Changes in sagittal spinopelvic alignment are associated with increased pain and impaired function in multiple myeloma patients.

Purpose: Multiple myeloma (MM), a type of B-cell non-Hodgkin lymphoma, frequently causes osteolytic spinal lesions, increasing the risk of fracture and poor sagittal spinopelvic alignment. In relapsed patients, these changes may contribute to increased pain and functional impairment.

Methods: The clinical data of 86 MM patients (48 males, 38 females) who underwent ≥ 3 whole-body CT scans between 2009 and 2024, with a mean interscan interval of 19.2 months and a total follow-up duration of 37.5 months, were analyzed in this retrospective study. Spinopelvic parameters were measured, and clinical data (pain intensity, analgesic use, ECOG classification, and ASIA classification) were assessed.

Results: Over the disease course, thoracic kyphosis (TK) increased significantly (from 38.5° to 46.7°, p < 0.0001), whereas the Dens axis-S1 distance decreased (from 53.2 cm to 49.3 cm, p < 0.0001). These changes correlated with increased pain levels (median VAS score increasing from 2.0 to 6.0, p < 0.0001) and increased analgesic use (median WHO analgesic level increasing from 1.0 to 3.0, p < 0.001). Other spinopelvic parameters remained stable, and no significant changes were observed in the ECOG or ASIA classifications. Notably, an increase in TK exceeding nine degrees was strongly associated with increased pain levels (mean VAS score of 7.3 vs. 4.9, p < 0.001), whereas new vertebral fractures did not significantly impact pain intensity or analgesic consumption.

Conclusion: In MM patients, progressive TK and a reduced Dens axis-S1 distance are key contributors to worsening pain and increased analgesic requirements. Surgical strategies should prioritize kyphosis correction, particularly in cases where increases in TK exceeding nine degrees, to optimize pain management. Future studies should further explore these findings.