A new stand-alone cervical anterior interbody fusion device: biomechanical comparison with established anterior cervical fixation devices.
METHODS
A new anchored spacer-a low-profile cervical interbody fusion cage with integrated anterior fixation-was compared biomechanically to established anterior cervical devices.


OBJECTIVE
To evaluate the fixation properties of the new stand-alone device and compare these properties with established fixation methods. The hypothesis is that the new device will provide stability comparable to that provided by an anterior cervical cage when supplemented with an anterior plate.


BACKGROUND
It is accepted that the use of anterior cervical plating increases the chance of achieving a solid fusion. However, its use may be associated with an increase in operation time and a higher postoperative morbidity caused by a larger anterior approach and disruption of the anterior musculature. This dilemma has led to the development of a new, low profile stand-alone cervical anterior cage device with integrated screw fixation.


METHODS
Twenty-four human cadaveric C4-C7 cervical spines were loaded nondestructively with pure moments in a nonconstraining testing apparatus to induce flexion, extension, lateral bending, and axial rotation while angular motion was measured optoelectronically. The specimens were tested: 1. Intact (N = 24). 2. After discectomy and anterior stabilization. a. Interbody cage + locking plate (N = 8). b. Interbody cage + dynamic plate (N = 8). c. Anchored spacer (N = 8). 3. After ventral plate removal of group 2a and 2b (N = 16).


RESULTS
All fixation techniques decreased range of motion (ROM) and lax zone (LZ) (P < 0.05) in all test modes compared with the intact motion segment and cage-only group. There were no significant differences between the anchored spacer and cage + locking plate or cage + dynamic plate.


CONCLUSIONS
The anchored spacer provided a similar biomechanical stability to that of the established anterior fusion technique using an anterior plate plus cage and has a potentially lower perioperative and postoperative morbidity. These results support progression to clinical trials using the cervical anchored spacer as a stand-alone implant.
Scholz
Matti
M
Center for Spinesurgery and Neurotraumatology, Trauma Clinic Frankfurt/Main, Germany. matti.scholz@bgu-frankfurt.de
Reyes
Phillip M
PM
Schleicher
Philipp
P
Sawa
Anna G U
AG
Baek
Seungwon
S
Kandziora
Frank
F
Marciano
Frederick F
FF
Crawford
Neil R
NR
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena / Q000502:physiology*; D001860:Bone Plates / Q000706:statistics & numerical data; D001863:Bone Screws / Q000639:trends; D002574:Cervical Vertebrae / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery*; D017586:Diskectomy; D005260:Female; D019416:Head Movements / Q000502:physiology; D006801:Humans; D016268:Internal Fixators / Q000639:trends*; D007405:Intervertebral Disc Displacement / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology; D013122:Spinal Diseases / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D055009:Spondylosis / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D016474:Weight-Bearing / Q000502:physiology