Cervical spine alignment, sagittal deformity, and clinical implications: a review

Analysis of Associating Factors With C2-7 Sagittal Vertical Axis After Two-level Anterior Cervical Fusion: Comparison Between Plate Augmentation and Stand-alone Cages

STUDY DESIGN

A retrospective review.

OBJECTIVE

We investigated the longitudinal change of cervical alignment parameters including C2-7 lordosis, C2-7 sagittal vertical axis (SVA), T1 slope, and segmental angle (SA) after two-level anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

Cervical alignment may influence postoperative clinical outcomes. Several studies have suggested that cervical alignment may serve as a parameter for assessing cervical deformities similar to those used to assess thoracolumbar spine deformities. However, to our knowledge, no studies have investigated the effect of ACDF on cervical sagittal alignment.

METHODS

We enrolled patients whom had ACDF, 23 patients with stand-alone cages and 22 with plate augmentation. Radiologic parameters including C2-7 lordosis, C2-7 SVA, T1 slope, and SA at the operated level were evaluated preoperatively and at 1 week and 6 months postoperatively. The differences between preoperative and 6-month postoperative parameter values were designated as Δvalues. T1S-CL was calculated as the T1 slope minus C2-7 lordosis. Clinical outcome were obtained by the Visual Analog Scale (VAS) and the Neck Disability Index (NDI).

RESULTS

ΔC2-7 SVA was significantly correlated with ΔT1S-CL and ΔC2-7 lordosis. ΔC2-7 lordosis was significantly correlated with ΔSA. ΔC2-7 lordosis had a significantly greater impact on ΔT1S-CL than did ΔT1 slope. The ΔSA and ΔC2-7 lordosis in the ACDF-plate were significantly higher than those in the in ACDF-cage. ΔT1S-CL and ΔC2-7 SVA in the ACDF-plate were significantly lower than those in the ACDF-cage.

CONCLUSION

C2-7 SVA after two-level ACDF was affected more significantly by the SA and C2-7 angle than by the T1 slope. Two-level ACDF with plate restored more cervical lordosis by obtaining more segmental lordosis at the operated level and was more effective in terms of cervical alignment compared with ACDF using stand-alone cages.

LEVEL OF EVIDENCE

3.

Recent and Emerging Advances in Spinal Deformity

BACKGROUND: Over the last several decades, significant advances have occurred in the assessment and management of spinal deformity.

OBJECTIVE: The primary focus of this narrative review is on recent advances in adult thoracic, thoracolumbar, and lumbar deformities, with additional discussions of advances in cervical deformity and pediatric deformity.

METHODS: A review of recent literature was conducted.

RESULTS: Advances in adult thoracic, thoracolumbar, and lumbar deformities reviewed include the growing applications of stereoradiography, development of new radiographic measures and improved understanding of radiographic alignment objectives, increasingly sophisticated tools for radiographic analysis, strategies to reduce the occurrence of common complications, and advances in minimally invasive techniques. In addition, discussion is provided on the rapidly advancing applications of predictive analytics and outcomes assessments that are intended to improve the ability to predict risk and outcomes. Advances in the rapidly evolving field of cervical deformity focus on better understanding of how cervical alignment is impacted by thoracolumbar regional alignment and global alignment and how this can affect surgical planning. Discussion is also provided on initial progress toward development of a comprehensive cervical deformity classification system. Pediatric deformity assessment has been substantially improved with low radiation-based 3-D imaging, and promising clinical outcomes data are beginning to emerge on the use of growth-friendly implants.

CONCLUSION: It is ultimately through the reviewed and other recent and ongoing advances that care for patients with spinal deformity will continue to evolve, enabling better informed treatment decisions, more meaningful patient counseling, reduced complications, and achievement of desired clinical outcomes.

Can segmental mobility be increased by cervical arthroplasty?

OBJECTIVE

Many reports have successfully demonstrated that cervical disc arthroplasty (CDA) can preserve range of motion after 1- or 2-level discectomy. However, few studies have addressed the extent of changes in segmental mobility after CDA or their clinical correlations.

METHODS

Data from consecutive patients who underwent 1-level CDA were retrospectively reviewed. Indications for surgery were medically intractable degenerative disc disease and spondylosis. Clinical outcomes, including visual analog scale (VAS)–measured neck and arm pain, Neck Disability Index (NDI), and Japanese Orthopaedic Association (JOA) scores, were analyzed. Radiographic outcomes, including C2–7 Cobb angle, the difference between pre- and postoperative C2–7 Cobb angle (ΔC2–7 Cobb angle), sagittal vertical axis (SVA), the difference between pre- and postoperative SVA (ΔSVA), segmental range of motion (ROM), and the difference between pre- and postoperative ROM (ΔROM), were assessed for their association with clinical outcomes. All patients underwent CT scanning, by which the presence and severity of heterotopic ossification (HO) were determined during the follow-up.

RESULTS

A total of 50 patients (mean age 45.6 ± 9.33 years) underwent a 1-level CDA (Prestige LP disc) and were followed up for a mean duration of 27.7 ± 8.76 months. All clinical outcomes, including VAS, NDI, and JOA scores, improved significantly after surgery. Preoperative and postoperative ROM values were similar (mean 9.5° vs 9.0°, p > 0.05) at each indexed level. The mean changes in segmental mobility (ΔROM) were −0.5° ± 6.13°. Patients with increased segmental mobility after surgery (ΔROM > 0°) had a lower incidence of HO and HO that was less severe (p = 0.048) than those whose ΔROM was < 0°. Segmental mobility (ROM) was significantly lower in patients with higher HO grade (p = 0.012), but it did not affect the clinical outcomes. The preoperative and postoperative C2–7 Cobb angles and SVA remained similar. The postoperative C2–7 Cobb angles, SVA, ΔC2–7 Cobb angles, and ΔSVA were not correlated to clinical outcomes after CDA.

CONCLUSIONS

Segmental mobility (as reflected by the mean ROM) and overall cervical alignment (i.e., mean SVA and C2–7 Cobb angle) had no significant impact on clinical outcomes after 1-level CDA. Patients with increased segmental mobility (ΔROM > 0°) had significantly less HO and similarly improved clinical outcomes than those with decreased segmental mobility (ΔROM < 0°).

Cervical sagittal alignment in adult hyperkyphosis treated by posterior instrumentation and in situ bending

BACKGROUND

In the normal adult spine, a link between thoracolumbar and cervical sagittal alignment exists, suggesting adaptive cervical positional changes allowing horizontal gaze. In patients with thoracic hyperkyphosis, cervical adaptation to sagittal global alignment might be different from healthy individuals. However, this relationship has not clearly been reported in hyperkyphotic deformity.

PURPOSE

The purpose of this study was to identify cervical sagittal alignment types observed on radiographs in young adults with thoracic hyperkyphosis. The relationship between cervical and thoracolumbar alignment as well as the effect of posterior instrumentation and adaptive positional changes of the mobile cervical segment were retrospectively analyzed.

PATIENTS AND METHODS

Twenty-three patients (32.7 years; 5-year follow-up) were included. Full spine radiographic measurements were: T1 slope, T1-T4 kyphosis, T4-T12 kyphosis, L1-S1 lordosis, pelvic incidence, pelvic tilt, sacral slope, SVA C7, SVA C2, lordosis between C0-C2, C2-C7, C2-C4 and C4-C7. A Bayesian model and Spearman correlation were used.

RESULTS

Two alignment types existed: cervical lordosis (group A) and cervical kyphosis (group B). Preoperatively, T4-T12 kyphosis and L1-S1 lordosis were significantly higher in group A: 76.6° versus 59.4° and -72.8° versus -65.8° (probability of>5° difference P (β>5)>0.95). Pelvic incidence was higher in group A (49.8° versus 44.2°) and C0-C2 lordosis in group B (-29.4° versus -21.6°). A significant correlation existed between: T4-T12 kyphosis and C2-C7 lordosis, L1-S1 lordosis and pelvic incidence, C2-C7 lordosis and T1 slope, C2-C7 lordosis and T1-T4 kyphosis. Postoperatively, T4-T12 kyphosis decreased by 33.1° P (β>5)=0.9995), L1-S1 lordosis decreased by 17.7° (P (β>5)=0.961), T1-T4 kyphosis increased by 14.1° (P (β>5)=0.973). SVA C2 (translation) increased by 13.8mm. C0-C2 lordosis (head rotation) remained unchanged. Six patients changed cervical alignment. PJK occurred in 15 patients, unrelated to cervical alignment or proximal instrumentation level.

DISCUSSION

Two cervical alignment types, lordotic or kyphotic, were observed thoracic hyperkyphosis patients. This alignment was mainly triggered by the amount of thoracic kyphosis and lumbar lordosis, linked to pelvic incidence. Moreover, the inclination of the C7-T1 junctional area plays a key role in the amount of cervical lordosis. The correction of T4-T12 kyphosis induced compensatory modifications at adjacent segments: T1-T4 kyphosis increase (PJK) and L1-S1 lordosis decrease. Global spino-pelvic alignment and head position did not change in the sagittal plane. The cervical spine tented to keep in its preoperative position in most patients.

LEVEL OF EVIDENCE

Level IV.

RADIOGRAPHIC ALIGNMENT OF CERVICAL SPINE ON A SAMPLE OF ASYMPTOMATIC SUBJECTS

ABSTRACT Objective: To present normality parameters for the cervical spine in a sample of the Brazilian population and its distribution by sex and age. Methods: This was a prospective study considering 94 asymptomatic individuals evaluated by panoramic radiograph of the spine for the analysis of the following parameters: cervical lordosis (CL), C2 sagittal vertical axis (SVA-C2), cervical sagittal vertical axis (cSVA), and T1 Slope (TA-T1). The parameter values were compared according to sex and age of individuals. Results: The mean CL was -16.5° (SD: ± 10.8°), SVA-C2 was -3.9 mm (SD: ± 29.2 mm), cSVA was 16.9 mm (SD: ± 10.6 mm) and TA-T1 was 24.8° (SD: ± 7.0°). There was no significant difference between the radiographic parameters when considered with respect to sex and age of individuals (P>0.05). The analysis of correlation among the radiographic parameters showed that the TA-T1 presented the highest correlation with the other parameters, including CL (r= 0.367, P<0.01), SVA-C2 (r= 0.434, P<0.001) and cSVA (r= 0.441, P<0.001). There was also a correlation between SVA-C2 and cSVA (r= 0.32, P= 0.001) and inverse correlation between CL and the cSVA (r= -0.242, P= 0.019). Conclusio: We introduced normality data of the cervical spine alignment in a Brazilian population sample. There was significant correlation among the analyzed parameters, especially considering TA-T1 in relation to the other parameters.

The efficacy of sagittal cervical spine subtyping: Investigating radiological classification methods within 150 asymptomatic participants

Aims:

The aim of this study is to (1) compare and contrast cervical subtype classification methods within an asymptomatic population, and (2) identify inter-methodological consistencies and describe examples of inconsistencies that have the potential to affect subtype classification and clinical decision-making.

Methods:

A total of 150 asymptomatic 18–30-year-old participants met the strict inclusion criteria. An erect neutral lateral radiograph was obtained using standard procedures. The Centroid, modified Takeshima/Herbst methods and the relative rotation angles in cases of nonagreement were used to determine subtype classifications. Cohen's kappa coefficient (κ) was used to assess the level of agreement between the two methods.

Results:

Nonlordotic classifications represented 66% of the cohort. Subtype classification identified the cohort as, lordosis (51), straight (37), global kyphosis (30), sigmoidal (13), and reverse sigmoidal (RS) (19). Cohen's kappa coefficient indicated that there was only a moderate level of agreement between methods (κ = 0.531). Methodological agreement tended to be higher within the lordotic and global kyphotic subtypes whereas, straight, sigmoidal, and RS subtypes demonstrated less agreement.

Conclusion:

This is the first study of its type to compare and contrast cervical classification methods. Subtypes displaying predominantly extended or flexed segments demonstrated higher levels of agreement. Our findings highlight the need for establishing a standardized multi-method approach to classify sagittal cervical subtypes.

Expansive open-door laminoplasty versus laminectomy and instrumented fusion for cases with cervical ossification of the posterior longitudinal ligament and straight lordosis

PURPOSE

To identify whether expansive open-door laminoplasty (Lam) is more appropriate than laminectomy and instrumented fusion (LIF) for cases with ossification of the posterior longitudinal ligament (OPLL) and straight cervical lordosis.

METHODS

A total of 67 cases were included and divided into Group Lam (n = 32) and Group LIF (n = 35), and the mean follow-up periods were 38 and 42 months, respectively. The cervical lordosis was elevated by C2-7 Cobb angle and cervical sagittal balance by C2-C7 sagittal vertical axis (SVA). Japanese Orthopedic Association (JOA), neurological recovery rate (RR) being calculated by the JOA, visual analog scale (VAS) and neck disability index (NDI) were used to assess clinical outcomes.

RESULTS

Differences in general data between two groups were not significant. Total blood loss and operation duration in Group Lam were both significantly less than that in the Group LIF. By the final follow-up, the cervical lordosis significantly decreased in Group Lam and increased in Group LIF, the SVA significantly increased in Group Lam and kept unchanged in Group LIF, and the JOA, VAS, NDI significantly improved in both groups. Although there was no significant difference in RR between the two groups, cases in Group Lam had significantly larger incidence of postoperative kyphosis and kyphotic change rate, and less VAS, NDI and incidence of axial pain than cases in Group LIF.

CONCLUSIONS

When compared with the LIF, the Lam is recommended for cases with OPLL and straight cervical lordosis when taking comparable neurological recovery, less axial pain and better neck function improvement into consideration.

Predicting Cervical Alignment Required to Maintain Horizontal Gaze Based on Global Spinal Alignment

STUDY DESIGN

A retrospective cohort.

OBJECTIVE

The aim of this study was to investigate the cervical alignment necessary for the maintenance of horizontal gaze that depends on underlying thoracolumbar alignment.

SUMMARY OF BACKGROUND DATA

Cervical Sagittal Curve (CC) is affected by thoracic and global alignment. Recent studies suggest large variability in normative CC ranging from lordotic to kyphotic alignment. No previous studies have assessed the effect of global spinal alignment on CC in maintenance of horizontal gaze.

METHODS

Patients without previous history of spinal surgery and able to maintain their horizontal gaze while undergoing full body imaging were included. Patients were stratified on the basis of thoracic kyphosis (TK) into (<30, 30-40, 40-50, and >50) and then by SRS-Schwab sagittal vertical axis (SVA) modifier into (posterior alignment SVA <0, aligned 0-50, and malaligned >50 mm). Cervical alignment was assessed among SVA grade in TK groups. Stepwise linear regression analysis was applied on random selection of 60% of the population. A simplified formula was developed and validated on the remaining 40%.

RESULTS

In each TK group (n = 118, 137, 125, 197), lower CC (C2-C7) was significantly more lordotic by increased Schwab SVA grade. T1 slope and cervical SVA significantly increased with increased thoracolumbar (C7-S1) SVA. Upper CC (C0-C2) and mismatch between T1 slope and CC (T1-CL) were similar. Regression analysis revealed LL minus TK (LL-TK) as an independent predictor (r = 0.640, r = 0.410) with formula: CC = 10- (LL-TK)/2. Validation revealed that the absolute difference between the predicted CC and the actual CC was 8.5°. Moreover, 64.2% of patients had their predicted C2-C7 values within 10° of the actual CC.

CONCLUSION

Cervical kyphosis may represent normal alignment in a significant number of patients. However, in patients with SVA >50 and greater thoracic kyphosis, cervical lordosis is needed to maintain the gaze. Cervical alignment can be predicted from underlying TK and lumbar lordosis, which may be clinically relevant when considering correction for thoracolumbar or cervical deformityLevel of Evidence: 3.

Influence of high-heeled shoes on the sagittal balance of the spine and the whole body

PURPOSE

Wearing high heels is associated with chronic pain of the neck, lower back and knees. The mechanisms behind this have not been fully understood. The purpose of this study was to investigate the influence of high-heeled shoes on the sagittal balance of the spine and the whole body in non-habitual wearers of high heels.

METHODS

Lateral standing whole body low-dose radiographs were obtained from 23 female participants (age 29 ± 6 years) with and without high heels and radiological parameters describing the sagittal balance were quantified. These were analyzed for differences between both conditions in the total sample and in subgroups.

RESULTS

Standing in high heels was associated with an increased femoral obliquity angle [difference (Δ) 3.0° ± 1.7°, p < 0.0001], and increased knee (Δ 2.4° ± 2.9°, p = 0.0009) and ankle flexion (Δ 38.7° ± 3.4°, p < 0.0001). The differences in C7 and meatus vertical axis, cervical and lumbar lordosis, thoracic kyphosis, spino-sacral angle, pelvic tilt, sacral slope, and spinal tilt were not significant. Individuals adapting with less-than-average knee flexion responded to high heels by an additional increase in cervical lordosis (Δ 5.8° ± 10.7° vs. 1.8° ± 5.3°).

CONCLUSIONS

In all participants, wearing high heels led to increased flexion of the knees and to more ankle flexion. While some participants responded to high heels primarily through the lower extremities, others used increased cervical lordosis to adapt to the shift of the body's center of gravity. This could explain the different patterns of pain in the neck, lower back and knees seen in individuals wearing high heels frequently.

Cervical radiographic parameters in 1- and 2-level anterior cervical discectomy and fusion

OBJECTIVE

Anterior cervical discectomy and fusion (ACDF) is one of the most commonly performed spine procedures. It can be used to correct cervical kyphotic deformity, which is the most common cervical deformity, and is often performed using lordotic interbody devices. Worsening of the cervical sagittal parameters is associated with decreased health-related quality of life. The study hypothesis is that through the use of machined lordotic allografts in ACDF, segmental and overall cervical lordosis can be maintained or increased, which will have a positive impact on overall cervical sagittal alignment.

METHODS

Seventy-four cases of 1-level ACDF (ACDF1) and 2-level ACDF (ACDF2) (40 ACDF1 and 34 ACDF2 procedures) were retrospectively reviewed. Upright neutral lateral radiographs were assessed preoperatively and at 6 weeks and 1 year postoperatively. The measured radiographic parameters included focal lordosis, disc height, C2–7 lordosis, C1–7 lordosis, T-1 slope, and C2–7 sagittal vertical axis. Correlation coefficients were calculated to determine the relationships between these radiographic measurements.

RESULTS

The mean values were as follows: preoperative focal lordosis was 0.574°, disc height was 4.48 mm, C2–7 lordosis was 9.66°, C1–7 lordosis was 42.5°, cervical sagittal vertebral axis (SVA) was 26.9 mm, and the T-1 slope was 33.2°. Cervical segmental lordosis significantly increased by 6.31° at 6 weeks and 6.45° at 1 year. C2–7 lordosis significantly improved by 1 year with a mean improvement of 3.46°. There was a significant positive correlation between the improvement in segmental lordosis and overall cervical lordosis. Overall cervical lordosis was significantly negatively correlated with cervical SVA. Improved segmental lordosis was not correlated with cervical SVA in ACDF1 patients but was significantly negatively correlated in ACDF2 patients. There was also a significant positive correlation between the T-1 slope and cervical SVA.

CONCLUSIONS

In the study population, the improvement of focal lordosis was significantly correlated with an improvement in overall lordosis (C1–7 and C2–7), and overall lordosis as measured by the C2–7 Cobb angle was significantly negatively correlated with cervical SVA. Using lordotic cervical allografts, we successfully created and maintained significant improvement in cervical segmental lordosis at the 6-week and 1-year time points with values of 6.31° and 6.45°, respectively. ACDF is able to achieve statistically significant improvement in C2–7 cervical lordosis by the 1-year followup, with a mean improvement of 3.46°. Increasing the number of levels operated on resulted in improved cervical sagittal parameters. This establishes a baseline for further examination into the ability of multilevel ACDF to achieve cervical deformity correction through the intervertebral correction of lordosis.

Multilevel Corpectomy With Anterior Column Reconstruction and Plating for Subaxial Cervical Osteomyelitis

STUDY DESIGN

A retrospective case series.

OBJECTIVE

The aim of this study was to evaluate patients with cervical spine osteomyelitis who underwent multilevel (≥2) subaxial corpectomies and anterior column reconstruction and plating.

