To identify the factors associated with secondary meniscal and chondral injuries after anterior cruciate ligament (ACL) injury.

We retrospectively collected the data of all patients who underwent ACL reconstruction for ACL injury at our institution between March 2011 and December 2018 and investigated the relationship between the incidence of meniscal and chondral injuries and the duration of injury, gender, age, and body mass index (BMI). Subjects were divided into groups based on the injury-to-surgery interval (≤1 month vs >1 month), Outer-bridge classification (mild injury [grades 0 and 1] vs severe injury [grades 2, 3, and 4]), age (≤20 years old vs >20 years old), and BMI (>24 kg/m² vs 24 kg/m²). The Chi-squared test was used to compare the incidence of meniscal and chondral injuries between groups, and factors with a P-value less than 0.05 were further analyzed using Logistic regression models.

In total, 607 patients (459 males and 148 females) were included this study. The average age was 29 years old (range, 10-52 years old). The average BMI was 21.3 kg/m². The mean duration from injury to surgery was 1.5 months, with a range from one day to 20 years. Approximately 138 patients suffered medial meniscus tears, 206 patients suffered lateral meniscal injuries, and 19.3% (117/607) suffered intra-articular cartilage lesions. Multivariable analysis demonstrated that BMI and sex were risk factors for lateral meniscus injury (P=0.040, odds ratio [OR]=1.21, 95%CI: 0.23-1.12; P=0.005, OR=0.50, 95%CI: 0.34-0.73). BMI, duration of injury, and gender were the risk factors for medial meniscus injury (P=0.0031, OR=1.32, 95%CI: 1.02-1.54; P=0.009, OR=1.63, 95%CI: 1.16-2.28; P=0.029, OR=0.64, 95%CI: 0.43-0.96). BMI and duration of injury were the risk factors for cartilage damage and its severity (BMI: P<0.001, OR=2.31, 95%CI: 1.04-2.36; P<0.001, OR=2.62, 95%CI: 0.68-2.55; duration of injury: P<0.001, OR=2.22, 95%CI: 1.39-3.55; P=0.007, OR=0.54, 95%CI: 0.34-0.86).

To reduce the risk for meniscal and chondral injuries, as well as the severity of cartilage lesions, ACL reconstruction should be performed actively once injury occurs. In addition, male gender as a risk factor for meniscal damage should be considered when making operation plan and giving preoperative discussions. Surgeons should pay more attention to patients with a BMI>24, because BMI is associated with an obvisouly increased risk of intra-articular lesions.