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Lateral border of patella

The lateral border of the patella is the external edge of the patella, a triangular sesamoid bone embedded within the quadriceps tendon. It plays a major role in transmitting forces from the quadriceps to the tibia through the patellar tendon, while also interacting with the femoral trochlea during knee flexion and extension. The lateral border provides attachment to key soft tissue structures that stabilize the patella and is an important landmark in knee imaging and surgery.

Synonyms

  • External border of patella

  • Lateral patellar margin

  • Lateral patellar edge

Muscular Attachments

  • Receives expansion fibers from the vastus lateralis muscle of the quadriceps femoris group

  • Anchored to the lateral patellar retinaculum, which reinforces the joint capsule

  • Indirectly connected to the iliotibial band via retinacular fibers

  • Contributes to lateral stabilization of the patella within the femoral trochlea

Relations

  • Anteriorly: Subcutaneous tissue and skin of the knee

  • Posteriorly: Lateral femoral condyle and trochlear groove (articular cartilage interface)

  • Superiorly: Quadriceps tendon fibers from vastus lateralis

  • Inferiorly: Patellar ligament leading to tibial tuberosity

  • Laterally: Lateral retinaculum, iliotibial band expansions

  • Medially (across joint): In contact with trochlear articular cartilage during knee movement

Nerve Supply

  • Periosteum and adjacent soft tissues supplied by articular branches of the femoral nerve and saphenous nerve

Arterial Supply

  • Superior and inferior lateral genicular arteries (branches of popliteal artery)

  • Contribution from descending branch of lateral circumflex femoral artery

Venous Drainage

  • Corresponding veins drain into the popliteal vein and femoral vein

Function

  • Provides structural anchoring for lateral quadriceps and retinacular fibers

  • Transmits quadriceps force to patellar tendon for knee extension

  • Contributes to patellar stability within femoral trochlea

  • Acts as a bony landmark in orthopedic surgery and imaging

Clinical Significance

  • Common site of pathology in patellofemoral pain syndrome and lateral patellar instability

  • Involved in patellar dislocations, where excessive lateral pull destabilizes the patella

  • May show enthesopathy or bony irregularity in chronic tendinopathies

  • Landmark in surgical procedures such as lateral release for patellar maltracking

  • Important in evaluating patellar fractures and osteochondral injuries

MRI Appearance

T1-weighted images:

  • Bone marrow of lateral border shows intermediate to bright signal

  • Cortical bone remains dark (low signal)

  • Adjacent fat provides bright contrast

T2-weighted images:

  • Bone marrow demonstrates intermediate to bright signal

  • Cortical bone remains dark

  • Cartilage overlying posterior surface appears bright

STIR (Short Tau Inversion Recovery):

  • Bone marrow shows low signal intensity under normal conditions

  • Pathology (edema, fracture, contusion) appears bright hyperintense

Proton Density Fat-Saturated (PD FS):

  • Bone marrow shows low signal intensity in normal state

  • Bone marrow edema or injury appears bright

  • Cortical bone remains dark

T1 Fat-Sat Post-Contrast:

  • Normal bone marrow shows minimal or no enhancement

  • Pathological conditions (osteomyelitis, tumor, active inflammation) show focal or diffuse enhancement

CT Appearance

Non-Contrast CT:

  • Lateral border seen as a dense cortical bone margin with inner trabecular structure

  • Marrow space visible with lower attenuation than cortex

  • Fractures, cortical irregularity, or sclerosis well demonstrated

Post-Contrast CT:

  • Normal bone does not enhance

  • Surrounding soft tissues or pathological processes (infection, tumor, inflammation) may show enhancement

  • Useful for detecting subtle cortical fractures or periosteal reaction

MRI image

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

MRI image

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

CT image

Lateral border of patella ct axial

CT VRT image

Lateral border of patella