SUMMARY OF BACKGROUND DATA

Neglected multilevel subaxial cervical osteomyelitis is a potentially dangerous disease. As it is rare, early radiographic and clinical outcomes after multilevel anterior corpectomy and reconstruction for subaxial cervical osteomyelitis are incompletely defined.

METHODS

Adults who underwent multilevel corpectomy and anterior plating/reconstruction for subaxial cervical osteomyelitis at two institutions were reviewed. Analysis of patient demographics, operative details, and radiographic cervical alignment parameters [segmental kyphosis, cervical lordosis, C2-7 sagittal vertical axis (SVA)] was performed.

RESULTS

Nineteen patients [15 males, four females; average age 48 years (20-81 yrs)] met inclusion criteria. The majority had pre-operative neurologic deficits or was immunosuppressed. All were treated with ≥6 weeks of intravenous antibiotics following operation. All had anterior plating/reconstruction with titanium cages (expandable-6; mesh-6) or structural bone graft (fibular allogaft-6; tricortical iliac crest-1). The average number of corpectomies was 2.4 (2-4). The average numbers of levels fused anteriorly was 4.4 (4-6) and posteriorly was 6.3 (4-9). The majority of patients (74%) was treated with an anterior/posterior approach. Average follow-up was 16 ± 9 months. There was significant improvement in all cervical alignment parameters (segmental kyphosis, C2-7 SVA, cervical lordosis). No intraoperative complications occurred and no patient deteriorated neurologically postoperatively. Postoperative complications included anterior cage/graft dislodgement (n = 2), recurrent neck hematomas requiring revision (n = 1), epidural hematoma (n = 1), and wound infection (n = 1). Sixty percent of patients had persistent neurologic dysfunction at final follow-up. None required reoperation for recurrent infection or pseudarthrosis.

CONCLUSION

Although overall prognosis and neurologic recovery are guarded in medically fragile patients with multilevel subaxial cervical osteomyelitis, reconstruction with multilevel (≥2) corpectomy and anterior reconstruction/plating results in excellent restoration of cervical alignment and low rates of recurrent infection and pseudarthrosis.

LEVEL OF EVIDENCE

4.

Predictive Model for Cervical Alignment and Malalignment Following Surgical Correction of Adult Spinal Deformity

STUDY DESIGN

Retrospective review of prospective multicenter database.

OBJECTIVE

Use predictive modeling to identify patient characteristics, radiographic, and surgical variables that predict reaching an outcome threshold of suboptimal cervical alignment after adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Cervical deformity (CD) after ASD correction has been defined with the following criteria: T1S-CL>20°, C2-C7 SVA>40 mm, and/or C2-C7 kyphosis >10°. While studies have analyzed CD predictors, few have defined and identified predictors of optimal cervical alignment after thoracolumbar surgery.

METHODS

Inclusion criteria were surgical ASD patients with baseline and 2-year follow-up. Postoperative cervical alignment (CA) and malalignment (nonCA) at 2 years was defined with the following radiographic criteria: 0°≤T1S-CL≤20°, 0 mm≤C2-C7 SVA≤40 mm, or C2-C7 lordosis >0°. Three thresholds classifying malalignment were defined: (T1) missing 1 criterion, (T2) missing 2 criteria, (T3) missing 3 criteria. Multivariable logistic stepwise regression models with bootstrap resampling procedure were performed for demographic, surgical, and radiographic variables. The model was validated with receiver operative characteristic and area under the curve.

RESULTS

Two hundred twenty-five surgical ASD patients were included. At 2 years 208 patients (92.4%) were grouped as CA in T3, while 17 (7.6%) were nonCA. Patients were similar in age (CA: 56.10 vs. nonCA: 55.78 years, P = 0.150), BMI (CA: 26.93 vs. nonCA: 26.94 kg/m, P = 0.716), and sex (CA: 76.5% vs. nonCA: 87.0%, P = 0.194). The final predictive model included C2 slope, C2-T3 CL, T1S-CL, C2-C7 CL, Pelvic Tilt, C2-S1 SVA, PI-LL, and Smith-Peterson osteotomies number. In this model (area under the curve 89.22% [97.49-80.96%]), the following variables were identified as predictors of nonCA: increased Smith-Peterson osteotomies use (OR: 1.336, P = 0.017), and C2-T3 angle (OR: 1.048, P = 0.005).

CONCLUSION

This study created a statistical model that predicts poor 2-year postoperative cervical malalignment in ASD patients. T3 (patients not meeting all three alignment criteria) was the most effective threshold for modeling nonCA, and included increased baseline C2-T3 angle and increased Smith-Peterson osteotomies during index.

LEVEL OF EVIDENCE

3.

Magnetic Resonance Imaging of the Cervical Spine Under-Represents Sagittal Plane Deformity in Degenerative Myelopathy Patients

BACKGROUND

In treating patients with cervical myelopathy, surgical approach may be dictated by sagittal balance, highlighting the need for accurate pre-operative assessment. Magnetic Resonance Imaging (MRI) is widely-recognized for its utility in the diagnosis and surgical planning of cervical myelopathy. Plain radiographs (X-rays) are a reliable tool to assess bony alignment. However, they may not always be included in standard pre-operative evaluation, especially in an era of restricted payer-environments. Failure to appropriately acknowledge a patients' preoperative kyphotic deformity may cause the surgeon to choose a posterior-only approach, which would provide suboptimal sagittal plane correction and decompression of anterior pathology.

METHODS

101 patients with cervical myelopathy with MRI and plain radiographs were identified. Cervical lordosis and kyphosis were measured using the Cobb method on standing lateral x-ray and sagittal T2-weighted MRI. CI (Ishihara) was also measured on standing lateral x-ray, and sagittal T2-weighted MRI. Bland-Altman plots were generated and used to compare subtle differences in measurement techniques and modalities. Odom's criteria were recorded.

RESULTS

The average difference between plain radiograph and MRI measurements for curvature angle was 3.5± 7.2 degrees (p< 0.001), and the average difference between plain radiograph and MRI measurements for curvature index was 1.5± 5.9 degrees (p= 0.015).

CONCLUSIONS

MRI may under-represent the respective sagittal plane deformity in patients with degenerative cervical myelopathy.

CLINICAL RELEVANCE

We would recommend the use of standing x-rays when considering surgical planning in all myelopathy patients. This manuscript was reviewed and approved by an institutional review board. Informed consent was not obtained because patient specific identifying information was not used. It was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.

Degenerative cervical myelopathy

Cervical myelopathy is the most common cause of acquired spinal cord compromise. The concept of degenerative cervical myelopathy (DCM), defined as symptomatic myelopathy associated with degenerative arthropathic changes in the spine axis, is being introduced. Given its progressive nature, treatment options have to be chosen in a timely manner. Surgical options include anterior discectomy and fusion (ACDF), anterior corpectomy and fusion (ACCF), arthroplasty (in highly select cases), posterior laminectomy with/without fusion, and laminoplasty. Indications for each should be carefully considered in individual patients. Riluzole, a sodium-glutamate antagonist, is a promising option to optimize neurologic outcomes post-surgery and is being examined in the CSM-Protect Randomized Controlled Trial. Preoperative risk assessment is mandatory for prognostication. Sagittal alignment is known to play an important role to optimize surgical outcome. Guidelines for optimal management of DCM are in process. In principle, all but the mildest cases of DCM should be offered surgery for optimal outcome.

Correlation and Reliability of Cervical Sagittal Alignment Parameters between Lateral Cervical Radiograph and Lateral Whole-Body EOS Stereoradiograph

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To evaluate the correlation and reliability of cervical sagittal alignment parameters obtained from lateral cervical radiographs (XRs) compared with lateral whole-body stereoradiographs (SRs).

METHODS

We evaluated adults with cervical deformity using both lateral XRs and lateral SRs obtained within 1 week of each other between 2010 and 2014. XR and SR images were measured by two independent spine surgeons using the following sagittal alignment parameters: C2-C7 sagittal Cobb angle (SCA), C2-C7 sagittal vertical axis (SVA), C1-C7 translational distance (C1-7), T1 slope (T1-S), neck tilt (NT), and thoracic inlet angle (TIA). Pearson correlation and paired t test were used for statistical analysis, with intra- and interrater reliability analyzed using intraclass correlation coefficient (ICC).

RESULTS

A total of 35 patients were included in the study. We found excellent intrarater reliability for all sagittal alignment parameters in both the XR and SR groups with ICC ranging from 0.799 to 0.994 for XR and 0.791 to 0.995 for SR. Interrater reliability was also excellent for all parameters except NT and TIA, which had fair reliability. We also found excellent correlations between XR and SR measurements for most sagittal alignment parameters; SCA, SVA, and C1-C7 had r > 0.90, and only NT had r < 0.70. There was a significant difference between groups, with SR having lower measurements compared with XR for both SVA (0.68 cm lower, p < 0.001) and C1-C7 (1.02 cm lower, p < 0.001). There were no differences between groups for SCA, T1-S, NT, and TIA.

CONCLUSION

Whole-body stereoradiography appears to be a viable alternative for measuring cervical sagittal alignment parameters compared with standard radiography. XR and SR demonstrated excellent correlation for most sagittal alignment parameters except NT. However, SR had significantly lower average SVA and C1-C7 measurements than XR. The lower radiation exposure using single SR has to be weighed against its higher cost compared with XR.

Hospital Readmission Within 2 Years Following Adult Thoracolumbar Spinal Deformity Surgery: Prevalence, Predictors, and Effect on Patient-derived Outcome Measures

STUDY DESIGN

A retrospective review of prospective multicenter database.

OBJECTIVE

The aim of this study was to identify factors influencing readmission, reoperation, and the impact on health-related quality of life outcomes (HRQoLs) in adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Many ASD patients experience complications requiring readmission. It is important to identify baseline/operative factors leading to rehospitalizations and reoperation, which may impact outcomes.

