C2-7 Sagittal Vertical Axis Research Articles

Radiological features of dropped head syndrome.

This study aimed to elucidate the specificity of the radiological features of Dropped head syndrome (DHS) from both reginal and global aspects. We enrolled 53 patients with DHS (8 men, 45 women; mean age 73.5 years), and captured their lateral spinopelvic radiographs in standing position. We also selected 21 age- and sex-matched controls with cervical spondylosis. Radiological parameters were measured and compared between two groups. Compensatory and decompensatory sites were also listed for each patient. Radiological factors such as sagittal vertical axis (SVA), clivo-axial angle (CAA), C2-7 angle, C2-7 SVA, anterior slippage of the vertebra, alignment. C1, C2, C3, C4, C5, C6 slopes, and T1 slope-C2-7 angle showed statistically significant differences between the groups. Multivariate logistic regression showed that SVA, C2-7 SVA, T1-slope-C2-7 angle, and C1 slope were the most important factors specific to DHS. Sole cervical spine and involvement of both cervical and thoracic spine accounted for 22% and 29% of the decompensatory sites in DHS respectively. Notably, 24% of the patients did not show decompensation of the cervical spine. While, 93% exhibited compensation at the craniovertebral junction. The thoracic spine contributed 70% to DHS compensation. This study indicated the radiological features of DHS from both regional and global aspects. Compensatory and decompensatory DHS mechanisms varied among individuals. Compensation was likely to be developed at the neighboring sites, with the craniovertebral and thoracic junctions as the proximal and distal parts for DHS, respectively.

Laminoplasty with foraminotomy versus anterior cervical discectomy and fusion for cervical myeloradiculopathy

BACKGROUND CONTEXTAnterior cervical discectomy and fusion (ACDF) combined with uncinate process resection and laminoplasty combined with foraminotomy (LPF) have been used to achieve cervical cord and root decompression in patients with combined cervical myeloradiculopathy (CMR). PURPOSETo compare the clinical and radiographic outcomes of ACDF with those of LPF for the treatment of CMR. STUDY DESIGN/SETTINGPropensity score-matched retrospective cohort study. PATIENT SAMPLEPatients with CMR who underwent ACDF or LPF and were followed up for at least 2 years. OUTCOME MEASURESC2–C7 lordosis, C2–C7 sagittal vertical axis, and cervical range of motion (ROM) were determined. The visual analog scale (VAS) scores for neck and arm pain, neck disability index (NDI), and Japanese Orthopedic Association (JOA) scores were analyzed. METHODSThe radiographic and clinical outcomes of the 2 groups were compared. RESULTSEighty-four patients were included (n=42 in each group) after application of the inclusion criteria and propensity score matching. A significant decrease in C2–C7 lordosis (p<.001) and ROM (p<.001) was observed in the LPF and ACDF groups, respectively. LPF was associated with a significant decrease in C2 to C7 lordosis (p<.001), while ACDF caused a significant decrease in cervical ROM (p<.001). ACDF effectively improved neck pain VAS (p<.001) and NDI (p<.001), while neck pain did not significantly improve after LPF (p=.103). Furthermore, neck pain VAS (p=0.026) and NDI (p=.021) at postoperative 6 months, were significantly greater in the LPF group than in the ACDF group, while the difference was not statistically significant at 2 years postoperatively (neck pain VAS, p=.502; NDI, p=.085). Arm pain VAS and JOA score both significantly improved after LPF (p=0.003 and 0.043, respectively) or ACDF (p<.001 and 0.039, respectively), and postoperative results were not significantly different between the 2 groups. CONCLUSIONLPF and ACDF yielded similar outcomes for arm pain and neurological recovery. More immediate neck pain improvement was observed with ACDF, while neck pain after 2 years postoperatively was similar between the LPF and ACDF groups. Furthermore, increased postoperative loss of lordosis was observed in the LPF group, whereas decreased postoperative ROM was observed in the ACDF group. These findings should be considered when deciding the surgical method for patients with CMR. LEVEL Of EVIDENCEIII.

The Effect of Global Spinal Alignment on Cervical Degeneration in Patients with Degenerative Lumbar Scoliosis

To elucidate the effect of global spinal alignment on cervical degeneration in patients with degenerative lumbar scoliosis (DLS). This study included 117 patients with DLS and 42 patients with lumbar spinal stenosis as a control group. Patients with DLS (study group) were categorized according to the Scoliosis Research Society-Schwab classification. Spinopelvic parameters were measured in cervical and full-length spine radiographs. Cervical degeneration was assessed using the cervical degeneration index (CDI) scoring system. There were significant differences in C2-C7 sagittal vertical axis, T1 slope, thoracic kyphosis, lumbar lordosis (LL), and pelvic tilt between DLS and control groups. Although the DLS and control groups did not differ significantly with regard to CDI scores, a striking difference was noted when sagittal spinopelvic modifiers were considered individually. Patients with a pelvic incidence (PI)-LL mismatch modifier grade of++ had significantly higher CDI scores than patients with grade 0, and patients with a PI-LL or sagittal vertical axis modifier grade of++ had significantly higher CDI scores than the control group. Disk narrowing scores were highest in patients with a PI-LL modifier grade of++ followed by patients with a grade of+. Additionally, CDI scores were more associated with LL rather than cervical lordosis. Patients with DLS may be at greater risk of cervical spine degeneration, especially patients with a PI-LL or sagittal vertical axis modifier grade of++. A surgical strategy for patients with DLS should be carefully selected considering the restoration of LL.

