Cervical sagittal deformity develops after PJK in adult thoracolumbar deformity correction: radiographic analysis utilizing a novel global sagittal angular parameter, the CTPA

Associations between NCLBP, spinal sagittal alignment and age groups: a cross-sectional cohort study

PURPOSE

Nonspecific chronic low back pain (NCLBP) is one of the most common manifestations of degenerative spondylitis. It affects many patients of all ages and seriously interferes with quality of life. However, the associations between NCLBP, sagittal alignment and age remain unclear. We aimed to investigate the typical features of sagittal alignment in individuals with NCLBP and to discuss the relationships between age and these NCLBP-related changes in sagittal alignment.

METHODS

We measured the sagittal parameters of patients with NCLBP and investigated their sagittal alignment and compensatory mechanisms by comparing them with those of asymptomatic individuals.

RESULTS

A total of 905 elderly patients (≥ 50 years old) and 1296 young patients (< 50 years old) were included. An analysis of sagittal parameters revealed that elderly patients with NCLBP had a smaller lumbar lordosis (LL, p = 0.001) and a greater T1 pelvic angle (TPA, p < 0.001). Age was significantly correlated with the TPA (rs = 0.549, p < 0.001) and pelvic tilt (PT, rs = 0.471, p < 0.001). The AUC value of the TPA was 0.782 (95% CI 0.764 to 0.799).

CONCLUSIONS

Although decreased lumbar lordosis is the most typical sagittal feature in patients with NCLBP, there are still differences in sagittal alignment between different ages. Compared with young patients, elderly patients with NCLBP more commonly present with a decompensated pattern of the anterior inclination of the trunk as the main sagittal alignment abnormality. TPA is more predictive than LL for the diagnosis of geriatric NCLBP.

The effect of cervical spine flexion-extension motion on odontoid parameters

OBJECTIVE

To assess the stability of odontoid parameters on flexion-extension motion and to validate the accuracy of the physiological cervical lordosis (CL) predictive formula across different cervical positions.

METHODS

Standard cervical spine lateral radiographs in neutral, flexion, and extension positions were collected to measure odontoid incidence (OI), odontoid tilt (OT), C2 slope (C2S), CL, T1 slope (T1S), and T1S minus CL (T1S-CL). Friedman's test was used to assess the differences in parameters among the three cervical spine positions. The predictive performance of the formula CL = 0.36× OI - 0.67 × OT - 0.69 × T1S was assessed and validated using the Pearson correlation coefficient (r), coefficient of determination (R²), mean squared error (MSE), and mean absolute error (MAE).

RESULTS

No significant differences were found for OI and T1S among the three different cervical spine positions (p = 0.162 and p = 0.186, respectively). There was a strong, significant positive correlation between the predicted value and actual value of physiological CL at three cervical positions (neutral, flexion, and extension). The predictions for the neutral position were the most accurate, with statistical measures of r = 0.85 (p < 0.01), R²=0.82, MAE = 4.28, and MSE = 27.77.

CONCLUSION

OI is a stable and reliable anatomic parameter, not affected by cervical spine flexion-extension motion. OI can serve as a supplementary parameter for evaluating cervical sagittal balance and compensatory ability. The formula CL = 0.36×OI - 0.67×OT - 0.69×T1S provides the best predictions for physiological CL in the neutral position.

Compensation from mild and severe cases of early proximal junctional kyphosis may manifest as progressive cervical deformity at two year follow-up

BACKGROUND

Postoperative reciprocal changes (RC) in the cervical spine associated with varying factors of proximal junctional kyphosis (PJK) following fusions of the thoracopelvic spine are poorly understood.

PURPOSE

Explore reciprocal changes in the cervical spine associated with varying factors (severity, progression, patient age) of PJK in patients undergoing adult spinal deformity (ASD) correction.

PATIENTS AND METHODS

Retrospective review of a multicenter ASD database.

INCLUSION

ASD patients > 18 y/o, undergoing fusions from the thoracic spine (UIV: T6-T12) to the pelvis with two-year radiographic data. ASD was defined as: Coronal Cobb angle ≥ 20°, Sagittal Vertical Axis ≥ 5 cm, Pelvic Tilt ≥ 25°, and/or Thoracic Kyphosis ≥ 60°. PJK was defined as a ≥ 10° measure of the sagittal Cobb angle between the inferior endplate of the UIV and the superior endplate of the UIV + 2. Patients were grouped by mild (M; 10°-20°) and severe (S; > 20°) PJK at one year. Propensity Score Matching (PSM) controlled for CCI, age, PI and UIV. Unpaired and paired t test analyses determined difference between RC parameters and change between time points. Pearson bi-variate correlations analyzed associations between RC parameters (T4-T12, TS-CL, cSVA, C2-Slope, and T1-Slope) and PJK descriptors.

RESULTS

284 ASD patients (UIV: T6: 1.1%; T7: 0.7%; T8: 4.6%; T9: 9.9%; T10: 58.8%; T11: 19.4%; T12: 5.6%) were studied. PJK analysis consisted of 182 patients (Mild = 91 and Severe = 91). Significant difference between M and S groups were observed in T4-T12 Δ1Y(- 16.8 v - 22.8, P = 0.001), TS-CLΔ1Y(- 0.6 v 2.8, P = 0.037), cSVAΔ1Y(- 1.8 v 1.9, P = 0.032), and C2 slopeΔ1Y(- 1.6 v 2.3, P = 0.022). By two years post-op, all changes in cervical alignment parameters were similar between mild and severe groups. Correlation between age and cSVAΔ1Y(R = 0.153, P = 0.034) was found. Incidence of severe PJK was found to correlate with TS-CLΔ1Y(R = 0.142, P = 0.049), cSVAΔ1Y(R = 0.171, P = 0.018), C2SΔ1Y(R = 0.148, P = 0.040), and T1SΔ2Y(R = 0.256, P = 0.003).

CONCLUSIONS

Compensation within the cervical spine differed between individuals with mild and severe PJK at one year postoperatively. However, similar levels of pathologic change in cervical alignment parameters were seen by two years, highlighting the progression of cervical compensation due to mild PJK over time. These findings provide greater evidence for the development of cervical deformity in individuals presenting with proximal junctional kyphosis.