INCLUSION CRITERIA

ASD surgical patients (age >18 yrs, major coronal Cobb ≥20°, sagittal vertical axis ≥5 cm, pelvic tilt ≥25°, and/or thoracic kyphosis >60°) with complete baseline, 1-, and 2-year follow-up. Patients were grouped on the basis of readmission occurrence (yes/no) and type [medical (no reoperation) vs. surgical (revision surgery)]. Readmissions caused by infections requiring surgical treatment (e.g., deep infections) were considered reoperations. Univariate and multivariate analyses determined readmission and reoperation predictors. Repeated measures mixed models evaluated readmission impact on HRQoLs at 1 and 2 years.

RESULTS

Three hundred thirty-four patients were included: 76 (22.8%) readmissions, involving 65 (85.5% of 76) reoperations (surgical readmission) and 11 (14.5% of 76) medical readmissions. The most common surgical readmission indication (n = 65) was implant complications (36.9%; rod breakage n = 13); the most common medical readmission indication was infection (36.4%, n = 4), treated with antibiotics. Noninfectious medical readmission (n = 7) included pleural effusion, deep vein thrombosis (DVT), intraoperative blood loss, neurologic, and unspecified. Readmission predictors: increased number of major peri-operative complications [odds ratio (OR) 5.13, P = 0.014], infection presence (OR 25.02, P = 0.001), implant complications (OR 6.12, P < 0.001), and radiographic complications (DJK, proximal junctional kyphosis, pseudoarthrosis, sagittal/coronal imbalance) (OR 16.94, P < 0.001). HRQoL analysis revealed overall improvement of the full cohort (P < 0.01), though the 76 readmitted improved less overall and at each time point P < 0.001) except in 6-week MCS (P = 0.14).

CONCLUSION

Major peri-operative, implant, radiographic, and infection complications during index were associated with increased readmission odds. Implant complications most frequently caused surgical readmissions. Readmitted patients improved in outcome scores, although less compared with the nonreadmitted cohort, yet displayed reduced 6-week SF-36 Mental Component Summary.

LEVEL OF EVIDENCE

3.

Postoperative Increase in Occiput-C2 Angle Negatively Impacts Subaxial Lordosis after Occipito-Upper Cervical Posterior Fusion Surgery

STUDY DESIGN

Retrospective case series.

PURPOSE

To elucidate the impact of postoperative occiput-C2 (O-C2) angle change on subaxial cervical alignment.

OVERVIEW OF LITERATURE

In the case of occipito-upper cervical fixation surgery, it is recommended that the O-C2 angle should be set larger than the preoperative value postoperatively.

METHODS

The present study included 17 patients who underwent occipito-upper cervical spine (above C4) posterior fixation surgery for atlantoaxial subluxation of various etiologies. Plain lateral cervical radiographs in a neutral position at standing were obtained and the O-C2 angle and subaxial lordosis angle (the angle between the endplates of the lowest instrumented vertebra (LIV) and C7 vertebrae) were measured preoperatively and postoperatively soon after surgery and ambulation and at the final follow-up visit.

RESULTS

There was a significant negative correlation between the average postoperative alteration of O-C2 angle (DO-C2) and the average postoperative alteration of subaxial lordosis angle (Dsubaxial lordosis angle) (r=-0.47, p=0.03).

CONCLUSIONS

There was a negative correlation between DO-C2 and Dsubaxial lordosis angles. This suggests that decrease of mid-to lower-cervical lordosis acts as a compensatory mechanism for lordotic correction between the occiput and C2. In occipito-cervical fusion surgery, care must be taken to avoid excessive O-C2 angle correction because it might induce mid-to-lower cervical compensatory decrease of lordosis.

Is more lordosis associated with improved outcomes in cervical laminectomy and fusion when baseline alignment is lordotic?

BACKGROUND CONTEXT

In cervical spondylotic myelopathy (CSM), cervical sagittal alignment (CSA) is associated with disease severity. Increased kyphosis and C2-C7 sagittal vertical axis (SVA) correlate with worse myelopathy and poor outcomes. However, when alignment is lordotic, it is unknown whether these associations persist.

PURPOSE

The study aimed to investigate the associations between CSA parameters and patient-reported outcomes (PROs) following posterior decompression and fusion for CSM when baseline lordosis is maintained.

STUDY DESIGN/SETTING

This is an analysis of a prospective surgical cohort at a single academic institution.

PATIENT SAMPLE

The sample includes adult patients undergoing primary cervical laminectomy and fusion for CSM over a 3-year period.

OUTCOME MEASURES

The PROs included EuroQol-5D, Short-Form-12 (SF-12) physical composite (PCS) and mental composite scales (MCS), Neck Disability Index, and the modified Japanese Orthopaedic Association scores. Radiographic CSA parameters measured included C1-C2 Cobb, C2-C7 Cobb, C1-C7 Cobb, C2-C7 SVA, C1-C7 SVA, and T1 slope.

METHODS

The PROs were recorded at baseline and at 3 and 12 months postoperatively. The CSA parameters were measured on standing radiographs in the neutral position at baseline and 3 months. Wilcoxon rank test was used to test for changes in PROs and CSA parameters, and Pearson correlation coefficients were calculated for CSA parameters and PROs preoperatively and at 12 months. No external sources of funding were used for this work.

RESULTS

There were 45 patients included with an average age of 63 years who underwent posterior decompression and fusion of 3.7±1.3 levels. Significant improvements were found in all PROs except SF-12 MCS (p=.06). Small but statistically significant changes were found in C2-C7 Cobb (mean change: +3.6°; p=.03) and C2-C7 SVA (mean change: +3 mm; p=.01). At baseline, only C2-C7 SVA associated with worse SF-12 PCS scores (r=-0.34, p=.02). Postoperatively, there were no associations found between PROs and any CSA parameters. Similarly, no CSA parameters were associated with changes in PROs.

CONCLUSIONS

Although creating more lordosis and decreasing SVA are associated with improved myelopathy and outcomes in patients with kyphosis, our study did not find such associationsin patients with lordosis undergoing posterior laminectomy and fusion for CSM. This suggests that any amount of lordosis may be sufficient.

Analysis of cervical kyphosis and spinal balance in young idiopathic scoliosis patients classified by the apex of thoracic kyphosis

PURPOSE

Sagittal balance has recently been the focus of studies aimed at understanding the correction force required for both coronal and sagittal malalignment. However, the correlation between cervical kyphosis and sagittal balance in AIS patients has yet to be thoroughly investigated. This study aimed to clarify the correlation between cervical alignment and spinal balance in patients with adolescent idiopathic scoliosis (AIS). Here, we hypothesized that cervical kyphosis patients can be classified into groups by the apex of thoracic kyphosis.

METHODS

This study included 92 AIS patients (84 females, 8 males; mean age, 15.1 years). Patients were divided into the cervical lordosis (CL), cervical sigmoid (CS), or cervical kyphosis (CK) groups and further classified according to the apex of thoracic kyphosis into High (above T3), Middle (T4-T9), and Low (below T10) groups.

RESULTS

There were 17 (18.5 %), 22 (23.9 %), and 53 (57.6 %) patients with CL, CS, and CK, respectively. In the CK group, 13 had CK-High, 35 had CK-Middle, and 5 had CK-Low. The C7 sagittal vertical axis (C7SVA) measurements were most backward in CK-High and most forward in CK-Low. The T5-12 kyphosis (TK) measurement was significantly lower in CK-High.

CONCLUSIONS

Most AIS patients had kyphotic cervical alignment. Patients with CK can be classified as having CK-High, CK-Middle, or CK-Low according to the apex of thoracic kyphosis. CK-High is due to thoracic hypokyphosis with a backward balanced C7SVA. CK-Middle is well-balanced cervical kyphosis. CK-Low has forward-bent global kyphosis of the cervicothoracic spine that positioned the C7SVA forward.

Efficacy and Safety of One-Stage Selective Discectomy Combined with Expansive Hemilaminectomy in the Treatment of Cervical Spondylotic Myelopathy

OBJECTIVES

We designed a novel surgical strategy named one-stage selective discectomy combined with expansive hemilaminectomy, which might theoretically reduce the postoperative complications of cervical spondylotic myelopathy (CSM). The objective of this study is to evaluate its efficacy and safety.

METHODS

Sixty-two patients with CSM were enrolled in this study. The procedure includes selective discectomy with fusion at 1 or 2 segments of maximal cord compression and expansive hemilaminectomy on the symptomatic or severe side of the body. Neurologic function was evaluated using the Japanese Orthopedics Association Score before and after surgery. Midsagittal dural sac diameter, dural sac transverse area at segments of discetomy on magnetic resonance imaging, and lordosis of the cervical spine on lateral plain film were measured. All patients were followed up for more than 1 year.

RESULTS

A total of 88 discs and 272 hemilaminas were resected from 62 patients. The Japanese Orthopedics Association Score improved from 8.7 ± 1.76 preoperatively to 13.4 ± 1.61 at 1 year follow-up (P < 0.001). The mean midsagittal dural sac diameter, dural sac area, and lordotic angle also increased from 0.45 ± 0.10 cm, 0.83 ± 0.14 cm², and 7.9 ± 2.60° to 0.81 ± 0.08 cm, 0.96 ± 0.14 cm², and 11.7 ± 3.06°, respectively (P < 0.05). No case of postoperative axial pain, C5 palsy, nonunion, or kyphosis was reported.

CONCLUSIONS

One-stage selective discectomy combined with expansive hemilaminectomy is an effective surgical approach for the treatment of CSM in patients whose neurologic function, midsagittal dura sac diameter, and dura transverse area can be improved and has few postoperative complications.

Dropped head syndrome after cervical laminoplasty: A case control study

Dropped head syndrome (DHS) is characterized by apparent neck extensor muscle weakness and difficulty extending the neck to raise the head against gravity. The aim of the present study was to elucidate possible risk factors for DHS after cervical laminoplasty. Five patients who developed DHS after cervical laminoplasty (DHS group) and twenty age-matched patients who underwent laminoplasty without DHS after surgery (control group) were compared. The surgical procedure was single-door laminoplasty with strut grafting using resected spinous processes or hydroxyapatite spacers from C3 to C6 or C7. Analyses of preoperative images including the C2-C7 angle, C7-T1 kyphosis, T1 tilt, center of gravity line from the head-C7 sagittal vertical axis (CGH-C7 SVA) were performed on lateral plain cervical spine radiographs. Preoperative T2-weighted MRI at the C5 vertebral level was used to measure the cross-sectional area of the deep extensor muscles. Widths of the lateral gutters were assessed postoperatively using CT scans of the C5 vertebral body. The average preoperative C2-C7 angle was significantly smaller in the DHS group compared with the control group. The average preoperative C7-T1 angle was significantly larger in the DHS group compared with the control group. The average preoperative CGH-C7 SVA was significantly larger in the DHS group compared with the control group. In conclusion, patients with more pronounced preoperative C2-C7 kyphosis, C7-T1 kyphosis, and CGH-C7 SVA are more likely to develop DHS following laminoplasty.

