# Septic Arthritis After Anterior Cruciate Ligament Reconstruction: A Comparative Study of Pediatric, Adolescent, and Young Adult Populations

## TL;DR

This study found that septic arthritis after ACL surgery is rare in adolescents and young adults, with no cases in children under 13.

## Contribution

The study provides comparative evidence on septic arthritis incidence after ACLR across pediatric, adolescent, and young adult populations.

## Key findings

- Septic arthritis occurred in 0.23% of ACLR cases, with no cases in the pediatric group.
- Staphylococcus species were the most common causative microbes in septic arthritis cases.
- Aggressive surgical treatment with multiple debridements allowed graft retention without increased rupture risk.

## Abstract

Limited evidence exists regarding septic arthritis (SA) after anterior cruciate ligament reconstruction (ACLR) in pediatric and adolescent patients.

The purpose of this study was to compare post-ACLR SA cases during a 21-year period in pediatric and adolescent patients to those in a young adult control cohort. It was hypothesized that the incidence would be similarly low in both subpopulations.

Case series; Level of evidence, 4.

Records of patients who underwent ACLR between 2000 and 2020 were retrospectively reviewed for diagnoses of postoperative SA of the ipsilateral knee, defined by culture-positive arthrocentesis or synovial fluid white blood cell count >50,000 cells/mL. Surgical details, culture results, and clinical course were analyzed. Age-based cohorts—pediatric (<13 years of age), adolescent (13-19 years of age), and young adult (20-35 years of age)—were compared using chi-square tests for age, graft source, graft type, concurrent meniscal procedures, and SA incidence. Time between ACLR and subsequent surgeries was analyzed utilizing t tests.

Of 5638 ACLR cases (pediatric: n = 606, 10.7%; adolescent: n = 4123, 73.1%; young adult: n = 909, 16.1%), SA was diagnosed in 13 patients (0.23%; adolescent: n = 12, 0.30%; young adult: n = 1, 0.11%) a median of 15 days (range 6-632 days) after ACLR. One or more arthroscopic irrigation and debridement (I&Ds) (mean, 2; range, 1-3) were performed, and anterior cruciate ligament (ACL) grafts were retained for all patients. The mean clinical follow-up was 3.5 years (range, 0.6-9.2 years). Subsequent surgeries include 2 lysis of adhesions, 3 meniscectomies, 1 meniscal repair, 3 patellar chondroplasties, 1 loose-body removal, 2 patellar biopsies, 1 debridement, and 1 revision ACLR 6 years postoperatively for acute ACL graft rupture. The most common microbes were Staphylococcus aureus (n = 3; 23.1%) and other forms of Staphylococcus species (n = 9; 69.2%). No significant associations were identified between age-based cohort and graft source, graft type, age, or concurrent meniscal surgery.

Post-ACLR SA was similarly rare for adolescents and young adults, and no cases were identified in 606 pediatric patients. No associations were identified between SA and demographic factors, graft source, graft type, or concurrent meniscal surgery. Staphylococcus species were identified in most cases. Aggressive initial surgical treatment with multiple I&Ds was associated with graft retention, with no disproportionate subsequent graft rupture risk.