Adult cervical spine deformity: a state-of-the-art review

Adult cervical deformity is a structural malalignment of the cervical spine that may present with variety of significant symptomatology for patients. There are clear and substantial negative impacts of cervical spine deformity, including the increased burden of pain, limited mobility and functionality, and interference with patients' ability to work and perform everyday tasks. Primary cervical deformities develop as the result of a multitude of different etiologies, changing the normal mechanics and structure of the cervical region. In particular, degeneration of the cervical spine, inflammatory arthritides and neuromuscular changes are significant players in the development of disease. Additionally, cervical deformities, sometimes iatrogenically, may present secondary to malalignment or correction of the thoracic, lumbar or sacropelvic spine. Previously, classification systems were developed to help quantify disease burden and influence management of thoracic and lumbar spine deformities. Following up on these works and based on the relationship between the cervical and distal spine, Ames-ISSG developed a framework for a standardized tool for characterizing and quantifying cervical spine deformities. When surgical intervention is required to correct a cervical deformity, there are advantages and disadvantages to both anterior and posterior approaches. A stepwise approach may minimize the drawbacks of either an anterior or posterior approach alone, and patients should have a surgical plan tailored specifically to their cervical deformity based upon symptomatic and radiographic indications. This state-of-the-art review is based upon a comprehensive overview of literature seeking to highlight the normal cervical spine, etiologies of cervical deformity, current classification systems, and key surgical techniques.

The Posterior Cranial Vertical Line: A Novel Radiographic Marker for Classifying Global Sagittal Alignment

OBJECTIVE

To define a novel radiographic measurement, the posterior cranial vertical line (PCVL), in an asymptomatic adult population to better understand global sagittal alignment.

METHODS

We performed a multicenter retrospective review of prospectively collected radiographic data on asymptomatic volunteers aged 20-79. The PCVL is a vertical plumb line drawn from the posterior-most aspect of the occiput. The horizontal distances of the PCVL to the thoracic apex (TA), posterior sagittal vertical line (PSVL, posterosuperior endplate of S1), femoral head center, and tibial plafond were measured. Classification was either grade 1 (PCVL posterior to TA and PSVL), grade 2 (PCVL anterior to TA and posterior to PSVL), or grade 3 (PCVL anterior to TA and PSVL).

RESULTS

Three hundred thirty-four asymptomatic patients were evaluated with a mean age of 41 years. Eighty-three percent of subjects were PCVL grade 1, 15% were grade 2, and 3% were grade 3. Increasing PCVL grade was associated with increased age (p < 0.001), C7-S1 sagittal vertical axis (SVA) (p < 0.001), C2-7 SVA (p < 0.001). Additionally, it was associated with decreased SS (p = 0.045), increased PT (p < 0.001), and increased knee flexion (p < 0.001).

CONCLUSION

The PCVL is a radiographic marker of global sagittal alignment that is simple to implement and interpret. Increasing PCVL grade was significantly associated with expected changes and compensatory mechanisms in the aging population. Most importantly, it incorporates cervical alignment parameters such as C2-7 SVA. The PCVL defines global sagittal alignment in adult volunteers and naturally distributes into 3 grades, with only 3% being grade 3 where the PCVL lies anterior to the TA and PSVL.

Long-Term Follow-up of Posterior Selective Thoracolumbar/Lumbar Fusion in Patients With Lenke 5C Adolescent Idiopathic Scoliosis: An Analysis of 10-Year Outcomes

STUDY DESIGN

Retrospective study.

OBJECTIVE

The aim of this study was to assess long-term radiographic and clinical outcomes in Lenke 5C adolescent idiopathic scoliosis (AIS) patients after posterior selective fusion.

METHODS

Lenke 5C AIS patients who underwent posterior selective thoracolumbar/lumbar (TL/L) fusion in our hospital from January 2007 to January 2010 were recruited. Radiographic parameters were measured preoperatively and at the 3-month, 1-year, 2-year, 5-year, and 10-year follow-ups. The SRS-22 (Scoliosis Research Society) questionnaire was used to assess the clinical outcomes.

RESULTS

We included 37 patients who underwent posterior selective TL/L fusion surgery in our study, and the mean follow-up time was 11.26 ± 0.85 years. The average preoperative Cobb angles of the thoracic and TL/L curves were 24.0 ± 9.0° and 45.4 ± 6.3°, respectively, which were corrected to 12.2° and 12.4° at the 3-month follow-up postoperatively, with correction losses of 2.2° and 1.5° at the 10-year follow-up. In the sagittal plane, the degree of thoracic kyphosis (TK) gradually increased over the follow-up period. The proximal junctional angle (PJA) also gradually increased from 6.7 ± 4.6 to 13.7 ± 5.6 during the follow-up period. For the clinical outcomes, correction surgery improved the SRS-22 scores in each domain, especially in the self-image domain.

CONCLUSIONS

Posterior selective TL/L fusion can effectively correct spinal deformities, leading to stable outcomes for 10 years postoperatively. During the follow-up period, the degree of TK presented an increasing trend that remained almost constant after the 1-year follow-up. Moreover, the variation in the PJA was highly significant in the postoperative period, and it showed an increasing trend until the 2-year follow-up.

Correlation between the cervical sagittal alignment and spine - pelvic sagittal alignment in asymptomatic adults

Background

Although there are studies that adequately document the linear correlation between pelvic incidence (PI), sacral slope, lumbar lordosis, and thoracic kyphosis, few have analyzed the pelvic-spine correlation including the cervical spine.

Methods:

This is a cross-sectional study, wherein the cervical spine was evaluated using radiography and computed tomography (CT) scans, the lumbosacral spine and the pelvis was evaluated using radiography, in adult patients without spinal pathology. Using the Surgimap tool, cervical and spinopelvic parameters were calculated by several investigators. To evaluate the correlation between cervical and spinopelvic parameters, Spearman's coefficient was calculated. To evaluate the concordance correlation of the measured parameters of cervical sagittal alignment on tomography and conventional radiography, Lin's coefficient was calculated and Bland–Altman plots were performed.

Results:

A total of 51 healthy adults were included in a follow-up from January 2019 to December 2020. Cervical sagittal alignment and sagittal spinopelvic alignment were assessed using radiography, and a correlation was observed between T1 slope (T1S) and lumbar mismatch (coefficient of 0.28, P = 0.047). Then, cervical sagittal alignment was evaluated using CT and sagittal spinopelvic alignment using radiography, and no correlation was observed between PI and thoracic inlet angle or cervical mismatch with lumbar mismatch.

