T1 Pelvic Angle Research Articles

132. A patient specific approach to alignment and proximal junctional kyphosis risk assessment in adult spinal deformity surgery: development and validation of a predictive tool

<h3>BACKGROUND CONTEXT</h3> While adult spinal deformity surgery has clinical benefit, the prevalence of proximal junctional kyphosis (PJK) remains between 10% and 40%. Currently accepted alignment targets adjust for age or pelvic incidence, but do not consider other risk factors for PJK. <h3>PURPOSE</h3> To develop a predictive model for PJK and PJK severity that adjusts for known preoperative factors and modifiable surgical alignment. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort of adult deformity patients undergoing instrumented fusion at a single institution with minimum 2-year follow-up. <h3>PATIENT SAMPLE</h3> This study included 145 adult spinal deformity patients undergoing surgery with minimum 2-year radiographic and clinical follow-up. <h3>OUTCOME MEASURES</h3> Proximal junctional kyphosis, proximal junctional failure, proximal junctional kyphosis severity. <h3>METHODS</h3> Patients undergoing adult deformity surgery between 2009 and 2017 with 2-year follow-up were retrospectively reviewed. Using the Hart-ISSG PJK severity score as an ordinal outcome, a proportional odds regression model was fit to estimate probability of PJK and PJK severity. Predictor variables included preoperative Charlson comorbidity index, vertebral Hounsfield units at the UIV (+/- 4 vertebra), pelvic incidence, T1 pelvic angle, and postoperative regional lumbar lordosis (L1-L4 and L4-S1). Predictor effects were assessed using adjusted odds ratios and a nomogram was constructed for computing probability of PJK. Model performance was assessed using robust internal validation with bootstrap resampling. <h3>Results</h3> Of 145 patients, 47 (32%) developed PJK with a median PJK severity score of 6 (IQR, 4 to 7.5). After adjusting for all predictors, Charlson comorbidity index, vertebral Hounsfield units, preoperative T1 pelvic angle, and postoperative L1-L4 and L4-S1 lordosis were significantly associated with PJK severity (P < 0.05). After adjusting model performance measures for potential overfitting, the predictive model showed acceptable discrimination (C-statistic (AUC) = 0.75) and overall accuracy (Brier score = 0.10). <h3>Conclusions</h3> We have developed a model for predicting probability of PJK while adjusting for preoperative alignment, comorbidity burden, vertebral bone density, and modifiable postoperative L1-L4 and L4-S1 lordosis. This approach may allow alignment targets to be selected based on patient-specific risk of PJK. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P102. Determining the impact of proximal junctional kyphosis on cost utility in adult spinal deformity patients

<h3>BACKGROUND CONTEXT</h3> With health care costs on the rise, hospitals have increasingly focused on providing economically efficient medical services. Adult spinal deformity surgery remains an expensive medical intervention with high risk for complications and revisions, especially following mechanical failure in the context of proximal junctional kyphosis (PJK). We sought to evaluate the impact of PJK on associated expenditures following an index surgery for ASD. <h3>PURPOSE</h3> To evaluate the effect of proximal junctional kyphosis on the cost effectiveness of corrective adult deformity surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study of a prospective single-center database of ASD patients. <h3>PATIENT SAMPLE</h3> A total of 147 Adult Spinal Deformity Patients. <h3>OUTCOME MEASURES</h3> Complications, HRQLs (Oswentry Disability Index [ODI]), Quality adjusted life years (QALY). <h3>METHODS</h3> Adult Spinal deformity patients with 2-year HRQL follow-up were included. Utility data was calculated using published conversion methods to convert ODI to SF-6D. QALYs utilized a 3% discount rate to account for residual decline to life expectancy (78.7 years). Costs were calculated using the PearlDiver database incorporating complications and comorbidities classified according to CMS standard definitions. Reimbursement consisted of a standardized estimate using regression analysis of Medicare pay-scales for all services rendered within a 30-day window, including estimates regarding costs of postoperative complications, outpatient health care encounters, reoperations and revisions. After accounting for all postoperative events, including mortality, cost per QALY by 2Y was calculated for revisions that occurred due to proximal junctional kyphosis. <h3>RESULTS</h3> A total of 147 adult spinal deformity patients met inclusion criteria (55.22years, 54% Female). At baseline, patients presented radiographically as: Pelvic Tilt (23.66±11.7), Pelvic Incidence- Lumbar Lordosis (-2.9±12.6), Sagittal Vertical Axis (60.5±76.8), T1 Pelvic Angle (22.6±14.3). Surgical details: EBL of 1823 mL, operative time of 327 min, with .4% undergoing an anterior approach, 90.2% posterior-only approach, and 9.3% combined approach. Overall, 54.3% of patients developed PJK within 2 years postoperatively, with 22% undergoing reoperation for PJK. Average cost of revision surgery due to PJK was $93,688 ± $21,467. The cost for PJK patients, including the cost associated with their revision surgery, was higher ($103,760 vs $71,000). Baseline ODI (39 vs 32) and 2Y ODI (39 vs 27) were higher for PJK patients, however, PJK patients did improve to a greater degree (-12 vs -10). The overall cost per QALY by 2Y was higher for PJK patients ($116,170 vs $95,347). <h3>CONCLUSIONS</h3> Patients that developed PJK had an almost $30,000 higher initial cost at 2 years. When looking at the cost per quality adjusted life years by 2Y, PJK resulted in slightly more than $20,000 in cost. These findings suggest prophylactic measures to mitigate PJK may improve the cost utility of adult spinal deformity surgery and can help policy efforts for adequate resource allocation for these complex patients. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P101. Pseudarthrosis and rod fracture at the distal levels of a long construct are associated with proximal junctional kyphosis after ASD surgery

