Extraarticular infection 9 years after anterior cruciate ligament reconstruction. Case report.

Extraarticular infection after anterior cruciate ligament reconstruction (ACLr) is a rare condition with challenging diagnosis because the symptoms are milder and more insidious when compared to septic arthritis. When late (>2 months after surgery), it tends to be associated with osteomyelitis, requiring more extensive surgical debridement and hardware removal. We report a case of extraarticular infection after ACLr, in the acute phase affecting the tibial site and 9 years after index surgery affecting around the femur site. There was no progression to osteomyelitis at any of the sites. The infection developed a large posterolateral encapsulated abscess, with the endobutton plate loose inside it with its loop intact. In addition to the absence of osteomyelitis progression, there was no sinus tract formation, graft or joint involvement. With open debridement and antibiotic therapy, the patient returned to his activities without limitations. The reported case highlights that extraarticular infection after ACLr, while rare, can be challenging to diagnose and treat. However, with appropriate treatment, it can lead to good results with no functional limitations.