Conclusion:

In asymptomatic patients, in whom cervical sagittal alignment and spinal-pelvic alignment were evaluated, only a positive correlation was found between lumbar mismatch and T1S, which lacks clinical significance. No concordance was identified between lumbar mismatch and cervical mismatch. Therefore, it is inferred that there is an independence between the sagittal spine-pelvic alignment with respect to the sagittal cervical alignment.

The impact of the lower instrumented level on outcomes in cervical deformity surgery

Background:

The lower instrumented vertebrae (LIVs) in cervical deformity (CD) constructs may have varying effects on patient outcomes that are still poorly understood.

Objective:

The objective of the study is to compare outcomes in CD patients undergoing instrumented correction according to the relation of LIV with primary driver (PD).

Methods:

Patients who met radiographic criteria for CD were included in the study. Patients were stratified by PD of deformity: cervical (C) through AMES classification (TS-CL >20 or cervical sagittal vertical axis >40) and thoracic (T) through hyper/hypokyphosis (TK) from T4-T12 (60 < TK < 40). Patients were further stratified by LIV in relation to curve apex (above/below). Univariate and multivariate analyses identified group differences in postoperative health-related quality-of-life and distal junctional kyphosis (DJK) (>10° LIV and LIV + 2) rate up to 1 year.

Results:

Sixty-two patients were analyzed. Twenty-one patients had a C-PD and 41 had a T-PD by definition. 100% of C-PDs had LIVs below CL apex, while 9.2% of T-PDs had LIVs below (caudal) to TK apex and 90.8% had LIVs above TK apex. By 1 year, C patients trended lower Neck Disability Index (NDI) (21.9 vs. 29.0, P = 0.245), lower numeric rating scales neck pain (4.2 vs. 5.1, P = 0.358), and significantly higher EuroQol five-dimensional questionnaire Visual Analog Scale (69.2 vs. 52.4, P = 0.040). When T patients with LIVs below TK apex were excluded, remaining T patients with LIV above apex had significantly higher 1-year NDI than C patients (37.5 vs. 21.9, P = .05). T patients also trended higher rates of postoperative DJK than C (19.5% vs. 4.8%, P = 0.119).

Conclusions:

Stopping before apex was more common in patients with a primary thoracic driver (T) and associated with deleterious effects. Primary cervical driver (C) tended to have LIVs inclusive of CL apex with lower rates of DJK.

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

OBJECTIVE

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.

METHODS

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).

RESULTS

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).

CONCLUSIONS

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.

Timing of conversion to cervical malalignment and proximal junctional kyphosis following surgical correction of adult spinal deformity: a 3-year radiographic analysis

OBJECTIVE

The goal of this study was to assess the conversion rate from baseline cervical alignment to postoperative cervical deformity (CD) and the corresponding proximal junctional kyphosis (PJK) rate in patients undergoing thoracolumbar adult spinal deformity (ASD) surgery.

METHODS

The operative records of patients with ASD with complete radiographic data beginning at baseline up to 3 years were included. Patients with no baseline CD were postoperatively stratified by Ames CD criteria (T1 slope-cervical lordosis mismatch [TS-CL] > 20°, cervical sagittal vertical axis [cSVA] > 40 mm), where CD was defined as fulfilling one or more of the Ames criteria. Severe CD was defined as TS-CL > 30° or cSVA > 60 mm. Follow-up intervals were established after ASD surgery, with 6 weeks postoperatively defined as early; 6 weeks-1 year as intermediate; 1-2 years as late; and 2-3 years as long-term. Descriptive analyses and McNemar tests identified the CD conversion rate, PJK rate (< -10° change in uppermost instrumented vertebra and the superior endplate of the vertebra 2 levels superior to the uppermost instrumented vertebra), and specific alignment parameters that converted.

RESULTS

Two hundred sixty-six patients who underwent ASD surgery (mean age 59.7 years, 77.4% female) met the inclusion criteria; 103 of these converted postoperatively, and the remaining 163 did not meet conversion criteria. Thirty-eight patients converted to CD early, 26 converted at the intermediate time point, 29 converted late, and 10 converted in the long-term. At conversion, the early group had the highest mean TS-CL at 25.4° ± 8.5° and the highest mean cSVA at 33.6 mm-both higher than any other conversion group. The long-term group had the highest mean C2-7 angle at 19.7° and the highest rate of PJK compared to other groups (p = 0.180). The early group had the highest rate of conversion to severe CD, with 9 of 38 patients having severe TS-CL and only 1 patient per group converting to severe cSVA. Seven patients progressed from having only malaligned TS-CL at baseline (with normal cSVA) to CD with both malaligned TS-CL and cSVA by 6 weeks. Conversely, only 2 patients progressed from malaligned cSVA to both malaligned cSVA and TS-CL. By 1 year, the former number increased from 7 to 26 patients, and the latter increased from 2 to 20 patients. The revision rate was highest in the intermediate group at 48.0%, versus the early group at 19.2%, late group at 27.3%, and long-term group at 20% (p = 0.128). A higher pelvic incidence-lumbar lordosis mismatch, lower thoracic kyphosis, and a higher thoracic kyphosis apex immediately postoperatively significantly predicted earlier rather than later conversion (all p < 0.05). Baseline lumbar lordosis, pelvic tilt, and sacral slope were not significant predictors.

CONCLUSIONS

Patients with ASD with normative cervical alignment who converted to CD after thoracolumbar surgery had varying radiographic findings based on timing of conversion. Although the highest number of patients converted within 6 weeks postoperatively, patients who converted in the late or long-term follow-up intervals had higher rates of concurrent PJK and greater radiographic progression.

Sagittal balance of the cervical spine: a systematic review and meta-analysis

PURPOSE

The purpose of this systematic review and meta-analysis was to compare the cervical sagittal parameters between patients with cervical spine disorder and asymptomatic controls.

