Isolated chondral fractures of the knee are rare injuries in pediatric patients and may be difficult to diagnose because of the absence of osseous attachment. We report an 11-year-old boy who sustained a right knee injury during soccer. Although radiographs and computed tomography showed no abnormalities, magnetic resonance imaging (MRI) revealed an isolated chondral fracture of the lateral femoral condyle. Fully automated 3-dimensional MRI visualized a full-thickness cartilage defect and enabled precise measurement of lesion morphology and area. The patient underwent anatomical reduction and fixation using bioabsorbable pins. Follow-up MRI at 5 months demonstrated complete cartilage healing, and the patient returned to competitive soccer 8 months postoperatively without symptoms. This case highlights the diagnostic and clinical utility of fully automated 3-dimensional MRI for preoperative assessment, surgical planning, and postoperative evaluation of isolated chondral fractures in pediatric patients, while demonstrating that timely fixation can achieve successful cartilage healing and return to sport.