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Biomechanical Evaluations of Novel Clip-Type Implants for Cervical Double-Door Laminoplasty, Compared with
Takahiro Mui1, Sachiko Kawasaki1, Hideki Shigematsu1
1Department of Orthopaedic Surgery, Nara Medical University, Nara, Japan.
Introduction:
Double-door laminoplasty is a common surgical approach; however, implant displacement and hinge fractures can cause lamina closure, leading to unfavorable outcomes. A novel clip-type implant has been introduced to improve rigid fixation safely; however, its biomechanical stability, compared with that of hydroxyapatite (HA) spacers, has not yet been evaluated. Therefore, the aim of this study was to compare the mechanical stability of polyetheretherketone clip implants versus that of HA spacers in freshly frozen cadaveric cervical spines.
Methods:
Seven freshly frozen cervical spines were used in this study. Double-door laminoplasty was performed at the C3-C6 cervical vertebral level. Clip-type implants and HA spacers were alternately placed on each specimen. Strain gauges were used to measure lamina displacement and reaction force at 0-mm to 2.5-mm lateral displacement. The reaction forces between the clip implant and HA spacer groups were compared.
Results:
Polyetheretherketone clip-type implants had significantly higher reaction force values than HA spacers at all displacement levels (p<0.001). Clip-type implants exhibited a 1.5- to 1.7-times higher reaction force than that of spacers at the middle of the lamina and a 1.9- to 2.0-times higher reaction force than that of spacers at the tip of the lamina.
Conclusions:
Novel clip-type implants provide greater stability than HA spacers. To the best of our knowledge, this study is the first to demonstrate the superior biomechanical stability of clip implants.