Single-position oblique lumbar interbody fusion with navigation: improved efficiency and screw accuracy compared to dual-position with fluoroscopy

Dual-position oblique lumbar interbody fusion with fluoroscopy (D-OLIF) requires repositioning the patient to a prone position for pedicle screw insertion. Recently, single-position surgery with navigation has been introduced. However, there are concerns regarding pedicle screw accuracy and achieving appropriate sagittal balance in single-position OLIF with navigation (S-OLIF). The purpose of this study is to evaluate the clinical and radiological outcomes of S-OLIF compared to D-OLIF. A retrospective analysis was conducted on 102 patients who underwent single-level OLIF at a single institution. The patients were divided into two groups: 55 in the S-OLIF group and 47 in the D-OLIF group. The numeric rating scale for back and leg, Oswestry disability index, and walking distance improvements showed no significant difference. However, the EuroQol 5-dimension 5-level index showed higher improvement in the S-OLIF (P = 0.029). The segmental lordosis, lumbar lordosis, and C7 sagittal vertical axis showed no significant difference. S-OLIF had significantly fewer cases of pedicle screw malposition (P = 0.045). Additionally, the surgery time was shorter in the S-OLIF (P = 0.002). In conclusion, S-OLIF exhibited clinical and radiological outcomes comparable to D-OLIF, with the added advantages of reduced surgery time and enhanced accuracy in pedicle screw placement.

Can the 6-minute Walking Test Assess Ambulatory Function Impairment in Patients With Cervical Spondylotic Myelopathy?

Prospective cohort study. Investigating the ability of a 6-minute walking test (6MWT) to assess functional status in patients with cervical spondylotic myelopathy (CSM). The 6MWT provides an objective assessment of a patient's ability to walk. There is the potential for its application to the assessment of functional status in patients with CSM. One hundred thirty-five patients from our institution were prospectively enrolled from July 2022 to August 2023. A control group of age-matched and sex-matched healthy individuals was established. The 6MWT was conducted in strict accordance with established guidelines. The Nurick score, the Prolo score, the Cooper-myelopathy-scale score (CMS), the Japanese Orthopedic Association score (JOA) and the European-myelopathy-scale score (EMS) were assessed preoperatively. Visual Analog Scale (VAS) for pain or numbness and Oswestry Neck Disability Index (NDI) were also collected. Radiographic parameters were measured and recorded. Continuous variables between patients and controls were compared by applying the t test. The χ 2 test was used to compare gender ratios between groups. Pearson correlation analysis was used to analyze the association between continuous variables and ordinal variables. Subgroups of CSM patients were analyzed according to global spinal alignment types based on whether the SVA was ≥50mm. Clinical scores and imaging parameters were compared by t test. The preoperative 6-minute walking distance (6MWD) of CSM patients was 309.34 ± 116.71m, which was significantly lower than that of the controls (464.30 ± 52.59m, P <0.01). The 6MWD was significantly correlated with scores on all clinical scales except the VAS. CMS Lower extremity score had the strongest correlation with preoperative 6MWD in CSM patients (r=-0.794, P <0.01). Of the sagittal alignment parameters, only C7 sagittal vertical axis (SVA) and T1 slope were significantly correlated with 6MWD(r=-0.510, -0.360, respectively). CSM patients with SVA >50mm had significantly lower 6MWD than CSM patients with SVA ≤50mm (168.00 ± 137.26 vs. 346.24 ± 84.27m, P <.01). The 6MWD of CSM patients was significantly lower than that of the healthy population and correlated well with commonly used clinical scales. The 6MWD can potentially assist in the assessment of functional status in patients with CSM.

Titanium-Coated Polyetheretherketone Cages Vs Full Titanium Cages for Stand-Alone 1- or 2-Level Anterior Cervical Discectomy and Fusion: A Comparative Study.