<h3>BACKGROUND CONTEXT</h3> More distal fusion levels and overall stiffness of a long fusion construct for ASD may result in larger range of motion and stress at the proximal junctional level. Stability of distal fixation, inferred by the presence or absence of pseudarthrosis and rod fracture, may affect proximal junctional stresses and contribute to proximal junctional kyphosis (PJK) and associated revision surgery.To date, very few studies have evaluated the relationship between achieving solid fusion at the base of a long construct and rate of PJK. <h3>PURPOSE</h3> To assess the relationship between lumbosacral rod fracture and pseudarthrosis and development of proximal junctional kyphosis (PJK) after long construct ASD surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of prospectively collected single center database. <h3>PATIENT SAMPLE</h3> We performed a review of 942 patients who underwent ASD surgery (Age: 55 ± 23 y; mFI: .41 ± .67; Levels fused: 10.1 ± 4.2; Revision: 22.3%; 3CO: 12.3%). <h3>OUTCOME MEASURES</h3> We assessed the rate of PJK at minimum 2-year follow-up, as well as the rate of pseudarthrosis or rod fracture at the lower lumbar levels or lumbosacral junction, and the association between these complications. <h3>METHODS</h3> A total of 942 patients were divided into PJK and non-PJK groups using whole spine standing radiographs. The incidences of PJK, and lumbar or lumbosacral pseudarthrosis were defined. The relationship between these complications was assessed. <h3>RESULTS</h3> The cohort had sagittal malalignment as demonstrated by PT 23.7 ± 12.4°, TPA 22.5 ± 26.2°, and SVA 77.8 ± 70 mm. The PJK and non-PJK groups comprised 350 and 592 cases respectively. Mean follow-up time was 48.9 months. There was no significant difference in baseline SVA, T1 pelvic angle, change in sagittal alignment postoperatively, and surgical invasiveness index between the two groups. There were 11.1% of patients who developed PJK had a pseudarthrosis at the lower lumbar levels or lumbosacral junction, versus 6.4% of those who did not develop PJK (p=0.011). Patients who developed PJK had a significantly higher rate of rod fracture in the lower lumbar levels or lumbosacral junction (15.4%) versus those who did not develop PJK (7.3%) (p<0.0001). Pseudarthrosis (OR: 1.963, 95% CI: 1.14-3.38, p=0.015) and rod fracture at the lower lumbar levels or lumbosacral junction (OR: 2.27, 95% CI: 1.41-3.64, p=0.001) were predictors of PJK at final follow-up by regression analysis. <h3>CONCLUSIONS</h3> Pseudarthrosis and rod fracture at the lower lumbar levels or lumbosacral junction were predictive of development of PJK at final follow-up. This may indicate that distal stability of a long construct has a significant impact on stresses at the proximal junction. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

179. Correcting ASD patients to normative alignment results in no functional benefit but more PJK and PJF

<h3>BACKGROUND CONTEXT</h3> A previous study utilized normative alignment to determine overcorrections and predict mechanical complications in adult spinal deformity (ASD) surgery. Other studies have recommended alignment targets that optimize age-appropriate physical function. The difference in functional outcomes and mechanical complications between these prescribed alignment targets has not been explored. This study utilizes a component angle of the T1 pelvic angle (TPA) within the fusion to compare normative and age-pelvic incidence (PI) optimal alignment in terms of proximal junctional kyphosis (PJK), proximal junctional failure (PJF) and health related quality of life measures (HRQL). Using the component of TPA within the fusion, the T4-pelvic angle (T4PA), allows for the measurement spinopelvic alignment separate from that of the unfused thoracic spine and any PJK that may occur postoperatively. <h3>PURPOSE</h3> To compare ASD patients corrected to normative alignment vs age-PI optimal alignment in terms of PJK/PJF and outcomes. <h3>STUDY DESIGN/SETTING</h3> Retrospective analysis of a prospective multicenter ASD database and a database of asymptomatic subjects. <h3>PATIENT SAMPLE</h3> This study included 1,916 ASD patients and 118 asymptomatic subjects for formula development; 288 ASD patients with 2-year X-ray and HRQL follow-up. <h3>OUTCOME MEASURES</h3> SF36-PCS, ODI, SRS-22, NRS back/leg, PJK (change in UIV to UIV+2 >10°), PJF (defined as severe PJK with change >21.6°, or UIV olisthesis, or proximal junctional fracture). <h3>METHODS</h3> Baseline relationships between age, PI and T4PA, were analyzed in the ASD patients and compared to the asymptomatic subjects. Linear regression modeling was used to determine alignment based on PI and age in asymptomatic subjects (normative alignment), and in ASD patients, alignment corresponding to age-appropriate functional status (optimal alignment). ASD patients with UIV above T4 were grouped based on their corrections: normative vs optimal. Extreme over or under corrected patients were excluded (greater than or less than 2SD from mean postop T4PA). For each group, the rate of PJK and PJF were determined. <h3>RESULTS</h3> In the multilinear regression analysis of the 119 asymptomatic subjects, T4PA correlated with age and PI, r=.713, p<.0001. 1916 ASD patients were included in the optimal formula development. In the 288 ASD patients included in the pre- to postop analysis (137 normative, 151 optimal), there was no difference in baseline alignment or HRQL between the groups. At 6 weeks, the normative aligned group had smaller T4PA (4.45 vs 14.1) and PI-LL (-7.24 vs 7.4), all p<.0001. Normative aligned patients had the higher PJK rate (40% vs 27.2%, p=.03) compared with optimal; and a higher PJF rate (17% vs 6.8%, p=.008). PJF patients had -1.2°of T4PA offset from normative alignment and -5.2°of offset from optimal alignment. By contrast, no PJF patients had 3.8° of T4PA offset from normative alignment and -0.42° of offset from optimal alignment. There was a trend toward worse 2-year SF36-PCS in patients who suffered PJF (37.7 vs 41.6, p=.09). Both the Normative and Optimal groups improved in outcomes from baseline to 2-year (p<.001) with no difference in 2-year HRQL. <h3>CONCLUSIONS</h3> Correcting ASD patients to normative alignment resulted in higher rates of PJK and PJF without improvements in HRQL. ASD patients should not be corrected to match the alignment of their asymptomatic unfused peers, rather they should be realigned optimally to match age-appropriate physical function. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Relationship between Sagittal Alignment and Anterior Bony Resorption of Cervical Vertebral Body in Patients with Ankylosing Spondylitis.

