Value of “Early Fusion”: Is Faster Fusion Beneficial for Patients Undergoing Anterior Cervical Decompression and Fusion?

Abstract

Since the first reports of ventral approaches to cervical disc pathology were introduced in the 1950s 1,2 , anterior cervical discectomy and fusion (ACDF) has become one of the most common procedures performed by spine surgeons for patients with symptomatic cervical spondylosis. A solid osseous fusion is necessary to achieve good clinical results. Spine surgeons have been trying to modify their own procedures using a variety of interbody fusion materials, such as structural autograft, allograft, titanium, polyetheretherketone (PEEK), or carbon fiber-reinforced polymer, with or without non-structural autograft or allograft. Although a number of clinical investigations have been performed evaluating how to achieve solid fusion, attention has not been focused on the time to fusion.Sheng et al. performed a prospective randomized controlled trial (RCT) and showed that cervical fusion could be achieved earlier after uncovertebral joint fusion (UJF) compared with end plate space fusion (ESF) for patients with single-level cervical spondylosis. Although no significant difference was observed in the fusion rate at 12 months, their results showed that fusion rates at 3 and 6 months after ACDF were much higher in the UJF group than in the ESF group (UJF versus ESF: 66.7% versus 13.2% at 3 months, 94.1% versus 66.7% at 6 months). Based on a previously published goat study 3 , the authors speculated that the reasons for these results were due to several factors. The uncovertebral joint had several anatomical advantages over ESF: a narrower gap, higher mechanical load, better osteogenic potential, and better blood supply, which could be advantageous for earlier cervical fusion. If early fusion can be achieved by UJF in ACDF, it may be possible to avoid issues with prolonged cervical bracing, such as cervical stiffness, dysphagia, and pressure ulcer, and to increase patient satisfaction and quality of life. It is also beneficial, especially for active patients (athletes), to return to play faster. Thus, the authors propose a new concept that the UJF can provide advantages over conventional ESF for the ACDF procedure.On the other hand, it is well known that the spinal fusion rate is dependent on the radiographic fusion criteria. Although Sheng et al. used relatively strict fusion criteria (both "interspinous mobility of £1 mm and formation of a bone bridge in the target area" confirmed by computed tomography [CT] had to be met simultaneously), a recent systematic literature review of osseous fusion after anterior cervical discectomy identified fusion rates for ESF of 51.1% at 3 months and 78.3% at 6 months, which are higher than those in the study by Sheng et al. (13.2% at 3 months and 66.7% at 6 months) 4 . Although the study was a prospective RCT, it was performed in a single center. It is still unclear whether the early fusion can be achieved when different spine surgeons are conducting the procedure using this new device in the same manner. Different surgical exposure, different graft materials, and/or different implant bed...