Abstract
Introduction: We studied whether a minimally invasive surgery (MIS) triad consisting of anterior column realignment (ACR), lateral lumbar interbody fusion (LLIF), and percutaneous pedicle screw (PPS) fixation in a select group of patients with adult spinal deformity (ASD) helped shorten the fusion length without compromising clinical and radiographic outcomes over a minimum 2-year follow-up period.
Methods: A series of 39 ASD patients (mean age, 73.9 years) with pelvic incidence (PI)/lumbar lordosis (LL) mismatch ≥10° underwent a short-segment MIS triad consisting of single level ACR at L3-L4, two levels of LLIF at L2-L3 and L4-L5, and PPS fixation at L2 through L5 as a single-stage operation. The exclusion criteria were: (1) thoracic scoliosis as the main deformity, (2) thoracolumbar junction kyphosis, (3) ankylosed facet joints, and (4) previous spinal fusion surgery.
Results: The segmental disc angle at the ACR level was more than quintupled, averaging 2.8° preoperatively to 19.1° at the latest follow-up (p<0.0001). The LL nearly doubled from 13.6° to 29.8° (p<0.0001), and the PI/LL mismatch decreased by nearly half from 28.9° to 12.7° (p<0.0001). Simultaneously, other spinopelvic deformity parameters and Oswestry Disability Index (ODI) scores significantly improved. The latest postoperative evaluation divided the patients into two groups: 23 patients whose PI/LL mismatch improved to <10° and 16 patients who remained with ≥10° mismatch. Binary logistic regression revealed that preoperative PI/LL mismatch was the only factor that significantly influenced this dichotomous separation postoperatively. Receiver operating characteristic curve analysis identified a critical preoperative mismatch of 24.2° with 52% sensitivity and 94% specificity. Despite these different radiographic consequences, the two groups showed equally successful clinical outcomes with no significant difference in ODI scores.
Conclusions: At a minimum 2-year follow-up after a 3-level MIS with ACR, LLIFs, and PPS fixation, ASD patients, consistent with our exclusion criteria, could achieve and maintain an ideal spinopelvic sagittal alignment of PI/LL mismatch <10° with 52% sensitivity and 94% specificity when associated with preoperative PI/LL mismatch <24.2°.
