Does titanium cage subsidence affect clinical outcomes in ACDF surgery? A tertiary centre experience

Abstract

Background Cage subsidence after anterior cervical discectomy and fusion (ACDF) surgery has been well documented with rates of up to 40%. Cages fill the void after cervical discectomy and promote fusion. These materials have different biomechanical profiles with differing rates of subsidence. This retrospective cohort study aimed to determine subsidence rates specifically associated with the novel Emerging Implant Technologies (EIT) titanium cage, identify risk factors associated with subsidence, and evaluate whether subsidence affects clinical outcomes. Methods ACDF with insertion of stand-alone EIT cage was performed in 39 patients (64 levels) between December 2016 and February 2019 with a median follow-up of 11 months. Patients were classified into two groups; subsidence and non-subsidence, and were compared in terms of the resultant clinical outcomes as well as presence of risk factors. Health-related quality of life (HRQOL) outcomes were assessed using Visual Analogue Scale (VAS) for neck and arm pain, EuroQol 5-Dimension 5-Level (EQ-5D-5L), EuroQol Visual Analogue Scale (EQ VAS) and Neck Disability Index (NDI) scores. Results Cage subsidence (>3mm) was present in nine patients (23%), which corresponded to ten levels treated (16%). Development of subsidence was not associated with gender (p = 0.12), age (p = 0.27), smoking (p = 0.13), number of treatment levels (p = 0.10) or cage size used (p = 0.34). It had no effect on any of the HRQOL outcomes, namely VAS Neck (p = 0.07), VAS Arms (p = 0.08), EQ-5D-5L (p = 0.36), EQ VAS (p = 0.85) and NDI (p = 0.80). Conclusions The EIT cage seems to be associated with lower rates of subsidence compared with other cage types. Cage subsidence was not associated with HRQOL outcomes or risk factors.

The Effect of Subsidence on Segmental and Global Lordosis at Long-term Follow-up After Anterior Cervical Discectomy and Fusion

“…30 However, further research is needed on this topic. Furthermore, while studies have found no correlation between subsidence of intervertebral cages and clinical outcomes, 3,5,7,8 one prospective randomized controlled trial performed by Kast et al 9 in 2009 concluded that subsidence of PEEK cages significantly correlated with poorer patient outcomes as measured by Odom's criteria. The current literature may not fully encompass the true effect of subsidence on clinical symptoms due to many studies reporting short-term follow-up less than 2 years.…”

“…However, further research is needed on this topic. Furthermore, while studies have found no correlation between subsidence of intervertebral cages and clinical outcomes [ 3 , 5 , 7 , 8 ], one prospective randomized controlled trial performed by Kast et al [ 9 ] in 2009 concluded that subsidence of PEEK cages significantly correlated with poorer patient outcomes as measured by Odom’s criteria.…”

“…Evidence of adverse clinical outcomes associated with subsidence has been mixed. Some studies suggest no impact on outcomes, [4][5][6][7] whereas others have found associations with worse pain and clinical outcomes when subsidence occurs. [8][9][10] Differing results may be due to heterogeneity in radiographic measurements, interbody cages, and length of follow-up.…”