Effects of Cervical Paravertebral Extensors in Patients with Cervical Ossification of the Posterior Longitudinal Ligament Grouped According to mK‐Line

Objectives The objective of this study was to quantify the morphology, composition, and asymmetry of the paravertebral extensor muscles (PSEMs) in patients with cervical ossification of the posterior longitudinal ligament (OPLL) who had different modified K‐line (mK‐line) and the minimum interval between the mK‐line and OPLL (INTmin) values and to investigate the relationship between PSEMs and symptoms and outcomes following laminoplasty. These original findings elucidated that the atrophy of PSEMs could predict decompression outcomes and provided a theoretical basis for paraspinal muscle rehabilitation. Methods A total of 94 consecutive patients who underwent laminoplasty for OPLL between January 2020 and January 2022 were enrolled in this retrospective study. The relative cross‐sectional areas (rCSA), functional cross‐sectional areas (rFCSA), and FCSA/CSA ratio of the multifidus (MF), semispinalis cervicalis (SSCe), semispinalis capitis (SSCa), and splenius capitis (SpCa) were measured at the C3–C7 segments on cervical magnetic resonance imaging (MRI). This study compared the differences between the mK‐line (+) group and the mK‐line (−) group, as well as between the INTmin