ± 1.9 years. Thirty patients (8.9%) were diagnosed with proximal junctional kyphosis radiographically. PJK incidence was found 3.2% (5/154) in the hook group and 13.3% (23/172) in the screw group and the difference found statistically significant. In the PJK group, preoperative thoracic kyphosis and the degree of kyphosis correction were also significantly higher than non-PJK patients. CONCLUSION: Placement of transverse process hooks at the UIV level in posterior spinal fusion surgery for AIS patients was associated with decreased risk of PJK. A larger preoperative kyphosis and greater degree of kyphosis correction correlated with PJK.

Description of age-related changes in cervical sagittal alignment based on pelvic incidence classification in asymptomatic Chinese population.

PURPOSE: To investigate the pelvic incidence (PI)- and age-related cervical alignment changes of Chinese healthy population. METHODS: Six hundred and twenty-five asymptomatic adult subjects, who underwent the standing whole spinal radiograph, were recruited in this work. The sagittal parameters were measured, including Occipito-C2 angle (O-C2), C2-7 angle (C2-7), cranial arch, caudal arch, T1-slope (T1S), C2-7 sagittal vertical axis (C2-7 SVA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), PI, and sagittal vertical axis (SVA). All subjects were stratified into 5 age groups, namely 40-59 years, 60-64 years, 65-69 years, 70-74 years, and 75 years and above, with each age group further divided into 2 subgroups based on PI (deeming PI < 50° as low PI, and PI ≥ 50° as high PI). The correlations between PI or age, and other sagittal parameters were assessed. The age-related changes of sagittal parameters in each PI subgroup were also assessed, followed by one-way analysis of variance analysis for change comparison between age groups. RESULTS: The average cervical sagittal parameters were as below: 18.2 ± 6.8° for O-C2, 10.4 ± 10.2° for C2-7, 3.9 ± 7.5° for cranial arch, 6.5 ± 7.1° for caudal arch, 23.6 ± 7.3° for T1S, and 21.0 ± 9.7 mm for C2-7 SVA. There was no obvious difference observed between PI and cervical sagittal parameters, excepting for caudal arch. While, C2-7, cranial arch, caudal arch, T1S, and C2-7 SVA increased remarkably with the age. Thereof, C2-7 exhibited great increases at the age of 60-64 years and 70-74 years, respectively, cranial arch increased notably at 60-64 years of age, and caudal arch developed obviously at 70-74 years of age, regardless of PI. CONCLUSION: This study showed the PI- and age-related cervical alignment changes of Chinese healthy population. Based on the classification in our study, high or low PI apparently did not correlate with the occurrence of cervical degenerative disease.

Distal junctional kyphosis in adult cervical deformity patients: where does it occur?

PURPOSE: To evaluate the impact of the lowest instrumented vertebra (LIV) on Distal Junctional kyphosis (DJK) incidence in adult cervical deformity (ACD) surgery. METHODS: Prospectively collected data from ACD patients undergoing posterior or anterior-posterior reconstruction at 13 US sites was reviewed up to 2-years postoperatively (n = 140). Data was stratified into five groups by level of LIV: C6-C7, T1-T2, T3-Apex, Apex-T10, and T11-L2. DJK was defined as a kyphotic increase > 10° in Cobb angle from LIV to LIV-1. Analysis included DJK-free survival, covariate-controlled cox regression, and DJK incidence at 1-year follow-up. RESULTS: 25/27 cases of DJK developed within 1-year post-op. In patients with a minimum follow-up of 1-year (n = 102), the incidence of DJK by level of LIV was: C6-7 (3/12, 25.00%), T1-T2 (3/29, 10.34%), T3-Apex (7/41, 17.07%), Apex-T10 (8/11, 72.73%), and T11-L2 (4/8, 50.00%) (p < 0.001). DJK incidence was significantly lower in the T1-T2 LIV group (adjusted residual = -2.13), and significantly higher in the Apex-T10 LIV group (adjusted residual = 3.91). In covariate-controlled regression using the T11-L2 LIV group as reference, LIV selected at the T1-T2 level (HR = 0.054, p = 0.008) or T3-Apex level (HR = 0.081, p = 0.010) was associated with significantly lower risk of DJK. However, there was no difference in DJK risk when LIV was selected at the C6-C7 level (HR = 0.239, p = 0.214). CONCLUSION: DJK risk is lower when the LIV is at the upper thoracic segment than the lower cervical segment. DJK incidence is highest with LIV level in the lower thoracic or thoracolumbar junction.

