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Lateral patellofemoral ligament

The lateral patellofemoral ligament (LPFL) is a specialized reinforcement of the knee’s lateral retinacular complex. It extends from the lateral femoral condyle to the lateral border of the patella, functioning as a key stabilizer of the patella, particularly against medial subluxation and dislocation. The LPFL works in balance with the medial patellofemoral ligament (MPFL) and other retinacular structures to maintain proper patellofemoral tracking.

This ligament is clinically important in cases of patellar instability, trauma, and during surgical planning for ligament reconstruction or realignment procedures.

Synonyms

  • LPFL of the knee

  • Lateral patellofemoral retinaculum

  • Lateral stabilizer of patella

Origin and Insertion

  • Origin: Lateral femoral condyle and adjacent capsule of the knee joint

  • Course: Runs transversely across the lateral aspect of the knee joint, blending with the lateral retinaculum

  • Insertion: Lateral border and margin of the patella

Relations

  • Anteriorly: Superficial fascia, iliotibial band, and subcutaneous tissue

  • Posteriorly: Lateral femoral condyle, lateral collateral ligament (LCL), and capsule of the knee

  • Superiorly: Vastus lateralis muscle fibers and quadriceps tendon

  • Inferiorly: Joint capsule and lateral meniscus region

Nerve Supply

  • Supplied by branches of the femoral nerve and possibly articular branches of the common peroneal nerve via the lateral capsule

Arterial Supply

  • Superior lateral genicular artery

  • Inferior lateral genicular artery

  • Contributions from the lateral femoral circumflex artery

Venous Drainage

  • Corresponding veins drain into the popliteal vein and femoral vein

Function

  • Provides lateral stabilization of the patella

  • Prevents medial dislocation of the patella during knee flexion and extension

  • Works with the medial patellofemoral ligament and retinaculum for balanced patellar tracking

  • Contributes to joint capsule reinforcement on the lateral side

Clinical Significance

  • Injury or laxity can lead to patellar maltracking, recurrent instability, or pain

  • May be injured in traumatic patellar dislocations or knee ligament injuries

  • Target for surgical repair in patellofemoral stabilization procedures

  • MRI evaluation is essential for detecting partial or complete tears

MRI Appearance

T1-weighted images:

  • LPFL appears as a thin, low-signal band from lateral femoral condyle to patella

  • Surrounded by bright fat for contrast

T2-weighted images:

  • Ligament remains low signal

  • Injury, edema, or partial tear shows focal bright signal intensity

STIR (Short Tau Inversion Recovery):

  • Normal LPFL is dark (low signal)

  • Injury or inflammation appears as bright hyperintensity

Proton Density Fat-Saturated (PD FS):

  • LPFL normally shows dark low signal

  • Partial or complete tears: focal or diffuse bright signal interruption

T1 Fat-Sat Post-Contrast:

  • Intact LPFL: minimal or no enhancement

  • Injured or inflamed LPFL: may show focal enhancement, especially at attachment sites

CT Appearance

Non-Contrast CT:

  • LPFL not directly visualized, but its course may be inferred by location and adjacent fat planes

  • Calcification at attachment sites may be seen in chronic injury

Post-Contrast CT:

  • Normal LPFL does not enhance significantly

  • Enhancement may be seen in surrounding tissues with inflammation, scarring, or post-traumatic change

  • Helpful for excluding associated fractures or bony avulsions

MRI images

Lateral patellofemoral ligament (LPFL) axial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI images

Lateral patellofemoral ligament (LPFL) coronal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

Lateral patellofemoral ligament ct axial