Cervical curvature after laminoplasty for spondylotic myelopathy--involvement of yellow ligament, semispinalis cervicis muscle, and nuchal ligament.

To assess the consequences of cervical laminoplasty on postoperative lordosis, a retrospective radiographic analysis of 31 patients undergoing laminoplasty for spondylotic myelopathy was completed. Special attention was paid to lordotic changes occurring at each level over more than 2 years. Preoperative lordosis remained unchanged with the patients wearing a cervical orthosis 1 week postoperatively. However the lordosis subsequently demonstrated a significant decrease in 87% of patients over an average of 3.1 years. Lordotic alignment at C2-C3 and C6-C7 before surgery significantly decreased in 81% and 58% of patients 1 week postoperatively, and 84% and 81% at last follow up, respectively, while lordotic alignment at other levels pre- and postoperatively did not significantly change. Loss of lordotic alignment was largely attributed to detachment of semispinalis cervicis muscle on C2 and nuchal ligament on C6/C7 with a posterior approach and/or section of yellow ligament at C2-C3.