The effect of smoking on the radiological and functional outcomes of anterior cervical discectomy and fusion with anchored standalone cages.

BACKGROUND

Anchored standalone cages for anterior cervical discectomy and fusion (ASC-ACDF) are easier to implant but have higher subsidence rates compared to anterior plating constructs. Smoking is a known risk factor for subsidence, however, there are conflicting reports on its effect on functional outcomes. This study aims to evaluate the impact of smoking on radiological and functional outcomes of patients undergoing ASC-ACDF.

METHODS

Patients who underwent primary single- and double-level ASC-ACDF between 2015-2022 were reviewed. Inclusion: diagnosis of cervical myelopathy, radiculopathy or myeloradiculopathy, age range 40-90 years old. Exclusion: previous cervical spine surgery, diagnosis of tumor or infection. Patients were divided into non-smokers (NS) or current and ex-smokers (CES). Data was collected radiological outcomes [postoperative subsidence rates, Δtotal intervertebral height (TIH), Δlordotic angle] at 1-year and functional outcomes [Japanese Orthopedic Association (JOA) score, Neck Disability Index (NDI), Visual Analogue Scores for Neck Pain (VASNP) and Upper Limb Pain (VASLP)] at 6 months and 2 years postoperatively.

RESULTS

A total of 71 patients were included (CES: 23; NS: 48). CES had higher subsidence rates at 1-year (60.9% vs. 35.4%, P=0.043) with greater TIH loss (ΔTIH -2.4 vs. -1.7 mm, P=0.038). Fusion rates (91.3% vs. 89.5%, P=0.82) and change in lordosis (-4.1° vs. -3.8°, P=0.78) were insignificantly different. Both groups demonstrated significant improvement in all functional scores after surgery (P<0.05) at similar rates (P<0.05). JOA scores were unaffected by smoking. However, CES consistently had higher NDI, VASNP, and VASLP scores at all timepoints.

CONCLUSIONS

Subsidence rates and functional scores (NDI, VASNP and VASLP) are nearly double in smokers after surgery. In ASC-ACDF, while smokers and NS benefit from surgery, smoking is associated with higher disability and pain scores.