Study DesignThis is a retrospective comparative cohort study.PurposeTo investigate the prevalence of anterior resorption of the cervical spine in ankylosing spondylitis (AS) and its relationship with sagittal alignment.Overview of LiteratureThis study believes that no published reports exist regarding the relationship between anterior resorption and spinopelvic alignment.MethodsThis retrospective study included 238 patients with AS who underwent surgical correction for thoracolumbar kyphosis. Of these, 80 patients with complete subaxial ankylosis were selected and divided into two groups: groups 1 (consisting of 28 patients with anterior bony resorption) and 2 (consisting of 52 patients without anterior resorption). Cervical sagittal parameters were analyzed and compared between the two groups.ResultsThe average lateral diameter measured in patients with C5 anterior resorption was 84.2%±7.8% (62.4%–96.8%). Cervical lordosis was 8.7° ±13.4° and 10.9°±11.5° in groups 1 and 2 (p=0.556), respectively. No significant differences were noted between the two groups on spinopelvic alignment in the T1 slope (52.2°±11.1° and 53.3°±9.9° in groups 1 and 2, respectively; p=0.742), C2–C7 sagittal vertical axis (SVA; 6.2±1.7 cm and 6.2±1.8 cm in groups 1 and 2, respectively; p=0.978), C7 SVA (14.3±4.9 cm and 14.6±6.2 cm in groups 1 and 2, respectively; p=0.823), or T1 pelvic angle (27.1°±8.9° and 31.6°±11.2° in groups 1 and 2, respectively; p=0.382). Correlation analyses were significant between the extent of anterior resorption and sagittal parameters, C2–C7 lordosis (R2=−0.428, p=0.021), and T1–T4 kyphosis (R2=−0.375, p=0.045).ConclusionsAnterior bony resorption could develop by stress concentration. However, the development was not related to the sagittal alignment. The particular segments involved in developing anterior resorption varied, possibly because of their dependence on the preceding pattern of ankylosis.

Clinical photographs in the assessment of adult spinal deformity: a comparison to radiographic parameters.

The goal of this study was to reliably predict sagittal and coronal spinal alignment with clinical photographs by using markers placed at easily localized anatomical landmarks. A consecutive series of patients with adult spinal deformity were enrolled from a single center. Full-length standing radiographs were obtained at the baseline visit. Clinical photographs were taken with reflective markers placed overlying C2, S1, the greater trochanter, and each posterior-superior iliac spine. Sagittal radiographic parameters were C2 pelvic angle (CPA), T1 pelvic angle (TPA), and pelvic tilt. Coronal radiographic parameters were pelvic obliquity and T1 coronal tilt. Linear regressions were performed to evaluate the relationship between radiographic parameters and their photographic "equivalents." The data were reanalyzed after stratifying the cohort into low-body mass index (BMI) (< 30) and high-BMI (≥ 30) groups. Interobserver and intraobserver reliability was assessed for clinical measures via intraclass correlation coefficients (ICCs). A total of 38 patients were enrolled (mean age 61 years, mean BMI 27.4 kg/m2, 63% female). All regression models were significant, but sagittal parameters were more closely correlated to photographic parameters than coronal measurements. TPA and CPA had the strongest associations with their photographic equivalents (both r2 = 0.59, p < 0.001). Radiographic and clinical parameters tended to be more strongly correlated in the low-BMI group. Clinical measures of TPA and CPA had high intraobserver reliability (all ICC > 0.99, p < 0.001) and interobserver reliability (both ICC > 0.99, p < 0.001). The photographic measures of spinal deformity developed in this study were highly correlated with their radiographic counterparts and had high inter- and intraobserver reliability. Clinical photography can not only reduce radiation exposure in patients with adult spinal deformity, but also be used to assess deformity when full-spine radiographs are unavailable.

The utility of supine radiographs in the assessment of thoracic flexibility and risk of proximal junctional kyphosis.

