Introduction: Fatty infiltration of lumbar extensor musculature has been associated with symptomatic degenerative deformity. Currently, little is known of cervical extensor musculature’s role in adult cervical deformity(CD) patients.
Methods: Operative CD patients(C2-C7 Cobb>10°, CL>10°, cSVA>4cm, or CBVA>25°) undergoing were included. Those with pre-operative(BL) MRIs and 1-year(1Y) post-operative cervical MRI or CT scans were assessed for fatty infiltration of cervical extensor musculature using dedicated imaging software at each intervertebral level from C2-C7, and the apex of deformity(apex). Fatty infiltration (FI) was gauged as a ratio of fat-free muscle cross-sectional(CSA) area over total muscle CSA, with lower values indicating increased FI. BL to 1Y ? in FI and postoperative outcomes were assessed using parametric and non-parametric tests.
Results: 22 patients were included (Age 59.22, 71.4%F, BMI 29.2, 71.4%White, 23.8%Black, CCI:0.75, Frailty:0.43). BL deformity presentation: TS-CL 30.32, CL -1.3, cSVA 32.1, PI-LL -3.9, PT 17.7, SVA -9.7. Greater FI was observed in the proximal cervical spine (C2-C3:0.52 vs. C6-C7:0.63, p<0.001). No associations between BL FI, sagittal alignment, or frailty were observed(p>0.05). Following surgical correction, C2-C7 FI improved (BL:0.59 vs 1Y:0.67), as well as apex FI (BL:0.59 vs. 1Y:0.66), both p<0.05. Less C2-C7 FI at BL was associated with 1Y cSVA realignment (rs:0.535, p=0.015), greater correction of T1SS (rs:-0.545, p=0.067), and achieving lowest level Ames cSVA modifier at 1Y (rs:0.394, p=0.334). Increased apex FI at BL was associated with minor complication occurences (rs:0.551, p=0.014). Less C2-C7 FI at 1Y was associated with TS-CL realignment (rs:0.806, p=0.05).
Conclusions: Fatty infiltration of cervical extensor musculature appears to influence susceptibility to complications and achievement of sagittal alignment. This analysis is a first step in elucidating cervical extensor musculature’s role in postoperative outcomes.
Patient Care: Having a greater understanding of cervical extensor musculature's role in the operative correction of adult cervical deformity, may improve treatment outcomes.
Learning Objectives: Investigate the role of cervical extensor musculature in adult cervical deformity patients.