Research Fellow Hospital for Special Surgery Hospital for Special Surgery
Introduction: Literature suggests recovery after transforaminal lumbar interbody fusion (TLIF) occurs mostly within 6 months; however, some patients improve early after surgery while others do not. Our primary objective was to compare early-improvers with non-early improvers after TLIF using a novel definition of improvement.
Methods: Patients > 18 years undergoing primary 1-level TLIF were included. Early-improvers (EI) achieved significant Oswestry Disability Index (ODI) improvement between consecutive postoperative timepoints at short-term (2 or 6 weeks), while non-EI did not. Significant ODI improvement was defined by optimal cutoff point of a receiver operating characteristic (ROC) curve using change in ODI to predict improvement on Global Rating of Change (GRC) between consecutive timepoints. Variables assessed included patient-reported outcomes (PROMs) (ODI, visual analog scale [VAS] for back and leg pain, and Patient-Reported Outcomes Measurement Information System for Physical Function [PROMIS-PF]), sagittal alignment, muscle health, and Goutallier. Poor muscle health was defined by lowest gender-specific quartile of L3-L4 cross-sectional area (CSA)/height-squared (psoas) and CSA/body mass index (paralumbars). Logistic regression covariates were determined using p < 0.20 on univariate analyses and clinical relevance.
Results: 157 patients (EI = 121, non-EI = 36) were included. AUC was 0.71. Optimal cutoff for ODI improvement was 6.4. There were no differences in demographics; EI cohort had greater preoperative ODI and VAS leg. EI cohort had lower short-term ODI (26.13 ± 16.8 versus 44.43 ± 19.46) and VAS back (2.84 ± 2.22 versus 4.26 ± 2.5), with no differences in long-term PROMs. There were no differences in sagittal alignment (pelvic incidence [PI], tilt, lordosis [LL], PI-LL, sacral slope [SS]), psoas or paralumbar muscle health, or Goutallier. Logistic regression including age, sex, preoperative VAS leg, low muscle health for psoas and paralumbars, and multifidus Goutallier, showed that low psoas muscle health is a negative predictor for early improvement (OR: 0.38 [0.15 - 0.95], p = 0.039).
Conclusion : Low psoas muscle health is a negative predictor for early improvement after 1-level TLIF. This information may help spine surgeons with perioperative patient counseling and may help to predict recovery based on preoperative muscle health on imaging.