Variation in Lumbar Shape and Lordosis in a Large Asymptomatic Population: A MEANS Study.

STUDY DESIGN: Prospective, cross-sectional cohort study. OBJECTIVE: To determine the relationship between lumbar shape and sagittal parameters. SUMMARY OF BACKGROUND DATA: Understanding the lumbar shape is vital for deformity surgery. Normative sagittal parameters and spine shape remain unstudied in large, multiethnic, asymptomatic cohorts. MATERIALS AND METHODS: A prospective, cross-sectional cohort of 468 asymptomatic volunteers between 18 and 80 years was enrolled across 5 countries. Demographic data and radiographic parameters such as pelvic incidence (PI) were collected. Pearson correlation test and linear regression were used to find the relationship between lumbar lordosis (LL) and other parameters. One-way analysis of variance and Welch 2-sample t test were performed to compare lumbar shape across such categories as PI and lumbar apex followed by post hoc Bonferroni correction if needed. RESULTS: PI was moderately correlated with proximal lumbar lordosis (pLL) ( r = -0.54) and weakly correlated with distal lumbar lordosis (dLL) ( r = -0.16). Thoracic kyphosis (T1-T12) was moderately correlated with pLL ( r = -0.35) and dLL ( r = -0.29). dLL was moderately correlated with LL ( r = 0.64). 2.6% (12/468) of subjects had lumbar apex at L2, 40.2% (188/468) at L3, 56.6% at L4 (265/468), and 0.6% (3/468) at other levels. Mean PI was different between volunteers with the apex at L3 and L4. A lower mean PI was associated with the apex at L4 (49.0°), whereas a higher mean PI was associated with the apex at L3 (55.8°). The mean PI-LL mismatch for volunteers was -5.4° with a range from -35° to 39.7°. PI-LL mismatch increased from a mean of -10.1° in volunteers with low PI to a mean of 2.2° in volunteers with high PI. Age was not correlated with LL ( P = 0.84). CONCLUSIONS: In asymptomatic adult volunteers, pLL showed a moderate correlation with PI and increased with PI, whereas dLL showed a weak correlation. The lumbar apex migrated proximally with increasing PI. Segmental lordosis and apex position instead of solely global lordosis should be emphasized. LEVEL OF EVIDENCE: Level III.

Scoliosis and Kyphosis Prevalence in Turner Syndrome: A Retrospective Review at a Pediatric Tertiary Care Medical Center.

BACKGROUND: The prevalence of major coronal and sagittal spinal curves (scoliosis and kyphosis) in Turner syndrome (TS) is not well established due to limited reporting. The relationship between growth hormone (GH) therapy and its effect on TS spinal curve incidence is also not well established. METHODS: A retrospective chart review of 306 TS patients from 2007 to 2021 evaluated major coronal and sagittal spinal curves, progression of the curve, and treatment with GH. Statistical significance (defined as P <0.05) between curvature rates and curve progression was compared between GH-treated patients and non-GH-treated patients using a χ 2 or Fisher exact test when appropriate. RESULTS: Thirty-seven of 306 (12%) TS patients had a radiographically relevant spinal deformity. Twenty-seven of 37 (73%) had mild; 4 of 37 (11%) had moderate, and 6 of 37 (16%) had severe curves. Of those with severe, 4 underwent spinal fusion, 1 was treated with bracing, and 1 was braced before a cardiovascular-related death. Regarding GH use among TS patients, 190 of 306 (62%) used GH versus 116 of 306 (38%) who did not. Of those with a spinal curve, 24 of 37 (65%) used GH compared with 13 of 37 (35%) who did not. On univariate analysis, GH therapy was not a risk factor for the diagnosis of a major spinal curve, a more severe degree of the curve at the time of diagnosis, or spinal curve progression ( P >0.05 for all). CONCLUSIONS: This is the largest single institution retrospective review of a TS cohort known to the authors assessing spinal curve prevalence and relation to GH treatment and demonstrates a TS spinal curve rate of 12% (37/306). Four of six (11%) TS patients with a severe curve underwent corrective spine fusion. There was no relationship between the use of GH and the presence of a spinal curve or curve progression. Further study is warranted to determine risk factors for curve progression. LEVEL OF EVIDENCE: Level III. CLINICAL RELEVANCE: This retrospective case series serves to review and address the prevalence of spinal deformity in TS patients and whether GH impacts worsening deformity.

Thirty-day unplanned reoperations of thoracic spine surgery: 10 years of data from a single center with 3242 patients.

