ABSTRACT
Objective To evaluate the biomechanical stability of pectin/polyvinyl alcohol composite （CoPP）hydrogel and to assess the range of motion(ROM) and intradiscal pressure (IDP) changes at the above adjacent segment after the anterior implantation of CoPP hydrogel and cage. Method Six fresh cadaveric lumbar spine specimens（L3～L5）were biomechanically tested on the robotic testing machine. ROM at L3/4 and L4/5 and intradiscal pressure at L3/4 were measured. All measurements were made with initially intact and followed by both CoPP and cage implantations. Results At the implanted level (L4/5), the CoPP spine showed no significant change in the other five motion directions except left lateral bending motion compared with the intact spine (P>0.05), whereas the cage spine decreased significantly in all motion directions when compared with the intact spine or CoPP spine (P0.05), whereas the ROM of cage spine significantly increased in all motion directions compared with the intact spine (P0.05). While the IDP of cage spine significantly increased in flexion/extension and left/right lateral bending compared with the intact spine or CoPP spine (P0.05). Conclusions The implantation of CoPP prosthetic nucleus can preserve the motion function at the operated level and maintain the lumbar stability. Compared with the lumbar fusion, the nucleus replacement has no significant effect on the ROM and IDP at adjacent level, which may decrease or avoid the adjacent segment degeneration.
ABSTRACT
[Objective]To analyze the reasons and counter treatment of complication after prosthetic disc nucleus implantation.[Method]From Feb 2002 to Aug 2004,80 patients of lumbar disc herniation were implanted with one single PDN device at our centre.65 patients of them came to the clinical,functional,and radiographic follow-up examinations,magnetic resonance images and follow-up records of all patients were reviewed carefully.They were divided into three groups.Group A:30 cases had at least 24 months follow-up data.Group B:23 cases had at least 36 months follow-up data.Group C:12 cases had at least 48 months follow-up data.[Result]After implantation,device migrations were noticed in 3 patients.24 cases experienced low back pain.In 24~48 month follow-up,the MR images of 39 patients had shown the abnormal signal pattern of the endplate where PDN-solo was implanted,even 32 of them had been found subsidence.In Group A,the height of intervertebral disc at the 24 month follow-up was decreased 4%.In Group B,at 36 month follow-up,it was decreased 12%.In Group C,at 48 month follow-up,it was decreased 18%.[Conclusion]After follow-up,the clinical effect of PDN is preferred.However,the complications of device dislocation,device subsidence remain problems that must be highlighted.This study suggested that the complications of PDN are serious.Therefore,the proper selecting patients for PDN replacement are crucial for good results.The indications for PDN must be restricted.