Anterior cervical discectomy and fusion (ACDF) for the surgical treatment of cervical degenerative disease often includes an intervertebral cage, which restores disc height and lordosis while promoting fusion . Cage materials include titanium (TTN) or polyetheretherketone (PEEK). Controversy in material selection stems from higher fusion rates with TNN, despite a higher subsidence rate, while PEEK cages demonstrate superior preservation of interspace height. Combining the advantages of both materials, TTN-coated PEEK (TCPEEK) cages were developed, featuring a PEEK core with similar stiffness to the bone, enveloped with a TTN coat, improving osteointegration. However, the potential superiority of TCPEEK over TTN cages has not been investigated. This study aimed to compare clinical and radiographic outcomes following single- or double-level ACDF using either TTN or TCPEEK cages. This retrospective single-center study included patients undergoing single- or double-level ACDF between 2017 and 2019. Clinical outcomes included the Neck Disability Index and revision surgery incidence. Radiographic parameters included cervical and segmental lordosis, C2 to C7 sagittal vertical axis, fusion, subsidence, and adjacent segment degeneration at a minimum 12-month follow-up. A total of 45 patients (16 TTN; 29 TCPEEK) and 58 cervical levels (21 TTN; 37 TCPEEK) were included. Both cages significantly improved Neck Disability Index scores (TTN -10.0; TCPEEK -14.1) without significant differences. Two single-level TCPEEK patients required revision surgery due to non-union. In the radiological assessments, no significant difference was found for subsidence rates (TTN 52.4%; TCPEEK 56.8%), adjacent segment degeneration, cervical and segmental lordosis, and changes in C2 to C7 sagittal vertical axis. Though not statistically significant, fusion rates trended slightly higher with TTN (90.5%) vs TCPEEK cages (86.5%). TTN and TCPEEK cages achieve satisfactory clinical and radiological outcomes in single- or double-level ACDF. This finding suggests that the choice between them can be based on other factors, such as surgeon preference or availability, rather than specific material properties. This study found that the selection of ACDF cage material did not affect clinical outcomes.

Cervical kyphosis after posterior cervical laminectomy with and without fusion

BackgroundCervical posterior instrumentation and fusion is often performed to avoid post-laminectomy kyphosis. However, larger comparative analyses of cervical laminectomy with or without fusion are sparse.MethodsA retrospective, two-center, comparative cohort study included patients after stand-alone dorsal laminectomy with (n = 91) or without (n = 46) additional fusion for degenerative cervical myelopathy with a median follow-up of 59 (interquartile range (IQR) 52) months. The primary outcome was the C2-7 Cobb angle and secondary outcomes were Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA) scale, revision rates, T1 slope and C2-7 sagittal vertical axis (C2-7 SVA) at final follow-up. Logistic regression analysis adjusted for potential confounders (i.e. age, operated levels, and follow-up). Results: Preoperative C2-7 Cobb angle and T1 slope were higher in the laminectomy group, while the C2-7 SVA was similar. The decrease in C2-7 Cobb angle from pre- to postoperatively was more pronounced in the laminectomy group (− 6° (IQR 20) versus −1° (IQR 7), p = 0.002). When adjusting for confounders, the decrease in C2-7 Cobb angle remained higher in the laminectomy group (coefficient − 12 (95% confidence interval (CI) −18 to −5), p = 0.001). However, there were no adjusted differences for postoperative NDI (− 11 (− 23 to 2), p = 0.10), mJOA, revision rates, T1 slope and C2-7 SVA. Conclusion: Posterior cervical laminectomy without fusion is associated with mild loss of cervical lordosis of around 6° in the mid-term after approximately five years, however without any clinical relevance regarding NDI or mJOA in well-selected patients (particularly in shorter segment laminectomies of < 3 levels).

Correlation between axial symptoms and cervical sagittal alignment parameters in patients with two-level or three-level cervical spondylotic myelopathy: anterior cervcial discectomy and fusion versus hybird surgery.

To comparatively analyze the correlation between axial symptoms (AS) and cervical sagittal alignment parameters after anterior cervical discectomy and fusion (ACDF) and hybrid surgery (HS). From January 2018 to June 2023, 74 patients who underwent ACDF (n = 36) or HS (n = 38) for two-level or three-level cervical spondylotic myelopathy were retrospectively analyzed. The Visual Analogue Scale (VAS), Japanese Orthopedic Association (JOA), Neck Disability Index (NDI) were recorded to assess clinical outcomes. Cervical sagittal alignment parameters (Cobb's angle C2-7, C7 slope [C7S], and C2-7 sagittal vertical axis [C2-7 SVA]) were measured preoperatively, 3days postoperatively, and at the last follow-up. The range of motion (ROM) of C2-7 and ROM of surgical segment were measured. The occurrence of AS was observed at the last follow-up. Logistic regression was used to analyze the correlation between postoperative AS and cervical sagittal alignment parameters. Both in ACDF group and HS group, VAS, JOA and NDI scores showed significant improvements at 3-day postoperation and at the last follow-up (P < 0.05). However, there was no significant difference between the two groups (P > 0.05). The Cobb's angle C2-7 and C7S were significantly increased at 3days postoperation compared with pre-operatively in both groups (P < 0.05). C2-7SVA was increased in both groups 3days after surgery compared with pre-operatively, but there was no significant difference (P > 0.05). At the last follow-up, the ROM of C2-7 in ACDF group was significantly smaller than HS group (P < 0.05). The prevalence of postoperative AS in the ACDF group and HS group was 41.7 and 18.4%, respectively, with statistical difference between the two groups (P < 0.05). When simple Logistic regression analysis was used, the last Cobb's angle C2-7 (β = -0.088), the last C2-7SVA (β = 0.099) in ACDF group and the last C2-7SVA (β = 0.222) in HS group were all correlated with the occurrence of postoperative AS. When multiple Logistic regression analysis was used, only the last C2-7SVA (β = 0.181) in the HS group was positively correlated with the occurrence of postoperative AS. Both ACDF and HS can achieve satisfied clinical outcomes. ACDF and HS can improve cervical sagittal balance to a certain extent, and HS is superior to ACDF in maintaining ROM. The decrease of the last Cobb's angle C2-7 and the increase of the last C2-7SVA may be related to the occurrence of AS after ACDF. The increase of the last C2-7SVA was an independent risk factor for the occurrence of AS after HS.

