Evaluation of lumbar stiffness after long-level fusion for degenerative lumbar scoliosis via a Chinese version of the lumbar stiffness disability index

Background context: Long-level spinal fusion for degenerative lumbar scoliosis (DLS)seeks to eliminate spinal motion in an attempt to alleviate pain, improve deformity, and reduce disability. However, this surgery considerably impairs the performance of activities of daily living (ADL) due to the resulting stiffness. The lumbar stiffness disability index (LSDI) is a validated measure of the effect of lumbar stiffness on functional activity, but this index might not be fully applicable to the elderly Chinese population given several specific lifestyle characteristics.

Purpose: To evaluate lumbar stiffness in patients with DLS after long-level fusion by Chinese-LSDI (C-LSDI).

Study design: A retrospective study.

Patient sample: A total of 129 DLS patients who underwent long-level (≧4 levels) fusion surgery with at least one-year follow-up from June 2009 to September 2017 were retrospectively included.

Outcome measures: The C-LSDI was designed by modifying LSDI and Korean-LSDI (K-LSDI) based on elderly Chinese lifestyles and the internal consistency and retest repeatability of the patient-reported outcome questionnaire in the measurement of the impact of lumbar stiffness on functional abilities was assessed.

Methods: The radiographic parameters including Cobb angle, apical vertebral translation (AVT), coronal vertical axis (CVA), sagittal vertical axis (SVA), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), pelvic tilt (PT), pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), and PI-LL, and clinical symptoms including visual analogue scale (VAS) for back and low extremity pain; Oswestry disability index (ODI), Japanese Orthopedic Association-29 (JOA-29), Scoliosis Research Society⁃22 (SRS-22), 36⁃Item short form survey (SF-36), physical component scores (PCS) and mental component scores (MCS) were measured preoperatively and at the last follow-up.

Results: Compared with LSDI and K-LSDI, the C-LSDI demonstrated higher internal consistency (Cronbach's alpha=0.902) and retest reliability (Internal consistency coefficients, ICC=0.904) in the elderly Chinese population. All patients showed increased lumbar stiffness and significant improvement in pain and deformity postoperatively. Regarding items, such as performing personal hygiene after toileting and getting out of a car, people reported more inconvenience with increasingly fixed levels.

Conclusions: This study demonstrated that the C-LSDI questionnaire was a reliable and valid instrument for assessing functional limitations due to lumbar stiffness among elderly Chinese patients with DLS after long-level fusion. Although the effects of stiffness did trend toward greater impacts among patients who underwent longer fusions, most patients were satisfied with trade-offs of function and pain relief in exchange for perceived increases in lumbar stiffness.