Aseptically Processed Allograft Implantation: A Safe Strategy for Knee Ligament Reconstructions

Postoperative infections after allograft implantation is a major concern in knee ligament reconstructions considering the theoretical risk of disease transmission and its potential severity. Here, we aimed to evaluate the postoperative infection rate after knee ligament reconstructions using aseptically processed allografts, and provide an overview of the allografts use in an academic tertiary hospital. A retrospective study was performed evaluating patients who underwent knee ligament reconstructions using aseptically processed allografts, including primary and revision surgeries, from 2005 to 2018. Demographic data, including the type of knee injury and trauma energy, and postoperative data were collected focusing on postoperative infections. Regarding these infected cases, further analyses were performed considering the presenting signs and symptoms, the isolated microorganism identified in culture, the time between graft implantation and diagnosis of infection (defined as acute, subacute, and late), and the need for graft removal. A total of 180 cases of ligament reconstructions were included. The mean follow-up was 8.2 (range: 2.1-15.6) years and the mean age at surgery was 34.1 (± 11.1) years. A total of 262 allografts were implanted in those 180 cases, 93 (35.5%) as bone plug allografts and 169 (64.5%) as soft tissue allografts. Common surgical indications included multiligament reconstruction (57.2%) and primary anterior cruciate ligament (ACL) reconstruction (15%). Seven cases (3.9%) presented postoperative infections. Knee pain (100%) and swelling (100%) were the most prevalent symptoms. Two cases (28.6%) presented sinus tract. Allografts were removed in two cases, the same cases that presented draining sinus (p = 0.04). High-energy trauma was the only statistically associated factor for infection (p = 0.04). No significant association between infection and the type of allograft (p > 0.99) or sex (p = 0.35) were observed. Four cases (57.1%) had monomicrobial staphylococcal infections. Based on that, the allograft-related infection rate was 1.7% (the remaining three infected cases). Nonirradiated, aseptically processed allografts have a low postoperative infection rate in knee ligament reconstructions, being a safe alternative for surgeries that require additional source, increased variety, and quantity of grafts.