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Base of patella

The base of the patella, also called the superior pole of the patella, is the broad proximal border of the patella. It serves as the insertion site for the quadriceps femoris tendon and plays a critical role in transmitting forces from the quadriceps to the tibia via the patellar ligament. As part of the extensor mechanism of the knee, it is essential for knee extension, gait, and stability.

It is also an important landmark in radiology and orthopedic surgery, particularly in conditions such as quadriceps tendon tears, bipartite patella, patellofemoral disorders, and fractures.

Synonyms

  • Superior pole of patella

  • Quadriceps tendon attachment site

  • Proximal border of patella

Muscular Attachments

  • Quadriceps femoris tendon attaches broadly to the base of the patella

    • Rectus femoris

    • Vastus medialis

    • Vastus lateralis

    • Vastus intermedius

  • These fibers converge and insert into the base, transmitting force to the patellar ligament, which continues to the tibial tuberosity

Relations

  • Anteriorly: Quadriceps tendon and prepatellar bursa

  • Posteriorly: Suprapatellar bursa and femoral trochlea

  • Superiorly: Quadriceps femoris muscle belly

  • Inferiorly: Patellar body and patellar ligament

Function

  • Acts as the primary attachment site of the quadriceps tendon

  • Distributes tensile forces across the patella to the patellar ligament

  • Enhances leverage of the quadriceps muscle for efficient knee extension

  • Protects anterior knee joint structures

Clinical Significance

  • Quadriceps tendon rupture often involves the base of the patella

  • Bipartite patella may involve accessory ossification centers at the base

  • Patellar stress fractures may occur in athletes

  • Common site of degenerative enthesopathy or bony irregularity in chronic overuse

MRI Appearance

T1-weighted images:

  • Marrow signal appears intermediate to bright

  • Cortical bone is dark (low signal)

  • Quadriceps tendon appears as a low-signal band attaching to the base

T2-weighted images:

  • Marrow signal appears intermediate to bright

  • Cortical bone remains dark

  • Quadriceps tendon low signal, but edema or tear at insertion appears bright

Proton Density (PD):

  • Marrow signal intermediate to bright

  • Cortical margins remain dark

  • Tendon and enthesis normally low signal

STIR (Short Tau Inversion Recovery):

  • Normal marrow signal is low

  • Pathology (edema, contusion, stress fracture) appears bright hyperintensity

  • Quadriceps tendon pathology also highlights with bright signal

Proton Density Fat-Saturated (PD FS):

  • Normal marrow signal is low

  • Bone marrow edema, enthesitis, or fracture shows bright hyperintensity

  • Quadriceps tendon tear or inflammation demonstrates bright signal

T1 Fat-Sat Post-Contrast:

  • Bone marrow normally shows mild uniform enhancement

  • Pathology (osteomyelitis, tumor, enthesitis) shows focal or diffuse abnormal enhancement

  • Abscesses show peripheral rim enhancement with non-enhancing center

CT Appearance

Non-Contrast CT:

  • Base of patella seen as dense cortical bone with central trabecular bone

  • Marrow appears as intermediate density

  • Enthesophytes, fractures, or calcifications are clearly visible

Post-Contrast CT:

  • Bone itself does not enhance

  • Surrounding soft tissue (tendon, bursa, synovium) may enhance in pathology

  • Abscess, tumor, or synovitis shows contrast uptake around the base

MRI image

Base of Patella sagittal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

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

CT image

Base of patella ct axial image