Supine radiographs have successfully been used for preoperative planning of lumbar deformity corrections. However, they have not been used to assess thoracic flexibility, which has recently garnered attention as a potential contributor to proximal junctional kyphosis (PJK). The purpose of this study was to compare supine to standing radiographs to assess thoracic flexibility and to determine whether thoracic flexibility is associated with PJK. A retrospective study was conducted of a single-institution database of patients with adult spinal deformity (ASD). Sagittal alignment parameters were compared between standing and supine and between pre- and postoperative radiographs. Thoracic flexibility was determined as the change between preoperative standing thoracic kyphosis (TK) and preoperative supine TK, and these changes were measured over the overall thoracic spine and the fused portion of the thoracic spine (i.e., TK fused). A case-control analysis was performed to compare thoracic flexibility between patients with PJK and those without (no PJK). The cohort was also stratified into three groups based on thoracic flexibility: kyphotic change (increased TK), lordotic change (decreased TK), and no change. The PJK rate was compared between the cohorts. A total of 101 patients (mean 63 years old, 82.2% female, mean BMI 27.4 kg/m2) were included. Preoperative Scoliosis Research Society-Schwab ASD classification showed moderate preoperative deformity (pelvic tilt 27.7% [score ++]; pelvic incidence-lumbar lordosis mismatch 44.6% [score ++]; sagittal vertical axis 42.6% [score ++]). Postoperatively, the average offset from age-adjusted alignment goals demonstrated slight overcorrection in the study sample (-8.5° ± 15.6° pelvic incidence-lumbar lordosis mismatch, -29.2 ± 53.1 mm sagittal vertical axis, -5.4 ± 10.8 pelvic tilt, and -7.6 ± 11.7 T1 pelvic angle). TK decreased between standing and supine radiographs and increased postoperatively (TK fused: -25.3° vs -19.6° vs -29.9°; all p < 0.001). The overall rate of radiographic PJK was 23.8%. Comparisons between PJK and no PJK demonstrated that offsets from age-adjusted alignment goals were similar (p > 0.05 for all). There was a significant difference in the PJK rate when stratified by thoracic flexibility cohorts (kyphotic: 0.0% vs no change: 18.4% vs lordotic: 35.0%; p = 0.049). Logistic regression revealed thoracic flexibility (p = 0.045) as the only independent correlate of PJK. Half of patients with ASD experienced significant changes in TK during supine positioning, a quality that may influence surgical strategy. Increased thoracic flexibility is associated with PJK, possibly secondary to fusing the patient's spine in a flattened position intraoperatively.

Comparison of 3D and 2D characterization of spinal geometry from biplanar X-rays: a large cohort study.

Biplanar X-ray system providing anteroposterior and sagittal plane with an ultra-low radiation dose and in weight-bearing position is increasingly used for spine imaging. The original three-dimensional (3D) reconstruction method from biplanar X-rays has been widely used for clinical parameters, however, the main issue is that manual adjustments of the 3D model was quite time-consuming and limited to thoracolumbar spine. A quasi-automated 3D reconstruction method of the spine from cervical vertebra to pelvis was proposed, which proved fast and accurate in 57 patients with adolescent idiopathic scoliosis. The aim of this study was to compare the newly developed technique of quasi-automatic 3D measurement with classical 2D measurements in a large cohort. A total of 494 adults with biplanar EOS X-ray scanning were included in this study and divided into health and deformity group according to the presence of spinal deformity. The proposed method of quasi-automatic 3D measurement was applied to all these subjects. The radiographic parameters included: thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sagittal vertical axis (SVA), T1 pelvic angle (TPA) in sagittal plane, and cobb angle in coronal plane. Comparison was made between quasi-automatic and manual measurement. The mean age was 53.7±19.9 years old. In the whole population, the mean differences between the two methods were 3.9° for TK (30.5°±9.9° vs. 26.5°±9.3°, P<0.001), -5.2° for LL (-47.5°±11.2° vs. -42.4°±11.0°, P<0.001), 3.6° for PI (46.9°±10.3° vs. 43.9°±10.3°, P<0.001), -0.2° for PT (11.9°±7.7° vs. 12.0°±8.2°, P=0.328), -2.1 mm for SVA (15.7±26.2 vs. 17.8±26.3 mm, P=0.221) and -1.1° for TPA (9.0°±7.6° vs. 10.1°±7.8°, P=0.051). The deformity group had similar mean differences with the asymptomatic group with the values ranged from -4.1° to 3.8° for sagittal parameters. The mean differences of Cobb angle were 1.9° for patients with Cobb angle <30° and 2.3° for patients with Cobb angle >30°, respectively. Correlation analysis showed r2 for all clinical parameters ranged from 0.667 to 0.923. On average, the new method takes 5 minutes to compute all the parameters for one case. In conclusion, this ergonomic and efficient quasi-automatic method for full spine proved fast and accurate measurement in a large population, which showed great potential in extensive clinical application.

Age- and gender-related normative value of whole-body sagittal alignment based on 584 asymptomatic Chinese adult population from age 20 to 89.

To establish the age- and sex-related normative values of sagittal alignment in asymptomatic Chinese adults, and to investigate the changes and possible associated compensation mechanisms across age groups. 584 asymptomatic Chinese adults aged 20-89 years were recruited. Subjects were grouped according to age and gender. Whole-body standing radiographs were acquired for evaluating sagittal alignment from spine to lower limb. Sagittal parameters between gender in different age groups were compared via independent t test. Pearson correlation analysis was used to demonstrate relationships between parameters. Thoracic kyphosis (TK) increased steadily while lumbar lordosis decreased gradually in both genders. Pelvic tilt (PT) in male is greater than in female across all age groups with age related gradual increase. There were significant differences between male and female from 20s to 60s in terms of knee flexion angle (KA) and ankle dorsiflexion angle (AA), but the differences were not significant after 60s. T1 pelvic angle (TPA) was significantly correlated with spinal, pelvic and lower-limb alignment. The older group (≥50 years) had a stronger correlation of TPA with PT and KA, whereas the younger (<50 years) had stronger correlation with TK. This study comprehensively presented the normative sagittal alignment based on a large asymptomatic population, which could serve as an age- and gender-specific reference value for spine surgeons when planning for correction surgery. Age can influence the recruitment of compensation mechanism that involve more pelvic and lower limb mechanisms for elderly people.

