Sitting-Related Sacral Pain in Patients With Sacral Metastases: Retrospective Cross-Sectional Study.

Abstract

Sacral metastases are uncommon but can substantially impair daily functioning through pain, neurological deficits, and instability. Sitting-related sacral pain is frequently observed clinically but has not been systematically investigated. To determine the prevalence of sitting-related sacral pain in those with sacral metastases and to examine the association with spinal instability and neurological symptoms. This retrospective cross-sectional study reviewed patients with radiologically confirmed symptomatic sacral metastases who underwent inpatient rehabilitation at a single university hospital (2011-2022). Sitting-related sacral pain was defined as sacral pain present during sitting (numerical rating scale ≥4). Spinal instability was assessed using the Spinal Instability Neoplastic Score (SINS). Sacral-level neurological symptoms, including motor and sensory impairment and bladder and bowel dysfunction, were evaluated. Functional status was assessed using the Functional Ambulation Categories and the Barthel Index. All data were extracted from medical records. Associations with sitting-related sacral pain were examined using Firth's penalized logistic regression. Among 71 patients, 32 (45%) reported sitting-related sacral pain, exhibiting significantly higher SINS and poorer transfer and ambulation outcomes. In logistic regression, higher SINS was independently associated with sitting-related sacral pain (adjusted odds ratio per point, 1.56; 95% confidence interval, 1.29-1.99; p < .001); neurological symptoms were not. Sensitivity analysis confirmed result consistency. Sitting-related sacral pain is common in patients with sacral metastases and is associated with spinal instability; early identification should guide rehabilitation, activity modification, and supportive care planning in palliative settings.