Importance of the cervical paraspinal muscles in postoperative patient-reported outcomes and maintenance of sagittal alignment after anterior cervical discectomy and fusion.

The aim of this study was to investigate the influence of preoperatively assessed paraspinal muscle parameters on postoperative patient-reported outcomes and maintenance of cervical sagittal alignment after anterior cervical discectomy and fusion (ACDF). Patients with preoperative and postoperative standing cervical spine lateral radiographs and preoperative cervical MRI who underwent an ACDF between 2015 and 2018 were reviewed. Muscles from C3 to C7 were segmented into 4 functional groups: anterior, posteromedial, posterolateral, and sternocleidomastoid. The functional cross-sectional area and also the percent fat infiltration (FI) were calculated for all groups. Radiographic alignment parameters collected preoperatively and postoperatively included C2-7 lordosis and C2-7 sagittal vertical axis (SVA). Neck Disability Index (NDI) scores were recorded preoperatively and at 2 and 4-6 months postoperatively. To investigate the relationship between muscle parameters and postoperative changes in sagittal alignment, multivariable linear mixed models were used. Multivariable linear regression models were used to analyze the correlations between the changes in NDI scores and the muscles' FI. A total of 168 patients with NDI and 157 patients with sagittal alignment measurements with a median follow-up of 364 days were reviewed. The mixed models showed that a greater functional cross-sectional area of the posterolateral muscle group at each subaxial level and less FI at C4-6 were significantly associated with less progression of C2-7 SVA over time. Moreover, there was a significant correlation between greater FI of the posteromedial muscle group measured at the C7 level and less NDI improvement at 4-6 months after ACDF. The findings highlight the importance of preoperative assessment of the cervical paraspinal muscle morphology as a predictor for patient-reported outcomes and maintenance of C2-7 SVA after ACDF.

Comparison of radiological and clinical outcomes of cervical laminoplasty versus lateral mass screw fixation in patients with ossification of the posterior longitudinal ligament

PurposeThis study aimed to compare cervical sagittal parameters and clinical outcomes between patients undergoing cervical laminoplasty(CL) and those undergoing lateral mass screw fixation(LMS).MethodsWe retrospectively studied 67 patients with multilevel ossification of the posterior longitudinal ligament (OPLL) of the cervical spine who underwent lateral mass screw fixation (LMS = 36) and cervical laminoplasty (CL = 31). We analyzed cervical sagittal parameters (C2-7 sagittal vertical axis (C2-7 SVA), C0-2 Cobb angle, C2-7 Cobb angle, C7 slope (C7s), T1 slope (T1s), and spino-cranial angle (SCA)) and clinical outcomes (visual analog scale [VAS], neck disability index [NDI], Japanese Orthopaedic Association [JOA] scores, recovery rate (RR), and minimum clinically significant difference [MCID]). The cervical sagittal parameters at the last follow-up were analyzed by binary logistic regression. Finally, we analyzed the correlation between the cervical sagittal parameters and each clinical outcome at the last follow-up after surgery in both groups.ResultsAt the follow-up after posterior decompression in both groups, the mean values of C2-C7 SVA, C7s, and T1s in the LMS group were more significant than those in the CL group (P ≤ 0.05). Compared with the preoperative period, C2-C7 SVA, T1s, and SCA gradually increased, and the C2-C7 Cobb angle gradually decreased after surgery (P < 0.05). The improvement in the JOA score and the recovery rate was similar between the two groups, while the improvement in the VAS-N score and NDI score was more significant in the CL group (P = 0.001; P = 0.043). More patients reached MCID in the CL group than in the LMS group (P = 0.036). Binary logistic regression analysis showed that SCA was independently associated with whether patients reached MCID at NDI postoperatively. SCA was positively correlated with cervical NDI and negatively correlated with cervical JOA score at postoperative follow-up in both groups (P < 0.05); C2-7 Cobb angle was negatively correlated with cervical JOA score at postoperative follow-up (P < 0.05).ConclusionCL may be superior to LMS in treating cervical spondylotic myelopathy caused by OPLL. In addition, smaller cervical SCA after posterior decompression may suggest better postoperative outcomes.

