Leveraging Personalized Interbody Implants for the Minimally Invasive Treatment of Adult Degenerative Scoliosis

BACKGROUND: Minimally invasive surgery (MIS) for adult degenerative scoliosis (ADS) offers favorable outcomes and lower complication rates compared with traditional open techniques, yet achieving precise alignment targets remains challenging. This study evaluates the impact of personalized interbody implants on realignment in MIS spinal deformity surgery. METHODS: A single-surgeon retrospective case series of 12 consecutive ADS patients was conducted. Preoperative computed tomography-based planning guided the design of patient-specific 3D-printed interbody cages and pre-bent personalized rods. Surgery involved first-stage multilevel oblique lumbar interbody fusion with L5 to S1 lateral anterior lumbar interbody fusion, followed by a second-stage robot-assisted MIS placement of pedicle and iliac screws with multiple rod constructs. Demographic, operative, radiographic, and patient-reported outcomes were analyzed. RESULTS: Twelve patients (7 men, mean age 65 years) were identified with a mean follow-up of 10 months. Most patients (8) had Obeid Type 1A1 coronal deformities. Per patient, means included 10.1 instrumented levels, 4.75 interbody cages, 3.2 iliac fixation points, and 3.2 rods. Significant sagittal improvements included sagittal vertical axis from 7.1 ± 3.0 cm to 5.7 ± 2.3 cm, pelvic incidence-to-lumbar lordosis mismatch from 20.4° ± 14.1° to 1.8° ± 8.7°, pelvic tilt from 21.9° ± 6.9° to 13.4° ± 4.7°, L4 to S1 lordosis from 29.7° ± 9.5° to 38.1° ± 7.3°. Coronal improvements included Cobb angles from 33.2° ± 12.6° to 6.1° ± 2.7°, central sacral vertical line from -0.4 ± 3.2 cm to 0.1 ± 1.2 cm, and fractional curve from 18.9° ± 10.3° to 3.8° ± 3.4°. Postoperatively, 4 patients improved to Bao type A; all pre-existing Bao type A patients remained stable. Complications included 1 pneumothorax and 1 reoperation for proximal junctional kyphosis. Significant clinical improvements were noted in the Oswestry Disability Index, Scoliosis Research Society-22, and pain scores. CONCLUSION: The use of personalized interbody implants in circumferential MIS for ADS demonstrates promising clinical improvements and radiographic results. This technology's ability to help restore coronal and sagittal realignment is noteworthy and should be considered a capable tool for patients with ADS. CLINICAL RELEVANCE: By achieving more precise patient-specific alignment targets, these technologies may help overcome the historical limitations of MIS approaches in complex deformity correction.