Biomechanical evaluation comparing zero-profile devices versus fixed profile systems in a cervical hybrid decompression model: a biomechanical in vitro study.
Spine J
; 20(4): 657-664, 2020 04.
Article
in En
| MEDLINE
| ID: mdl-31634616
ABSTRACT
BACKGROUND CONTEXT The use of zero-profile devices and the need for posterior fixation in conjunction with a cervical hybrid decompression model have yet to be investigated. PURPOSE:
To compare the biomechanics of zero-profile and fixed profile cervical hybrid constructs composed of anterior cervical discectomy and fusion (ACDF) and anterior cervical corpectomy and fusion (ACCF). Fixed profile devices included anterior plating, whereas zero-profile devices included integrated screws. STUDYDESIGN:
In vitro cadaveric biomechanical study.METHODS:
Twelve fresh-frozen cadaveric spines (C2-C7) were divided into two groups of equal bone mineral density, fixed profile versus zero profile (n=6). Groups were instrumented from C3-C6 with either (1) an expandable ACCF device and a static ACDF spacer with an anterior plate (Hybrid-AP) or (2) a zero-profile ACCF spacer with adjacent zero-profile ACDF spacer (Hybrid-Z). Motion was captured for the (1) intact condition, (2) a hybrid model with lateral mass screws (LMS), (3) a hybrid model without LMS, and (4) a hybrid model without LMS following simulated repetitive loading (fatigue).RESULTS:
Hybrid-AP with LMS reduced motion in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) by 77%, 88%, and 82%, respectively, compared with intact. Likewise, Hybrid-Z with LMS exhibited the greatest reduction in motion relative to intact in FE, LB, and AR by 90%, 95%, and 66%, respectively. Following simulated in vivo fatiguing, an increase in motion was observed for both groups in all planes, particularly during Hybrid-Z postfatigue condition where motion increased relative to intact by 29%. Overall, biomechanical equivalency was observed between Hybrid-AP and Hybrid-Z groups (p>.05). Three (50%) of the Hybrid-Z group specimens exhibited signs of implant migration from the inferior endplate during testing.CONCLUSIONS:
Fixed profile systems using an anterior plate for supplemental fixation is biomechanically more favorable to maintain stability and prevent dislodgement. Dislodgement of 50% of the Hybrid-Z group without LMS emphasizes the necessity for posterior fixation in a zero-profile cervical hybrid decompression model.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Spinal Fusion
/
Cervical Vertebrae
Limits:
Humans
Language:
En
Journal:
Spine J
Journal subject:
ORTOPEDIA
Year:
2020
Document type:
Article
Affiliation country:
United States