Lower Hounsfield Units and Severe Multifidus Sarcopenia Are Independent Predictors of Increased Risk for Proximal Junctional Kyphosis and Failure Following Thoracolumbar Fusion

Abstract

Study Design. Retrospective cohort study.Objective. The purpose of the present study was to assess the impact of sarcopenia on the development of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) following thoracolumbar spine fusion surgery using opportunistic evaluation of paraspinal fatty degeneration on preoperative magnetic resonance imaging. Summary of Background Data. While paraspinal sarcopenia has been shown to have detrimental consequences following posterior cervicothoracic fusions, the impact of paraspinal sarcopenia on PJK and PJF following thoracolumbar spine fusion surgery remains unknown. Materials and Methods. We performed a retrospective review of patients who underwent posterior spine fusion surgery that extended caudally to the pelvis and terminated cranially between T10 and L2 between 2010 and 2017. The cohort was divided into three groups: (1) patients without PJK or PJF, (2) patients with PJK but no PJF, and (3) patients with PJF. Univariate and multivariate analyses were performed to determine risk factors for the development of proximal junctional complications. Results. We identified 150 patients for inclusion in this study. Mean Hounsfield Units at the upper instrumented vertebra (UIV) was 148.3 ± 34.5 in the cohort of patients without PJK or PJF, which was substantially higher than values recorded in the PJK (117.8 ± 41.9) and PJF (118.8 ± 41.8) subgroups (P < 0.001). Severe multifidus sarcopenia was identified at a much higher rate in the subgroups of patients who developed PJK (76.0%) and PJF (78.9%) than in the subgroup of patients who developed neither PJK nor PJF (34.0%; P < 0.001). Multivariate analysis demonstrated both low HU at the UIV and moderate-severe multifidus sarcopenia to be risk factors for the development of PJK and PJF. Conclusion. The results of this study suggest severe paraspinal sarcopenia and diminished bone density at the UIV impart an increased risk of developing PJK and PJF, while markers of systemic frailty such as modified Frailty Index and Charlson Comorbidity Index are not associated with an increased risk of these complications.

Paraspinal Sarcopenia is Associated With Worse Patient-Reported Outcomes Following Laminoplasty for Degenerative Cervical Myelopathy

“…40 While cross-sectional measurements are simple to perform on readily available preoperative advanced imaging studies, subsequent studies have demonstrated that cross-sectional area measurements do not correlate with qualitative assessments of paraspinal fatty infiltration and are not reliably tied to outcomes following spine surgery, leading to the recommendation that qualitative assessments be used preferentially. 22,24,41 Koshimizu et al investigated 171 patients undergoing laminoplasty and found that sarcopenic patients, as determined by appendicular skeletal muscle mass, had lower Japanese Orthopedic Association scores, higher C2-7 sagittal vertical axis measurements, and lower short form-36 scores. 14 While these findings highlight the impact of sarcopenia on postoperative outcomes, appendicular skeletal muscle index is determined using dual-energy x-ray absorptiometry, which is not part of routine preoperative testing and only serves as a proxy for paraspinal sarcopenia rather than as a direct measurement of the quality of the muscles of interest.…”

“…In their study of 144 patients undergoing cervical laminoplasty for DCM, Lee et al reported that decreased cross-sectional area of the semispinalis cervicis at C5-6 on advanced preoperative imaging was associated with loss of cervical lordosis postoperatively 40. While cross-sectional measurements are simple to perform on readily available preoperative advanced imaging studies, subsequent studies have demonstrated that cross-sectional area measurements do not correlate with qualitative assessments of paraspinal fatty infiltration and are not reliably tied to outcomes following spine surgery, leading to the recommendation that qualitative assessments be used preferentially 22,24,41. Koshimizu et al investigated 171 patients undergoing laminoplasty and found that sarcopenic patients, as determined by appendicular skeletal muscle mass, had lower Japanese Orthopedic Association scores, higher C2-7 sagittal vertical axis measurements, and lower short form-36 scores 14.…”

“…[19][20][21][22][23] Using this methodology, recent studies have demonstrated that paraspinal sarcopenia is associated with proximal junctional failures following thoracolumbar fusions and poor patient-reported outcomes (PROMs) and worsening cervical sagittal alignment following posterior cervical decompression and fusion. 20,24,25 Despite increasing awareness of the detrimental effects of sarcopenia following spine fusion surgery, the impact of paraspinal sarcopenia on outcomes following cervical laminoplasty remains unknown.…”

“…In recent years, a novel approach to qualitatively assess paraspinal sarcopenia opportunistically on preoperative magnetic resonance imaging (MRI) has emerged, which has improved both the ease and reliability of sarcopenia assessments 19–23. Using this methodology, recent studies have demonstrated that paraspinal sarcopenia is associated with proximal junctional failures following thoracolumbar fusions and poor patient-reported outcomes (PROMs) and worsening cervical sagittal alignment following posterior cervical decompression and fusion 20,24,25. Despite increasing awareness of the detrimental effects of sarcopenia following spine fusion surgery, the impact of paraspinal sarcopenia on outcomes following cervical laminoplasty remains unknown.…”

Sarcopenia in Lumbar and Cervical Spine Surgery

“…Patients undergoing multilevel thoracolumbar fusions with multifidus fatty degeneration and decreased lean multifidus CSA have been shown to independently predict rates of PJK and PJF on multivariate analyses. 39,40 In the case of smaller fusion constructs, evidence demonstrates the value of radiographic evidence of paraspinal sarcopenia. In 1 study of patients undergoing 2 or more level fusions extending caudally into the sacrum, paraspinal muscle markers (lean CSA, FI, and SMI) at the UIV were more predictive of ASD as opposed to signs of psoas degeneration.…”