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Prefemoral fat pad

The prefemoral fat pad is a triangular intracapsular but extrasynovial fat pad located in the anterior knee. It lies superior to the trochlear groove of the femur and anterior to the suprapatellar recess, serving as one of the key intra-articular fat pads of the knee along with the infrapatellar (Hoffa’s) and quadriceps (suprapatellar) fat pads.

The fat pad cushions and protects the anterior femoral surface, facilitates smooth motion of the suprapatellar recess during knee movement, and acts as a buffer between the quadriceps tendon and femur.

Synonyms

  • Supratrochlear fat pad

  • Prefemoral adipose pad

  • Anterior femoral fat pad

Location

  • Situated within the anterior knee joint capsule

  • Found superior to the trochlea of the femur

  • Lies posterior to the quadriceps tendon and anterior to the suprapatellar recess

Relations

  • Anteriorly: Quadriceps tendon

  • Posteriorly: Suprapatellar recess of the knee joint

  • Superiorly: Quadriceps fat pad

  • Inferiorly: Suprapatellar bursa and femoral trochlea

  • Laterally/Medially: Joint capsule and retinacula

Function

  • Provides cushioning and protection for the anterior femur

  • Reduces friction between quadriceps tendon and femur during knee motion

  • Contributes to joint lubrication dynamics with suprapatellar recess

  • Acts as a shock absorber for the anterior knee structures

Clinical Significance

  • May become inflamed or hypertrophied in fat pad impingement syndrome

  • Can mimic or coexist with suprapatellar bursitis

  • Appears enlarged or signal altered in osteoarthritis, trauma, or inflammatory arthropathy

  • Important landmark in knee MRI interpretation

MRI Appearance

T1-weighted images:

  • Fat pad appears bright (high signal intensity), similar to subcutaneous fat

  • Capsule and synovial margins appear as thin low-signal borders

T2-weighted images:

  • Fat pad normally shows bright signal intensity

  • Edema or inflammation: appears heterogeneously hyperintense with surrounding low-signal capsule

STIR (Short Tau Inversion Recovery):

  • Normal fat is suppressed (dark)

  • Inflammation, edema, or impingement: shows bright hyperintensity

Proton Density Fat-Saturated (PD FS):

  • Normal fat is suppressed and dark

  • Pathology (edema, inflammation, fibrosis) appears bright

T1 Fat-Sat Post-Contrast:

  • Normal fat pad shows minimal or no enhancement

  • Pathologic fat pad (inflammation, synovitis, tumor infiltration) may show focal or diffuse enhancement

CT Appearance

Non-Contrast CT:

  • Fat pad appears as a homogeneous low-density structure (-80 to -120 HU)

  • Outlined by soft tissue capsule and adjacent tendon surfaces

  • Inflammation or scarring may obscure fat planes

Post-Contrast CT:

  • Normal fat pad does not enhance

  • Surrounding synovium or capsule may enhance if inflamed

  • Pathologic changes (synovitis, tumor) appear as enhancing soft tissue encroaching into fat pad

MRI image

prefemoral fat pad axial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image1

MRI image

prefemoral fat pad sagittal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

prefemoral fat pad

CT image

prefemoral fat pad ct sagittal image