Knee Infection After Anterior Cruciate Ligament Reconstruction

Abstract

Knee infection is a challenging scenario. One way to classify the infection would be as spontaneous or post-surgery, the latter having a particular relevance given the presence of synthetic materials such as screws or prostheses surrounding the joint. Open surgery has a higher rate of infection than arthroscopic procedures. Periprosthetic infection is a complication that follows arthroplasty, with an incidence that varies between 0.4% and 2.0%, while arthroscopic procedures have an incidence varying between 0.001% and 1.100%. Anterior cruciate ligament (ACL) reconstruction complication rate is low, with septic arthritis one of the most frequently seen. Early diagnosis of complications is vital to improve functional outcome. In these cases, knee pain, decreased range of motion, fever, and high C-reactive protein levels should alert any physician, and infection must not be ruled out. This article presents a case of infection after ACL reconstruction and discusses risk factors, treatment choice, antibiotic treatment length, and functional outcomes, proposing a guide for the treatment. The clinical case presented is a chronic infection due to Staphylococcus aureus that resulted in extensive cartilage damage and graft loosening; delayed diagnosis was an essential modifiable risk factor in this case. Treatment success is defined as the eradication of the infection without the need to remove the ACL graft. Risk factors for a worse outcome after ACL reconstruction infection are allograft compared to autograft and S. aureus or polymicrobial infection compared to coagulase-negative staphylococcus infection. Functional outcome is compromised by infection; however, if early diagnosis and treatment are performed, good functional results and a return to sports activities can be expected.