Optimal chin-brow vertical angle for sagittal visual fields in ankylosing spondylitis kyphosis

PURPOSE

Chin-brow vertical angle (CBVA) is very important in correction of thoracolumbar kyphotic deformity in ankylosing spondylitis (AS), especially for the patients with cervical ankylosis. In previous study, Suk et al. stated that the patients with CBVA between -10° and 10° had better horizontal gaze. Unfortunately, in our clinical practice, we found the patients with CBVA between -10° and 10° after surgery usually complained of difficulty in cooking, cleaning, desk working and the like, although they had excellent horizontal gaze. In other words, for the patients with cervical ankylosis, good horizontal gaze existed together with poor downward gaze. Then, which condition do the patients prefer? Is there a compromise solution that makes a better quality life possible for the patients? In this research, we studied AS patients with cervical ankylosis, aiming to investigate the optimal CBVA for deformity correction.

METHODS

25 AS thoracolumbar kyphotic patients with cervical ankylosis were studied, whose function and expectation of visual field related to life quality were assessed by questionnaire before and after surgery. Pre- and post-operative CBVA were obtained on lateral photos of the patients with free-standing posture, and 50 cases of CBVA were included, which were divided into six groups according to the angle irrespective of surgery (Group A, CBVA <0°; Group B, 0° ≤ CBVA < 10°; Group C, 10° ≤ CBVA < 20°; Group D, 20° ≤ CBVA < 30°; Group E, 30° ≤ CBVA < 40°; Group F, CBVA ≥ 40°). Kruskal-Wallis test was used to assess all the groups in terms of various items in the questionnaire, while Mann-Whitney test was used to assess every two groups.

RESULTS

In overall evaluation, Group C (10°-20°) obtained the optimal expectation (p < 0.05); Group B, C and D (0°-30°) obtained better function (p < 0.05), and there was no significant difference between the 3 groups. In appearance, Group A, B and C (<20°) were better than the other groups both in function and expectation (p < 0.05), without dramatic difference among the three groups. In outdoor activities, Group A, B, C and D (<30°) were better in most of the items (p < 0.05). In indoor activities, Group C and D (10-30°) were much better (p < 0.05).

CONCLUSION

AS thoracolumbar kyphotic patients with cervical ankylosis had the best satisfaction when 10° ≤ CBVA < 20°.

Is There a Gender-Specific Full Body Sagittal Profile for Different Spinopelvic Relationships? A Study on Propensity-Matched Cohorts

DESIGN

Retrospective review.

OBJECTIVE

To evaluate gender-related differences in compensatory recruitment to progressive sagittal malalignment.

SUMMARY OF BACKGROUND DATA

Recent research has elucidated compensatory mechanisms recruited in response to sagittal malalignment, but gender-specific differences in compensatory recruitment patterns is unknown.

METHODS

Single-center study of patients with full body x-rays. A female group was propensity matched by age, body mass index (BMI), and pelvic incidence (PI) to a male group. Patients were then stratified into five groups of progressive PI-lumbar lordosis (LL) mismatch (<0°, 0°-10°, 10°-20°, 20°-30°, >30°). Differences between PI-LL groups were assessed with analysis of variance, and between genders by unpaired t test. Knee flexion to pelvic tilt (PT) ratio was computed and compared between genders. Multivariate regression to develop predictive models for PT was performed for each gender, first with spinopelvic parameters and subsequently with inclusion of lower limb parameters.

RESULTS

A total of 942 patient visits were included: 471 females (mean age 54 years, BMI 27, PI 51°) and 471 males (mean age 52 years, BMI 27, PI 51°). At the lowest level of malalignment, females had greater PT and less knee flexion. With progressive malalignment, females continued to exhibit a pattern of greater pelvic retroversion and less knee flexion compared to males. Hip extension was higher in females with progressive PI-LL mismatch groups. Both genders progressively recruited knee flexion and pelvic retroversion with increased PI-LL mismatch, except that at the higher PI-LL mismatch groups, only males continued to recruit knee flexion (all p < .05). Inclusion of lower limbs in the regression for PT markedly improved correlation coefficients for females but not for males.

CONCLUSIONS

With progressive sagittal malalignment, men recruit more knee flexion and women recruit more pelvic tilt and hip extension. Knee flexion is a possible mechanism to gain pelvic tilt for females whereas for males, knee flexion is an independent compensatory mechanism.

Pelvic Evaluation in Thoracolumbar Corrective Spine Surgery: How I Do It

Surgeons and radiologists have traditionally focused on frontal radiographs and the measurement of scoliosis curves as important tools in the management of spinal deformity. It has become evident, however, that the management of spinal deformity should use a multidimensional approach with an increased emphasis on standing lateral radiographs and the sagittal position of the spine. Furthermore, they have come to realize the critical role that the pelvis plays in the maintenance of posture. Failure to recognize pelvic compensation can lead to under-treatment and poor postoperative outcomes.

Osteotomies in the Cervical Spine

Rigid cervical deformities are difficult problems to treat. The goals of surgical treatment include deformity correction, achieving a rigid fusion, and performing a thorough neural decompression. In stiff and ankylosed cervical spines, osteotomies are required to restore sagittal and coronal balance. In this chapter, we describe the clinical and radiographic workup for patients with cervical deformities, and delineate the various factors that must be considered when planning surgical treatment. We also describe in detail the various types of cervical osteotomies, along with their surgical technique, advantages, and potential complications.

Decreased Vertebral Artery Hemodynamics in Patients with Loss of Cervical Lordosis

Background

Because loss of cervical lordosis leads to disrupted biomechanics, the natural lordotic curvature is considered to be an ideal posture for the cervical spine. The vertebral arteries proceed in the transverse foramen of each cervical vertebra. Considering that the vertebral arteries travel in close anatomical relationship to the cervical spine, we speculated that the loss of cervical lordosis may affect vertebral artery hemodynamics. The aim of this study was to compare the vertebral artery values between subjects with and without loss of cervical lordosis.

Material/Methods

Thirty patients with loss of cervical lordosis and 30 controls matched for age, sex, and body mass index were included in the study. Sixty vertebral arteries in patients with loss of cervical lordosis and 60 in controls without loss of cervical lordosis were evaluated by Doppler ultrasonography. Vertebral artery hemodynamics, including lumen diameter, flow volume, peak systolic velocity, end-diastolic velocity, and resistive index, were measured, and determined values were statistically compared between the patient and the control groups.

Results

The means of diameter (p=0.003), flow volume (p=0.002), and peak systolic velocity (p=0.014) in patients were significantly lower as compared to controls. However, there was no significant difference between the 2 groups in terms of the end-diastolic velocity (p=0.276) and resistive index (p=0.536) parameters.

Conclusions

The present study revealed a significant association between loss of cervical lordosis and decreased vertebral artery hemodynamics, including diameter, flow volume, and peak systolic velocity. Further studies are required to confirm these findings and to investigate their possible clinical implications.

Clinical and Radiographic Evaluation of Adult Spinal Deformity

Adult spinal deformity (ASD) is a complex disease comprised of different deformity types that often involve the entire spine. Accurate assessment of ASD requires a thorough radiographic evaluation of both the spine and pelvis, including concomitant assessment of the cervical, thoracic, and lumbar spine, as well as the femoral heads and pelvis. Radiographic measurements should include assessment of regional alignment (including lumbar lordosis, thoracic kyphosis, C2-C7 lordosis), global alignment (including C7 SVA, C2-C7 SVA, and T1 pelvic angle), and measures of pelvic compensation and morphology (pelvic tilt, pelvic incidence, T1 slope, and C2-pelvic tilt). Together these radiographic parameters provide important information regarding how the ASD patient maintains upright posture and correlate with the patient's pain and disability. ASD surgical planning must integrate regional, global, and pelvic compensatory/morphologic parameters to adequately correct deformity and thereby provide pain relief and improve function. Radiographic classifications for cervical and thoracolumbar deformities have been developed that utilize the regional and global measures of spinal deformity that are most predictive of patient-reported pain and function. These classifications are aimed to standardize the assessment of ASD to aid in clinical management and to facilitate future research on the evaluation and treatment of ASD.

Influence of T1 Slope on the Cervical Sagittal Balance in Degenerative Cervical Spine: An Analysis Using Kinematic MRI

STUDY DESIGN

A retrospective kinematic magnetic resonance imaging (kMRI) study.

OBJECTIVE

To evaluate the utility of kMRI in determining the relationship between cervical sagittal balance and TI alignment.

SUMMARY OF BACKGROUND DATA

Thoracic inlet parameters play an important role in cervical spine sagittal balance. However, most of the literature is based on lower resolution cervical X-rays or CT scans in the supine position.

METHODS

Cervical spine kMRI of 83 patients with degenerative cervical spine conditions (20-68 yr of age) was analyzed for: (1) cervical spine parameters: C2-C7 angle, C2-C7 sagittal vertical axis (SVA), cranial tilt, and cervical tilt; and (2) T1 parameters: thoracic inlet angle (TIA), T1 slope, and neck tilt (NT). Multiple logistic regression analysis and Pearson correlation coefficients were performed.

RESULTS

The mean TIA, T1 slope, and NT were 78.0, 33.2, and 44.8°, respectively. The mean C2-7 angle, SVA of C2-C7, cervical tilt, and cranial tilt were -15.4°, 22.0 mm, 18.1°, and 15.1°, respectively. The ratio of cervical:cranial tilt was maintained as 55:45%. A significant correlation was found between the C2-C7 angle and T1 slope (r = 0.731), TIA and C2-C7 angle (r = 0.406), cervical tilt with C2-C7 angle (r = 0.671), T1 slope with TIA (r = 0.429), TIA with neck tilt (r = 0.733), TIA with cervical tilt (r = 0.377), SVA C2-C7 with cervical tilt (r = -0.480), SVA C2-C7 with cranial tilt (r = 0.912), and C2-7 SVA with the ratio of cranial tilt to cervical tilt (r = 0.694).