The Effect of C2 Muscular Exposure Technique on Radiographic and Clinical Outcomes After C2-T2 Posterior Cervical Fusion.

Retrospective cohort analysis. To determine whether the C2 exposure technique was a predictor of change in cervical alignment and patient-reported outcomes measures (PROMs) after posterior cervical decompression and fusion (PCDF) for degenerative indications. In PCDF handling of the C2 posterior paraspinal musculature during the operative approach varies by surgeon technique. To date, no studies have investigated whether maintenance of the upper cervical semispinalis cervicis attachments as compared with complete reflection of upper cervical paraspinal musculature from the posterior bony elements is associated with superior radiographic and clinical outcomes after PCDF. All adult patients who underwent C2-T2 PCDF for myelopathy or myeloradiculopathy at multi-institutional academic centers between 2013 and 2020 were retrospectively identified. Patients were dichotomized by the C2 exposure technique into semispinalis preservation or midline muscular reflection groups. Preoperative and short and long-term postoperative radiographic outcomes (upper cervical alignment, global alignment, and fusion status) and PROMs (Visual Analog Scale-Neck, Neck Disability Index, and Short Form-12) were collected. Univariate analysis compared patient factors, radiographic measures, and PROMs across C2 exposure groups. A total of 129 patients met the inclusion/exclusion criteria (73 muscle preservation and 56 muscle reflection). Patients in the muscular preservation group were on average younger (P= 0.005) and more likely to have bone morphogenic protein (P< 0.001) and C2 pars screws (P= 0.006) used during surgery. Preoperative to postoperative changes in C2 slope, C2 tilt, C2-C3 segmental lordosis, C2-C3 listhesis, C0-C2 Cobb angle, proximal junctional kyphosis, ADI, C1 lamina-occiput distance, C2 sagittal vertical axis, C2-C7 lordosis, and PROMs at all follow-up intervals did not vary significantly by C2 exposure technique. Likewise, there were no significant differences in fusion status, C2-C3 pseudoarthrosis, C2 screw loosening, and complication and revision rates between C2 exposure groups. Preservation of C2 semispinalis attachments versus muscular reflection did not significantly impact cervical alignment, clinical outcomes, or proximal junction complications in long-segment PCDF. Level III.

The effect of C2 screw type on perioperative outcomes and long-term stability after C2-T2 posterior cervical decompression and fusion.

To determine if C2 pedicle versus pars screw type predicts change in fusion status, C2 screw loosening, cervical alignment, and patient-reported outcomes measures (PROMs) after C2-T2 posterior cervical decompression and fusion (PDCF). All adult patients who underwent C2-T2 PCDF for myelopathy or myeloradiculopathy between 2013-2020 were retrospectively identified. Patients were dichotomized by C2 screw type into bilateral C2 pedicle and bilateral C2 pars screw groups. Preoperative and short- and long-term postoperative radiographic outcomes and PROMs were collected. Univariate and multivariate analysis compared patient factors, fusion status, radiographic measures, and PROMs across groups. A total of 159 patients met the inclusion/exclusion criteria (76 bilateral pedicle screws, 83 bilateral pars screws). Patients in the C2 pars relative to C2 pedicle screw group were on average more likely to have bone morphogenic protein (p = 0.001) and four-millimeter diameter rods utilized intraoperatively (p = 0.033). There were no significant differences in total construct and C2-3 fusion rate, C2 screw loosening, or complication and revision rates between C2 screw groups in univariate and regression analysis. Changes in C2 tilt, C2-3 segmental lordosis, C0-2 Cobb angle, proximal junctional kyphosis, atlanto-dens interval, C1 lamina-occiput distance, C2 sagittal vertical axis, C2-7 lordosis, and PROMs at all follow-up intervals did not vary significantly by C2 screw type. There were no significant differences in fusion status, hardware complications, and radiographic and clinical outcomes based on C2 screw type following C2-T2 PCDF. Accordingly, intraoperative usage criteria can be flexible based on patient vertebral artery positioning and surgeon comfort level.