Association of global sagittal spinal deformity with functional disability two years after total hip arthroplasty

BackgroundThe relationship between spinopelvic alignment and functional disability after total hip arthroplasty (THA) has not been fully elucidated despite the growing recognition of its importance on patient-reported outcome measures. Therefore, our aim was to assess the effect of global sagittal spinal deformity on post-operative disability.MethodsThis analysis was based on 208 cases of THA, with functional disability measured at a follow-up of 2 years. The Hip Disability and Osteoarthritis Outcome Score-Joint Replacement (HOOS-JR), ranging from a scale of 0 (complete joint disability) to 100 (perfect joint health), was used to divide eligible patients into two groups, namely with and without disability, using a score of 70 as the cut-off. The following factors were compared between the two groups using multivariate analysis: age, sex, body height, body mass index, spinopelvic parameters, and surgeon experience. To identify the cut-off value of the parameters for predicting disability (HOOS-JR < 70/100), we used the receiver-operating characteristic curve.ResultsThe disability (30 hips) and control (178 hips) groups showed a significant difference in pre-operative body height (p = 0.020), T1 pelvic angle divided by pelvic incidence (T1PA/PI; p = 0.018), PI minus lumbar lordosis (p = 0.027), post-operative HOOS-JR (p = 0.010), patient satisfaction (p = 0.033), and the modified Harris Hip Score (p = 0.038). On multivariate analysis, the following factors were associated with persistent disability: T1PA/PI > 0.2 (odds ratio [OR], 2.11; 95% confidence interval [CI], 1.19–4.14; p < 0.001) and height < 148 cm equivalent to legal standards as short stature (OR, 1.26; 95% CI, 1.09–1.48; p = 0.011). The cut-off value of pre-operative T1PA/PI was > 0.19, with a sensitivity of 95% and specificity of 85%. Post-operative satisfaction (p < 0.001), HOOS-JR (p = 0.023), and EuroQol 5-Dimension (p = 0.041) differed between the two groups when the pre-operative cut-off value was chosen as 0.2.ConclusionsA T1PA/PI > 0.2 was associated with greater disability after THA. Clinicians should be aware that patient-related factors, including global spinal deformities, particularly in patients with a short stature, can influence THA outcomes at 2 years postoperatively.

Factors Negatively Influencing Postoperative Improvement After Laminoplasty in Degenerative Cervical Myelopathy.

This was a retrospective study of prospectively collected data. In this study, we aimed to characterize a population of patients with degenerative cervical myelopathy (DCM) and a history of poor postoperative neurological recovery and to identify risk factors associated with poor neurological recovery after laminoplasty. Kyphotic cervical alignment has been considered a relative contraindication to laminoplasty in recent years; hence, laminoplasty has been decreasingly performed for the treatment of DCM in patients with cervical kyphosis. However, the effect of global spinal alignment on postoperative outcomes has not been extensively investigated. We prospectively enrolled patients who were scheduled for laminoplasty for DCM. Outcome (at enrollment and 1 y after surgery) and risk factor analyses were performed by comparing the good recovery and poor recovery groups. The Spearman correlation coefficient was used to evaluate the relationships between the recovery rate and the preoperative radiographic factors. In total, 101 patients completed the 1-year follow-up. Regarding clinical outcomes, the Japanese Orthopedic Association score for the assessment of cervical myelopathy, European Quality of Life-5 Dimensions, and Neck Disability Index scores improved postoperatively. The recovery rate was significantly correlated with the preoperative sagittal vertical axis (SVA). The patients in the poor recovery group were older than those in the good recovery group. Univariate analyses showed that the SVA and T1 pelvic angle were significantly higher in the poor recovery group. Lastly, stepwise logistic regression analysis showed that a higher SVA was an independent predictor of poor recovery after laminoplasty. The SVA and T1 pelvic angle were significantly higher in the poor recovery group. A high preoperative SVA is an independent predictor for poor recovery after laminoplasty. Therefore, indications for laminoplasty in elderly DCM patients with a high preoperative SVA should be carefully considered. Level III.

Global sagittal alignment of the spine, pelvis, lower limb after vertebral compression fracture and its effect on quality of life