CONCLUSION

An individual with a large T1 slope required large cervical lordosis to preserve physiologic sagittal balance of the cervical spine. Cranial tilt was the cervical parameter most strongly correlated with SVA C2-C7, and thus may be a good parameter to assess decompensation of cervical sagittal balance.

LEVEL OF EVIDENCE

3.

A retrospective study to reveal the effect of surgical correction of cervical kyphosis on thoraco-lumbo-pelvic sagittal alignment

PURPOSE

Recent studies suggest that cervical lordosis is influenced by thoracic kyphosis and that T1 slope is a key factor determining cervical sagittal alignment. However, no previous study has investigated the influence of cervical kyphosis correction on the remaining spinopelvic balance. The purpose of this study is to assess the effect of surgical correction of cervical kyphosis on thoraco-lumbo-pelvic alignment.

METHODS

Fifty-five patients who underwent ≥2 level cervical fusions for cervical radiculopathy or myelopathy were included. All patients had regional or global cervical kyphosis, which was surgically corrected into lordosis. Radiographic measurements were made using whole spine standing lateral radigraphs pre- and postoperatively to analyze various sagittal parameters. The visual analogue scale (VAS) for neck pain and the neck disability index (NDI) were calculated. The paired t test was used to compare pre- and post-operative radiographic measures and functional scores. Correlations between changes in cervical sagittal parameters and those of other sagittal parameters were analyzed by Pearson's correlation method.

RESULTS

Preoperative kyphosis (11.4° ± 8.3°) was corrected into lordosis (-9.3° ± 8.1°). The average fusion levels were 3.3 ± 1.0. With increasing C2-C7 lordosis after surgery (from -3.4° ± 10.0° to -15° ± 7.9°), C0-C2 lordosis decreased significantly (from -34.6° ± 8.2° to -27.7° ± 8.0°) (P < 0.001). Thoracic kyphosis (from 24.8 ± 13.9° to 33.5 ± 11.9°) and T1 slope (from 12.8° ± 7.9° to 20.4° ± 5.2°) significantly increased after surgery (P < 0.001). However, other parameters did not significantly change (P > 0.05). Neck pain VAS and NDI scores (31.8 ± 16.2) significantly improved (P < 0.001). The degree of increasing C2-C7 lordosis by surgical correction was negatively correlated with changes in both thoracic kyphosis and T1 slope (P < 0.01).

CONCLUSIONS

Surgical correction of cervical kyphosis affects T1 slope and thoracic kyphosis, but not lumbo-pelvic alignment. These results indicate that the compensatory mechanisms to minimize positive sagittal malalignment of the head may occur mainly in the thoracic, and not in the lumbosacral spine.

Association between preoperative cervical sagittal deformity and inferior outcomes at 2-year follow-up in patients with adult thoracolumbar deformity: analysis of 182 patients

OBJECT

A high prevalence of cervical deformity (CD) has been identified among adult patients with thoracolumbar spinal deformity undergoing surgical treatment. The clinical impact of this is uncertain. This study aimed to quantify the differences in patient-reported outcomes among patients with adult spinal deformity (ASD) based on presence of CD prior to treatment.

METHODS

A retrospective review was conducted of a multicenter prospective database of patients with ASD who underwent surgical treatment with 2-year follow-up. Patients were grouped by the presence of preoperative CD: 1) cervical positive sagittal malalignment (CPSM) C2–7 sagittal vertical axis ≥ 4 cm; 2) cervical kyphosis (CK) C2–7 angle > 0; 3) CPSM and CK (BOTH); and 4) no baseline CD (NONE). Health-related quality of life (HRQOL) scores included the Physical Component Summary and Mental Component Summary (PCS and MCS) scores of the 36-Item Short Form Health Survey (SF-36), Oswestry Disability Index (ODI), Scoliosis Research Society-22 questionnaire (SRS-22), and minimum clinically important difference (MCID) of these scores at 2 years. Standard radiographic measurements were conducted for cervical, thoracic, and thoracolumbar parameters.

RESULTS

One hundred eighty-two patients were included in this study: CPSM, 45; CK, 37; BOTH, 16; and NONE, 84. Patients with preoperative CD and those without had similar baseline thoracolumbar radiographic measurements and similar correction rates at 2 years. Patients with and without preoperative CD had similar baseline HRQOL and on average both groups experienced some HRQOL improvement. However, those with preoperative CPSM had significantly worse postoperative ODI, PCS, SRS-22 Activity, SRS-22 Appearance, SRS-22 Pain, SRS-22 Satisfaction, and SRS-22 Total score, and were less likely to meet MCID for ODI, PCS, SRS-22 Activity, and SRS-22 Pain scores with the following ORs and 95% CIs: ODI 0.19 (0.07–0.58), PCS 0.17 (0.06–0.47), SRS-22 Activity 0.23 (0.09–0.62), SRS-22 Pain 0.20 (0.08–0.53), and SRS-22 Appearance 0.34 (0.12–0.94). Preoperative CK did not have an effect on outcomes. Interestingly, despite correction of the thoracolumbar deformity, 53.3% and 51.4% of patients had persistent CPSM and persistent CK, respectively.

CONCLUSIONS

Patients with thoracolumbar deformity without preoperative CD are likely to have greater improvements in HRQOL after surgery than patients with concomitant preoperative CD. Cervical positive sagittal alignment in adult patients with thoracolumbar deformity is strongly associated with inferior outcomes and failure to reach MCID at 2-year follow-up despite having similar baseline HRQOL to patients without CD. This was the first study to assess the impact of concomitant preoperative cervical malalignment in adult patients with thoracolumbar deformity. These results can help surgeons educate patients at risk for inferior outcomes and direct future research to identify an etiology and improve patient outcomes. Investigation into the etiology of the baseline cervical malalignment may be warranted in patients who present with thoracolumbar deformity.

Reliability of cervical lordosis measurement techniques on long-cassette radiographs

PURPOSE

Lateral radiographs are commonly used to assess cervical sagittal alignment. Three assessment methods have been described and are commonly utilized in clinical practice. These methods are described for perfect lateral cervical radiographs, however in everyday practice radiograph quality varies. The aim of this study was to compare the reliability and reproducibility of 3 cervical lordosis (CL) measurement methods.

METHODS

Forty-four standing lateral radiographs were randomly chosen from a lateral long-cassette radiograph database. Measurements of CL were performed with: Cobb method C2-C7 (CM), C2-C7 posterior tangent method (PTM), sum of posterior tangent method for each segment (SPTM). Three independent orthopaedic surgeons measured CL using the three methods on 44 lateral radiographs. One researcher used the three methods to measured CL three times at 4-week time intervals. Agreement between the methods as well as their intra- and interobserver reliability were tested and quantified by intraclass correlation coefficient (ICC) and median error for a single measurement (SEM). ICC of 0.75 or more reflected an excellent agreement/reliability. The results were compared with repeated ANOVA test, with p < 0.05 considered as significant.

RESULTS

All methods revealed excellent intra- and interobserver reliability. Agreement (ICC, SEM) between three methods was (0.89°, 3.44°), between CM and SPTM was (0.82°, 4.42°), between CM and PTM was (0.80°, 4.80°) and between PTM and SPTM was (0.99°, 1.10°). Mean values CL for a CM, PTM, SPTM were 10.5° ± 13.9°, 17.5° ± 15.6° and 17.7° ± 15.9° (p < 0.0001), respectively. The significant difference was between CM vs PTM (p < 0.0001) and CM vs SPTM (p < 0.0001), but not between PTM vs SPTM (p > 0.05).

CONCLUSIONS

All three methods appeared to be highly reliable. Although, high agreement between all measurement methods was shown, we do not recommend using Cobb measurement method interchangeably with PTM or SPTM within a single study as this could lead to error, whereas, such a comparison between tangent methods can be considered.

Reliability assessment of a novel cervical spine deformity classification system

OBJECT

Despite the complexity of cervical spine deformity (CSD) and its significant impact on patient quality of life, there exists no comprehensive classification system. The objective of this study was to develop a novel classification system based on a modified Delphi approach and to characterize the intra- and interobserver reliability of this classification.

METHODS

Based on an extensive literature review and a modified Delphi approach with an expert panel, a CSD classification system was generated. The classification system included a deformity descriptor and 5 modifiers that incorporated sagittal, regional, and global spinopelvic alignment and neurological status. The descriptors included: “C,” “CT,” and “T” for primary cervical kyphotic deformities with an apex in the cervical spine, cervicothoracic junction, or thoracic spine, respectively; “S” for primary coronal deformity with a coronal Cobb angle ≥ 15°; and “CVJ” for primary craniovertebral junction deformity. The modifiers included C2–7 sagittal vertical axis (SVA), horizontal gaze (chin-brow to vertical angle [CBVA]), T1 slope (TS) minus C2–7 lordosis (TS–CL), myelopathy (modified Japanese Orthopaedic Association [mJOA] scale score), and the Scoliosis Research Society (SRS)-Schwab classification for thoracolumbar deformity. Application of the classification system requires the following: 1) full-length standing posteroanterior (PA) and lateral spine radiographs that include the cervical spine and femoral heads; 2) standing PA and lateral cervical spine radiographs; 3) completed and scored mJOA questionnaire; and 4) a clinical photograph or radiograph that includes the skull for measurement of the CBVA. A series of 10 CSD cases, broadly representative of the classification system, were selected and sufficient radiographic and clinical history to enable classification were assembled. A panel of spinal deformity surgeons was queried to classify each case twice, with a minimum of 1 intervening week. Inter- and intrarater reliability measures were based on calculations of Fleiss k coefficient values.

