Factors Associated With an Intra-articular Infection After Anterior Cruciate Ligament Reconstruction: A Large Single-Institution Cohort Study

Abstract

Background: An intra-articular infection after anterior cruciate ligament (ACL) reconstruction (ACLR) is a rare complication but one with potentially devastating consequences. The rare nature of this complication raises difficulties in detecting risk factors associated with it and with worse outcomes after one has occurred. Purpose: To (1) evaluate the association between an infection after ACLR and potential risk factors in a large single-center cohort of patients who had undergone ACLR and (2) assess the factors associated with ACL graft retention versus removal. Study Design: Case-control study; Level of evidence, 3. Methods: All ACLR procedures performed at our institution between January 2010 and December 2018 were reviewed; a total of 11,451 procedures were identified. A retrospective medical record review was performed to determine the incidence of infections, patient and procedure characteristics associated with an infection, infection characteristics, incidence of ACL graft retention, and factors associated with the retention versus removal of an ACL graft. Multivariable logistic regression analysis was used to identify potential risk factors for an infection after ACLR. Results: Of the 11,451 ACLR procedures, 48 infections were identified (0.42%). Multivariable logistic regression analysis revealed revision ACLR (odds ratio [OR], 3.13 [95% CI, 1.55-6.32]; P = .001) and younger age (OR, 1.06 [95% CI, 1.02-1.10]; P = .001) as risk factors for an infection. Compared with bone–patellar tendon–bone autografts, both hamstring tendon autografts (OR, 4.39 [95% CI, 2.15-8.96]; P < .001) and allografts (OR, 5.27 [95% CI, 1.81-15.35]; P = .002) were independently associated with an increased risk of infections. Overall, 15 ACL grafts were removed (31.3%). No statistically significant differences besides the number of irrigation and debridement procedures were found for retained versus removed grafts, although some trends were identified ( P = .054). Conclusion: In a large single-center cohort of patients who had undergone ACLR and those with an infection after ACLR, patients with revision cases and younger patients were found to have a higher incidence of infection. The use of bone–patellar tendon–bone autografts was found to be associated with the lowest risk of infection after ACLR compared with both hamstring tendon autografts and allografts. Larger cohorts with a larger number of infection cases are needed to determine the factors associated with graft retention versus removal.

Factors Associated With an Intra-articular Infection After Anterior Cruciate Ligament Reconstruction: Letter to the Editor

“…

A cohort study recently investigated factors associated with intra-articular infection after anterior cruciate ligament reconstruction (ACLR). 2 In this study, which involved 11,451 ACLR procedures, the authors found a higher incidence of infection in revision cases and younger patients. Additionally, bone-patellar tendon-bone autografts were associated with the lowest risk of infection after ACLR as compared with hamstring tendon autografts and allografts.

…”

“…In addition, we noted that the definition of “younger” in this study 2 is unclear, and it is suggested that a clear definition be provided. Finally, we sincerely thank the authors for their great contribution, which provides significant evidence for further reducing infection after ACLR.…”

“…As described in this study, 2 “multivariable logistic regression analysis was used to identify potential risk factors for an infection after ACLR,” and it can be learned that multivariable logistic regression analysis was performed to screen risk factors. Generally, the number of events per variable (EPV) should be considered before performing logistic regression analysis.…”

“…Furthermore, Harrell et al 1 demonstrated that the EPV value should be ≥20. According to the information provided in Table 3 in Marom et al’s 2 study, 7 variables were included in the multivariable logistic regression analysis. Thus, in theory, a minimum of 70 infected cases is required to comply with EPV principles.…”

Postoperative complications following ACL reconstruction: Prevention and management

“…It is possible to use either an internal or external focus of attention to learn and get better at motor tasks. With an internal focus of attention, the athlete would concentrate on the movements themselves, giving cues to keep their knee correctly positioned over their second toe, for example [38] . The athlete would concentrate on the effect and result of the movement if there was an external focus of attention, such as giving cues to keep their knee in line with a cone or another target.…”