BACKGROUND CONTEXT: Unplanned reoperation is a useful quality indicator for spine surgery. However, the rates of a 30-day unplanned reoperation in patients undergoing thoracic spinal surgery are not well established. PURPOSE: To assess the rates, reasons, and risk factors of 30-day unplanned reoperations for thoracic spine surgeries in a single center study. STUDY DESIGN: A retrospective observational study. PATIENT SAMPLE: A total of 3242 patients who underwent thoracic spinal surgery at our institution in the past decade were included. OUTCOME MEASURES: The incidence, chief reasons, and risk factors for unplanned reoperations within 30 days after thoracic spinal surgery. METHODS: We retrospectively analyzed the data of all patients who underwent thoracic spinal surgery between January 2012 and December 2021. Statistical methods, including univariate and multivariate analyses, were performed to assess the incidence, reasons, and risk factors for thoracic degenerative diseases, spinal tumors, kyphosis deformity, and spinal trauma. RESULTS: Of the 3242 patients who underwent thoracic spinal surgery, 107 (3.30%) required unplanned reoperations within 30 days due to epidural hematoma (1.17%), wound complications (0.80%), implant complications (0.43%), inadequate decompression (0.25%), and other causes (0.65%). Patients with degenerative disease (3.88%), spinal tumor (2.98%), and kyphosis deformity (3.33%) had significantly higher incidences of reoperation than those with spinal trauma (1.47%). Unplanned reoperations were classified as hyperacute (30.84%), acute (31.76%), and subacute (37.38%). After univariate analysis, several factors were associated with unplanned reoperation in the 4 cohorts of thoracic spine diseases (p<.05). Multivariate logistic regression analysis revealed that upper thoracic spine surgery (p=.001), concomitant dekyphosis (p=.027), and longer activated partial thromboplastin time (p=.025) were risk factors of unplanned reoperation for thoracic degenerative disease. Whereas American Society of Anesthesiologists (ASA) grade III (p=.015), combined approach (p=.016), and operation time longer than 420 min (p=.042) for spinal tumor, and similar ankylosing spondylitis (p=.023) and operation time longer than 340 min (p=.041) were risk factors of unplanned reoperation for kyphosis deformity. CONCLUSIONS: The unplanned reoperation rate for thoracic spine surgery was 3.30%, with epidural hematoma and wound complications being the most common reasons. However, upper thoracic spine surgery, concomitant dekyphosis, underlying coagulation disorder, longer operation time, higher ASA grade, and comorbidities of ankylosing spondylitis led to an increased risk of unplanned reoperation within 30 days of thoracic spine surgery.

Impact of the preoperative nutritional status on postoperative kyphosis in geriatric patients undergoing cervical laminoplasty.

PURPOSE: This study aimed to determine the association of preoperative malnutrition with an increased risk of cervical kyphosis after laminoplasty in geriatric patients with cervical spondylotic myelopathy (CSM). METHODS: Geriatric patients who underwent cervical laminoplasty were included. Malnutrition was defined as a geriatric nutritional risk index < 98 before surgery. The C2-7 angle and the global alignment parameters were analyzed on standing radiographs. The postoperative kyphosis was defined as a C2-7 angle < 0° during a 2-year follow-up. RESULTS: Ninety patients without preoperative kyphotic alignment were enrolled (mean age, 73.5 years old; 41.1% female). Twenty-one patients (23.3%) had malnutrition status (74.2 years old). Preoperatively, the global alignment parameters were comparable between the malnutrition and normal nutrition groups (SVA, 43.3 mm vs. 42.4 mm; T1S, 29.7° vs. 28.4°; TPA, 21.4° vs. 17.8°), with no significant difference in the C2-7 angle (15.1° vs. 15.2°). At 2 years postoperatively, the malnutrition group showed a significantly lower C2-7 angle than the normal nutrition group (9.3° vs. 15.8°, P = 0.03). Postoperative kyphosis was more prevalent in the malnutrition group (33.3% vs. 7.2%, P = 0.005). The preoperative nutritional status and C2-7 angle were independent predictors of postoperative kyphosis. The predictive C2-7 angles differed by preoperative nutritional status (malnutrition group, 11°; normal nutrition group, 7°). CONCLUSION: Among geriatric CSM patients, preoperative malnutrition was closely associated with the increased occurrence of cervical kyphosis after laminoplasty. Our results underscore the importance of preoperative nutritional assessment and management in geriatric populations undergoing cervical spine surgery, as malnutrition is a perioperative modifiable risk factor.

