Association Between Cervical Sagittal Alignment and Subaxial Paraspinal Muscle Parameters

Area of Science:

• Spine surgery
• Orthopedics
• Biomechanical analysis

Background:

• Cervical paraspinal muscle morphology and its relation to sagittal alignment remain unclear.
• Understanding this relationship is crucial for optimizing surgical outcomes and patient recovery.

Purpose of the Study:

• To investigate the association between functional characteristics of cervical paraspinal muscles and sagittal alignment parameters.
• To explore how muscle composition (cross-sectional area and fat infiltration) influences spinal alignment in patients undergoing anterior cervical discectomy and fusion.

Main Methods:

• Retrospective review of prospectively collected data from 172 patients undergoing anterior cervical discectomy and fusion (2015-2018).
• Analysis of radiographic parameters including C2-7 lordosis and sagittal vertical axis (SVA).
• Assessment of functional cross-sectional area (fCSA) and fat infiltration (FI) in four muscle groups (sternocleidomastoid, anterior, posteromedial, posterolateral) using custom Matlab software.

Main Results:

• Greater C2-7 SVA was associated with increased fat infiltration in the anterior muscle group (C3-5) and larger fCSA in the posterolateral (PL) group (C3-4, C6-7).
• A larger C2 slope correlated with increased FI in the anterior group (C3-4) and higher fCSA in the PL group (C3-5).

Conclusions:

• Cervical paraspinal muscle characteristics significantly interact with sagittal alignment.
• Hypothesizes that degeneration reduces anterior muscle stabilization, leading to compensatory PL muscle hypertrophy and altered sagittal alignment (increased SVA and C2 slope).