Incidence of postoperative anterior cruciate ligament reconstruction infections: graft choice makes a difference

Background: Infections after anterior cruciate ligament reconstruction (ACLR) can be devastating. Hamstring tendon autografts may be more susceptible to infections than other graft types.

Purpose: To determine the incidence of surgical site infections (SSIs) in a large sample of patients who underwent ACLR and to evaluate the risk of superficial and deep SSIs associated with grafts used for ACLR.

Study design: Cohort study; Level of evidence, 2.

Methods: All primary ACLRs performed between February 2005 and September 2010 registered in the Kaiser Permanente ACLR registry were included in the study. The graft types evaluated included the bone-patellar tendon-bone (BPTB) autograft, hamstring tendon autograft, and allograft (all types). The main end point of the study, SSIs (deep and superficial), was prospectively ascertained using an electronic screening algorithm and adjudicated by the principal investigator. Descriptive statistics were used to describe the cohort, and logistic regression models were used to evaluate the likelihood of an infection.

Results: There were 10,626 cases that fit the study criteria. The overall cohort was 64% male, mean age was 29 ± 11 years, and mean body mass index (BMI) was 27 ± 5 kg/m2. The overall incidence of SSIs was 0.48% (n = 51), with 17 (0.16%) superficial infections and 34 (0.32%) deep infections. Hamstring tendon autografts (n = 20; 0.61%) had the highest incidence of deep SSIs of the graft types (BPTB autograft, n = 2 [0.07%]; allograft, n = 12 [0.27%]; P < .001). After adjusting for age, sex, and BMI, the likelihood of a patient with a hamstring autograft having a deep SSI was 8.24 times higher (95% CI, 1.91-35.55; P = .005) than someone receiving a BPTB autograft. The risk of infections in allografts was not statistically significantly higher than BPTB autografts.

Conclusion: The overall SSI rate after ACLR was 0.48%. Deep SSIs were identified in 0.32% of the ACLR cases and superficial SSIs in 0.16%. An 8.2-times higher risk of SSIs was observed in hamstring tendon autografts compared with BPTB autografts. No difference in SSI incidence was identified between allografts and BPTB autografts. Surgeons should bear in mind that although the overall infection rates after ACLR are low, there is an increased risk of deep infections with hamstring tendon autografts.