Patellar Tendon (Patellar Ligament): Anatomy, Origin, Insertion, Blood Supply, Function, MRI & CT Imaging

Topic

Patellar tendon (patellar ligament)

The patellar tendon, also called the patellar ligament, is a strong, flat band of connective tissue that connects the apex of the patella to the tibial tuberosity. It is a continuation of the quadriceps femoris tendon, transmitting the force of the quadriceps muscle group to the tibia, thereby enabling extension of the knee joint. Despite its name “ligament,” it functions as a tendon since it links muscle to bone, but it is also classified as a ligament because it connects two bones (patella and tibia).

It is a key structure in the knee extensor mechanism, crucial for walking, running, squatting, and jumping. Pathologies of the patellar tendon such as tendinopathy (“jumper’s knee”) and rupture are common in athletes and can be assessed effectively on imaging.

Synonyms

Patellar ligament
Ligamentum patellae
Distal quadriceps tendon continuation

Attachments

Proximal attachment: Apex and lower half of the posterior surface of the patella
Course: Descends vertically from patella to tibial tuberosity, anterior to the knee joint capsule and infrapatellar fat pad
Distal attachment: Tibial tuberosity

Relations

Anteriorly: Subcutaneous tissue and skin of anterior knee
Posteriorly: Infrapatellar (Hoffa’s) fat pad, anterior surface of tibia
Medially and laterally: Retinacular expansions of the quadriceps tendon
Superiorly: Patella
Inferiorly: Tibial tuberosity

Nerve Supply

No motor innervation; receives sensory fibers from branches of the femoral nerve via the infrapatellar branch of the saphenous nerve

Arterial Supply

Superior and inferior genicular arteries (branches of popliteal artery)
Anterior tibial recurrent artery

Venous Drainage

Parallels arterial supply, draining into popliteal and anterior tibial veins

Function

Transmits force from quadriceps femoris to tibia, enabling knee extension
Stabilizes the anterior aspect of the knee joint
Plays a key role in absorbing and distributing loads during locomotion and jumping
Serves as a clinical landmark for knee surgery and injections

Clinical Significance

Patellar tendinopathy (jumper’s knee): Chronic overuse injury common in athletes
Patellar tendon rupture: May occur spontaneously or after trauma; results in loss of active knee extension
Post-surgical relevance: Used as a graft source in anterior cruciate ligament (ACL) reconstruction
Inflammatory/infectious conditions: Rarely affected but can show enhancement and swelling
Osgood-Schlatter disease: Involves insertion of patellar tendon at tibial tuberosity in adolescents

MRI Appearance

T1-weighted images:

Patellar tendon appears as a low-signal intensity band
Surrounding fat (bright) provides contrast
Partial tears may appear as areas of intermediate signal

T2-weighted images:

Normal tendon: low-signal band
Tendinopathy or tear: focal or diffuse hyperintense areas within tendon substance

STIR (Short Tau Inversion Recovery):

Normal tendon: dark low signal
Tendinopathy, partial tears, or inflammatory changes: bright hyperintense areas

Proton Density Fat-Saturated (PD FS):

Normal tendon: dark low signal
Pathology (tendinopathy, tear, inflammation): bright hyperintense regions, especially at proximal attachment

T1 Fat-Sat Post-Contrast:

Normal tendon: minimal enhancement
Pathological tendon: focal, diffuse, or rim enhancement depending on inflammation or tear
Abscess or infection: rim enhancement with central non-enhancing region

CT Appearance

Non-Contrast CT:

Tendon appears as a dense soft tissue band from patella to tibial tuberosity
Calcifications may be seen in chronic tendinopathy
Partial or complete ruptures may appear as tendon discontinuity with surrounding fat stranding or hematoma

Post-Contrast CT: