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Medial border of patella

The medial border of the patella is an important anatomical region forming the inner margin of the kneecap. It contributes to the stability of the patellofemoral joint and serves as an attachment site for key soft tissue stabilizers, including the vastus medialis obliquus (VMO) fibers and the medial patellofemoral ligament (MPFL). It is clinically significant because of its role in patellar tracking, medial stability, and as a frequent site of pathology in cases of patellar dislocation or instability.

Synonyms

  • Medial facet border of patella

  • Inner margin of patella

  • Medial patellar edge

Muscular Attachments

  • Fibers of the vastus medialis obliquus (VMO) insert along the superomedial border of the patella

  • Medial patellofemoral ligament (MPFL) attaches to the medial border, particularly the upper half

  • Fibrous expansions from the quadriceps tendon blend with medial soft tissue structures here

Relations

  • Anteriorly: Subcutaneous tissue, skin of the knee, medial retinaculum

  • Posteriorly: Medial patellar articular facet, articulating with the medial femoral condyle

  • Superiorly: Quadriceps tendon and vastus medialis fibers

  • Inferiorly: Patellar ligament leading to tibial tuberosity

  • Laterally: Central patellar body and lateral border of patella

  • Medially: Medial retinaculum, medial capsule, and MPFL

Function

  • Provides attachment for medial stabilizing structures of the patella

  • Helps maintain proper patellofemoral alignment during knee motion

  • Distributes quadriceps forces medially via VMO attachment

  • Acts as a buttress to prevent lateral patellar displacement

Clinical Significance

  • Patellar instability: MPFL tears commonly occur at the medial patellar attachment

  • Dislocation: Medial border injuries are frequent in lateral patellar dislocation

  • Overuse syndromes: VMO dysfunction may affect medial patellar stabilization

  • Surgical relevance: Landmark for MPFL reconstruction and medial retinacular repair

MRI Appearance

T1-weighted images:

  • Medial border cortical bone: low signal (dark)

  • Adjacent marrow: intermediate to bright signal intensity

T2-weighted images:

  • Cortical bone: low signal

  • Marrow: intermediate to bright signal intensity

  • Pathology (edema, fracture, bone bruise): bright hyperintense signal

STIR (Short Tau Inversion Recovery):

  • Cortical bone: low signal

  • Marrow: normally low signal

  • Edema, contusion, or fracture: bright hyperintensity

Proton Density Fat-Saturated (PD FS):

  • Cortical bone: low signal

  • Marrow: intermediate to bright signal

  • Pathology: edema or stress fracture shows bright hyperintensity

T1 Fat-Sat Post-Contrast:

  • Normal cortex: no enhancement (remains dark)

  • Marrow: mild uniform enhancement

  • Pathology (fracture, infection, tumor): enhancing marrow changes, sometimes rim or patchy enhancement

CT Appearance

Non-Contrast CT:

  • Medial border appears as a dense cortical bony margin

  • Fractures or cortical irregularities readily visible

  • Subtle erosions can indicate early arthritis or inflammatory disease

Post-Contrast CT:

  • Bone cortex itself does not enhance

  • Adjacent marrow, retinaculum, or MPFL attachments may show enhancement if inflamed or injured

  • Useful in evaluation of tumors, infection, or postsurgical changes

MRI image

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

MRI image

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

CT image

Medial border of patella ct axial

CT VRT image

Medial border of patella