RESULTS

Twenty spinal deformity surgeons participated in this study. Interrater reliability (Fleiss k coefficients) for the deformity descriptor rounds 1 and 2 were 0.489 and 0.280, respectively, and mean intrarater reliability was 0.584. For the modifiers, including the SRS-Schwab components, the interrater (round 1/round 2) and intrarater reliabilities (Fleiss k coefficients) were: C2–7 SVA (0.338/0.412, 0.584), horizontal gaze (0.779/0.430, 0.768), TS-CL (0.721/0.567, 0.720), myelopathy (0.602/0.477, 0.746), SRS-Schwab curve type (0.590/0.433, 0.564), pelvic incidence-lumbar lordosis (0.554/0.386, 0.826), pelvic tilt (0.714/0.627, 0.633), and C7-S1 SVA (0.071/0.064, 0.233), respectively. The parameter with the poorest reliability was the C7–S1 SVA, which may have resulted from differences in interpretation of positive and negative measurements.

CONCLUSIONS

The proposed classification provides a mechanism to assess CSD within the framework of global spinopelvic malalignment and clinically relevant parameters. The intra- and interobserver reliabilities suggest moderate agreement and serve as the basis for subsequent improvement and study of the proposed classification.

Impact of dynamic alignment, motion, and center of rotation on myelopathy grade and regional disability in cervical spondylotic myelopathy

OBJECT

Cervical stenosis is a defining feature of cervical spondylotic myelopathy (CSM). Matsunaga et al. proposed that elements of stenosis are both static and dynamic, where the dynamic elements magnify the canal deformation of the static state. For the current study, the authors hypothesized that dynamic changes may be associated with myelopathy severity and neck disability. This goal of this study was to present novel methods of dynamic motion analysis in CSM.

METHODS

A post hoc analysis was performed of a prospective, multicenter database of patients with CSM from the AOSpine North American study. One hundred ten patients (34%) met inclusion criteria, which were symptomatic CSM, age over 18 years, baseline flexion/extension radiographs, and health-related quality of life (HRQOL) questionnaires (modified Japanese Orthopaedic Association [mJOA] score, Neck Disability Index [NDI], the 36-Item Short Form Health Survey Physical Component Score [SF-36 PCS], and Nurick grade). The mean age was 56.9 ± 12 years, and 42% of patients were women (n = 46). Correlations with HRQOL measures were analyzed for regional (cervical lordosis and cervical sagittal vertical axis) and focal parameters (kyphosis and spondylolisthesis between adjacent vertebrae) in flexion and extension. Baseline dynamic parameters (flexion/extension cone relative to a fixed C-7, center of rotation [COR], and range of motion arc relative to the COR) were also analyzed for correlations with HRQOL measures.

RESULTS

At baseline, the mean HRQOL measures demonstrated disability and the mean radiographic parameters demonstrated sagittal malalignment. Among regional parameters, there was a significant correlation between decreased neck flexion (increased C2–7 angle in flexion) and worse Nurick grade (R = 0.189, p = 0.048), with no significant correlations in extension. Focal parameters, including increased C-7 sagittal translation overT-1 (slip), were significantly correlated with greater myelopathy severity (mJOA score, Flexion R = −0.377, p = 0.003; mJOA score, Extension R = −0.261, p = 0.027). Sagittal slip at C-2 and C-4 also correlated with worse HRQOL measures. Reduced flexion/extension motion cones, a more posterior COR, and smaller range of motion correlated with worse general health SF-36 PCS and Nurick grade.

CONCLUSIONS

Dynamic motion analysis may play an important role in understanding CSM. Focal parameters demonstrated a significant correlation with worse HRQOL measures, especially increased C-7 sagittal slip in flexion and extension. Novel methods of motion analysis demonstrating reduced motion cones correlated with worse myelopathy grades. More posterior COR and smaller range of motion were both correlated with worse general health scores (SF-36 PCS and Nurick grade). To our knowledge, this is the first study to demonstrate correlation of dynamic motion and listhesis with disability and myelopathy in CSM.

Cervical Sagittal Alignment in Scheuermann Disease

STUDY DESIGN

Retrospective evaluation of radiographs.

OBJECTIVE

The aim of this study was to assess sagittal cervical balance in patients with the two types Scheuermann disease (SD).

SUMMARY OF BACKGROUND DATA

The structural hyperkyphosis characterizing SD may be localized in the thoracic (SDT) or thoraco-lumbar (SDTL) spine segments. This may affect sagittal cervical balance.

METHODS

Seventy-one patients (41 males and 30 females), aged 16.3 ± 3.8 years with SD, were enrolled into the study. On standing lateral long-cassette radiographs, the following measurements were made: C0-2 angle, C2-7 angle (CL), C1-C2 angle, relative rotation angle (RRA)-measured at levels from C2 to C7, cervical tilt (CT), thoracic inlet angle (TIA), T1 slope, neck tilt (NT), C0-angle, cranial offset (CO), and cranial tilt (CRT). Comparison with t test was performed with significance level P < 0.05.

RESULTS

There were 38 SDT and 33 SDTL patients. In SDT, the T1 slope was significantly greater than that in SDTL (38.1° vs. 28.9°; P = 0.0002), and consequently CL (-19.8° vs. -8.9°; P = 0.0160), CT (29.8° vs. 24.3°; P = 0.0190), and TIA (81.9° vs. 71.1°; P = 0.0022) in SDT were significantly greater as well. The difference in CL was expressed mainly in C6-C5 (-4.8° vs. -1.4°; P = 0.0146) and C5-C4 (-4.4°; vs. -1.5° P = 0.0464) segments. There were no significant differences in proximal cervical lordosis: C0-2 angle (-21.6° vs. -20.8°; P = 0.7597), C1-C2 angle (-30.8°vs. -27.5°; P = 0.1746), C3-C2 (-5.4° vs. -5.1°; P = 0.7976), and C4-C3 (3.5° vs. -1.5°; P = 0.1464) segments. There was no significant difference in cranial parameters C0-angle, CRT, and CO.

CONCLUSION

Scheuermann disease type has an influence on cervical sagittal balance. Localization of structural kyphosis affects the T1 slope as well as C2-C7 lordosis, cervical tilt, and thoracic inlet angle. Significant difference in C2-C7 lordosis in comparison to similar C0-2 lordosis demonstrates that compensation is present in subaxial cervical spine. Position of the head center of gravity is not dependent on the SD type.

LEVEL OF EVIDENCE

4.

Assessment of Impact of Long-Cassette Standing X-Rays on Surgical Planning for Cervical Pathology

BACKGROUND:

Understanding the role of regional segments of the spine in maintaining global balance has garnered significant attention recently. Long-cassette radiographs (LCR) are necessary to evaluate global spinopelvic alignment. However, it is unclear how LCRs impact operative decision-making for cervical spine pathology.

OBJECTIVE:

To evaluate whether the addition of LCRs results in changes to respondents' operative plans compared to standard imaging of the involved cervical spine in an international survey of spine surgeons.

METHODS:

Fifteen cases (5 control cases with normal and 10 test cases with abnormal global alignment) of cervical pathology were presented online with a vignette and cervical imaging. Surgeons were asked to select a surgical plan from 6 options, ranging from the least (1 point) to most (6 points) extensive. Cases were then reordered and presented again with LCRs and the same surgical plan question.

RESULTS:

One hundred fifty-seven surgeons completed the survey, of which 79% were spine fellowship trained. The mean response scores for surgical plan increased from 3.28 to 4.0 (P = .003) for test cases with the addition of LCRs. However, no significant changes (P = .10) were identified for the control cases. In 4 of the test cases with significant mid thoracic kyphosis, 29% of participants opted for the more extensive surgical options of extension to the mid and lower thoracic spine when they were provided with cervical imaging only, which significantly increased to 58.3% upon addition of LCRs.

CONCLUSION:

In planning for cervical spine surgery, surgeons should maintain a low threshold for obtaining LCRs to assess global spinopelvic alignment.

Prospective Multicenter Assessment of Early Complication Rates Associated With Adult Cervical Deformity Surgery in 78 Patients

BACKGROUND

Acute kidney injury (AKI) is a serious postoperative complication.

OBJECTIVE

To determine whether AKI in patients after craniotomy is associated with heightened 30-day mortality.

METHODS

We performed a 2-center, retrospective cohort study of 1656 craniotomy patients who received critical care between 1998 and 2011. The exposure of interest was AKI defined as meeting RIFLE (Risk, Injury, Failure, Loss of Kidney Function, and End-stage Kidney Disease) class risk, injury, and failure criteria, and the primary outcome was 30-day mortality. Adjusted odds ratios were estimated by multivariable logistic regression models with inclusion of covariate terms thought to plausibly interact with both AKI and mortality. Additionally, mortality in craniotomy patients with AKI was analyzed with a risk-adjusted Cox proportional hazards regression model and propensity score matching as a sensitivity analysis.

RESULTS

The incidences of RIFLE class risk, injury, and failure were 5.7%, 2.9%, and 1.3%, respectively. The odds of 30-day mortality in patients with RIFLE class risk, injury, or failure fully adjusted were 2.79 (95% confidence interval “CI”, 1.76-4.42), 7.65 (95% CI, 4.16-14.07), and 14.41 (95% CI, 5.51-37.64), respectively. Patients with AKI experienced a significantly higher risk of death during follow-up; hazard ratio, 1.82 (95% CI, 1.34-2.46), 3.37 (95% CI, 2.36-4.81), and 5.06 (95% CI, 2.99-8.58), respectively, fully adjusted. In a cohort of propensity score-matched patients, RIFLE class remained a significant predictor of 30-day mortality.

Anterior cervical corpectomy for cervical spondylotic myelopathy: Reconstruction with expandable cylindrical cage versus iliac crest autograft. A retrospective study

OBJECTIVES

To compare retrospectively the clinical and radiographic outcomes between cervical reconstruction with expandable cylindrical cage (ECC) and iliac crest autograft after one- or two-level anterior cervical corpectomy for spondylotic myelopathy.

PATIENTS AND METHODS

Forty-two patients underwent cervical reconstruction with either iliac crest autograft and plating (20 patients) or ECC and plating (22 patients). The average clinical and radiological follow-up period was 77.54 ± 44.28 months (range 14-155 months). The authors compared clinical parameters (Nurick Myelopathy Grade, modified Japanese Orthopedic Association (mJOA) scores), perioperative parameters (hospital stays, complications) and radiological parameters (Cobb's angles of the fused segments and C2-C7 segments, cervical subsidence, fusion rate). Fusion was assessed on flexion-extension X-ray films.

