TIBIAL PERIPROSTHETIC FRACTURE COMBINED WITH TIBIAL STEM STRESS FRACTURE FROM TOTAL KNEE ARTHROPLASTY.

Total knee arthroplasty complications related to the prosthetic material are very rare, except for polyethylene wear. We report the case of a 58-year-old woman who came to the emergency service of our hospital with a periprosthetic tibial fracture (Mayo Clinic type I). Careful examination showed that this fracture was concomitantly associated with a tibial stem fatigue fracture. The prosthesis and the stem were sent to an independent biomechanics laboratory for evaluation. A finite-element CAD system was used to make a reconstruction, so as to ascertain whether there had been any manufacturing defect and what the causes of the event might have been. After evaluation of several hypotheses, it was concluded that the fracture in the prosthetic material had been caused by overloading at the plate/stem transition zone secondary to previous bone failure (fracture). From the evaluation of this case, the need to make appropriate assessment of bone mineralization can again be emphasized. In cases of doubt, a longer stem should be used.