Summary

In a large cohort of 6,741 patients, ACL reconstruction with quadriceps tendon yielded a significantly lower rate of septic arthritis than hamstring tendon (0.10% vs 0.72%, respectively, providing useful information for patients and surgeons when counseling on infection risk during ACL reconstruction.

Abstract

Introduction

Septic arthritis is a rare but catastrophic complication after anterior cruciate ligament reconstruction (ACLR). Although the infection rates for bone-patella tendon-bone autograft (BTB), hamstring tendon autograft (HT) and allograft have been reported previously, there is limited data available for large cohorts of quadriceps tendon autograft (QT). The aim of this study is to compare rates of septic arthritis after primary and revision ACLR with QT, BTB, HT, and allograft.

Methods

All ACLR cases performed by 10 high-volume sports medicine fellowship-trained ACL surgeons between January 2000 and January 2022 were retrospectively analyzed. Minimum follow-up was 90 days after ACLR, and all multi-ligament reconstructions were excluded. Demographic information, surgical variables, infection characteristics and incidence of ACL graft retention were collected for all included patients. Post-operative septic arthritis was defined by at least 1 of the following criteria: purulent drainage from a deep incision, knee joint aspiration suggestive of a bacterial infection, culture-positive aspiration, or positive physical examination findings consistent with septic arthritis. The Mann-Whitney U test was used for group comparison for nonparametric values or where normality assumption was violated. Depending on the sample, the chi-square test or Fisher exact test (n<5) was used to analyze discrete variables.

Results

6,741 patients were included in this study. The most commonly used graft was allograft (n=2510, 37.2%), followed by HT (n=1784, 26.5%), BTB (n=1488, 22.1%), and QT (n=959, 14.2%) autografts. The overall post-operative infection rate was 0.34% (n=23). Infection rates based on graft type were 0.72% for HT autograft, 0.23% for allograft, 0.20% for BTB autograft, and 0.10% for QT autograft. A statistically significant difference in infection rate was observed between QT and HT autografts (p < 0.05), but not between QT and BTB autografts or QT and allograft (p > 0.05 for both). All grafts were retained during irrigation and debridement treatment. The mean time from the index surgery to the onset of symptoms was 29 days (min: 5, max: 69). Staphylococcus aureus (n=2) and Enterococcus faecalis (n=2) were the most common bacterial pathogens in culture-positive septic arthritis cases (n = 10, 43.4% of all infection patients).

Conclusion

Septic arthritis was detected at an overall rate of 0.34% after ACLR, with the highest rate being observed after the use of HT autograft (0.73%). QT autograft (0.1%) was found to have the lowest infection rate of all graft types, and was significantly lower than HT autograft. Surgeons can utilize this information when counseling patients on the risks of graft options for ACLR and determining ideal graft choice.