METHODS

Two independent authors systematically searched online databases including Pubmed, Scopus, Cochrane library, and Web of Science up to June 2020. Cervical sagittal balance parameters, such as T1 slope, cervical SVA (cSVA), and spine cranial angle (SCA), were compared between the cervical spine in healthy, symptomatic, and pre-operative participants. Where possible, we pooled data using random-effects meta-analysis, by CMA software. Heterogeneity and publication bias were assessed using the I-squared statistic and funnel plots, respectively.

RESULTS

A total of 102 studies, comprising 13,802 cases (52.7% female), were included in this meta-analysis. We used the Newcastle-Ottawa Scale (NOS) to evaluate the quality of studies included in this review. Funnel plot and Begg's test did not indicate obvious publication bias. The pooled analysis reveals that the mean (SD) values were: T1 slope (degree), 24.5 (0.98), 25.7 (0.99), 25.4 (0.34); cSVA (mm), 18.7 (1.76), 22.7 (0.66), 22.4 (0.68) for healthy population, symptomatic, and pre-operative assessment, respectively. The mean value of the SCA (degree) was 79.5 (3.55) and 75.6 (10.3) for healthy and symptomatic groups, respectively. Statistical differences were observed between the groups (all P values < 0.001).

CONCLUSION

The findings showed that the T1 slope and the cSVA were significantly lower among patients with cervical spine disorder compared to controls and higher for the SCA. Further well-conducted studies are needed to complement our findings.

Cervical Sagittal Alignment: Literature Review and Future Directions

Cervical alignment as a concept has come to the forefront for spine deformity research in the last decade. Studies on cervical sagittal alignment started from normative data, and expanded into correlation with global sagittal balance, prognosis of various conditions, outcomes of surgery, definition and classification of cervical deformity, and prediction of targets for ideal cervical reconstruction. Despite the recent robust research efforts, the definition of normal cervical sagittal alignment and cervical spine deformity continues to elude us. Further, many studies continue to view cervical alignment as a continuation of thoracolumbar deformity and do not take into account biomechanical features unique to the cervical spine that may influence cervical alignment, such as the importance of musculature connecting cranium-cervical-thoracic spine and upper extremities. In this article, we aim to summarize the relevant literature on cervical sagittal alignment, discuss key results, and list potential future direction for research using the '5W1H' framework; "WHO" are related?, "WHY" important?, "WHAT" to evaluate and "WHAT" is normal?, "HOW" to evaluate?, "WHEN" to apply sagittal balance?, and "WHERE" to go in the future?

Poor spinal alignment in females with obesity: The Yakumo study

Objective

The goal of this prospective study was prospectively to investigate the relationship between obesity and spinal sagittal alignment.

Methods

286 were referred for orthopedic evaluation. Differences in spinal parameters among these groups and between males and females were evaluated.

Results

Obese subjects had significantly higher C2S, CPA, CTPA, PI-LL, and lower cervical lordosis, L4S1, lumbar lordosis, and sacral slope. In multivariate logistic regression analysis adjusted for age in females, CTPA was identified as the only independent and significant factor associated with obesity.

Conclusions

Obesity in females has significant relationships with spinal sagittal alignment and results in poorer physical QOL.

Changes in Cervical Spinal Alignment After Thoracolumbar Corrective Surgery in Adult Patients With Adolescent Idiopathic Scoliosis

STUDY DESIGN

Case-control study.

OBJECTIVE

To examine factors influencing cervical alignment after corrective surgery for adult patients with adolescent idiopathic scoliosis (AdIS) SUMMARY OF BACKGROUND DATA.: Corrective surgery for spinal deformity influences postoperative cervical spinal alignment, but changes in the cervical alignment in adults with AdIS are scarcely reported.

METHODS

We retrospectively examined 85 patients with AdIS who underwent posterior corrective surgery for thoracic or lumbar major curve and were followed up for 2 years. Clinical characteristics, radiographic parameters, and health-related quality of life (HRQOL) were evaluated. Cervical deformity (CD) was defined as one of the following cases: (1) T1 tilt minus C2-C7 angle more than 20°, (2) C2-C7 SVA more than 40 mm, (3) and C2-C7 angle less than -10°. Patients were divided into those with and without CD based on the defined criteria; statistically relevant factors were analyzed.

RESULTS

There were 19 patients in the postoperative CD group. The average age at the time of surgery was lower in the CD group (26.5 vs. 31.4). In the CD group, the average preoperative T1 tilt was smaller (1.1° vs. 12.5°), and the C2-C7 angle was kyphotic (-16.1° vs. 3.0°). The average kyphotic angle at thoracic spine (T5-T12) was lower in the CD group preoperatively (12.5° vs. 19.5°) and postoperatively (15.2° vs. 20.8°). HRQOL outcomes were comparable between the groups. Of the patients with preoperative CD, 51.5% (n = 17) maintained their deformity at the final follow-up, and baseline C2-C7 angle was lower than those who converted to non-CD following surgery (n = 16) (-17.0° vs. -10.3°).

CONCLUSION

More than half of the patients with baseline CD maintained their cervical malalignment postoperatively. Patients with postoperative CD presented cervical kyphotic and thoracic hypokyphotic alignments before surgery. Because CD has the potential to lead to cervical degeneration, careful follow-up observation is necessary for these young patients.

LEVEL OF EVIDENCE

3.

Incidence and risk factors of proximal junctional kyphosis after internal fixation for adult spinal deformity: a systematic evaluation and meta-analysis

