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Lateral epicondyle of femur

The lateral epicondyle of the femur is a bony prominence located on the lateral aspect of the distal femur, just superior and lateral to the lateral femoral condyle. It serves as an important attachment site for muscles and ligaments, and acts as a key landmark in the anatomy of the knee joint. The prominence is more prominent than the medial epicondyle and projects further laterally, forming a palpable bony structure on the outer aspect of the knee.

This region is clinically significant due to its association with the iliotibial band, lateral collateral ligament, and its role in knee stabilization. It is frequently evaluated in trauma, sports injuries, degenerative conditions, and surgical planning.

Synonyms

  • External epicondyle of the femur

  • Lateral femoral epicondyle

Muscular Attachments

  • Attachment for the lateral head of the gastrocnemius muscle

  • Provides anchorage for the plantaris muscle (variable, when present)

Ligamentous and Fascial Attachments

  • Fibular (lateral) collateral ligament (LCL): Attaches to the lateral epicondyle and extends to the fibular head

  • Iliotibial band (ITB): Inserts near the lateral epicondyle at Gerdy’s tubercle on the tibia, crossing over the region and influencing biomechanics

  • Joint capsule of the knee: Reinforced laterally at this site

Relations

  • Anteriorly: Quadriceps tendon and patella (via the knee joint capsule)

  • Posteriorly: Popliteal fossa structures (popliteus tendon, vessels, and nerves deeper)

  • Medially: Lateral femoral condyle and articular surface of the knee joint

  • Laterally: Iliotibial band and superficial fascia

  • Inferiorly: Lateral meniscus of the knee joint (within articulation)

Function

  • Provides bony leverage and stability to the distal femur

  • Acts as an attachment point for ligaments and muscles that stabilize the knee joint

  • Contributes to control of lateral knee stability during weight bearing and locomotion

  • Serves as a radiographic and surgical landmark in knee imaging and reconstruction

Clinical Significance

  • Trauma: Avulsion injuries at the attachment of LCL or gastrocnemius may occur

  • Overuse injuries: Iliotibial band syndrome often involves irritation around the lateral epicondyle

  • Arthritis: Osteophyte formation and degeneration can involve this region in knee osteoarthritis

  • Surgical relevance: Used as a landmark in ligament reconstruction and total knee arthroplasty

MRI Appearance

T1-weighted images:

  • Bone cortex: low signal intensity

  • Bone marrow: intermediate to bright signal

  • Muscle and ligament attachments visible as low-signal structures against marrow fat

T2-weighted images:

  • Cortex remains dark (low signal)

  • Bone marrow: intermediate to bright signal

  • Edema, contusion, or pathology: bright hyperintense regions in marrow or soft tissue attachments

STIR (Short Tau Inversion Recovery):

  • Cortex remains dark

  • Marrow edema, soft tissue inflammation, or enthesitis appear as bright hyperintensity

  • Iliotibial band or ligament injuries visible as increased signal near attachments

Proton Density Fat-Saturated (PD FS):

  • Bony cortex remains dark

  • Marrow and attachments appear dark after fat suppression

  • Pathology (edema, strain, partial tear) appears as bright signal

T1 Fat-Sat Post-Contrast:

  • Normal marrow: mild homogeneous enhancement

  • Inflammation or neoplasm: heterogeneous or focal enhancement

  • Abscess or severe inflammation: rim or irregular enhancement

CT Appearance

Non-Contrast CT:

  • Cortex appears as high-density bone outline

  • Marrow appears as lower attenuation than cortex

  • Fractures or avulsions visible as cortical irregularity or displaced fragments

Post-Contrast CT:

  • Bone itself does not enhance

  • Surrounding soft tissue pathology (abscess, tumor, inflammatory change) may enhance

  • Useful for identifying periosteal reaction, enthesopathy, or calcification

MRI image

Lateral epicondyle of femur axial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

Lateral epicondyle of femur coronal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

Lateral epicondyle of femur sagittal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

CT image

Lateral epicondyle of femur ct axial image