title: Biomechanical analysis of a newly developed shape memory alloy hook in a transforaminal lumbar interbody fusion (TLIF) in vitro model.
abstract: OBJECTIVE
  The objective of this biomechanical study was to evaluate the stability provided by a newly developed shape memory alloy hook (SMAH) in a cadaveric transforaminal lumbar interbody fusion (TLIF) model.
  
  
  METHODS
  Six human cadaveric spines (L1-S2) were tested in an in vitro flexibility experiment by applying pure moments of ±8 Nm in flexion/extension, left/right lateral bending, and left/right axial rotation. After intact testing, a TLIF was performed at L4-5. Each specimen was tested for the following constructs: unilateral SMAH (USMAH); bilateral SMAH (BSMAH); unilateral pedicle screws and rods (UPS); and bilateral pedicle screws and rods (BPS). The L3-L4, L4-L5, and L5-S1 range of motion (ROM) were recorded by a Motion Analysis System.
  
  
  RESULTS
  Compared to the other constructs, the BPS provided the most stability. The UPS significantly reduced the ROM in extension/flexion and lateral bending; the BSMAH significantly reduced the ROM in extension/flexion, lateral bending, and axial rotation; and the USMAH significantly reduced the ROM in flexion and left lateral bending compared with the intact spine (p<0.05). The USMAH slightly reduced the ROM in extension, right lateral bending and axial rotation (p>0.05). Stability provided by the USMAH compared with the UPS was not significantly different. ROMs of adjacent segments increased in all fixed constructs (p>0.05).
  
  
  CONCLUSIONS
  Bilateral SMAH fixation can achieve immediate stability after L4-5 TLIF in vitro. Further studies are required to determine whether the SMAH can achieve fusion in vivo and alleviate adjacent segment degeneration.
authors.affiliation: Department of Orthopaedic Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, PR China.
authors.forename: Xi
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Orthopaedic Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Orthopaedic Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, PR China.
authors.forename: Yuexing
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Department of Orthopaedic Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, PR China.
authors.forename: Jiukun
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Anatomy, Guilin Medical College, Guilin, PR China.
authors.forename: Si
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Department of Anatomy, Guilin Medical College, Guilin, PR China.
authors.forename: Shunliang
authors.initials: S
authors.lastname: Tian
authors.affiliation: Department of Orthopaedic Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, PR China.
authors.forename: Yucheng
authors.initials: Y
authors.lastname: Xiang
authors.affiliation: Department of Orthopaedic Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, PR China.
authors.forename: Xingmo
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Nutrition, Guangdong General Hospital, Guangzhou, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Department of Orthopaedic Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Pan
mesh_terms: D000497:Alloys / Q000627:therapeutic use; D001696:Biomechanical Phenomena; D002102:Cadaver; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*; D008161:Lumbosacral Region / Q000503:physiopathology / Q000601:surgery*; D020393:Manipulation, Spinal; D008866:Microsurgery / Q000295:instrumentation; D065289:Pedicle Screws; D018583:Pliability; D011187:Posture; D016059:Range of Motion, Articular; D013123:Spinal Fusion; D013131:Spine / Q000503:physiopathology / Q000601:surgery*
chemical_list: D000497:Alloys