Incidental enchondromas of the knee.

Academic Article


  • OBJECTIVE: The purpose of our study was to determine the prevalence of incidental enchondromas on routine MR knee imaging. MATERIALS AND METHODS: We retrospectively reviewed 449 consecutive routine knee MR examinations for the presence of enchondromas. MRI was considered positive when a focal geographic area of lobular marrow replacement (nonsubchondral) was identified on T1 weighting and high signal intensity was seen on T2 weighting. Patients with enchondromas were further evaluated for demographics; lesion site, size, and relationship to the physeal plate; aggressive imaging features described with chondrosarcoma; concurrent internal derangement; and study indication. RESULTS: The prevalence of incidental enchondromas was 2.9% on routine knee MR examinations. The prevalence was highest in the distal femur (2.0%), followed by the proximal tibia (0.7%) and the proximal fibula (0.2%). The average lesion size was 1.9 x 1.2 x 1.3 cm (57% of lesions were < 1 cm). Most lesions were located in the metaphysis (71%) or diaphysis (21%). Enchondromas were within 1.5 cm of the physeal plate in 72% of cases. No aggressive imaging features to suggest chondrosarcoma were seen. All patients had evidence of internal derangement as the cause of symptoms and the request for imaging. CONCLUSION: Incidental enchondromas can be identified on 2.9% of routine MR knee examinations, most frequently in the distal femur (2.0%). This significant prevalence is much higher than in an autopsy series (0.2%), likely reflecting the increased sensitivity of MRI for detecting small lesions, and is important to recognize to avoid confusion with other pathologic entities.
  • Authors

    Published In


  • Adolescent, Adult, Aged, Aged, 80 and over, Bone Neoplasms, Child, Chondroma, Female, Humans, Incidental Findings, Knee, Magnetic Resonance Imaging, Male, Middle Aged, Prevalence, Retrospective Studies, Risk Factors, United States
  • Digital Object Identifier (doi)

    Author List

  • Walden MJ; Murphey MD; Vidal JA
  • Start Page

  • 1611
  • End Page

  • 1615
  • Volume

  • 190
  • Issue

  • 6