Association Between Cervical Sagittal Alignment and Subaxial Paraspinal Muscle Parameters

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

The authors aim to investigate the association between muscle functional group characteristics and sagittal alignment parameters in patients undergoing anterior cervical discectomy and fusion.

SUMMARY OF BACKGROUND DATA

The relationship between the morphology of cervical paraspinal muscles and sagittal alignment is not well understood.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

How do C2 tilt and C2 slope correlate with patient reported outcomes in patients after anterior cervical discectomy and fusion?

BACKGROUND/CONTEXT

C2 tilt and C2 slope are quick and easy measurements to obtain on lateral radiographs and may be used to determine overall cervical sagittal alignment; however, the influence of these measurements on patient outcomes has not been well established in literature.

PURPOSE

To determine if C2 tilt and/or C2 slope predict patient outcomes better compared with conventional radiographic measures after an anterior cervical discectomy and fusion (ACDF).

STUDY DESIGN/SETTING

Retrospective cohort study.

PATIENT SAMPLE

A total of 249 patients who underwent 1 to 3 level ACDF to address radiculopathy and/or myelopathy at a single academic institution between 2011 and 2015 were identified. Patients with less than 1 year of follow-up were excluded.

OUTCOME MEASURES

Patient Reported Outcomes: Neck Disability Index (NDI), Physical Component Score-12 (PCS-12), and Mental Component Score (MCS-12), Visual Analog Score (VAS) Neck and Arm scores Cervical radiographic measurements: C2 tilt, C2 slope, C2-C7 lordosis, cervical SVA, T1 slope, T1 slope minus cervical lordosis (TS-CL), and C2-C7 ROM METHODS: Pearson correlation tests were performed to assess for significant associations between radiographic measurements and patient outcomes. Multiple linear regression models were developed adjusting for demographics and radiographic parameters to determine which factors were predictive of patient outcomes.

RESULTS

C2 tilt and TS-CL correlated with all postoperative physical outcome scores (NDI, PCS-12, VAS Neck and ARM; p<.05), however no association was seen between C2 slope and postoperative outcomes. After accounting for the presence of subaxial deformity, C2 tilt and TS-CL remained strongly correlated to patient outcome scores. With multiple linear regression, C2 tilt was a significant predictor for NDI, whereas TS-CL was a significant predictor for PCS-12, VAS Neck and VAS Arm.

CONCLUSIONS

C2 tilt significantly correlated with well-described conventional cervical parameters as well as postoperative physical outcomes measures, especially NDI, on multivariate analysis. C2 tilt may provide an easy and practical tool for predicting physical outcomes after ACDF.

Clinical recovery after 5 level of posterior decompression spine surgeries in patients with cervical spondylotic myelopathy: A retrospective cohort study

BACKGROUND/OBJECTIVE

The selection of surgical technique in patients with cervical spondylotic myelopathy relies on the surgeon(s) and patients' conditions. The objectives of the study were to test the hypotheses that French-door laminoplasty recovers faster than laminectomy and has good outcome measures.

METHODS

Data regarding surgical, radiological, and clinical outcome measures of 330 patients with cervical spondylotic myelopathy operated under French-door laminoplasty (fdLP group, n = 110), open-door laminoplasty (odLP group, n = 110), or laminectomy (LC group, n = 110) were collected from the records of institute and analyzed.

RESULTS

Patients of fdLP group (p < 0.0001, q = 11.65) and odLP group (p < 0.0001, q = 11.27) both had significantly improved modified Rankin scale score than those of LC group. In addition, patients of fdLP group had minimum blood loss during operations and that was maximum for patients of the LC group. Unlike patients of fdLP group (p < 0.0001, q = 80) and LC group (p < 0.0001, q =122), those of odLP group had lost more amount of cervical lordotic after surgery. Open-door laminoplasty had significantly reduced cervical range of motion than laminectomy (p < 0.0001, q = 15.45) and French-door laminoplasty (p < 0.0001, q = 13.45). After 12-months, fdLP group had higher bone union rate than odLP group (p = 0.007, q = 3.395) and LC group (p = 0.007, q = 4.243). French door laminoplasty had a better postoperative quality of life.

CONCLUSIONS

Among the posterior decompression spine surgeries, French-door laminoplasty is superior surgical procedure than laminectomy and could be superior surgical technique than open-door laminoplasty.