Characteristics and standards of severe sagittal imbalance in adult patients with spinal deformities: a retrospective analysis

ObjectiveTo analyze the characteristics of “severe” dynamic sagittal imbalance (DSI) in patients with adult spinal deformity (ASD) and establish criteria for them.MethodsWe retrospectively analyzed 102 patients with ASD presenting four cardinal signs of lumbar degenerative kyphosis. All patients underwent deformity corrective surgery and were divided into three groups according to the diagnostic criteria based on the Oswestry disability index and dynamic features (△Timewalk: time until C7 sagittal vertical axis [C7SVA] reaches ≥ 20 cm after the start of walking) of sagittal imbalance. The paravertebral back muscles were analyzed and compared using T2-weighted axial imaging. We performed a statistically time-dependent spinopelvic sagittal parameter analysis of full standing lateral lumbar radiographs. Lumbar flexibility was analyzed using dynamic lateral lumbar radiography.ResultsThe patients were classified into the mild (△Timewalk ≥ 180 s, 35 patients), moderate (180 s > △Timewalk ≥ 30 s, 38 patients), and severe (△Timewalk < 30 s, 29 patients) groups. The back muscles in the severe group exhibited a significantly higher signal intensity (533.4 ± 237.5, p < 0.05) and larger area of fat infiltration (35.2 ± 5.4, p < 0.05) than those in the mild (223.8 ± 67.6/22.9 ± 11.9) and moderate groups (294.4 ± 214.7/21.6 ± 10.6). The analysis of lumbar flexibility revealed significantly lower values in the severe group (5.8° ± 2.5°, p < 0.05) than in the mild and moderate groups (14.2° ± 12.4° and 11.4° ± 8.7°, respectively). The severe group had significantly lower lumbar lordosis (LL, 25.1° ± 22.7°, p < 0.05) and Pelvic incidence-LL mismatch (PI-LL, 81.5° ± 26.6°, p < 0.001) than those of the mild (8.2° ± 16.3°/58.7° ± 18.8°) and moderate (14.3° ± 28.6°/66.8° ± 13.4°) groups. On receiver operating characteristic curve analysis, PI-LL was statistically significant, with an area under the curve of 0.810 (95% confidence interval) when the baseline was set at 75.3°. The severe group had more postoperative complications than the other groups.ConclusionsOur results suggest the following criteria for severe DSI: C7SVA > 20 cm within 30 s of walking or standing, a rigid lumbar curve < 10° on dynamic lateral radiographs, and a PI-LL mismatch > 75.3°.Level of evidence3.

Are There Advantages in Cervical Intrafacetal Fusion With Minimal Posterolateral Fusion (PLF) Compared to Conventional PLF in Posterior Cervical Fusion?

We propose that cervical intrafacetal fusion (cIFF) using bone chip insertion into the facetal joint space additional to minimal PLF is a supplementary fusion method to conventional posterolateral fusion (PLF). Patients who underwent posterior cervical fixation accompanied by cIFF with minimal PLF or conventional PLF for cervical myelopathy from 2012 to 2023 were investigated retrospectively. Radiological parameters including Cobb angle and C2-7 sagittal vertical axis (SVA) were compared between the 2 groups. In cIFF with minimal PLF group, cIFF location and PLF location were carefully divided, and the fusion rates of each location were analyzed by computed tomography scan. Among enrolled 46 patients, 31 patients were in cIFF group, 15 in PLF group. The postoperative change of Cobb angle in 1-year follow-up in cIFF with minimal PLF group and conventional PLF group were 0.1° ± 4.0° and -9.7° ± 8.4° respectively which was statistically lower in cIFF with minimal PLF group (p = 0.022). Regarding the fusion rate in cIFF with minimal PLF group in postoperative 6 months, the rates was achieved in 267 facets (98.1%) in cIFF location, and 244 facets (89.7%) in PLF location (p < 0.001). Postoperative sagittal alignment was more preserved in cIFF with minimal PLF group compared with conventional PLF group. Additionally, in cIFF with minimal PLF group, the bone fusion rate of cIFF location was higher than PLF location. Considering the concerns of bone chip migration onto the spinal cord and relatively low fusion rate in PLF method, applying cIFF method using minimized PLF might be a beneficial alternative for posterior cervical decompression and fixation.

C4 constant vertebra: a novel benchmark of physiological cervical sagittal alignment.

Cervical sagittal alignment is essential, and there is considerable debate as to what constitutes physiological sagittal alignment. The purpose of this study was to identify constant parameters for characterizing cervical sagittal alignment under physiological conditions. A cross-sectional study was conducted in which asymptomatic subjects were recruited to undergo lateral cervical spine radiographs. Each subject was classified according to three authoritative cervical sagittal morphology classifications, followed by the evaluation of variations in radiological parameters across morphotypes. Moreover, the correlations among cervical sagittal parameters, age, and cervicothoracic junction parameters were also investigated. A total of 183 asymptomatic Chinese subjects were enrolled with a mean age of 48.4 years. Subjects with various cervical sagittal morphologies had comparable C4 endplate slope angles under all three different typing systems. Among patients of different ages, C2-C4 endplate slope angles remained constant. Regarding the cervicothoracic junction parameters, T1 slope and thoracic inlet angle affected cervical sagittal parameters, including cervical lordosis and C2-7 sagittal vertical axis, and were correlated with the endplate slope angles of C5 and below and did not affect the endplate slope angles of C4 and above. In general, the slope of the C4 inferior endplate ranges between 13° and 15° under different physiological conditions. In the asymptomatic population, the C4 vertebral body maintains a constant slope angle under physiological conditions. The novel concept of C4 as a constant vertebra would provide a vital benchmark for diagnosing pathological sagittal alignment abnormalities and planning the surgical reconstruction of cervical lordosis.

