Nonunion Rates After Anterior Cervical Discectomy and Fusion: Comparison of Polyetheretherketone vs Structural Allograft Implants

Abstract

BACKGROUND Although advances in implant materials, such as polyetheretherketone (PEEK), have been developed aimed to improve outcome after anterior cervical discectomy and fusion (ACDF), it is essential to confirm whether these changes translate into clinically important sustained benefits. OBJECTIVE To compare the radiographic and clinical outcomes of patients undergoing up to 3-level ACDF with PEEK vs structural allograft implants. METHODS In this cohort study, radiographic and symptomatic nonunion rates were compared in consecutive patients who underwent 1 to 3 level ACDF with allograft or PEEK implant. Prospectively collected clinical data and patient-reported outcome (PRO) scores were compared between the allograft and PEEK groups. Regression analysis was performed to determine the predictors of nonunion. RESULTS In total, 194 of 404 patients met the inclusion criteria (79% allograft vs 21% PEEK). Preoperative demographic variables were comparable between the 2 groups except for age. The rate of radiographic nonunion was higher with PEEK implants (39% vs 27%, P = .0035). However, a higher proportion of nonunion in the allograft cohort required posterior instrumentation (14% vs 3%, P = .039). Patients with multilevel procedures and PEEK implants had up to 5.8 times the risk of radiographic nonunion, whereas younger patients, active smokers, and multilevel procedures were at higher risk of symptomatic nonunion. CONCLUSION Along with implant material, factors such as younger age, active smoking status, and the number of operated levels were independent predictors of fusion failure. Given the impact of nonunion on PRO, perioperative optimization of modifiable factors and surgical planning are essential to ensure a successful outcome.

Morphologic Change of CorticoCancellous Allograft Used for Anterior Cervical Discectomy and Fusion

“…Furthermore, the use of corticocancellous allografts need not be avoided due to its similar or better fusion rate compared with that of other interbody spacers, as demonstrated in previous studies, and clinical results were not adversely affected, as demonstrated in the present study. 32 Still, caution is needed when using corticocancellous allografts owing to the high rate of graft resorption or fracture and negative implications of these risks on radiographic outcomes.…”

“…Furthermore, the use of corticocancellous allografts need not be avoided to its similar or better fusion rate compared with that of other interbody spacers, as demonstrated in studies, and clinical results were not adversely affected, as demonstrated in the present study. 32 Still, caution is needed when using corticocancellous allografts owing to the high rate of graft resorption or fracture and negative implications of these risks on radiographic outcomes. Although improvement of patient symptoms is the primary purpose of the operation, attempts should be made to decrease the rate of radiographic complications such as pseudarthrosis and subsidence, since these complications can occasionally lead to revision operations or worse clinical outcomes.…”

“…29,30 Although the pseudarthrosis and subsidence rates of this study are higher than generally thought, recent reports have demonstrated that the pseudarthrosis rate after ACDF could have been underestimated, with the incidence reaching 13.0% to 22.6% for one-level operation and 45.5% to 47.0% for three-level operation. [31][32][33] The subsidence rate could have been detected with increased sensitivity since subsidence was assessed using multiple CT images. 34 Furthermore, frequent occurrence of allograft morphologic change, as demonstrated in this study, could have been attributed to a higher incidence of pseudarthrosis or subsidence Although the radiographic results, including solid union, subsidence, and lordosis, demonstrated worse outcomes in the morphologic change group, clinical outcomes measured by neck pain VAS, arm pain VAS, and NDI did not demonstrate significant differences between the morphologic change and unchanged groups.…”

Predictive nomogram of cage nonunion after anterior cervical discectomy and fusion: A retrospective study in a spine surgery center

“…Previous researchers showed that the proportion of nonunion in cages after ACDF was <10%. [ 4 , 6 , 11 ] Nonunion after spinal fusion procedures can result in recurrent pain, radiculopathy, and kyphotic deformity. However, its risk factors are controversial.…”

“…Although the cage nonunion is not very high, it may cause serious consequences, including recurrent pain, radiculopathy, and kyphotic deformity. [4][5][6] Several studies showed that implant material, age, low bone mineral density, smoking status, low level of vitamin D and multilevel ACDF were risk factors for cage nonunion. [7][8][9] However, its risk factors are controversial (Table S1, Supplemental Digital Content 1, http://links.lww.com/MD/H389).…”