Reduced Psoas Muscle Index is Associated with Hypothyroidism in Adult Spinal Deformity

Area of Science:

• Spine Surgery
• Endocrinology
• Geriatrics

Background:

• Hypothyroidism impacts metabolism and muscle function, potentially contributing to sarcopenia.
• The relationship between hypothyroidism and psoas muscle index (PMI) in adult spinal deformity (ASD) patients is not well understood.

Purpose of the Study:

• To investigate the association between hypothyroidism, psoas muscle index (PMI), and surgical parameters in patients undergoing corrective surgery for ASD.

Main Methods:

• Retrospective review of 235 ASD patients undergoing ≥4-level fusion (2016-2021).
• Collected data included hypothyroidism status, demographics, surgical details, and PMI at L3 and L4.
• Used regression analyses and global database comparisons to assess prevalence and predictors.

Main Results:

• Hypothyroidism was more prevalent in ASD patients (14%) than controls (8%) and increased with surgical complexity.
• Hypothyroid patients had significantly lower PMI at L3 and L4.
• Lower PMI was independently associated with hypothyroidism, and hypothyroidism was linked to fewer fused levels.

Conclusions:

• Hypothyroidism is independently associated with reduced psoas muscle mass in ASD patients, suggesting sarcopenic changes.
• Thyroid dysfunction warrants increased attention in preoperative evaluations for ASD patients due to its prevalence and surgical implications.