Establishment of an Individualized Distal Junctional Kyphosis Risk Index following the Surgical Treatment of Adult Cervical Deformities.

STUDY DESIGN: A retrospective review of a multicenter comprehensive cervical deformity (CD) database. OBJECTIVE: To develop a novel risk index specific to each patient to aid in patient counseling and surgical planning to minimize postop distal junctional kyphosis (DJK) occurrence. BACKGROUND: DJK is a radiographic finding identified after patients undergo instrumented spinal fusions which can result in sagittal spinal deformity, pain and disability, and potentially neurological compromise. DJK is considered multifactorial in nature and there is a lack of consensus on the true etiology of DJK. MATERIALS AND METHODS: CD patients with baseline (BL) and at least one-year postoperative radiographic follow-up were included. A patient-specific DJK score was created through use of unstandardized Beta weights of a multivariate regression model predicting DJK (end of fusion construct to the second distal vertebra change in this angle by <-10° from BL to postop). RESULTS: A total of 110 CD patients included (61 yr, 66.4% females, 28.8 kg/m 2 ). In all, 31.8% of these patients developed DJK (16.1% three males, 11.4% six males, 62.9% one-year). At BL, DJK patients were more frail and underwent combined approach more (both P <0.05). Multivariate model regression analysis identified individualized scores through creation of a DJK equation: -0.55+0.009 (BL inclination)-0.078 (preinflection)+5.9×10 -5 (BL lowest instrumented vertebra angle) + 0.43 (combine approach)-0.002 (BL TS-CL)-0.002 (BL pelvic tilt)-0.031 (BL C2 - C7) + 0.02 (∆T4-T12)+ 0.63 (osteoporosis)-0.03 (anterior approach)-0.036 (frail)-0.032 (3 column osteotomy). This equation has a 77.8% accuracy of predicting DJK. A score ≥81 predicted DJK with an accuracy of 89.3%. The BL reference equation correlated with two year outcomes of Numeric Rating Scales of Back percentage ( P =0.003), reoperation ( P =0.04), and minimal clinically importance differences for 5-dimension EuroQol questionnaire ( P =0.04). CONCLUSIONS: This study proposes a novel risk index of DJK development that focuses on potentially modifiable surgical factors as well as established patient-related and radiographic determinants. The reference model created demonstrated strong correlations with relevant two-year outcome measures, including axial pain-related symptoms, occurrence of related reoperations, and the achievement of minimal clinically importance differences for 5-dimension EuroQol questionnaire.

The postoperative course of mechanical complications in adult spinal deformity surgery.

PURPOSE: (a) Describe the time course of each mechanical complication, and (b) compare radiographic measurements and preoperative patient-reported outcome measures (PROMs) among each mechanical complication type. METHODS: A single-institution case-control study was undertaken of patients undergoing adult spinal deformity (ASD) surgery from 2009-2017. Exposure variables included patient demographics, operative variables, radiographic measurements, and preoperative PROMs, including Oswestry Disability Index (ODI), Numeric Rating Scale Back/Leg-pain scores (NRS-Back/Leg), and EuroQol-5D (EQ-5D). The primary outcomes were occurrence of a mechanical complication and time to complication. Due to overlapping occurrence, rod fracture and pseudarthrosis were grouped into one composite category. RESULTS: 145 patients underwent ASD surgery and were followed for at least 2 years. 30/47 (63.8%) patients with proximal junctional kyphosis (PJK) required reoperation, whereas 27/31 (87.1%) patients with pseudarthrosis/rod fracture required reoperation (63.8% vs. 87.1%, Χ2 = -0.23, 95% CI -0.41, -0.05, p = 0.023). Cox regression showed no significant difference in time to reoperation between PJK and rod fracture/pseudarthrosis (HR = 0.97, 95% CI 0.85-1.11, p = 0.686). Distal junctional kyphosis (DJK) (N = 3; 2 reoperation) and implant failures (N = 4; 0 reoperations) were rare. Patients with PJK had significantly lower Hounsfield Units preoperatively compared to those with pseudarthrosis/rod fracture (138.2 ± 43.8 vs. 160.3 ± 41.0, mean difference (MD) = -22.1, 95% CI -41.8, -2.4, p = 0.028), more prior fusions (51.1% vs. 25.8%, Χ2 = 0.253, 95% CI 0.41, 0.46, p = 0.026), fewer instrumented vertebrae (9.2 ± 2.6 vs. 10.7 ± 2.5, MD = -1.5, 95% CI -2.7, -0.31, p = 0.013), and higher postoperative thoracic kyphosis (TK) (46.3 ± 12.7 vs. 34.9 ± 10.6, MD = 11.4, 95% CI 5.9, 16.9, p < 0.001). Higher postoperative C7 sagittal vertical axis (SVA) did not achieve a significant difference (80.7 ± 72.1 vs. 51.9 ± 57.3, MD = 28.8, 95% CI -1.9, 59.5, p = 0.066). No differences were seen in preoperative PROMs. CONCLUSION: Patients with pseudarthrosis/rod fracture had a higher reoperation rate compared to those with PJK with similar time to reoperation. Moreover, patients with PJK had higher postoperative TK, lower Hounsfield Units, more prior fusions, and fewer instrumented levels compared to those with pseudarthrosis/rod fracture. The results of this single-institution study suggest that even though mechanical complications are often analyzed as a single group, important differences may exist between them. LEVEL OF EVIDENCE: III.