BackgroundVertebral compression fractures (VCFs) are the most common among all osteoporotic fractures. The body may compensate to the kyphosis from vertebral compression fractures with lordosis of the adjacent spinal segments, rotation of the pelvis, knee flexion and ankle dorsiflexion. However, the detailed degree of body compensation, especially the lower limb, remains uncertain. Herein, the aim of this study is to investigate the values of global sagittal alignments (GSA) parameters, including the spine, pelvis and lower limbs, in patients with and without VCFs, as well as to evaluate the effect of VCFs on various quality of life (QoL) parameters.MethodsA cross-sectional study was conducted from May 2015 to June 2018. A total of 142 patients with VCFs aged over 60 years old and 108 age-matched asymptomatic controls were recruited. Whole body sagittal alignment including thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), sagittal vertical axis (SVA), T1-pelvic angle (TPA), knee-flex angle (KA) and ankle-flex angle (AA) were measured. In addition, lower back pain and quality of life were assessed using self-reported questionnaires.ResultsCompared to asymptomatic controls, patients with VCF showed significantly greater TK (33.4o ± 16.4o vs 28.4o ± 11.4o; p < 0.01), PT (25.4o ± 10.5o vs 16.6o ± 8.9o; p < 0.001), PI (54.6o ± 11.8o vs 45.8o ± 12.0o; p < 0.001), SVA (49.1 mm ± 39.6 mm vs 31.5 mm ± 29.3 mm; p < 0.01), and TPA (28.6o ± 10.8o vs 14.8o ± 8.6o; p < 0.001). Whereas for lower limb alignment, patients with VCF showed significantly higher KA (10.1o ± 7.8o vs 6.0o ± 6.4o; p < 0.001) and AA (7.0o ± 3.9o vs 4.8o ± 3.6o; p < 0.001) than controls. The number of VCF significantly correlated with lower limb alignments (KA and AA) and global sagittal balance (TPA). VCF patients showed poorer quality of life assessment scores in terms of SF-12 (30.0 ± 8.3 vs 72.4 ± 16.9; p < 0.001), ODI (37.8 ± 24.0 vs 18.7 ± 16.6; p < 0.001) and VAS (3.8 ± 2.8 vs 1.9 ± 2.2; p < 0.001).ConclusionThis is the first study to illustrate the abnormal lower limb alignment exhibited in patients with VCF. Patients with VCF showed an overall worse global sagittal alignment and decreased quality of life. Poorer global sagittal alignment of VCF patients also imply worse quality of life and more severe VCF.

Predicting Reciprocal Thoracic Change, Proximal Junctional Kyphosis, and Revision Surgery in Adult Spinal Deformity

Compensatory mechanisms in patients with adult spinal deformity (ASD) that lead to poor quality of life include positive sagittal balance and pelvic retroversion. The objective of this retrospective review was to identify demographic and radiographic parameters of sagittal alignment that are correlated with thoracic kyphosis (TK), PJK, and reoperation in patients undergoing surgical correction for ASD. A single-center database of 155 patients with ASD undergoing surgery from 2008 to 2015 was reviewed. Patients >18 years old who underwent multilevel thoracolumbar fusion or fusion of thoracic vertebrae to the pelvis were included. Demographics and radiographic measurements of sagittal alignment were collected preoperatively, 6 weeks postoperatively, and 1 year postoperatively. Statistical analysis was performed to compare groups that did or did not develop change in thoracic kyphosis or PJK at early or late follow-up. Additionally, patients requiring reoperation were evaluated. Increased thoracic kyphosis was associated with older age, hypolordosis, and comorbid PJK. Early PJK was associated with older age, hypolordosis, and increased T1 pelvic angle. Reoperation was associated with older age, higher positive sagittal balance, hypolordosis, and pelvic retroversion; PJK and thoracic kyphosis did not increase risk for reoperation. Thoracic reciprocal change following surgical correction of ASD is highly associated with PJK, although neither increased risk of reoperation. PJK may be predicted by older age, hypolordosis, and increased T1 pelvic angle. Reoperation in patients with ASD is more likely in older patients with positive sagittal balance, a compensatory flat lower back, and compensatory pelvic retroversion.

Predictors for quality of life improvement after surgery for degenerative cervical myelopathy: a prospective multi-center study

BackgroundDegenerative cervical myelopathy (DCM) can significantly impair a patient’s quality of life (QOL). In this study, we aimed to identify predictors associated with QOL improvement after surgery for DCM.MethodsThis study included 148 patients who underwent surgery for DCM. The European QOL-5 Dimension (EQ-5D) score, the Japanese Orthopedic Association for the assessment of cervical myelopathy (C-JOA) score, and the Nurick grade were used as outcome measures. Radiographic examinations were performed at enrollment. The associations of baseline variables with changes in EQ-5D scores from preoperative to 1-year postoperative assessment were investigated using a multivariable linear regression model.ResultsThe EQ-5D and C-JOA scores and the Nurick grade improved after surgery (P < 0.001, P < 0.001, and P < 0.001, respectively). Univariable analysis revealed that preoperative EQ-5D and C-JOA scores were significantly associated with increased EQ-5D scores from preoperative assessment to 1 year after surgery (P < 0.0001 and P = 0.045). Multivariable regression analysis showed that the independent preoperative predictors of change in QOL were lumbar lordosis (LL), sacral slope (SS), and T1 pelvic angle (TPA). According to the prediction model, the increased EQ-5D score from preoperatively to 1 year after surgery = 0.308 − 0.493 × EQ-5D + 0.006 × LL − 0.008 × SS + 0.004 × TPA.ConclusionsPreoperative LL, SS, and TPA significantly impacted the QOL of patients who underwent surgery for DCM. Less improvement in QOL after surgery was achieved in patients with smaller LL and TPA and larger SS values. Patients with these risk factors may therefore require additional support to experience adequate improvement in QOL.