To investigate the factors associated with proximal junctional kyphosis (PJK). A systematic search was performed. The weighted mean difference (WMD) was pooled for continuous variables, and the odds ratio (OR) was calculated for dichotomous variables. The PJK group had higher values for age (WMD = 2.53, 95%CI = 1.38 ~ 3.68, P < 0.001), female gender (OR = 1.56, 95%CI = 1.29 ~ 1.87, P < 0.001), and diagnosed osteoporosis (OR = 1.58, 95%CI = 1.11 ~ 2.26, P = 0.01). Preoperatively, significant differences were detected in sagittal vertical axis (SVA) (WMD = 19.29, 95%CI = 16.60 ~ 21.98, P < 0.001), pelvic incidence minus lumbar lordosis (PI-LL) (WMD = 2.71, 95%CI = 0.25 ~ 5.18, P = 0.03), pelvic tilt (PT) (WMD = 2.64, 95%CI = 1.38 ~ 3.90, P < 0.001), lumbar lordosis (LL) (WMD = - 1.76, 95%CI = - 2.73 ~ -0.79, P < 0.001), and sacral slope (SS) (WMD = - 2.80, 95%CI = - 5.57 ~ -0.04, P = 0.001). At follow-up, the following were higher in the PJK group: thoracic kyphosis (TK) (WMD = 5.51, 95%CI = 2.23 ~ 8.80, P < 0.001), proximal junctional angle (PJA) (WMD = 9.07, 95%CI = 4.21 ~ 13.92, P < 0.001), and PT (WMD = 1.51, 95%CI = 0.31 ~ 2.72, P = 0.01). However, there was no significant difference in SS (P = 0.49), and SVA (P = 0.11) between groups. Fusion to S1 or pelvis significantly increased the risk of PJK (OR = 2.08, P < 0.001). Ligament augmentation reduced the risk of PJK (OR = 0.34, 95%CI = 0.21 ~ 0.53, P < 0.001) better than the use of laminar hook (OR = 0.46, P < 0.001). Although no difference was detected for preoperative SRS-22 score (P = 0.056), a lower score (WMD = - 0.24, 95%CI = - 0.35 ~ -0.14, P < 0.001) was detected in PJK group at follow-up. The elderly female ASD patients were more susceptible to PJK, especially for those with osteoporosis, high preoperative SVA, low LL, large PT, and LIV extended to pelvis. The use of laminar hook and ligament reinforcement at the proximal end might prevent PJK.

A review of cervical spine alignment in the normal and degenerative spine

With recent advancements in surgical spine technology and techniques, the importance of regional and global spine alignment has become an important factor in surgical planning. Our review aims to consolidate the current literature on cervical and global alignment parameters and its relationship to cervical symptomatology, quality of life (QOL), requirements for surgery, potential surgical complications and health-related quality of life (HRQOL) outcomes.

The morphology of cervical deformities: a two-step cluster analysis to identify cervical deformity patterns

OBJECTIVE

Cervical deformity (CD) is difficult to define due to the high variability in normal cervical alignment based on postural- and thoracolumbar-driven changes to cervical alignment. The purpose of this study was to identify whether patterns of sagittal deformity could be established based on neutral and dynamic alignment, as shown on radiographs.

METHODS

This study is a retrospective review of a prospective, multicenter database of CD patients who underwent surgery from 2013 to 2015. Their radiographs were reviewed by 12 individuals using a consensus-based method to identify severe sagittal CD. Radiographic parameters correlating with health-related quality of life were introduced in a two-step cluster analysis (a combination of hierarchical cluster and k-means cluster) to identify patterns of sagittal deformity. A comparison of lateral and lateral extension radiographs between clusters was performed using an ANOVA in a post hoc analysis.

RESULTS

Overall, 75 patients were identified as having severe CD due to sagittal malalignment, and they formed the basis of this study. Their mean age was 64 years, their body mass index was 29 kg/m2, and 66% were female. There were significant correlations between focal alignment/flexibility of maximum kyphosis, cervical lordosis, and thoracic slope minus cervical lordosis (TS-CL) flexibility (r = 0.27, 0.31, and -0.36, respectively). Cluster analysis revealed 3 distinct groups based on alignment and flexibility. Group 1 (a pattern involving a flat neck with lack of compensation) had a large TS-CL mismatch despite flexibility in cervical lordosis; group 2 (a pattern involving focal deformity) had focal kyphosis between 2 adjacent levels but no large regional cervical kyphosis under the setting of a low T1 slope (T1S); and group 3 (a pattern involving a cervicothoracic deformity) had a very large T1S with a compensatory hyperlordosis of the cervical spine.

CONCLUSIONS

Three distinct patterns of CD were identified in this cohort: flat neck, focal deformity, and cervicothoracic deformity. One key element to understanding the difference between these groups was the alignment seen on extension radiographs. This information is a first step in developing a classification system that can guide the surgical treatment for CD and the choice of fusion level.

The Importance of C2 Slope, a Singular Marker of Cervical Deformity, Correlates With Patient-reported Outcomes

STUDY DESIGN

Retrospective review of a prospectively collected database.

OBJECTIVE

To define a simplified singular measure of cervical deformity (CD), C2 slope (C2S), which correlates with postoperative outcomes.

SUMMARY OF BACKGROUND DATA

Sagittal malalignment of the cervical spine, defined by the cervical sagittal vertical axis (cSVA) has been associated with poor outcomes following surgical correction of the deformity. There has been a proliferation of parameters to describe CD. This added complexity can lead to confusion in classifying, treating, and assessing outcomes of CD surgery.

METHODS

A prospective database of CD patients was analyzed. Inclusion criteria were cervical kyphosis>10°, cervical scoliosis>10°, cSVA>4 cm, or chin-brow vertical angle >25°. Patients were categorized into two groups and compared based on whether the apex of the deformity was in the cervical (C) or the cervicothoracic (CT) region. Radiographic parameters were correlated to C2S, T1 slope (T1S) and 1-year health-related quality-of-life outcomes as measured by the EuroQol 5 Dimension questionnaire (EQ5D), modified Japanese Orthopedic Association Scale, numeric rating scale for neck pain, and the Neck Disability Index (NDI).

RESULTS

One hundred four CD patients (C = 74, CT = 30; mean age 61 yr, 56% women, 42% revisions) were included. CT patients had higher baseline cSVA and T1S (P < 0.05). C2S correlated with T1 slope minus cervical lordosis (TS-CL) (r = 0.98, P < 0.001) and C0-C2 angle, cSVA, CL, T1S (r = 0.37-0.65, P < 0.001). Correlation of cSVA with C0-C2 was weaker (r = 0.48, P < 0.001). At 1-year postoperatively, higher C2S correlated with worse EQ-5D (r = 0.28, P = 0.02); in CT patients, higher C2S correlated with worse NDI, modified Japanese Orthopedic Association Scale, numeric rating scale for neck pain, and EQ5D (all r > 0.5, P≤0.05). Using linear regression, moderate disability by EQ5D corresponded to C2S of 20°(r = 0.08). For CT patients, C2S = 17° corresponded to moderate disability by NDI (r = 0.4), and C2S = 20° by EQ5D (r = 0.25).

