Incidence and Risk Factors of Mechanical Complications After Posterior-Based Osteotomies for Correction of Moderate to Severe Adult Cervical Deformity: 1-Year and 2-Year Follow-up.

Background: Rigid cervical deformity (CD) requires multilevel and/or high-grade osteotomies and long-construct fusions to achieve adequate correction. The incidence of mechanical complications (MCs) remains incompletely studied.

Objective: To define the incidence and risk factors for MC.

Methods: A retrospective review of consecutive patients with CD who underwent correction from 2010 to 2018 was performed. Inclusion criteria were cervical kyphosis >20° and/or cervical sagittal vertical axis (cSVA) >4 cm. MCs (junctional kyphosis/failure, pseudarthrosis, and implant failure) and reoperation at 1 and 2 yr were examined.

Results: Eighty-three patients were included. The mean age was 63.4 yr, and 61.0% were female. Fifty-three percent underwent 3-column osteotomies. After surgery, cervical parameters were significantly improved: cSVA (6.2 vs 3.8 cm, P < .001), cervical lordosis (6.3 vs -8.3°, P < .001), cervical scoliosis (CS) (6.5 vs 2.2°, P < .001), and T1 slope (41.7 vs 36.3°, P = .007). The MC rate was 28.9%: junctional (18.1%), implant (16.9%), and pseudarthrosis (10.8%). MC rates at 1 and 2 yr were 14.5% and 25.5%, respectively: junctional (9.6% and 17.6%), implant (9.6% and 17.6%), and pseudarthrosis (2.4% and 7.8%). The overall reoperation rate was 24.1%: 14.5% at 1 yr and 19.6% at 2 yr. Body mass index (BMI) (P = .015) and preoperative CS (P = .040) were independently associated with higher odds of MC. Receiver operating characteristic curves defined CS >5° to be the threshold of risk for MCs and reoperation.

Conclusion: Correction of CD is effective by posterior-based osteotomes, but MCs are relatively high at 1 and 2 yr. BMI >30 and preoperative CS >5° predispose patients for MC and reoperation.