Background: Relationship between sarcopenia, malnutrition and postoperative outcomes after spinal surgery has not yet been established. Our study aims to identify such relationships and reveal effects of preoperative patient's status on follow-up patient-reported outcome measurements.

Methods: This is a prospective observational cohort conducted at the Seoul St. Mary's Hospital, including patients aged between 50 and 90 years who underwent elective lumbosacral fusion between May 2021 and August 2024. Patient's sarcopenia status was determined via muscle mass, physical performance, and muscle strength measurements following the Asian Working Group for Sarcopenia (AWGS) 2025 criteria. Primary outcomes included in-hospital outcomes such as length-of-stay, ICU admission, and postoperative complications, and secondary outcomes included patient-reported outcomes measurements such as visual analog scale (VAS) for pain, Oswestry disability index (ODI), and EuroQol-5 Dimension (EQ-5D) index.

Results: A total of 90 patients with spinal stenosis or degenerative disc disease who planned lumbosacral fusion between May 2021 and August 2024 were included in the study. There were 37 (41.11%) patients who were identified with preoperative sarcopenia. There were no statistically significant differences regarding in-hospital outcomes between normal and sarcopenia patients. However, there were slower improvement in terms of gait speed and grip strength in the sarcopenia and sarcopenia with malnutrition patients compared to normal patients. Multivariable logistic regression analysis showed no statistical significance regarding the effects of sarcopenia and malnutrition on VAS, ODI, or EQ-5D.

Conclusions: Albeit its variable effects, sarcopenia leads to worse surgical outcomes in patients who underwent spinal fusion surgery. The effect of malnutrition was modest at best, although with combination of sarcopenia lead to a more slower improvement in terms of gait speed and grip strength.