Distal Quadriceps Femoris Tendon: Anatomy, Insertion, Function, Clinical Significance, MRI & CT Imaging

Topic

Distal quadriceps femoris tendon

The distal quadriceps femoris tendon is the common tendon formed by the convergence of the four quadriceps muscles — rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. It is the strongest tendon in the body and inserts into the superior pole of the patella, continuing as the patellar ligament to the tibial tuberosity.

The tendon plays a crucial role in knee extension, gait, jumping, and squatting. Due to its load-bearing function, it is prone to degeneration, partial tears, or complete rupture, especially in athletes and elderly patients.

Synonyms

Quadriceps tendon
Common quadriceps femoris tendon
Proximal patellar tendon (functional description)

Origin and Insertion

Origin: Formed by the fusion of the tendinous fibers of the four quadriceps femoris muscles in the distal thigh
Insertion: Superior border and base of the patella; fibers continue as the patellar ligament to insert into the tibial tuberosity

Nerve Supply

Supplied indirectly by motor innervation of the quadriceps muscles via the femoral nerve (L2–L4)

Arterial Supply

Branches of the femoral artery
Descending genicular artery
Lateral circumflex femoral artery
Superior medial and lateral genicular arteries

Venous Drainage

Follows arterial supply, draining into femoral and popliteal veins

Function

Transmits force from quadriceps muscles to the patella and tibial tuberosity
Essential for knee extension
Stabilizes the anterior aspect of the knee joint
Plays a role in high-demand activities like running, jumping, squatting, and climbing

Clinical Significance

Site of tendinopathy in overuse conditions (e.g., athletes, weightlifters)
Partial tears often occur at the patellar attachment
Complete rupture usually occurs after sudden eccentric loading; inability to extend the knee is characteristic
Commonly evaluated in pre-operative planning for total knee replacement and in trauma imaging

MRI Appearance

T1-weighted images:

Tendon appears as a uniformly low-signal band inserting into the patella
Surrounding fat appears bright, providing contrast

T2-weighted images:

Normal tendon shows low signal intensity
Partial tears or degeneration appear as focal bright signal within tendon fibers

STIR (Short Tau Inversion Recovery):

Tendon normally dark
Pathology (tendinopathy, strain, tear) shows bright hyperintensity in tendon and adjacent soft tissues

Proton Density Fat-Saturated (PD FS):

Normal tendon shows dark low signal
Areas of degeneration, tendinopathy, or partial tear show focal bright signal
Excellent for evaluating fiber integrity

T1 Fat-Sat Post-Contrast:

Normal tendon shows minimal to no enhancement
Inflammation or partial tears show linear or focal enhancement
Post-operative scar tissue or neoplasm shows heterogeneous enhancement

CT Appearance

Non-Contrast CT:

Tendon appears as a soft tissue density band inserting into the superior patella
Calcific tendinopathy may show as linear or nodular calcifications
Acute tendon rupture may be inferred from discontinuity and associated soft tissue swelling

Post-Contrast CT:

Normal tendon shows minimal enhancement
Inflammatory or neoplastic processes show soft tissue enhancement along tendon margins
Abscess or postoperative infection may show rim-enhancing low-density collections

MRI images

CT image

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