The Impact of Sarcopenia on Cervical Spine Sagittal Alignment After Cervical Laminoplasty.

Abstract

This was a prospective follow-up study. The main objective of this study was to evaluate the effects of sarcopenia on the sagittal alignment of the cervical spine after cervical laminoplasty in order to investigate the relationship between sarcopenia and spinal malalignment. Sarcopenia, a progressive and all over loss of skeletal muscle mass and strength associated with aging, has been reported to be related to spinal malalignment. The causes of poor surgical outcome after cervical laminoplasty have been examined in recent years, including the sagittal malalignment of the cervical spine. However, there are few reports about the impact of sarcopenia on the sagittal alignment of the cervical spine. A total of 171 patients who underwent cervical laminoplasty at our hospital between 2009 and 2015 were assigned to this study. The appendicular skeletal muscle mass [appendicular skeletal muscle index (SMI)] is commonly used to assess sarcopenia. Appendicular SMI (kg/m) was obtained from arm and leg muscle mass using dual-energy x-ray absorptiometry. Sanada and colleagues reference value for the Japanese appendicular SMI was used to diagnose sarcopenia. C2-C7 sagittal vertical axis (SVA), C2-C7 lordosis angle, and C2-C7 range of motion were measured for evaluation. The primary outcome was evaluated using the Japanese Orthopedic Association Score System for Cervical Myelopathy (JOA score) and the SF-36 Health Survey Physical Function (PF). Of the 171 patients, 48 were diagnosed with sarcopenia. Preoperative (P=0.001), postoperative (P=0.011), and 1-year follow-up (P=0.007) C2-C7 SVA were greater in the sarcopenia group. Preoperative (P=0.009), postoperative (P=0.018), and 1-year follow-up (P=0.023) SF-36 scores were higher in the nonsarcopenia group. Preoperative (P<0.001), postoperative (P<0.001), and 1-year follow-up (P=0.002) JOA scores were higher in the nonsarcopenia group. C2-C7 SVA and JOA scores were negatively correlated at 1-year follow-up (R=-0.213, P=0.005). C2-C7 SVA and SF-36 scores were not correlated at 1-year follow-up (R=-0.167, P=0.070). C2-C7 SVA was greater and postoperative outcome was worse after cervical laminoplasty in the sarcopenia group than in the nonsarcopenia group; thus, we believe it is necessary to evaluate sarcopenia before cervical laminoplasty, because sarcopenia may impact postoperative cervical alignment and postoperative outcome. Level III.