CONCLUSION

C2S correlated with upper-cervical and subaxial alignment. C2S correlated strongly with TS-CL (R = 0.98, P < 0.001) because C2S is a mathematical approximation of TS-CL. C2S is a useful marker of CD, linking the occipitocervical and cervico-thoracic spine. C2S defines the presence of a mismatch between cervical lordosis and thoracolumbar alignment. Worse 1-year postoperative C2 slope correlated with worse health outcomes.

LEVEL OF EVIDENCE

3.

Cervical, Thoracic, and Spinopelvic Compensation After Proximal Junctional Kyphosis (PJK): Does Location of PJK Matter?

STUDY DESIGN

Retrospective case series.

OBJECTIVE

Compensatory changes above a proximal junctional kyphosis (PJK) have not been defined. Understanding these mechanisms may help determine optimal level selection when performing revision for PJK. This study investigates how varying PJK location changes proximal spinal alignment.

METHODS

Patients were grouped by upper instrumented vertebrae (UIV): lower thoracic (LT; T8-L1) or upper thoracic (UT; T1-7). Alignment parameters were compared. Correlation analysis was performed between PJK magnitude and global/cervical alignment.

RESULTS

A total of 369 patients were included; mean age of 63 years, body mass index 28, and 81% female, LT (n = 193) versus UT (n = 176). The rate of radiographic PJK was 49%, higher in the LT group (55% vs 42%, P = .01). The UT group displayed significant differences in all cervical radiographic parameters (P < .05) between PJK versus non-PJK patients, while the LT group displayed significant differences in T1S and C2-T3 sagittal vertical axis (SVA) (CTS). In comparing UT versus LT patients, UT had more posterior global alignment (smaller TPA [T1 pelvic angle], SVA, and larger PT [pelvic tilt]) and larger anterior cervical alignment (greater cSVA [cervical SVA], T1S-CL [T1 slope-cervical lordosis] mismatch, CTS) compared to LT. Correlation analysis of PJK magnitude and location demonstrated a correlation with increases in CL, T1S, and CTS in the UT group. In the LT group, PT increased with PJK angle (r = 0.17) and no significant correlations were noted to SVA, cSVA, or T1S-CL.

CONCLUSIONS

PJK location influences compensation mechanisms of the cervical and thoracic spine. LT PJK results in increased PT and CL with decreased CTS. UT PJK increases CL to counter increases in T1S with continued T1S-CL mismatch and elevated cSVA.

Predictive formula of cervical lordosis in asymptomatic young population

BACKGROUND

Not a large number of previous studies have reported the normal sagittal balance of the cervical spine and physiological cervical lordosis (CL) has not been clearly defined yet.

METHODS

This was a prospective radiological analysis of asymptomatic subjects. The following cervical sagittal parameters were measured: CL, thoracic inlet angle (TIA), T1 slope (T1S), neck tilt (NT), and C2-7 sagittal vertical axis (C2-7 SVA). The Pearson correlation test was calculated, and the stepwise multiple regression analysis was conducted by using the CL (dependent variable) and the other cervical sagittal parameters (independent variables) to determine the best sets of predictors. A paired sample t test was conducted between the predicted and measured values.

RESULTS

The mean age of 307 participants was 24.54 + 3.07. The mean CL, TIA, T1S, NT, and C2-C7 SVA was 17.11° ± 6.31°, 67.87° ± 7.78°, 25.84° ± 5.36°, 42.53° ± 6.68°, and 14.60 ± 8.20 mm, respectively. The formula was established as follows: CL = 0.762 × T1S - 0.392 × C2-C7 SVA + 0.25 × TIA - 13.795 (R = 0.812, R2 = 0.660) (stepwise multiple regression) and CL = 0.417 × TIA - 11.193 (R = 0.514, R2 = 0.264) (simple linear regression). There was no statistical difference between the predicted CL and the measured CL (t = 0.034, P = 0.973).

CONCLUSIONS

There was a significant correlation between CL and other cervical sagittal parameters, including TIA, T1S, NT, and C2-C7 SVA in asymptomatic Chinese population. The results of this study may serve as a normal reference value for the study of asymptomatic population.

How does the cervical spine respond to hyperkyphosis correction in Scheuermann's disease?

OBJECTIVE

This study aimed to quantify the response of the cervical spine to the surgical correction of Scheuermann's kyphosis (SK) and to postoperative proximal junctional kyphosis (PJK).

METHODS

Fifty-nine patients (mean age 14.6 ± 2.3 years) were enrolled in the study: 35 patients in a thoracic SK (T-SK) group and 24 in a thoracolumbar SK (TL-SK) group. The mean follow-up period was 47.2 ± 17.6 months. Radiographic data, PJK-related complications, and patient-reported outcomes were compared between groups.

RESULTS

The global kyphosis significantly decreased postoperatively, and similar correction rates were observed between the two groups (mean 47.1% ± 8.6% [T-SK] vs 45.8% ± 9.4% [TL-SK], p = 0.585). The cervical lordosis (CL) in the T-SK group notably decreased from 21.4° ± 13.3° to 13.1° ± 12.4° after surgery and was maintained at 14.9° ± 10.7° at the latest follow-up, whereas in the TL-SK group, CL considerably increased from 7.2° ± 10.7° to 11.7° ± 11.1° after surgery and to 13.8° ± 8.9° at the latest follow-up. PJK was identified in 16 patients (27.1%). Its incidence in the TL-SK group was notably higher than it was in the T-SK group (41.6% [n = 10] vs 17.1% [n = 6], p = 0.037). Compared with non-PJK patients, PJK patients had greater CL and lower pain scores on the Scoliosis Research Society-22 questionnaire (p < 0.05).

CONCLUSIONS

Hyperkyphosis correction eventually resulted in reciprocal changes in the cervical spine, with CL notably decreased in the T-SK group but significantly increased in the TL-SK group. Patients developing PJK have increased CL, which seems to have a negative effect on patients' health-related quality of life.

Cervical Alignment Changes in Patients Developing Proximal Junctional Kyphosis Following Surgical Correction of Adult Spinal Deformity

BACKGROUND

Proximal junctional kyphosis (PJK) following adult spinal deformity (ASD) surgery is a well-documented complication, but associations between radiographic PJK and cervical malalignment onset remain unexplored.

OBJECTIVE

To study cervical malalignment in ASD surgical patients that develop PJK.

