General Session: Innovative Technologies II - Hall F

Presented by: F. Segreto

Author(s):

P. Passias(1), C. Wang(1), G. Poorman(1), S. Horn(1), F. Segreto(1), C. Bortz(1), N. Stekas(1), D. Ge(1), H.J. Kim(2), V. Lafage(2), M. Gerling(1)

(1) New York University Langone Orthopedic Hospital, Division of Spinal Surgery, New York, NY, United States
(2) Hospital for Special Surgery, Department of Orthopaedic Surgery, New York, NY, United States

Abstract

Introduction: Degenerative changes in the cervical spine often develop insidiously and spinal cord impairment, malalignment, and muscle impairment frequently co-occur. Cervical extensor musculature is known to play an important role in the physical support of the neck buts its role in the disease history of degenerative cervical disease and surgical correction of degenerative changes is poorly researched in the literature. Muscle fatty infiltration may have an effect on cervical deformity, including success of surgical intervention. The purpose of the present study is to examine the relationship between cervical muscle area and fatty infiltration on baseline kyphosis in surgical cervical deformity patients.

Methods: Consecutive patients undergoing multi-level posterior fusions for cervical deformity were prospectively enrolled by two surgeons. Preoperative cervical extensor musculature (multifidus, semispinalis cervicis, semispinalis capitis, and splenius capitis) were quantitatively measured from the T2-weighted axial MR images of the intervertebral disc levels from C2-C3 to C6-C7 using ImageJ imaging software. These measurements included total cross sectional area, functional area (fat free area; FFA), and a ratio of FFA to total area as an indication of fatty infiltration. T-tests and Pearson correlation tests were used to examine how mal-alignment (cervical lordosis/kyphosis [C2-C7], cervical Sagittal Vertical Angle [C2-C7 cSVA], and Cervical Lordosis minus T1 Slope [TS-CL]) correlated to fatty infiltration and total muscle area. Secondary analysis examined baseline predictors of fatty infiltration and total area.

Results: 20 patients underwent surgical correction for cervical deformity (Average age: 55.8 years, 70% female). Fatty infiltration increased in the inferior aspect of the cervical spine (C2-C3: 0.51 to C6-C7: 0.64, p< 0.001). Gender, age, and BMI did not show any significant relationship with fatty infiltration or total muscle area. However, total muscle area was significantly lower in smokers (smoker: 532.3 cm2 vs. non-smokers: 954.0 cm2, p=0.031). While fatty infiltration showed a significant relationship with cervical kyphosis (r2=0.529, p=0.016) and TSCL (r2=0.659, p-0.028), total muscle area had no significant correlation with radiographic sagittal alignment in this cervical deformity population (C2-C7, cSVA, and TS-CL all p>0.05). In analyzing disability and pain scores, fatty infiltration and total muscle area did not correlate with lower mJOA scores, NDI scores, NSR back pain, or NSR neck pain scores (all p>0.05).

Conclusions: In this study of preoperative cervical deformity patients, there was a significant relationship between cervical sagittal alignment and posterior muscle fatty infiltration. Fatty infiltration was associated with positive sagittal balance. Patient factors including gender, age and BMI did not correlate with muscle area or fatty infiltration, while smoking had a substantial negative correlation with muscle area.