Distal Rectus Femoris Tendon: Anatomy, Attachments, Relations, Function, Clinical Significance, MRI & CT Imaging

Topic

Distal rectus femoris tendon

The distal rectus femoris tendon is the terminal part of the rectus femoris muscle, one of the four quadriceps muscles. It contributes to the common quadriceps tendon, which inserts into the patella and continues as the patellar ligament to the tibial tuberosity. The distal tendon is critical for knee extension and stability of the patellofemoral joint. It is clinically important because it is frequently involved in quadriceps tendon tears, degenerative tendinopathy, and traumatic injuries.

Synonyms

Rectus femoris insertion tendon
Quadriceps femoris tendon (rectus femoris portion)
Distal tendon of rectus femoris

Origin and Insertion

Origin: Rectus femoris arises proximally by two heads (straight head from the anterior inferior iliac spine, and reflected head from the superior acetabular rim).
Distal tendon course: The muscle belly narrows distally, forming a thick tendon that blends with the other quadriceps tendons.
Insertion: Inserts into the superior pole of the patella as part of the quadriceps tendon, which continues as the patellar ligament to insert into the tibial tuberosity.

Relations

Anteriorly: Subcutaneous tissue and skin overlying the anterior thigh and knee
Posteriorly: Suprapatellar bursa, anterior femur, and knee joint capsule
Medially: Vastus medialis tendon component
Laterally: Vastus lateralis tendon component
Inferiorly: Patella and continuation into the patellar ligament

Nerve Supply

Supplied by the femoral nerve (L2–L4) via the rectus femoris muscle belly

Arterial Supply

Branches of the lateral circumflex femoral artery
Contributions from the femoral artery and superior genicular arteries

Venous Drainage

Follows arterial supply into the femoral vein and profunda femoris vein

Function

Extends the leg at the knee joint (primary action)
Provides anterior stability to the patellofemoral joint
Assists in maintaining patellar alignment
Contributes to hip flexion via its proximal muscular portion

Clinical Significance

Common site of tendinopathy and partial tears, particularly in athletes
Quadriceps tendon rupture often involves the distal rectus femoris portion
Degenerative changes may predispose to tendon rupture
Important landmark in orthopedic surgery and knee arthroplasty planning

MRI Appearance

T1-weighted images:

Tendon appears as a low-signal linear structure
Surrounding fat appears bright, highlighting the tendon margins

T2-weighted images:

Normal tendon shows low signal intensity
Partial tears, tendinosis, or edema appear as bright hyperintense foci or streaks within the tendon

STIR (Short Tau Inversion Recovery):

Normal tendon appears dark
Tendinopathy, strain, or tears appear bright hyperintense
Peritendinous edema also brightens

Proton Density Fat-Saturated (PD FS):

Tendon appears dark
Injury, microtears, or tendinosis appear as bright hyperintense regions within or around tendon fibers

T1 Fat-Sat Post-Contrast:

Normal tendon shows minimal enhancement
Inflamed tendon or postoperative changes show focal or diffuse enhancement
Abscess or infection shows rim enhancement with non-enhancing core

CT Appearance

Non-Contrast CT:

Tendon not well visualized directly; seen as a soft tissue density blending into the quadriceps tendon
Chronic calcific tendinopathy may show calcific densities near the patellar insertion
Peritendinous fat planes highlight the tendon margins

Post-Contrast CT:

Tendon itself shows minimal enhancement
Inflammation, neoplasm, or postsurgical changes may cause enhancing soft tissue thickening around the tendon
Hematoma or abscess presents as low-attenuation lesion with rim enhancement

MRI images