What is the Preferable Method for the C3 and C7 Segments in Unilateral Open-Door Laminoplasty for Patients Diagnosed with Cervical Spondylotic Myelopathy?

BackgroundTraditional C3–C7 unilateral open-door laminoplasty (UOLP) often lead to various postoperative complications due to damage of cervical posterior muscles and nuchal ligaments. We aimed to thoroughly evaluate postoperative outcomes of following our modified UOLP versus traditional UOLP in treating multilevel cervical spondylotic myelopathy (MCSM). MethodsSeventy-six patients with MCSM who underwent the modified UOLP with C3 laminectomy and C7 upper hemi-laminectomy (40 patients) or traditional C3–C7 UOLP (36 patients) were included. Pre- and postoperative cervical radiological parameters, as well as clinical and surgical outcomes were evaluated. ResultsPostoperatively, JOA scores improved significantly in modified UOLP group than traditional UOLP group (P=0.028), while VAS scores and NDI scores improved similarly in both groups. Follow-up scores for JOA, NDI and VAS were not significantly different between two groups. At final follow-up, C2-7 sagittal vertical axis and T1 slope increased in traditional UOLP group and did not change in modified UOLP group and were unchanged in modified UOLP group. The C2−C7 Cobb angle decreased significantly in traditional UOLP group and did not change in modified UOLP group. The modified UOLP group lost less cervical posterior muscles area compared to traditional UOLP group (3.72±3.54%vs6.67±2.81%, P<0.001). The range of motion in modified UOLP group showed significantly greater than traditional UOLP group at final follow-up (P<0.001). Also, modified UOLP group experienced a notable reduction in operative time, blood loss volume, and postoperative hospital stay. ConclusionWe recommend performing our modified UOLP with C3 laminectomy and C7 upper hemi-laminectomy instead of traditional C3-C7 UOLP.

Comparison of anterior cervical diskectomy with fusion (ACDF) and laminoplasty treating multilevel cervical spondylotic myelopathy with developmental canal stenosis: a retrospective study

PurposeTo evaluate clinical effectiveness and radiologic results of anterior cervical diskectomy with fusion (ACDF) comparing with laminoplasty (LP) in treating multilevel cervical spondylotic myelopathy (MCSM) with developmental canal stenosis (DCS).MethodsThis was a retrospective analysis of 41 patients who had MCSM with DCS treated with ACDF or LP from December 2018 to April 2023. Patients were split into ACDF and LP groups for comparison, and patients were further separated into subgroups based on whether or not a reserving canal space was present. The operation time, hemoglobin, hospital stay, modified Japanese Orthopaedic Association (mJOA) score, and visual analog scale (VAS) score were used to assess clinical efficacy. The C2–C7 Cobb angle, C2–C7 sagittal vertical axis, T1 slope, and cervical range of motion were applied to evaluate imaging changes.ResultsOf the 41 patients, 19 received ACDF, and 22 received LP. At the final follow-up, both groups’ mJOA scores significantly improved, and the intercomparison showed no differences; the VAS score was much lower in the ACDF group but remained unchanged in the LP group. At the final follow-up, the C2–C7 Cobb angle and T1 slope had significantly increased in the ACDF group, while the LP group showed no change; the cervical range of motion had significantly decreased in both groups, with the ACDF group exhibiting a more marked reduction. Within the ACDF subgroup, there was no postoperative symptom improvement for those with reserving space, whereas there was postoperative symptom resolution for those with non-reserving space; however, postoperative symptom in the LP subgroup was resolved.ConclusionsBoth ACDF and LP were efficacious for MCSM patients with DCS. While ACDF could improve cervical lordosis and alleviate neck pain more effectively, it can also result in cervical sagittal imbalance and decreased mobility. Furthermore, the recovery from LP was superior to that from ACDF for patients with reserving space. In contrast, the recovery from both decompression techniques was comparable for individuals in non-reserving space.

Upper and lower cervical alignment parameters measured on supine magnetic resonance imaging with the occipital slope as a key marker of cervical alignment.

Cervical spine alignment is evaluated by measuring the cervical angles or parameters on standing plain radiography. In this study, we aimed to evaluate mainly the upper cervical alignment and the correlation between upper and lower cervical sagittal parameters measured on supine magnetic resonance imaging (MRI). Cervical MRIs of 210 outpatients were reviewed to measure the upper and lower cervical sagittal parameters. Their mean values were compared with normative values measured on standing X-ray from the literature. Correlations between the parameters were analyzed using the Pearson's correlation coefficient. The C0 slope was correlated with all other parameters, except for the C2-7 sagittal vertical axis. The strongest correlations (r > 0.500) were between the CL and C2 slope, between the CO2 and C0 slope, and between the C2 slope and C0 slope. On supine MRI, the C0 slope is a key marker of cervical spinal alignment. A strong correlation was observed between the C2 slope and C0 slope; therefore, the relationship between upper and lower cervical alignment could be assessed using slopes on MRI.

