5-Year Durability of Satisfactory Functional Outcomes Following Adult Cervical Deformity Surgical Correction

Introduction: Functional improvement is the primary driver for surgical correction in adult cervical deformity. Elucidating factors that influence the sustained durability of health related quality of life measures can improve patient reported outcomes.

Methods: Surgical ACD patients >18yr with a minimum 2-year follow-up were included. Patients were stratified into two groups, those that achieved MCID by 6 months and sustained it at further follow-ups(S), and those that did not(NS). Descriptive analysis included demographic, HRQLs, radiographic, surgical information, and complications. Univariate and multivariable regression analyses were used to assess differences in these parameters.

Results: 258 patients ACD patients were included. 66 patients met inclusion criteria, with 31 (47%) reaching MCID by 6M in at least 1 HRQL (NDI, EQ5D, mJOA). 47 of those (71.2%) in S and 19 in NS. 31/47 of the S cohort had achieved MCID by 3 months. No significant difference in baseline demographics and HRQLs (NDI, EQ-5D, mJOA) between groups. Furthermore, no significant differences in radiographic parameters (cSVA, TS-CL, PI-LL, PT, SVA) amongst the groups were present, however rate of osteotomies was higher in NS. NS had worse baseline NDI (53.2 in NM vs 42.3 in M, p<.001) and EQ-5D(9.5 in NS vs 10.9 in M, p=.005), however no difference in mJOA was seen. Similarly, at 1 year, there was no statistical difference in mJOA, while NDI and EQ-5D showed significant improvement in those who had MCID. Those that achieved MCID by 6 months were 6 times as likely to maintain MCID till 2 years and further while those who achieved MCID at 1-year were likely to have maintenance of durability in patient reported outcomes at later follow-ups (OR 10.5, p= <.001).

Conclusion : Patients with worse baseline health related quality of life measures were less likely to reach MCID after surgery, despite no statistical difference in baseline deformity. Achieving MCID initially is a significant factor for sustained health related quality of life measures.