The Role of Psoas Muscle in Scoliosis: A Review of the Literature.

Scoliosis, a lateral curvature of the spine, is influenced by various factors, including muscular imbalances. The psoas muscle, due to its anatomical positioning and function, has been hypothesized to influence scoliotic changes. The aim of this review is to evaluate the current evidence on the role of the psoas muscle in scoliosis. A search was performed using PubMed, Scopus, and Web of Science databases for studies published up to July 2024. Keywords used included "psoas" AND "scoliosis". Inclusion criteria were studies that examined the anatomical, physiological, and clinical aspects of the psoas muscle in scoliosis. Systematic reviews, studies in languages other than English language and conference papers were excluded. Studies not specifically addressing the psoas muscle were also excluded. After the application of research methodology, 32 studies remained for analysis. The psoas muscle plays a significant role in the pathogenesis and progression of scoliosis through mechanisms involving asymmetrical activity, biomechanical imbalances, neuromuscular factors, and growth and development. The cross-sectional area (CSA) of the psoas muscle affects spinal stability, increasing the likelihood of asymmetrical loading and subsequent curvature of the spine. Moreover, it affects the outcome of scoliosis surgery. The transpsoas approach is a novel minimally invasive technique for scoliosis surgery offering reduced tissue damage, quicker recovery, and improved visualization of the disc space. Psoas-related complications of scoliosis surgery, such as psoas weakness or psoas hematoma, exist and cannot be overlooked. Randomized trials are needed to validate psoas-targeted exercises or botulinum toxin injections in the treatment of scoliosis. Future research should focus on elucidating the mechanisms by which the psoas muscle affects scoliosis and exploring comprehensive treatment approaches.