TY - JOUR
T1 - Biomechanical evaluation comparing zero-profile devices versus fixed profile systems in a cervical hybrid decompression model
T2 - a biomechanical in vitro study
AU - Kinon, Merritt D.
AU - Greeley, Samantha L.
AU - Harris, Jonathan A.
AU - Gelfand, Yaroslav
AU - Yassari, Reza
AU - Nakhla, Jonathan
AU - De la Garza-Ramos, Rafael
AU - Patel, Pavan
AU - Mirabile, Belin
AU - Bucklen, Brandon S.
N1 - Publisher Copyright:
© 2019 Elsevier Inc.
PY - 2020/4
Y1 - 2020/4
N2 - 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. STUDY DESIGN: 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.
AB - 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. STUDY DESIGN: 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.
KW - Anterior cervical corpectomy and fusion
KW - Anterior cervical discectomy and fusion
KW - Anterior plating
KW - Fixed profile system
KW - Integrated screws
KW - Zero-profile device
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U2 - 10.1016/j.spinee.2019.10.004
DO - 10.1016/j.spinee.2019.10.004
M3 - Article
C2 - 31634616
AN - SCOPUS:85075379507
SN - 1529-9430
VL - 20
SP - 657
EP - 664
JO - Spine Journal
JF - Spine Journal
IS - 4
ER -