Anterior Cervical Discectomy and Fusion With a No-Profile Integrated Fixation Allograft Device: An In Vitro Biomechanical Analysis and Clinical Case Series.

Abstract

No-profile anterior cervical discectomy and fusion (ACDF) devices are commonplace in spinal surgery. Contained within the intervertebral margins, these devices diminish risks associated with anterior cervical plating, while also marginalizing cage migration and subsidence. However, these devices have been limited in their scope of implant material. Accordingly, a no-profile ACDF (npACDF) device supporting a machined allograft implant body with a connected load-sharing fixation interface was developed. However, it is not established in the literature whether the device supports early mechanical stability and subsequent boney fusion. The objective of this study was to assess this device in both the clinical and preclinical settings. Biomechanical Analysis: Twenty-four functional spinal units (FSUs) were divided into 4 groups (n = 6). Each group would receive a single construct: (1) npACDF device with connected polyetheretherketone (PEEK) body, (2) npACDF with connected allograft body, (3) npACDF (allograft body) with nonconnected fixation plate, and (4) standard ACDF plate and PEEK interbody cage. FSUs were subjected to pure moment loading (flexion/extension, lateral bending, and axial rotation) via a kinematic test machine in their intact state and then following instrumentation. Vertebral motion was recorded and range-of-motion (ROM) reduction, relative to intact, was calculated.Clinical Case Series: Ten patients receiving single-level ACDF with the npACDF allograft (connected) device for the treatment of persistent cervical radiculopathy or myelopathy were retrospectively reviewed at 12 months. Radiographic and patient reported outcomes were reported. No differences in ROM existed between the npACDF constructs (P ≥ 0.99). Standard ACDF achieved more ROM reduction than the npACDF constructs in all directions (P ≥ 0.04). All subjects achieved fusion at 12 months. The npACDF allograft device supported less motion reduction in comparison to traditional plating; however, case series data suggest the device provides clinically effective stability resulting in quality radiographic fusion and pain improvement. This report provides both clinical and preclinical insight into a device which offers alternative design features to traditional continuous/rigid ACDF device designs.