Evaluation of bony fusion after anterior cervical discectomy: a systematic literature review

Abstract

Purpose Anterior cervical discectomy and fusion (ACDF) has proven effective in treating radicular arm pain. Post-operatively, cervical spine stability is temporarily challenged, but data on bony fusion and speed of fusion are ambiguous; optimum evaluation method and criteria are debated. Aim To study bony fusion accomplishment and to obtain an overview of methods to evaluate fusion. Methods A literature search was performed in PubMed and Embase. Included studies had to report original data concerning 1-or 2-level ACDF with intervertebral device or bone graft, where bony fusion was assessed using CT scans or X-rays. Results A total of 146 articles comprising 10,208 patients were included. Bony fusion was generally defined as "the presence of trabecular bridging" and/or "the absence of motion". Fusion was accomplished in 90.1% of patients at the final follow-up. No gold standard for assessment could be derived from the results. Addition of plates and/or cages with screws resulted in slightly higher accomplishment of fusion, but differences were not clinically relevant. Eighteen studies correlated clinical outcome with bony fusion, and 3 found a significant correlation between accomplishment and better clinical outcome. Conclusions In approximately 90% of patients, bony fusion is accomplished one year after ACDF. As there is no generally accepted definition of bony fusion, different measuring techniques cannot be compared to a gold standard and it is impossible to determine the most accurate method. Variations in study design hamper conclusions on optimising the rate of bony fusion by choice of material and/or additives. Insufficient attention is paid to correlation between bony fusion and clinical outcome.Graphical abstract These slides can be retrieved from electronic supplementary material.

Is the fusion order of the cranial and caudal levels different in two-level anterior cervical discectomy and fusion for cervical spondylopathy? A retrospective study

“…In previous studies, the fusion rate of two-level ACDF varied; a systematic review [ 10 ] reported a mean fusion rate of 90.1%, which ranged from 30 to 100%. Smoking, osteoporosis, diabetes, preoperative range of motion (ROM), and preoperative T1 slope are the factors that influence the fusion rate or fusion speed [ 11 – 16 ].…”

Biomechanical Comparison of Optimal Shapes for the Cervical Intervertebral Fusion Cage for C5–C6 Cervical Fusion Using the Anterior Cervical Plate and Cage (ACPC) Fixation System: A Finite Element Analysis

“…Midterm follow-up of the clinical and radiological results achieved by tantalum intervertebral fusion cages for single-level ACDF have shown that the cages remain in good condition for up to 11 years postoperatively, and similar results with the use of autologous bone grafts and plating were also reported [7]. The use of plates and fusion cages with screws can promote fusion, but no clinically significant differences have been shown [8]. Kettler et al [9] reported that the design of the implants used determines the relationship between the activity and the subsidence rate.…”

Preliminary results in anterior cervical discectomy and fusion with the uncovertebral joint fusion cage in a goat model

“…Even in the absence of ideal criteria at present, the combination of X-rays with flexion-extension X-rays and CT scans was frequently used for determining clinical fusion quality after a cervical spine surgery [19,20]. For animal studies, several methods with different advantages and limitations are available for evaluation of spinal fusion including X-rays, CT scans, magnetic resonance imaging (MRI), micro-CT scans, biomechanical tests, histologic analysis, bone mineral density tests and other uncommon methods.…”