Purpose or Learning Objective: To investigate the epidemiology and morphological patterns of deep medial collateral
ligament (dMCL) injuries in pediatric patients.
Methods or Background: Patients < 18 years of age who underwent standard knee magnetic resonance imaging
(MRI) between January 1, 2021, and February 24, 2023, at Heim Pál National Pediatric
Institute, Budapest, Hungary, were collected retrospectively. All patients were scanned
on a 3-T MRI machine with a dedicated eight-channel knee coil. The studies performed
with a nonstandard knee MRI protocol were excluded. Two board-certified musculoskeletal
radiologists with 2 and 3 years of experience, respectively, evaluated the knee studies
for dMCL injuries. Demographic data, laterality of the injuries, patency of the physis
(open, fusing, or closed), and type of dMCL injuries were assessed. All injuries were
classified as either attachment site avulsion injuries or intraligamentous lesions.
Avulsion fractures were subgrouped into simple (only perichondrial) and complex (perichondrial
and cartilage/bone) avulsions. Intraligamentous injuries were subgrouped into partial-
or full-thickness lesions. Inter-reader agreement was also evaluated.
Results or Findings: A total of 992 studies were reviewed, of which 92 patients had a dMCL injury (69
intraligamentous and 23 avulsion-type injuries). We identified 55 boys and 37 girls.
There was no significant difference in age between boys and girls (mean ± standard
deviation: 13.7 ± 2.89 versus 14.2 ± 2.75; P = 0.402). Similarly, no difference was detected in the type of injury between boys
and girls (P = 0.269). Between avulsion versus intraligamentous injury, age showed a significant
difference (11.3 ± 3.24 versus 14.67 ± 2.09; P < 0.0001). Patients with an avulsion-type injury were significantly younger. The
chi-square test detected no significant difference between the type of injury and
the laterality (P = 0.698); however, there was a significant difference between the type of injury
and the patency of the physis (P < 0.0001). In univariate logistic regression analysis, only age proved to be a significant
predictor for the type of injury (odds ratio: 0.6255; 95% confidence interval, 0.4885–0.7650;
P < 0.0001). The inter-reader agreement on the injury patterns was good (κ = 0.8).
Conclusion: Our study showed that dMCL injuries are commonly seen in routine knee MRI studies.
Their morphological patterns indicate a strong relationship with the age of the patient.
