Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Two stage fracture of a polyethylene post in a 9-year-old posterior-stabilized knee prosthesis: a case report | D Angelo et al. Journal of Medical Case Reports 2010 4 65 http content 4 1 65 JOURNALOF medical ÌỤr case REPORTS CASE REPORT Open Access Two stage fracture of a polyethylene post in a 9-year-old posterior-stabilized knee prosthesis a case report Fabio D Angelo1 Daniele Marcolli1 Paolo Bulgheroni1 Luigi Murena1 Terenzio Congiu2 Paolo Cherubino1 Abstract Introduction Several cases of tibial post breakage are reported in the literature. To the best of our knowledge only three cases of NexGen knee prosthesis Zimmer Warsaw Indiana USA tibial post failure have been reported. Case presentation In November 1999 a 63-year-old Caucasian woman from Italy with a history of symptomatic left knee osteoarthritis underwent a total knee arthroplasty. In March 2008 while rising from a chair she felt a sudden pain and instability in her left knee. She reported a fracture of the polyethylene post of the tibial insert. No malposition or malalignment of either the femoral or tibial components were identified. The polyethylene tibial insert was studied under light microscopy and scanning electron microscopy. The fracture was also noted to have occurred without any notable polyethylene wear. Conclusion Scanning electron microscopy revealed two different damage patterns that could be explained with a two-stage rupture of our patient s polyethylene post. This could have been caused by a non-optimal ligamentous balancing during first implant surgery. Her knee probably developed a varus instability that weakened the post and then a posterior anterior stress finally broke the polyethylene. Introduction The interaction between the polyethylene post of the tibial tray and the femoral cam is necessary for the proper functioning of posterior stabilized PS knee prosthesis 1 . PS total knee arthroplasty TKA was developed to grant stability to achieve a higher range of motion due to rollback and to prevent posterior subluxation of the implant 2 . The polyethylene spine .
