Clinical and radiological outcomes of a cervical cage with integrated fixation

Abstract

Cervical cages with integrated fixation have been increasingly used in anterior cervical discectomy and fusion (ACDF) to avoid complications associated with anterior cervical plates. The purpose of this paper is to provide 2-year follow-up results of a prospective study after implantation of a cervical cage with an integrated fixation system.This was a prospective multicenter outcome study of 90 patients who underwent ACDF with a cage with integrated fixation. Fusion was evaluated from computed tomography images (CT-images) by an independent laboratory at 2-year follow-up (FU). Clinical and radiological findings were recorded preoperatively and at FU visits and complications were reported.At 24 months, the fusion rate was 93.4%. All average clinical outcomes were significantly improved at 2 years FU compared to baseline: neck disability index (NDI) 18.9% vs 44.4%, visual analog scale (VAS) for arm pain 18.2 mm vs 61.9 mm, VAS for neck pain 23.9 mm vs 55.6 mm. Short form-36 (SF-36) scores were significantly improved. One case of dysphagia, which resolved within 12 months, and 1 reoperation for symptomatic pseudarthrosis were reported. Subsidence with no clinical consequence or reoperation was reported for 5/125 of the implanted cages (4%). There was also 1 case of per-operative vertebral body fracture that did not require additional surgery. Superior and inferior adjacent discs showed no significant change of motion at 2-year FU compared to baseline. Disc height index (DHI) and lordosis were enhanced and these improvements were maintained at 1 year.The ACDF using cages with an integrated fixation system demonstrated reliable clinical and radiological outcomes and a high interbody fusion rate. This rate is comparable to the rate reported in recent series using other implants with integrated fixation, but the present device had a lower complication rate.

Figure 1

(A) Functional spinal unit alignment in flexion. (B) Functional spinal unit alignment in extension. (C) Radiographic measurements of disc height: (a) Anterior disc height, (b) Middle disc height, (c) Posterior disc height, (d) Sagittal diameter of the overlying vertebral body. Disc height index = [(a + b + c)/3]/d.

Figure 2

Clinical outcomes over follow-up. Results are expressed as mean ± SEM. ∗P ≤ .05 compared to preoperative baseline: (A) visual analog scale (VAS 0–100 mm) for neck pain. (B) visual analog scale (VAS 0–100 mm) for arm pain. (C) Neck disability index (NDI 0–100%). (D) SF-36 score (PCS = physical composite score; MCS = mental composite score).

Figure 3

Lordosis over follow-up. Results are expressed as mean ± SEM. ∗P ≤ .05 compared to preoperative baseline: (A) Disc height index (DHI). (B) Cervical and FSU lordosis. DHI = disc height index, FSU = functional spine unit.

Figure 4

Mobility over follow-up. Results are expressed as mean ± SEM. ∗P ≤ .05 compared to preoperative baseline: (A) ROM at the index FSU. (B) ROM at adjacent levels. FSU = functional spine unit, ROM = range of motion.