Predictors associated with neurological recovery after anterior decompression with fusion for degenerative cervical myelopathy

BackgroundAnterior decompression with fusion (ADF) has often been performed for degenerative cervical myelopathy (DCM) in patients with poor cervical spine alignment and/or anterior cord compression. We aimed to identify clinical and radiological predictors associated with neurological recovery after ADF.MethodsThis post-hoc analysis from a prospective multicenter study included patients who were scheduled for ADF for DCM. The patients who received other surgeries (laminoplasty, posterior decompression and fusion) were excluded. The associations between baseline clinical and radiographic variables (age, sex, body mass index, etiology, cervical lordosis, range of motion, C7 slope, C2-7 sagittal vertical axis [SVA], thoracic kyphosis [TK], lumbar lordosis, sacral slope, SVA, pelvic tilt, T1 pelvic angle [TPA], the Japanese Orthopedic Association score for the assessment of cervical myelopathy [C-JOA], European Quality of Life Five Dimensions Scale [EQ-5D], Neck Disability Index [NDI], Physical Component Summary of the SF-36 [PCS], and Mental Component Summary of the SF-36) and the recovery rates as the outcome variables were investigated in the univariate regression analysis. Then, the independent predictors for increased recovery rates were evaluated using a stepwise multiple regression analysis.ResultsIn total, 37 patients completed the 1 year follow-up. The recovery rate was significantly correlated with SVA (p = 0.001) and TPA (p = 0.03). Univariate regression analyses showed that age (Regression coefficient = − 0.92, p = 0.049), SVA (Regression coefficient = − 0.57, p = 0.004) and PCS (Regression coefficient = 0.80, p = 0.03) score were significantly associated with recovery rate. Then, a stepwise multiple regression analysis identified the independent predictors of recovery rate after ADF as TK (p = 0.01), PCS (p = 0.03), and SVA (p = 0.03). According to this prediction model, the following equation was obtained: recovery rate = − 8.26 + 1.17 × (TK) − 0.45 × (SVA) + 0.85 × (PCS) (p = 0.002, R2 = 0.44).ConclusionPatients with lower TK, lower PCS score, and higher SVA were more likely to have poor neurological recovery after ADF. Therefore, patients with DCM and these predictors who undergo ADF should be warned about poor recovery and be required to provide adequate informed consent.

A Comprehensive Analysis of the Behavior of Pelvic Incidence After Different Posterior Spinal Procedures in Elderly Patients With Spinal Deformity.

A retrospective case-control study. To evaluate the behavior of pelvic incidence (PI) after different posterior spinal procedures in elderly patients with adult spinal deformity (ASD), to determine the potential associated factors with the variability in PI after spinal surgery and to comprehensively analyze its mechanisms. Elderly patients underwent long fusion to sacrum with and without pelvic fixation were assigned to Group L+P and Group L-P, respectively. In Group L-P, those with severe sagittal deformity were selected as Group A. 20 elderly patients with severe sagittal deformity underwent short lumbar fusion were included as Group B. The following radiographic parameters were evaluated: thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL), PI-LL, sagittal vertical axis (SVA), T1 pelvic angle (TPA), and pelvic parameters. PI changing more than 5° (△PI > 5°) was considered as substantially changed. For the whole cohort and in Group L+P, PI were not substantially changed (△PI ≤ 5°) after surgery. Besides the severer sagittal malalignment in patients with △PI > 5° in Group L-P, relatively larger mean age, greater proportion of female and lower preoperative PI were found than those in patients with △PI ≤ 5°. 70.8% of patients had substantial increase of PI in Group A, while only 10% of patients had in Group B (P < 0.001). PI behaves differently under different conditions in elderly ASD patients. Besides severe sagittal deformity, aging, female and low preoperative PI are also the potential risk factors of PI increasing after long fusion to sacrum.

Does Achieving Global Spinal Alignment Lead to Higher Patient Satisfaction and Lower Disability in Adult Spinal Deformity?

Multicenter retrospective review of prospective database. The aim of this study was to investigate potential associations between postoperative alignment and satisfaction. Achieving high satisfaction is the main goal of any treatment, including adult spinal deformity (ASD) surgery. Despite being one of the key elements, literature is sparse regarding postoperative factors influencing patient satisfaction. ASD patients with 2-year follow-up were retrospectively reviewed. Patients without revision after the index procedure were stratified according to deformity type: sagittal (T1 pelvic angle >22°), coronal (C7 plumb line [C7PL] >5 cm or MaxCobb >50°), or mixed. Bivariate correlation between satisfaction and postoperative data was conducted on the entire cohort as well as by type of preoperative deformity. Multivariate regression controlling for pre-op alignment and demographic information was used to identify independent predictors of 2Y satisfaction. A total of 509 patients were included in the analysis (58.7 ± 14.8, 80% females). The quality of life significantly improved between pre- and 2-year (ΔOswestry Disability Index [ODI]: 17.6, p < 0.001). At 2 years, SRS22 satisfaction was 4.27 ± 0.89 (median 4.5). Significant associations were found between satisfaction and disability (ODI, r = -0.50) and global coronal (C7PL r = -0.15) and sagittal (sagittal vertical axis [SVA], r = -0.10) alignment (all p < 0.01) but not with the coronal clavicle angle. Stratification by preoperative deformity revealed significant associations between satisfaction and SVA for sagittal deformity only, C7PL and MaxCobb for coronal only, and C7PL for combined deformity. In the multivariate analysis controlling for demographic and pre-op deformity, 2-year ODI and 2-year C7PL were independent predictors of satisfaction. Multilinear regression demonstrated 2-year SVA, pre-op ODI and patient's age were the independent predictors 2-year ODI. The ability to restore global alignment depends on the severity of the preoperative deformity as well as the correction of the main aspect of the deformity. Achieving global coronal and sagittal alignment is an independent predictor of both satisfaction and disability at 2 years post-op. Patients who continue to be disabled are also not satisfied.Level of Evidence: 3.