Proximal junctional kyphosis is a compensation for post-operative negative C2-FH in ASD patients: a cross-sectional study.

BACKGROUND: Recent studies have found that C2-FH is close to 0 cm in both standing and sitting position for asymptomatic adults. We hypothesize that the thoracic spine may compensate with PJK when the immediate post-operative C2-FH was not ideally restored in adult spinal deformity (ASD). METHODS: The inclusion criteria were as follows: ASD patients over 45 years old; Cobb angle > 30°; with posterior spinal correction surgery; at least 2 years follow-up. C2-FH was defined as the distance between the femoral heads to the C2 vertical line. All participants were divided into two groups according to the occurrence of PJK at the last follow-up: PJK group and non-PJK group. RESULTS: 68 ASD patients, with a minimum follow-up of 2.5 years, were included. PJK was found in 24 patients (35.3%) while the rest 44 patients remained no sagittal malalignment. Immediately post-operative C2-FH showed significant difference between PJK group and non-PJK group (p = 0.015). However, at the last follow-up, C2-FH showed no significant difference between PJK and non-PJK group and the mean value of C2-FH in both groups was approximately - 1 cm, indicating that ASD patients could develop various compensatory mechanisms to maintain sagittal global balance. The AUC was 0.84 (95%CI 0.68-0.97), indicating the well effectiveness of ROC curve and cut-off value in predicting occurrence of PJK in ASD patients. Based on the ROC curve, the optimal cut-off value of C2-FH as indicators for occurrence of PJK was - 42.3 mm. CONCLUSION: Immediate postoperative negative global malalignment (C2-FH < - 42.3 mm) may predict proximal junctional kyphosis in ASD patients. The normal value of C2-FH, - 1 cm, may be the target of global sagittal compensation, and PJK is a compensatory mechanism. TRIAL REGISTRATION: 2021-LCYJ-DBZ-05, 2021.07, Retrospective study.

Incidence of cervical kyphosis and cervical posterior translation in neck pain associated with radiological evidence of degenerative disc disease.

BACKGROUND: Cervical kyphosis mechanically influences the intervertebral discs, which may lead to neck, shoulder, and scapular pain. OBJECTIVES: To investigate the incidence of cervical kyphosis and posterior displacement of cervical vertebrae (cervical posterior translation index) in patients with radiologically evident degenerative disc disease. DESIGN: Retrospective-cohort study. METHODS: Ninety-five patients with radiologically evident degenerative disc disease were recruited at our clinic from 2015 to 2019. Radiography images were used to analyze the straight-line index in each patient in the upright posture. The straight-line index was calculated by drawing a reference line connecting the posterior inferior edges of C2 to C7 and normalizing the addition of the distances from the posterior inferior edges of C3, C4, C5, and C6 to the reference line, respectively. Straight-line index <0 was defined as cervical kyphosis and ≥0 as cervical lordosis, the cervical kyphosis. In cervical kyphosis group, the distance from the posterior inferior edges of C3, C4, C5, and C6 to the reference line was normalized by the reference line distance to determine posterior displacement. Multiple comparison tests aside from simple and multiple linear regression analysis were performed. RESULTS: The incidence of cervical kyphosis in patients with radiologically evident degenerative disc disease was 60% (57/95 patients). Multiple comparison tests revealed that the cervical posterior translation indexes of C4 and C5 were significantly higher than those of C3, C4, and C6, in cervical kyphosis group. CONCLUSIONS: Cervical kyphosis was present in 60% of patients with radiologically evident degenerative disc disease, with C5 showing the most posterior displacement.