Correlation of Functional Outcomes and Sagittal Alignment After Long Instrumented Fusion for Degenerative Thoracolumbar Spinal Disease

Kuang-Ting Yeh, MD, PhD; Ru-Ping Lee, RN, PhD; Ing-Ho Chen, MD; Tzai-Chiu Yu, MD; Kuan-Lin Liu, MD, PhD; Cheng-Huan Peng, MD; Jen-Hung Wang, MD; Wen-Tien Wu, MD, PhD


Spine. 2018;43(19):1355-1362. 

In This Article

Abstract and Introduction


Study Design: A retrospective function and radiography study of the patients who have received long instrumented thoracolumbar fusion.

Objective: To investigate the correlation between the sagittal spinopelvic alignment and the functional outcomes after long instrumented fusion for degenerative thoracolumbar spinal disease.

Summary of Background Data: Restoring better sagittal alignment is known as a key factor to spine fusion surgeries. The relationship between function and radiographic results in the elderly group is barely known.

Methods: Between 2009 and 2013, data of 120 patients with multilevel degenerative thoracolumbar spinal disease who underwent long instrumented fusion were collected retrospectively. Perioperative radiographic and functional parameters were measured and analyzed for their correlations. Receiver operating characteristic (ROC) method was used to define ideal cutoff points of postoperative spinopelvic alignment to avoid poor outcome.

Results: Oswestry disability index (ODI) more than or equal to 20 or Visual analogue scale (VAS) more than or equal to 4 were defined as poor functional outcomes. The optimal cutoff points of the radiographic parameters were found as below: the mismatch between pelvic incidence and lumbar lordosis was 16.2°, sagittal vertical axis was 38.5 mm, and pelvic tilt was 23.4°. Poor functional outcomes were significantly correlated with bad sagittal alignment, older age, and poor preoperative function.

Conclusion: Postoperative functional outcomes were highly impacted by the spinopelvic sagittal alignment.


The spinal column comprises the vertebrae, intervertebral disks, and surrounding soft tissues and performs several critical functions such as protection of neural elements and maintenance of the balance and alignment of the human body. People have unique patterns of spinopelvic balance and sagittal alignment to achieve the physiological upright standing posture.[1] These patterns can be affected by numerous variables such as patient age, sex, weight, and especially pelvic morphology and pelvic orientation.[2,3] The optimal alignment of the spine and its position in relation to the pelvis and lower extremities have been observed in several studies on asymptomatic adults of different ethnic backgrounds. A significant chain of correlations exists between positional pelvic and spinal parameters and pelvic incidence.[4–7] The indications of spinal instrumented fusion for degenerative spinal disease are correction of deformity and prevention of additional complications after decompression of neural elements including the progression of spondylolisthesis and the supplementation of spinal stability in the absence of intact posterior elements.[8,9] Long instrumented fusion is required when multiple segmental lesions exist. An increased incidence of loss of sagittal plane alignment resulting from flatback deformity and adjacent segmental disease has been noted in patients who have undergone long-level spinal fusion.[10,11] Prior studies of adult scoliosis have attempted to correlate radiographic appearance with clinical symptoms.[12] The functional outcomes of these patients are probably closely associated with the balanced sagittal alignment of the postoperative spine; however, very few reports focus on this association, particularly in patients with degenerative thoracolumbar spinal disease. We aimed to obtain an association between sagittal parameters and Oswestry Disability Index (ODI)[13] and visual analog scale (VAS)[14] as well as to perform risk factor analysis by examining postoperative functional outcomes in long instrumented spinal fusion.