Analysis of sagittal profile and radiographic parameters in symptomatic thoracolumbar disc herniation patients

BackgroundFew studies describe thoracolumbar disc herniation (TLDH) as an isolated category, it is frequently classified as the lower thoracic spine or upper lumbar spine. Thus, less is known about the morphology and aetiology of TLDH compared to lumbar disc herniation (LDH). The aim of study is to investigate sagittal alignment in TLDH and analyze sagittal profile with radiographic parameters.MethodsData from 70 patients diagnosed with TLDH were retrospectively reviewed. The thoracic-lumbar alignment was depicted by description of curvatures (the apex of lumbar curvature, the apex of thoracic curvature, and inflexion point of the two curvatures) and radiographic parameters from complete standing long-cassette spine radiographs. The rank sum test was utilised to compare radiographic parameter values in each subtype.ResultsWe found two subtypes differentiated by the apex of thoracic kyphotic curves. The sagittal profile was similar to that of the normal population in type I, presenting the apex of the thoracic kyphotic curve located in the middle thoracic spine. The well aligned thoracic-lumbar curve was disrupted in type II, presenting the apex of the thoracic kyphotic curve located in the thoracolumbar region in type II patients. Thirty-six patients were classified as type I, and 34 patients were classified as type II. The mean sagittal vertical axis, T1 pelvic angle and L1 pelvic angle were 27.9 ± 24.8°, 8.2 ± 7.3° and 6.2 ± 4.9°, respectively. There was significant difference (p < 0.001) of thoracolumbar angle between type I (14.9 ± 7.9°) and type II patients (29.1 ± 13.7°).ConclusionsWe presented two distinctive sagittal profiles in TLDH patients, and a regional kyphotic deformity with a balanced spine was validated in both subtypes. In type I patients, disc degeneration was accelerated by regional kyphosis in the thoracolumbar junction and eventually caused disc herniation. In type II patients, excessive mechanical stress was directly loaded at the top of the curve (thoracolumbar apex region) rather than being diverted by an arc as in a normal population or type I patients. Mismatch between shape and sacral slope value was observed, and better agreement was found in Type II patients.

The Ankle-Pelvic Angle (APA) and Global Lower Extremity Angle (GLA): Summary Measurements of Pelvic and Lower Extremity Compensation.

Adult sagittal spinal deformity (SSD) leads to the recruitment of compensatory mechanisms to maintain standing balance. After regional spinal compensation is exhausted, lower extremity compensation is recruited. Knee flexion, ankle flexion, and sacrofemoral angle increase to drive pelvic shift posterior and increase pelvic tilt. We aim to describe 2 summary angles termed ankle-pelvic angle (APA) and global lower extremity angle (GLA) that incorporate all aspects of lower extremity and pelvic compensation in a comprehensive measurement that can simplify radiographic analysis. Full-body sagittal stereotactic radiographs were retrospectively collected and digitally analyzed. Spinal and lower extremity alignment were quantified with existing measures. Two angles-APA and GLA-were drawn as geometrically complementary angles to T1-pelvic angle (TPA) and global sagittal axis (GSA), respectively. Regression analysis was used to represent the predictive relationship between TPA and APA and between GSA and GLA. A total of 518 propensity score-matched patient records were available for analysis. Patients with lower extremity compensation had higher APA (21.83° versus 19.47°, P = .007) and GLA (6.03° versus 1.19°, P < .001) than those without compensation. APA and GLA demonstrated strong correlation with TPA (r = 0.81) and GSA (r = 0.77), respectively. Furthermore, the change between preoperative and postoperative values were strongly correlative between ΔAPA and ΔTPA (r = 0.71) and between ΔGLA and ΔGSA (r = 0.77). APA above 20.6° and GLA above 3.6° were indicative of lower extremity compensation. Patients with increased GLA values had significantly higher Oswestry Disability Index scores (48.67 versus 41.04, P = .005). TPA and GSA are measures of global spinal alignment and APA and GLA, respectively, and are geometrically complementary angles that vary proportionately to SSD and balance the body. APA and GLA increase in SSD patients with lower extremity compensation and decrease with corrective surgery. 4. APA and GLA offer a concise and simple method of communicating pelvic and lower extremity compensation.

Predictors of Falls in Patients with Degenerative Cervical Myelopathy: A Prospective Multi-institutional Study.

Prospective multicenter study. The purpose of this study was to characterize a population of patients with degenerative cervical myelopathy (DCM) combined with a history of falling, and to identify the predictors associated with those falls. Falls among patients with DCM are common and can lead to the worsening of neurological symptoms. However, there are no prospective studies that have investigated the risk factors for falls in these patients. We prospectively enrolled patients scheduled for surgery for DCM and evaluated the significance of various preoperative measures for predicting falls. We then examined the correlation between the number of falls and the preoperative factors. Lastly, we performed stepwise logistic regression analysis to assess the concurrent effects of various factors on the occurrence of falls. Among the 135 patients analyzed, 64 experienced one or more falls from the time of enrollment to 1 year postoperatively. Univariate analysis showed that the preoperative potassium and albumin levels, handgrip strength, and the Japanese Orthopaedic Association score for the assessment of cervical myelopathy (C-JOA score) were lower and Nurick grade was higher in the fallers group. Serum potassium level, handgrip strength, C-JOA score, Nurick grade, European Quality of Life-5 Dimensions (EQ-5D) score, t1 pelvic angle, and sagittal vertical axis had weak correlations with the number of falls. The fallers group had a lower C-JOA and EQ-5D scores and a lower recovery rate at one year postoperatively. Stepwise multiple logistic regression analysis identified preoperative potassium level and handgrip strength as the independent preoperative predictors for falling. We identified preoperative lower serum potassium level and weaker handgrip strength as significant predictors of falls in patients with DCM. Therefore, DCM patients with these risk factors should be cautious about falls and might be candidates for immediate surgical intervention.Level of Evidence: 3.