Biomechanical analysis of a new titanium rubber cervical disc prosthesis

English Keywords:Metal rubber cervical disc prosthesis  Artificial cervical disc  Biomechanics  Spine stability

English Abstract:

  【Abstract】 Objectives: To evaluate the biomechanical properties of a new titanium rubber cervical disc prosthesis. Methods: A new metal rubber cervical disc prosthesis was produced, the electron microscope was used to observe the prosthesis′ surface structure, and the mechanical properties as well as the fatigue properties were tested. 24 fresh sheep cervical spine specimens were used, and procedured by C4/5 intact, replacement, artificial disc replacement(ADR), anterior cervical discectomy and fusion(ACDF) treatment subsequently, 2.5Nm stress was added as load simulation, the range of motion(ROM) of the involved segment and adjacent segments were measured in flexion, extension, lateral bending and rotation. Results: The prosthesis had a porosity rate of 60%-80%, the pore size was 90-500μm, and the elastic modulus amount was about 7MPa. After the fatigue test(cycle times of 500×104 times, the limit load was 200N), there was no incidence of prosthesis fracture or no height loss. The ROM in the replacement group was significantly greater than that of the intact group(P<0.05), the ROM of the ACDF group was significantly less than that of the intact group(P<0.05), while the ADR group showed no significant difference compared with the intact one(P>0.05). For the superior adjacent segment, no significant difference was noted between the ADR group and intact group(P>0.05), while the ROM of ACDF group was greater than that of the intact group(P<0.05). For the inferior adjacent segment, in ADR group, there was no difference in flexion compared wtih intact group(P>0.05), extension ROM less than intact group(P<0.05), lateral bending and torsionmotion more than intact group(P<0.05), but the change was smaller than the ACDF group(P<0.05). Conclusions: The titanium rubber artificial cervical disc prosthesis is a new homogeneous elastic porous material which can reconstruct the cervical spine stability and preserve the ROM.