Does the Lumbar Paraspinal Muscle Status Have a Role in Predicting Mechanical Complications After Adult Spinal Deformity Surgery?

Abstract

Study designRetrospective analysis.ObjectivesTo assess the role of paraspinal muscle morphology in predicting complications after adult spinal deformity (ASD) surgery.Materials and MethodsA total of 93 patients who underwent surgery for ASD from 2017 to 2022 were enrolled. Using early postoperative X-ray, they were divided into proportioned (P), moderately proportioned (MP), and severely proportioned (DP) groups based on the Global Alignment and Proportion (GAP) scores. Further, they were classified into two groups: Group A (presence of mechanical complications) and Group B (no mechanical complications). In addition, other parameters including preoperative BMI, smoking status, cross-sectional area (CSA), and grades of paraspinal muscle fatty infiltration (FI) were calculated in all patients using preoperative MRI. These parameters were compared across the groups using a one-way analysis of variance (ANOVA). Post-hoc pairwise testing was done using Bonferroni's method. These were also compared between groups A and B using a 2-sample t-test.ResultsThe mean follow-up period was 32.7 months (24-64 months). 27 (29%) of 93 patients developed mechanical complications following ASD surgery. Of the 27 patients, 6 (22.2%) were proportioned, 10 (37%) were from MP and 11 (40.7%) were from the DP group. Group A had low CSA (P = 0.014), and high FI (P = 0.003) grades compared to group B. Further, 22.2% (6/27) had a history of smoking before surgery (OR = 6.57).ConclusionsWe recommend consideration of preoperative smoking, CSA, and FI of paraspinal muscles in addition to the GAP score to minimize mechanical complications in patients undergoing ASD surgery.

Keywords: adult spinal deformity; postoperative complications; sarcopenia; smoking; spine.

Figure 1.

Muscular location and fat infiltration grades on T2 axial MRI slice (evaluation with 4-grade system) (A) Grade 1 = < 10% fat infiltration, (B) Grade 2 = 10%-30% fat infiltration, (C) Grade 3 = 30%-50% fat infiltration, (D) Grade 4 = > 50% fat infiltration.

Figure 2.

Axial T2-weighted MRI obtained at the level of the upper endplate of L3. CSA of paraspinal (ES and MF) (in cm²) muscles is measured by drawing a region of interest around the muscles, excluding epimuscular fat.

Figure 3.

The overall distribution of the GAP score in the present study. 0-2: proportioned (P), 3-6: moderately disproportioned (MP), >7: severely disproportioned (DP).

Figure 4.

A 70-year-old man with the T2WI axial image showing grade 3 FI of paraspinal muscles, low CSA (11.310 cm²) (A), and a whole spine standing lateral X-ray showing ASD (B). During the postoperative period, the GAP score was 3 (C). PJK was noted at the 3-year follow-up (D), Which required revision and extension of fixation up to D7 (E).

Figure 5.

A 65-year-old woman with T2WI axial image showing grade 4 FI of paraspinal muscle, low CSA (9.56 cm²) (A), and a whole spine standing lateral X-ray after ASD surgery at 8-month post-op period (B). Underwent revision and extension of fixation up to D9 (C, D).

Figure 6.

A 60-year-old woman with T2WI axial image showing grade 1 FI of paraspinal muscle, CSA of 13.322 cm²) (A), and a whole spine standing lateral X-ray (B). Underwent ASD surgery showing immediate post-op (C) and 5-year post-op (D) requiring no revision.

Figure 7.

The box and whisker plot show the distribution of SVA and CSA of paraspinal muscles based on grades of FI.