METHODS

Retrospective review of prospective multicenter database. Inclusion: primary ASD patients (≥5 levels fused, upper instrumented vertebra [UIV] at T2 or above, and 1-yr minimum follow-up) without baseline cervical deformity (CD), defined as ≥2 of the following criteria: T1 slope minus cervical lordosis < 20°, cervical sagittal vertical axis < 4 cm, C2-C7 cervical lordosis < 10°. PJK presence (<10° change in UIV and UIV + 2 kyphosis) and angle were identified 1 yr postoperative. Propensity score matching between PJK and nonPJK groups controlled for baseline alignment. Preoperative and 1-yr postoperative cervical alignment were compared between PJK and nonPJK patients.

RESULTS

One hundred sixty-three patients without baseline CD (54.9 yr, 83.9% female) were included. PJK developed in 60 (36.8%) patients, with 27 (45%) having UIV above T7. PJK patients had significantly greater baseline T1 slope in unmatched and propensity score matching comparisons (P < .05). At 1 yr postoperative, PJK patients had significantly higher T1 slope (P < .001), C2-T3 Cobb (P = .04), and C2-T3 sagittal vertical axis (P = .02). New-onset CD rate in PJK patients was 15%, and 16.5% in nonPJK patients (P > .05). Increased PJK magnitude was associated with increasing T1 slope and C2-T3 SVA (P < .05).

CONCLUSION

Patients who develop PJK following surgical correction of ASD have a 15% incidence of development of new-onset CD. Patients developing PJK following surgical correction of ASD tend to have an increased preoperative T1 slope. Increased progression of C2-T3 Cobb angle and C2-T3 SVA are associated with development of PJK following surgical correction of thoracolumbar deformity.

Comparison of Best Versus Worst Clinical Outcomes for Adult Cervical Deformity Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Factors that predict outcomes for adult cervical spine deformity (ACSD) have not been well defined. To compare ACSD patients with best versus worst outcomes.

METHODS

This study was based on a prospective, multicenter observational ACSD cohort. Best versus worst outcomes were compared based on Neck Disability Index (NDI), Neck Pain Numeric Rating Scale (NP-NRS), and modified Japanese Orthopaedic Association (mJOA) scores.

RESULTS

Of 111 patients, 80 (72%) had minimum 1-year follow-up. For NDI, compared with best outcome patients (n = 28), worst outcome patients (n = 32) were more likely to have had a major complication (P = .004) and to have undergone a posterior-only procedure (P = .039), had greater Charlson Comorbidity Index (P = .009), and had worse postoperative C7-S1 sagittal vertical axis (SVA; P = .027). For NP-NRS, compared with best outcome patients (n = 26), worst outcome patients (n = 18) were younger (P = .045), had worse baseline NP-NRS (P = .034), and were more likely to have had a minor complication (P = .030). For the mJOA, compared with best outcome patients (n = 16), worst outcome patients (n = 18) were more likely to have had a major complication (P = .007) and to have a better baseline mJOA (P = .030). Multivariate models for NDI included posterior-only surgery (P = .006), major complication (P = .002), and postoperative C7-S1 SVA (P = .012); models for NP-NRS included baseline NP-NRS (P = .009), age (P = .017), and posterior-only surgery (P = .038); and models for mJOA included major complication (P = .008).

CONCLUSIONS

Factors distinguishing best and worst ACSD surgery outcomes included patient, surgical, and radiographic factors. These findings suggest areas that may warrant greater awareness to optimize patient counseling and outcomes.

Analysis of Successful Versus Failed Radiographic Outcomes After Cervical Deformity Surgery

STUDY DESIGN

Prospective multicenter cohort study with consecutive enrollment.

OBJECTIVE

To evaluate preoperative alignment and surgical factors associated with suboptimal early postoperative radiographic outcomes after surgery for cervical deformity.

SUMMARY OF BACKGROUND DATA

Recent studies have demonstrated correlation between cervical sagittal alignment and patient-reported outcomes. Few studies have explored cervical deformity correction prospectively, and the factors that result in successful versus failed cervical alignment corrections remain unclear.

METHODS

Patients with adult cervical deformity (ACD) included with either cervical kyphosis more than 10°, C2-C7 sagittal vertical axis (cSVA) of more than 4 cm, or chin-brow vertical angle of more than 25°. Patients were categorized into failed outcomes group if cSVA of more than 4 cm or T1 slope and cervical lordosis (TS-CL) of more than 20° at 6 months postoperatively.

RESULTS

A total of 71 patients with ACD (mean age 62 yr, 56% women, 41% revisions) were included. Fourty-five had primary cervical deformities and 26 at the cervico-thoracic junction. Thirty-three (46.4%) had failed radiographic outcomes by cSVA and 46 (64.7%) by TS-CL. Failure to restore cSVA was associated with worse preoperative C2 pelvic tilt angle (CPT: 64.4° vs. 47.8°, P = 0.01), worse postoperative C2 slope (35.0° vs. 23.8°, P = 0.004), TS-CL (35.2° vs. 24.9°, P = 0.01), CPT (47.9° vs. 28.2°, P < 0.001), "+" Schwab modifiers (P = 0.007), revision surgery (P = 0.05), and failure to address the secondary, thoracolumbar driver of the deformity (P = 0.02). Failure to correct TS-CL was associated with worse preoperative cervical kyphosis (10.4° vs. -2.1°, P = 0.03), CPT (52.6° vs. 39.1°, P = 0.04), worse postoperative C2 slope (30.2° vs. 13.3°, P < 0.001), cervical lordosis (-3.6° vs. -15.1°, P = 0.01), and CPT (37.7° vs. 24.0°, P < 0.001). Multivariate analysis revealed postoperative distal junctional kyphosis associated with suboptimal outcomes by cSVA (odds ratio 0.06, confidence interval 0.01-0.4, P = 0.004) and TS-CL (odds ratio 0.15, confidence interval 0.02-0.97, P = 0.05).

CONCLUSION

Factors associated with failure to correct the cSVA included revision surgery, worse preoperative CPT, and concurrent thoracolumbar deformity. Failure to correct the TS-CL mismatch was associated with worse preoperative cervical kyphosis and CPT. Occurrence of early postoperative distal junctional kyphosis significantly affects postoperative radiographic outcomes.

LEVEL OF EVIDENCE

3.

