Introduction
Improvement of sagittal alignment after adult spinal deformity (ASD) surgery is associated with improved health-related quality of life (HRQOL). However, the improvement of the lumbar function domain in the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) is limited because of the restricted lumbar spine function after long-range corrective fusion surgery from the thoracic spine to the pelvis. This study aimed to investigate factors contributing to improved lumbar spine function after ASD surgery.
Methods
This was a retrospective, single-center, cohort study. In this study, 30 patients (mean age 73±8.7 years) who underwent thoracic spine to pelvis deformity correction surgery for ASD and have been followed for > 1 year were included. The lumbar dysfunction score on the JOABPEQ at 1 year postoperatively was compared between 11 patients in the group that improved > 20 points from the preoperative level (group H) and 19 patients in the group that decreased (group L). The study included age, sex, BMI, existing vertebral fractures, nutritional status (PNI, GNRI), psoas major index, presence of rod fracture and proximal junctional kyphosis (PJK), pre- and postoperative HRQOL (JOABPEQ, ODI), pre- and postoperative sagittal spinopelvic parameters (TK, LL, PI, PI-LL, PT, SVA, TPA), and femoral tilt angle (FOA). The correlation between the amount of change in lumbar function score (pre- and postoperative) and each parameter was evaluated.
Results
Preoperative PT and pre- and postoperative FOA were significantly lower in group H (p=0.01, p=0.003, p=0.025). There were no significant differences in other radiographic parameters between the two groups. Preoperative HRQOL was significantly worse in group H; particularly, lumbar function, social life function, and mental health of the JOABPEQ and ODI, while postoperative lumbar function was significantly better in group H. The correlations between the amount of change in lumbar function score and each parameter were as follows; preoperative FOA (r=-0.483, p<0.001), postoperative FOA (r=-0.361, p<0.05), and preoperative PT (r=-0.282, p=0.13).
Discussion
The study results showed that postoperative lumbar function domains improved in patients with small preoperative PT and FOA, such as those with relatively less advanced pelvic and hip compensations for ASD. Posterior pelvic tilt has been reported to be associated with hip ROM limitation. In group H, hip ROM may have been maintained preoperatively. The study results suggest that preoperative hip flexibility may be important in lumbar spine function after ASD surgery.