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

Abstract

Study design Retrospective study. Objective This study aimed to compare the fusion order between the cranial and caudal levels in two-level anterior cervical discectomy and fusion (ACDF) with a zero-profile device in the treatment of cervical spondylopathy. Summary of background data Fusion is the standard used to judge the success of ACDF. However, the fusion order in two-level ACDF remains uncertain. The mechanical environment of different levels is different, which may affect the fusion rate or fusion order. Methods From 2014 to January 2019, data of consecutive patients with two-level cervical disk degenerative disease who underwent ACDF were retrospectively reviewed. Radiological assessments were based on the range of motion of the fusion level, segment slope, and disk height, and complications were assessed. Data were analyzed using the paired t, Mann-Whitney U, χ2, Fisher exact, and rank-sum tests and logistic regression analysis. Results In total, 118 patients were ultimately enrolled for analysis in the study. The respective fusion rates of the cranial and caudal levels were 26.27% and 10.17% (p < 0.05) at 3 months, 58.47% and 42.37% (p < 0.05) at 6 months, 86.44% and 82.20% (1 0.05) at 1 year, and 92.37% and 89.83% (p > 0.05) at the last follow-up. Multivariate logistic regression analysis indicated that the preoperative segmental slope and cranial level were independent risk factors for non-fusion. The adjacent segment degeneration (ASD) and subsidence rates were comparable between the two levels. Conclusion The caudal level had a slower fusion process than the cranial level. A higher preoperative segment slope was a risk factor for fusion. However, the subsidence and ASD rate were comparable between the caudal and cranial levels in the two-level ACDF.

Risk Factors of Nonfusion after Anterior Cervical Decompression and Fusion in the Early Postoperative Period: A Retrospective Study

“…Previous studies reported that the rate of cage nonfusion after ACDF was less than 10% at 1‐year follow‐up 32 . However, in the early period after ACDF (during the first 90 days postoperatively), the fusion rate was much lower (15%–62%) at 3‐month follow‐up 33–36 . Lower fusion rates in the early period would result in higher rates of subsidence, cage displacement, and pseudarthrosis.…”

“…Following radiographic recommendations for evaluating cervical fusion, 39,40 fusion was defined as the presence of continuous bone bridges behind the surgical segments on CT three‐dimensional reconstruction. According to our previous study, ‘fusion’ is defined as the presence of ≤2°or 3°motion and/or ≤2 mm of motion of the interspinous distance on flexion–extension X‐rays 33–36,41 . Further, different implant and surgical procedures, as well as screw length and angle, would result in a different fusion rate 9 …”

“…According to our previous study, 'fusion' is defined as the presence of ≤2 or 3 motion and/or ≤2 mm of motion of the interspinous distance on flexion-extension X-rays. [33][34][35][36]41 teriparatide administration in the acute postoperative period resulted in significantly greater bone formation and a higher rate of the complete fusion by increasing BGP and CTX over 6 months. 42,43 It indicated that the patients whose surgical segments achieved fusion within 3 months of follow-up have higher bone turnover markers.…”

Uncovertebral Joint Fusion Versus End Plate Space Fusion in Anterior Cervical Spine Surgery

“…The exclusion criteria were as follows: (1) previous cervical surgery; (2) ossification of the posterior longitudinal ligament or stenosis of the cervical spinal canal, spinal fracture, severe osteoporosis, or a history of metabolic bone disease; (3) local infection and ulceration of the neck skin, systemic inflammatory disease, rheumatoid arthritis, uncontrolled diabetes, or malignant tumor; (4) a psychological disorder preventing compliance with study requirements as described above; (5) poor general condition, serious diseases of important organs, or substantial risk associated with surgery (American Society of Anesthesiologists classification ‡IV); (6) continuous immunosuppressive therapy for >1 month within the previous 12 months; (7) hypersensitivity to the implant material (polyetheretherketone or titanium alloy); (8) severe obesity; (9) a history of drug abuse; (10) pregnancy or planned pregnancy during the study; and (11) participation in another clinical study that may have an impact on the outcomes of this study.…”

“…However, the early fusion rates (at 3 and 6 months postoperatively) are often unsatisfactory. According to available reports 8-12 , the 3-month and 6-month fusion rates have ranged from 2.9% to 43.1% and 30% to 68.8%, respectively. Although a lack of fusion may be asymptomatic, it may potentially lead to complications 13,14 , even a reoperation.…”