RESULTS

No significant differences between the two groups were found in demographics, neurological presentation, preoperative sagittal alignment, clinical improvement and length of hospitalization. Patients of the autograft group experienced more postoperative complications, although the difference between the two treatment groups was not statistically significant (15 versus 4.5%, p=0.232). The fusion rate was 100% in both groups. The average lordotic increase of the segmental angle was significantly greater in the ECC group (p<0.05). Other radiological parameters were not significantly different in the two groups.

CONCLUSION

Cervical reconstruction either with iliac crest autograft and plating or ECC and plating provides good clinical results and similar fusion rates after one- or two-level corpectomy for spondylotic myelopathy. However, the use of ECC obviates donor site complications and provides a more significant increase of lordosis in segmental angle.

Analysis of Cervical Sagittal Balance Parameters in MRIs of Patients with Disc-Degenerative Disease

Background

The aim of this study was to explore the correlations between the different parameters of the cervical sagittal balance in magnetic resonance images (MRI) and evaluate the criteria for their clinical application in disc-degenerative diseases.

Material/Methods

We conducted a retrospective review of the MRIs of 125 adult outpatients with disc-degenerative diseases of the cervical spine; the images were obtained between May and July 2014 at our institute. The control group comprised 50 volunteers whose MRIs were also obtained. The parameters measured in the MRIs were: neck tilt (NT), T1 slope (T1S), thoracic inlet angle (TIA), and Cobb’s angle (C2–7). The correlation between the various parameters was analyzed using the Pearson correlation coefficient.

Results

The outpatients group showed moderate correlation between TIA and T1S, a significant correlation between TIA and NT, a weak correlation between T1S and Cobb’s angle, and a weakly negative correlation between T1S and NT. Further, the TIA showed no significant difference between the outpatient group and the control group, as per the sample t test.

Conclusions

Our findings indicate that TIA, T1S, and NT could be used as indices for the evaluation of cervical sagittal balance and that the TIA could be used as a reference to assess the cervical compensation. Restoration of the NT and T1S should be considered as a goal of surgical treatment during the preoperative planning in patients with disc-degenerative diseases.

Correlation between cervical spine sagittal alignment and clinical outcome after cervical laminoplasty for ossification of the posterior longitudinal ligament

OBJECTIVE

The goal of this study was to determine the relationship between cervical spine sagittal alignment and clinical outcomes after cervical laminoplasty in patients with ossification of the posterior longitudinal ligament (OPLL).

METHODS

Fifty consecutive patients who underwent a cervical laminoplasty for OPLL between January 2012 and January 2013 and who were followed up for at least 1 year were analyzed in this study. Standing plain radiographs of the cervical spine, CT (midsagittal view), and MRI (T2-weighted sagittal view) were obtained (anteroposterior, lateral, flexion, and extension) pre- and postoperatively. Cervical spine alignment was assessed with the following 3 parameters: the C2-7 Cobb angle, C2-7 sagittal vertical axis (SVA), and T-1 slope minus C2-7 Cobb angle. The change in cervical sagittal alignment was defined as the difference between the post- and preoperative C2-7 Cobb angles, C2-7 SVAs, and T-1 slope minus C2-7 Cobb angles. Outcome assessments (visual analog scale [VAS], Oswestry Neck Disability Index [NDI], 36-Item Short-Form Health Survey [SF-36], and Japanese Orthopaedic Association [JOA] scores) were obtained in all patients pre- and postoperatively.

RESULTS

The average patient age was 56.3 years (range 38-72 years). There were 34 male patients and 16 female patients. Cervical laminoplasty for OPLL helped alleviate radiculomyelopathy. Compared with the preoperative scores, improvement was seen in postoperative VAS and JOA scores. After laminoplasty, 35 patients had kyphotic changes, and 15 had lordotic changes. However, cervical sagittal alignment after laminoplasty was not significantly associated with clinical outcomes in terms of postoperative improvement of the JOA score (C2-7 Cobb angle: p = 0.633; C2-7 SVA: p = 0.817; T-1 slope minus C2-7 lordosis: p = 0.554), the SF-36 score (C2-7 Cobb angle: p = 0.554; C2-7 SVA: p = 0.793; T-1 slope minus C2-7 lordosis: p = 0.829), the VAS neck score (C2-7 Cobb angle: p = 0.263; C2-7 SVA: p = 0.716; T-1 slope minus C2-7 lordosis: p = 0.497), or the NDI score (C2-7 Cobb angle: p = 0.568; C2-7 SVA: p = 0.279; T-1 slope minus C2-7 lordosis: p = 0.966). Similarly, the change in cervical sagittal alignment was not related to the JOA (p = 0.604), SF-36 (p = 0.308), VAS neck (p = 0.832), or NDI (p = 0.608) scores.

CONCLUSIONS

Cervical laminoplasty for OPLL improved radiculomyelopathy. Cervical laminoplasty increased the probability of cervical kyphotic alignment. However, cervical sagittal alignment and clinical outcomes were not clearly related.

Postoperative Recovery After Adult Spinal Deformity Surgery: Comparative Analysis of Age in 149 Patients During 2-year Follow-up

STUDY DESIGN

Retrospective review of a multicenter, prospective adult spinal deformity (ASD) database.

OBJECTIVE

We hypothesized that increased age and increased preoperative disability would negatively impact both the length of time needed to achieve maximal recovery and the amount of functional improvement achieved. In order to gauge the recovery process, a normalization process was used to calculate an integrated health state (IHS) during the 2-year postoperative period.

SUMMARY OF BACKGROUND DATA

Elderly patients with ASD generally have worse baseline health-related quality of life (HRQOL) measures than younger patients. Current methods of reporting outcomes are limited, perhaps diminishing the health impact of the entire postoperative recovery experience.

METHODS

Inclusion criteria included 18 or more years and ASD. Patient groups: young (≤45 yr), middle (46-64), elderly (≥65) as well as by baseline Oswestry Disability Index (ODI) scores: MILD (0-30), MEDIUM (31-49), and HIGH (≥50). Collected HRQOL measures included ODI, Short Form-36(PCS/MCS), and Scoliosis Research Society-22 (SRS22) at baseline, 6 weeks, 1, and 2-year postoperative. All HRQOL measures were normalized to each patient's baseline scores. A 2-year IHS was calculated for each individual patient and the means were compared between groups.

RESULTS

149 patients were included (≤45:32, 46-64:67, ≥65:50). All groups significantly improved in all HRQOL at 2-year compared with baseline (P < 0.05) except for MCS, ODI, and SRS activity for the 45 or less group (P > 0.05). Normalized IHS HRQOL for young patients was worse than elderly for ODI, PCS, MCS, SRS activity, pain and total during the 2-year recovery period from index surgery. The MILD ODI group had significantly worse 2-year IHS values than the HIGH group for all HRQOL measured (P < 0.05) except SRS appearance and satisfaction (P > 0.05).

CONCLUSION

Contrary to our hypothesis, an IHS analysis suggested that the recovery process was significantly better for elderly patients than young patients and better for patients with high baseline disability.

LEVEL OF EVIDENCE

3.

Magnitude of preoperative cervical lordotic compensation and C2-T3 angle are correlated to increased risk of postoperative sagittal spinal pelvic malalignment in adult thoracolumbar deformity patients at 2-year follow-up

BACKGROUND CONTEXT

Cervical deformity (CD) is prevalent among patients with adult spinal deformity (ASD). The effect of baseline cervical alignment on achieving optimal thoracolumbar alignment in ASD surgery is unclear.

PURPOSE

This study assesses the relationship between preoperative (preop) cervical spinal parameters and global alignment after thoracolumbar ASD surgery at 2-year follow-up.

STUDY DESIGN/SETTING

This study is a retrospective review of a multicenter, prospective database.

PATIENT SAMPLE

Surgical ASD patients with 2-year follow-up and cervical X-rays were included.

OUTCOME MEASURES

The outcome measures were radiographic parameters and self-reported health-related quality-of-life measures (Short-Form 36 [SF-36], Oswestry Disability Index [ODI], and Scoliosis Research Society 22 [SRS-22]).

METHODS

Surgical ASD patients of 18 years and older with scoliosis greater than or equal to 20° and one of the following radiographic parameters were included: sagittal vertical axis (SVA) greater than or equal to 5 cm, pelvic tilt (PT) greater than or equal to 25°, or thoracic kyphosis (TK) greater than 60°. The SRS-Schwab sagittal modifiers (PT, global alignment, and pelvic incidence and lumbar lordosis [PI-LL]) were assessed at 2-year postoperatively as either normal ("0") or abnormal ("+" or "++"). Patients were classified in the aligned group (AG) or malaligned group (MG) at 2-year follow-up if all three sagittal modifiers were normal or abnormal, respectively. Patients were assessed for CD based on the following criteria: C2-C7 SVA greater than 4 cm, C2-C7 SVA less than 4 cm, cervical kyphosis (CL greater than 0), cervical lordosis (CL less than 0), any deformity (C2-C7 SVA greater than 4 cm or CL greater than 0), and both CD (C2-C7 SVA greater than 4 cm and CL greater than 0). Univariate testing was performed using t or chi-square test, looking at the following preop parameters: CD, C2-C7 SVA, C2-T3 SVA, CL, T1 slope (T1S), T1S-CL, C2-T3 angle, LL, TK, PT, C7-S1 SVA, and PI-LL.

RESULTS

One hundred four patients met the initial inclusion criteria with 70 in the AG and 34 in MG. Preoperative, patients in the MG had a higher CL (11.7 vs. 4.9, p=.03), higher C2-T3 angle (13.59 vs 4.9 p=.01), higher PT (p<.0001), higher SVA (p<.0001), and higher PI-LL (p<.0001) compared with the AG. Interestingly, the prevalence of CD at baseline was similar for both groups. There was no statistically significant difference among groups in the amount of improvement more than 2 years on the ODI or the Physical Component Summary of SF-36.

CONCLUSIONS

Patients with sagittal spinal malalignment associated with significant cervical compensatory lordosis are at increased risk of realignment failure at 2-year follow-up. Assessment of the degree of cervical compensation may be helpful in preop evaluation to assist in realignment outcome prediction.