T1 Slope Minus Cervical Lordosis (TS-CL), the Cervical Answer to PI-LL, Defines Cervical Sagittal Deformity in Patients Undergoing Thoracolumbar Osteotomy

BACKGROUND

Cervical kyphosis and C2-C7 plumb line (CPL) are established descriptors of cervical sagittal deformity (CSD). Reciprocal changes in these parameters have been demonstrated in thoracolumbar deformity correction. The purpose of this study was to investigate the development of CSD, using T1 slope minus cervical lordosis (TS-CL) to define CSD and to correlate TS-CL and a novel global sagittal parameter, cervical-thoracic pelvic angle (CTPA), with CPL.

METHODS

A multicenter, retrospective analysis of patients with thoracolumbar deformity undergoing three-column osteotomy was performed. Preoperative and postoperative cervical parameters were investigated. Linear regression for postoperative values resulted in a CPL of 4 cm corresponding to a TS-CL threshold of 17°. Patients were classified based on postoperative TS-CL into uncompensated (TS-CL > 17°) or compensated cohorts (TS-CL < 17°); the two were compared using an unpaired t test. Logistic regression modeling was used to determine predictors of postoperative CSD.

RESULTS

A total of 223 patients with thoracolumbar deformity (mean age, 57.56 years) were identified. CTPA correlated with CPL (preoperative r = .85, postoperative r = .69). TS-CL correlated with CTPA (preoperative r = .52, postoperative r = .37) and CPL (preoperative r = .52; postoperative r = .37). CSD had greater preoperative CPL (P < .001) and CTPA (P < .001). The compensated cohort had a decrease in TS-CL (from 10.2 to 8.0) with sagittal vertical axis (SVA) correction, whereas the uncompensated had an increase in TS-CL (from 22.3 to 26.8) with all P < .001. Reciprocal change was demonstrated in the compensated group given that CL decreased with SVA correction (r = .39), but there was no such correlation in the uncompensated. Positive predictors of postoperative CSD included baseline TS-CL > 17° (P = .007), longer fusion (P = .033), and baseline CTPA (P = .029).

CONCLUSIONS

TS-CL and CTPA correlated significantly with established sagittal balance measures. Whereas reciprocal change in cervical and thoracolumbar alignment was demonstrated in the compensated cohort, the uncompensated population had progression of their cervical deformities after three-column osteotomy.

CLINICAL RELEVANCE

The balance between TS-CL mirrors the relationship between pelvic incidence minus lumbar lordosis in defining deformities of their respective spinal regions.

Changes in Cervical Alignment after Multilevel Schwab Grade II Thoracolumbar Osteotomies for Adult Spinal Deformity

STUDY DESIGN

A retrospective cohort.

OBJECTIVE

The aim of this study was to describe changes in cervical alignment (CA) and cervical deformity (CD) after multilevel Schwab Grade II Osteotomies for adult spinal deformity (ASD).

SUMMARY OF BACKGROUND DATA

Reciprocal cervical and global changes after ASD surgery have not been previously described in the setting of multilevel osteotomy.

METHODS

Patients with long-segment (> five levels) fusion and osteotomy for ASD were radiographically evaluated. Pre- and postoperative cervical parameters evaluated included cervical lordosis (CL), C2-C7 sagittal vertical axis (C2-C7 SVA), and the T1 slope (T1S) minus the CL (T1S-CL). CD was defined as C2-C7 SVA >4 cm, CL < 0°, or T1S-CL ≥15°.

RESULTS

Eighty-five patients (mean age 64 ± 11.1) were identified. Preoperative lumbar lordosis (LL) was 28.7° ± 13.8°, thoracic kyphosis (TK) was 28.2° ± 17.0°, C7 plumbline (C7 SVA) was 7.54 ± 6.7 cm, pelvic tilt (PT) was 30.0° ± 8.96°, lumbopelvic mismatch was 32° ± 17.1°, and the T1 pelvic angle (TPA) was 26.8° ± 12.9°. The C7 SVA and TPA corrected to 3.90 cm (P < 0.0001) and 17.5°, respectively (P < 0.0001). CD increased from 41 (48%) to 47 (55%) patients. The mean CL changed from 16.5° to 11.9° (P < 0.013), C2 SVA from 10.1 to 6.37 cm (P < 0.0001), T1S-CL from 10.2° to 14.3° (P = 0.021), and TK from 28° to 39° (P < 0.0001). A correlation was observed between T1S and CL (ρ = 0.435, P < 0.0001) and C2-C7 SVA (ρ = 0.624, P < 0.0001). T1S was the only independent predictor of both the postoperative C2-C7 SVA and CL.In this study, the presence of any single preoperative CD criterion was noted to be a risk for persistent global deformity on postoperative radiograph [odds ratio (OR) = 2.5] and the development of PJK (OR = 2.1). The T1-CL < 15° may indicate an even greater risk for persistent global deformity (OR = 3.5).

CONCLUSION

Thoracolumbar fusion with multilevel Schwab Grade II Osteotomies was associated with a decreased CL and reciprocal increases in TK and T1S-CL.

LEVEL OF EVIDENCE

3.

Correction of dropped head deformity through combined anterior and posterior osteotomies to restore horizontal gaze and improve sagittal alignment

OBJECTIVE

The aim of this study is to present our technique for a large focal correction of a partially flexible dropped head deformity through combined anterior and posterior osteotomies, as well as anterior soft tissue releases.

METHODS

One patient with dropped head deformity underwent an anterior and posterior osteotomy with anterior soft tissue release.

RESULTS

The patient recovered well, with postoperative radiographs demonstrating significant improvement in coronal and sagittal alignment. His C2-C7 sagittal vertical axis improved from 7.5 cm preoperatively to less than 4 cm postoperatively and his C2-C7 sagittal Cobb improved from 35° of kyphosis to 10° of lordosis.

CONCLUSION

In this report, we present our technique for a large focal correction of a partially flexible dropped head deformity through combined anterior and posterior osteotomies and anterior soft tissue releases. These more conservative osteotomies permitted gradual deformity correction and alleviated the need for pedicle subtraction osteotomy. We were able to restore horizontal gaze and improve sagittal malalignment. Although the technique we present here is one of many possible options for managing the deformity, we believe this combined approach is safe and effective and well tolerated by patients.