Efficacy and outcomes of dynamic-plated single-level anterior diskectomy/fusion with additional analysis of comparative costs

Abstract

Background: Few studies focus on the fusion rates and outcomes for single-level anterior cervical diskectomy/fusion (1-ACDF) utilizing iliac autograft and dynamic plates.

Methods: Fusion rates and outcomes were prospectively evaluated in 60 consecutive patients undergoing 1-ACDF utilizing iliac autograft and dynamic plates (ABC; Aesculap, Tuttlingen, Germany). Eighteen patients had radiculopathy, while 42 were myelopathic (average Nurick Score 3.3). Pathology included single-level disc disease/spondylosis (38 patients) and/or ossification of the posterior longitudinal ligament (OPLL, 22 patients). Fusion was assessed at 3, 6, and up to 12 months postoperatively utilizing dynamic X-rays and 2D-CT scans. Outcomes were evaluated up to 24 months postoperatively utilizing Odom's Criteria, Nurick Grades, and Short-Form 36 (SF-36) outcome questionnaires. Patients were followed for an average of 4.8 postoperative years (minimum 2 years).

Results: Although dynamic X-rays/2D-CT studies documented 100% fusion an average of 3.8 months (range 2.5-8 months] postoperatively, 5 heavy smokers exhibited delayed fusions [6-8 months postoperatively]. Two years postoperatively, the average Nurick Score was 0.3 (mild radiculopathy), while Odom's Criteria revealed 52 excellent, 6 good, and 2 fair outcomes [the latter 8 patients were heavy smokers]). Utilizing SF-36 outcome questionnaires, patients markedly improved (>10.0 point gain) on 5 of 8 Health Scales within 6 months, 7 of 8 within 1 year, and all 8 within 2 postoperative years.

Conclusions: For 60 patients undergoing 1-ACDF utilizing dynamic plates, ultimately a 100% fusion rate was achieved (5 heavy smokers exhibited delayed fusions). Two years postoperatively, Nurick Grades, Odom's Criteria, and SF-36 questionnaires revealed adequate outcomes.

Keywords: Anterior Cervical Diskectomy/Fusion; Autograft; Dynamic Plates; Fusion Rates; SF-36 Outcomes; Single-level.

Figure 1

This transaxial CT examination readily demonstrates the “smooth-layer sign” associated with OPLL seen at the disc space level alone. The “smooth-layer sign” is rarely associated with a cerebrospinal fluid fistula during 1-ACDF surgery.

Figure 2

On this noncontrast axial CT study, at the level of the interspace, a central ossified intradural mass is seen which is separated from the posterior margin of the vertebral body by the interposed hypodense dura. This is the classical image of the “double-layer sign” for OPLL that is highly associated with cerebrospinal fluid fistulas during anterior cervical surgery. This patient developed an intraoperative CSF fistula which was effectively treated with a sewn-in [7-0 Gortex Sutures] dural graft, fibrin sealant, and microfibrillar collagen

Figure 3

This lateral cervical plain X-ray demonstrates adequate dynamic plate and graft localization. The interbody graft appears incorporated, as there is bony trabeculation and no lucency at the graft/vertebral body interface. Note the 3-4 mm superior and inferior migration of the plate over the vertebral body screw heads

Figure 4

This AP cervical plain X-ray demonstrates maximal cephalad and caudad migration of the screws within the slots of the dynamic plate

Figure 5

The sagittal midline 2D-CT study obtained 6 months postoperatively following iliac autograft and dynamic ABC plate placement documented an adequate fusion. Observe the lack of lucency and the presence of bony trabeculation at the graft/vertebral body interfaces superiorly and inferiorly. A further fusion criterion is the lack of lucency surrounding the vertebral screws. Also note the 3-4 mm of cephalad and caudad screw migration within the plate minimizing stress shielding and allowing for graft settling/fusion.