Intrinsic paraspinal muscle pathophysiology associated with spine related disorders
The paraspinal muscles are essential for the proper functioning of the spine and whole body, however, reports of muscle dysfunction and insufficiency in chronic low back pain disorder patients are common. Notably, the intrinsic cellular mechanisms responsible for active muscle contraction and force production in the spine muscles have never been investigated in any manner, thus impeding proper prevention and resolution. In this research I aim to satisfy two key objectives: 1) increase our understanding of the intrinsic (dys)functioning of the spine muscles in human degenerative spine patients, and 2) unravel the direct mechanistic interplay between paraspinal muscle and spine pathology. In study #1 intraoperative biopsies were obtained from degenerative spine patients undergoing surgery, and muscle function was tested using single muscle fibre contractility experiments. The findings suggest that degenerative spine and spinal deformity patients have intrinsic muscle contractile impairments compared to healthy age-matched literature norms, with sagittally imbalanced patients being most significantly affected. In studies # 2 and #3, I assessed single muscle fibre contraction from genetically engineered (study #2) and experimental myopathic (study #3) mice. These animal studies demonstrate that 1) the functional properties of the paraspinal muscles remodel, resulting in contractile impairment, in direct response to pathological changes to the spine, and 2) the initiation of paraspinal muscle pathology directly leads to kyphotic spinal deformity.