Association Between Cervical Sagittal Alignment and Subaxial Paraspinal Muscle Parameters.

Retrospective review of prospectively collected data. The authors aim to investigate the association between muscle functional group characteristics and sagittal alignment parameters in patients undergoing anterior cervical discectomy and fusion. The relationship between the morphology of cervical paraspinal muscles and sagittal alignment is not well understood. Patients with preoperative cervical magnetic resonance imaging and cervical spine lateral radiographs in standing position who underwent anterior cervical discectomy and fusion between 2015 and 2018 were reviewed. Radiographic alignment parameters included C2 to 7 lordosis, C2 to 7 sagittal vertical axis (SVA), C2 slope, neck tilt, T1 slope, and thoracic inlet angle. Muscles from C3 to C7 were categorized into four functional groups: sternocleidomastoid group, anterior group, posteromedial group, and posterolateral group (PL). A custom-written Matlab software was used to assess the functional cross-sectional area (fCSA) and percent fat infiltration (FI) for all groups. Multivariable linear regression analyses were conducted and adjusted for age, sex, and body mass index. A total of 172 patients were included. Regression analyses demonstrated that a greater C2 to 7 SVA was significantly associated with a greater FI of the anterior group from C3 to C5 and with a higher fCSA of the PL group at C3 to C4, and C6 to 7. A larger C2 slope was significantly correlated with a greater FI of the anterior group at C3 to C4 and a higher fCSA of the PL group from C3 to C5. This work proposes new insights into the complex interaction between sagittal alignment and cervical paraspinal muscles by emphasizing the importance of these muscles in sagittal alignment. The authors hypothesize that with cervical degeneration, the stabilizing function of the anterior muscles decreases, which may result in an increase in the compensatory mechanism of the PL muscles. Consequently, there may be a corresponding increase in the C2 to C7 SVA and a larger C2 slope.

The "Sandwich" Extended Pedicle Subtraction Osteotomy for the Treatment of Fixed Sagittal Malalignment: Technical Description, Case Series, and Early Results With 2-Year Outcomes.

Adult spinal deformity (ASD) with fixed sagittal malalignment (FSM) may require a pedicle subtraction osteotomy (PSO) for greater focal lordosis and restoration of global alignment. Despite growing trends in minimizing PSOs given their associated high risks, a considerable portion of patients with ASD still require a lumbar PSO most commonly because of iatrogenic flat back deformity. The purpose of this article is to describe a modified extended PSO technique with additional anterior column support coined the "sandwich" extended PSO (SE-PSO) to promote arthrodesis and report the outcomes in a consecutive case series. Patients with ASD treated with a lumbar SE-PSO at a single institution from 2015 to 2020 were analyzed. Complications, radiographic data, and patient-reported outcomes were compared preoperatively, at immediate postoperative follow-up, and at a 2-year postoperative follow-up (FU). Fourteen patients who underwent revision operations for FSM were included. Improvements in segmental lordosis across the PSO site (14.8 ± 6.8 vs 39.9 ± 7.1, P < .0001), overall lumbar lordosis (14.6 ± 15.4 vs 44.6 ± 12.1, P < .0001), sacral slope (21.0 ± 10.5 31.1 ± 10.7, P = .0150), C7 sagittal vertical axis (140.1 ± 59.0 mm vs 35.9 ± 28.5, P < .0001), and spinopelvic mismatch (52.5 ± 21.3 vs 18.6 ± 14.1, P = .0001) were obtained in all patients. Eight patients experienced perioperative complications, with intraoperative durotomy being the most common (n = 7). Eight patients had a 2-year FU and demonstrated improvements in their segmental lordosis across the PSO site (14.3 ± 7.0 vs 41.3 ± 7.3, P = .0003), overall lumbar lordosis (8.7 ± 17.8 vs 46.1 ± 14.2, P = .0014), sacral slope (19.1 ± 12.8 vs 32.3 ± 12.5, P = .0479), C7 sagittal vertical axis (173.6 ± 54.4 mm vs 35.8 ± 30.0, P < .0001), and spinopelvic mismatch (63.0 ± 19.7 vs 21.1 ± 18.3, P < .0001), all of which were maintained at final FU (P > .05). At 2 years, a significant increase in Scoliosis Research Society-22r total score (2.5 ± 0.8 vs 3.6 ± 0.7, P = .0023 was reported. There were no reports of symptomatic pseudarthrosis or mechanical complications. SE-PSO is an effective technique to correct FSM and is associated with low complications, improved patient-reported outcomes, and spinopelvic parameters that are maintained at 2 years.