Diabetes Is Associated With Higher Odds of Junctional Complications and More Reoperations After Adult Spinal...

Mechanical complications remain a major concern after adult spinal deformity surgery. Diabetes has been associated with impaired bone quality and delayed healing in orthopaedic surgery, but its relationship with mechanical complications and patient-reported outcomes after adult spinal deformity surgery remains incompletely understood.

(1) Is diabetes associated with a higher odds of mechanical complications after adult spinal deformity surgery? (2) Is revision-free survivorship for proximal junctional failure lower in patients with diabetes than in those without diabetes? (3) Do radiographic alignment parameters differ between groups after surgery? (4) Are patient-reported outcomes lower in patients with diabetes at 2 years?

Between January 2010 and December 2023, a total of 585 patients underwent corrective fusion for adult spinal deformity at our institution. Of these, 11% (65) had diabetes and 89% (520) did not. Among patients with diabetes, none died before 2 years, but 3% (2 of 65) were lost to follow-up for reasons other than death. Among patients without diabetes, 0.6% (3 of 520) died, and 4% (23) were lost to follow-up before 2 years. This analysis therefore consisted of 557 patients, of whom 11% (63) had diabetes and 89% (494) did not; their data were analyzed at least 2 years after the index fusion. Diabetes was defined as a documented diagnosis being treated with medical therapy or hemoglobin A1c of at least 6.5%. Patients with diabetes were propensity score matched 1:2 with patients without diabetes based on age, gender, BMI, bone mineral density, deformity characteristics, osteotomy, pelvic fixation, and number of fused levels. The purpose of propensity matching was to improve comparability between groups by adjusting for measured baseline covariates rather than to establish causal inference. Proximal junctional failure was defined as structural failure at the upper instrumented vertebra or adjacent segment, accompanied by concordant symptoms and subsequent revision surgery. We compared the matched groups of patients with and without diabetes in terms of mechanical complications, revision-free survivorship using Kaplan-Meier analysis, postoperative alignment parameters on standing full-length AP and lateral radiographs, and patient-reported outcome scores (Oswestry Disability Index [ODI] and Scoliosis Research Society-22 [SRS-22] scores). For patient-reported outcomes, we focused on whether between-group differences exceeded prespecified minimum clinically important differences (MCIDs).

Patients with diabetes had a higher odds of proximal junctional failure compared with patients without diabetes (19% [12 of 63] versus 9% [11 of 126], OR 2.5 [95% confidence interval (CI) 1.02 to 5.9]; p = 0.04). Revision-free survivorship for proximal junctional failure at 2 years was lower in patients with diabetes than in those without it (85% [95% CI 83% to 97%] versus 93% [95% CI 93% to 99%]; p = 0.02). We found no difference between groups in most radiographic alignment parameters at 1 and 2 years after surgery. Sagittal vertical axis was greater at the first standing radiograph in patients with diabetes than in those without it (mean ± SD 71 ± 53 mm versus 54 ± 49 mm, mean difference 17 [95% CI 1 to 33]; p = 0.04). Although patient-reported outcomes improved in both groups, none of the between-group differences exceeded reasonable MCID thresholds for the ODI or SRS-22 domains.

Patients with diabetes undergoing corrective fusion for adult spinal deformity had a higher odds of proximal junctional failure and lower revision-free survivorship. Surgeons may consider discussing the possibility of junctional complications when counseling patients with diabetes and may consider closer postoperative surveillance and improvement of metabolic control in this population. Future studies should examine how glycemic control and bone quality influence junctional complications after deformity correction.

Level Ⅲ, therapeutic study.