Actualización en osteonecrosis y fractura de rótula tras prótesis total de rodilla.

Periprosthetic patella fractures are much more common in knee prostheses in which the patella has been replaced. The aetiology of periprosthetic patella fractures has a traumatic origin in 12% of cases and atraumatic secondary to avascular necrosis in the remaining 88%. Peri-implant fractures, in which the patella has been replaced and the implant is stable with an integral extensor mechanism, resolve with conservative treatment. In cases of stable implant, with a displaced fracture of the upper or lower pole of the patella, the implant is left in situ and the extensor apparatus is repaired according to standard techniques. If there is disruption of the extensor apparatus with an unstable implant, the patellar button should be removed and continuity of the extensor apparatus repaired with a patellectomy. In these cases, internal fixation with wire cerclages is discouraged. In cases where the extensor mechanism is intact and the implant is unstable, the removal of the patellar button is sufficient. The risk of infection after surgery for a periprosthetic patella fracture is high.