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Lateral articular facet of patella

The lateral articular facet of the patella is the broadest and deepest articular surface of the patella, covered by thick hyaline cartilage. It articulates with the lateral femoral condyle and plays a major role in patellofemoral joint stability. Its larger size compared to the medial facet helps resist lateral patellar dislocation, especially during knee flexion.

The facet is clinically important in conditions such as patellofemoral pain syndrome, lateral patellar dislocation, osteoarthritis, and chondromalacia patellae.

Synonyms

  • Lateral facet of patella

  • External articular surface of patella

  • Lateral patellar facet

Muscular Attachments

  • Indirectly receives attachments from the quadriceps femoris tendon superiorly

  • Inferiorly related to the patellar ligament

  • Laterally reinforced by the vastus lateralis expansion and lateral patellar retinaculum

Relations

  • Superiorly: Quadriceps femoris tendon and suprapatellar pouch

  • Inferiorly: Patellar ligament and anterior tibial tuberosity (via ligament)

  • Laterally: Vastus lateralis fibers, lateral patellar retinaculum, lateral femoral condyle

  • Medially: Median ridge separating it from the medial facet

  • Posteriorly: Thick hyaline cartilage articulating with lateral femoral condyle

Function

  • Provides articulation between patella and lateral femoral condyle

  • Contributes to patellar tracking during knee flexion and extension

  • Acts as a stabilizing surface, resisting lateral displacement of the patella

  • Distributes compressive forces across the patellofemoral joint

Clinical Significance

  • Common site of cartilage degeneration in patellofemoral osteoarthritis

  • Involved in chondromalacia patellae (cartilage softening and irregularity)

  • Important in patellar instability and dislocation (larger lateral facet prevents outward slip)

  • Fractures may extend through the articular facet, compromising joint congruity

MRI Appearance

T1-weighted images:

  • Subchondral bone marrow: intermediate to bright signal intensity

  • Hyaline cartilage: intermediate signal

  • Cortical bone: uniformly dark (low signal)

T2-weighted images:

  • Subchondral marrow: intermediate to bright signal

  • Hyaline cartilage: intermediate to high signal

  • Cortical bone: dark (low signal)

Proton Density (PD):

  • Marrow: intermediate to bright signal

  • Cartilage: intermediate signal, useful for cartilage defects

  • Cortex: dark

STIR (Short Tau Inversion Recovery):

  • Normal marrow: low signal

  • Pathological marrow (edema, contusion, inflammation): bright hyperintensity

  • Cortex: dark

Proton Density Fat-Saturated (PD FS):

  • Normal marrow: low signal after fat suppression

  • Marrow edema or pathology: bright hyperintensity

  • Cartilage defects and fissures highlighted

T1 Fat-Sat Post-Contrast:

  • Normal marrow: minimal homogeneous enhancement

  • Cartilage lesions, synovitis, or neoplasm: focal or heterogeneous enhancement

  • Subchondral pathology (e.g., osteomyelitis, tumor): marked enhancement

CT Appearance

Non-Contrast CT:

  • Cortical bone: hyperdense (bright) outlining the facet

  • Subchondral bone: homogenous, intermediate density

  • Cartilage not well visualized without contrast

Post-Contrast CT:

  • Bone: no intrinsic enhancement

  • Surrounding soft tissues (synovium, retinaculum, capsule) may enhance if inflamed or infiltrated

  • Subchondral lesions (e.g., tumors, infection): may appear as lucent or destructive areas with enhancing margins

MRI image

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

CT image

Lateral articular facet of patella ct axial