So Close yet So Far: The impact of undercorrection of cervical sagittal alignment during adult cervical deformity surgery - An Incremental correction analysis.

Abstract

BackgroundTo compare degrees of cSVA correction and to theorize possible minimum and maximum thresholds of cSVA correction for patients to benefit clinically.Methods657 operative ACD patients in a retrospective cohort study of a prospectively enrolled database with complete baseline and two year radiographic and HRQL data were examined. Patients were grouped into an optimally corrected cohort (OC; postop cSVA ≤ 4 cm) and an undercorrected cohort (UC; postop cSVA > 4 cm) based on postoperative radiographs.Results265 patients met inclusion criteria (mean age 58.2 ± 11.4 years, BMI 28.9 ± 7.5, CCI 0.9 ± 1.3). 11.2 % of patients were UC, while 88.8 % of patients were OC. UC cohort experienced a significantly greater occurrence of radiographic complications (47.8 % v. 27.6 %, p = 0.046). UC also demonstrated a significantly greater rate of severe 6 M DJK (p < 0.001) and 1Y DJK (26.1 % v. 2.7 %, p < 0.001). In terms of HRQLs, the OC cohort demonstrated significantly greater 2Y EQ5D-Health values (76.9 v. 46.7, p = 0.012). Being UC was a significant predictor of moderate-high 1Y mJOA score (OR 3.0, CI 95 % 1.2-7.3, p = 0.015) Still, in terms of CIT, the threshold for DJF risk increased significantly (p = 0.026) when the cSVA were surgically corrected greater than 5 cm.ConclusionUndercorrection of cSVA yielded worse clinical outcomes and posed a significant risk for radiographic complications. Although undercorrection does not seem to be efficacious, surgical correction beyond certain thresholds should still be respected as there is a risk for DJK on either end of the spectrum.