Fracture of the polyethylene tibial post in a NexGen posterior-stabilized knee prosthesis

We reported a case of fracture of a polyethylene tibial post in a 44-year-old woman after 3 years of NexGen posterior-stabilized total knee arthroplasty (Zimmer, Warsaw, IN). Burnishing and delamination of the polyethylene was found around the breakage site of the post, especially over the anterior aspect of the post base. It indicated that the possible failure mechanism was the repeated anterior impingement between the metal femoral cam and polyethylene tibial post. After replacement of the broken insert, the patient obtained complete relief of previous symptoms. To our knowledge, this is the first report of post breakage of a NexGen posterior-stabilized knee prosthesis.