Quadriceps tendon !
The quadriceps tendon is the broad tendon of the four front thigh muscles, attaching to the top of the kneecap; it straightens the knee.
Official name: Tendon of quadriceps femoris muscle
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What it is
A broad, thick tendon where the four quadriceps muscles join and attach to the top of the kneecap.
What it does
Carries the pull of the quadriceps through the kneecap to straighten the knee.
Key facts
- Attaches
- Converging tendons of rectus femoris and the three vasti to base of patella
- Function
- Transmits quadriceps force to patella; continues below as patellar ligament
- Tight in
- Knee flexion, especially with hip extended
Relations
- Superficial
- Fascia lata and skin
- Deep
- Suprapatellar bursa (continuous with the knee joint) and the prefemoral fat pad over the femur
- Medial
- Vastus medialis obliquus, whose aponeurosis continues as the medial retinaculum
- Lateral
- Vastus lateralis, whose aponeurosis continues as the lateral retinaculum
- Below
- Base of the patella; superficial fibres continue over its front into the patellar tendon
How to find it
Just above the patella, felt as a broad firm band that hardens when the person tightens the thigh with the knee straight.
Examination
- Straight-leg raise: inability to lift the straight leg or to hold the knee fully extended against gravity suggests disruption of the extensor mechanism; a gap may be felt just above the patella
On imaging
Lateral X-ray after rupture: a low-riding patella (baja), soft-tissue swelling above it, sometimes small bone flecks from the upper pole. Ultrasound or MRI shows the gap and which layers are torn. A tooth sign (vertical spurs on the upper front of the patella on skyline views) marks enthesopathy.
Common problems
- Quadriceps tendinopathy: pain just above the kneecap with jumping or squatting.
- Rupture, more common after age 40: the leg cannot be straightened against gravity.
How it is diagnosed
Physical exam (a gap above the kneecap, unable to lift the straight leg); ultrasound or MRI.
Treatment
- Tendinopathy: physical therapy and load management.
- Complete rupture: surgical repair, usually soon after the injury.
- A strip of this tendon can also be used as a graft for ACL reconstruction.
Clinical notes
- If the retinacula are intact, some active extension may remain despite a complete tendon tear, so the rupture is often missed
- Acute complete ruptures are repaired early; delayed repairs are more difficult because the tendon retracts
- On a lateral X-ray a low-riding patella (patella baja) points to a quadriceps tendon rupture, whereas a high-riding patella (patella alta) points to a patellar tendon rupture
Anatomical variants
- An extra muscle belly, the tensor of the vastus intermedius, lies between vastus lateralis and intermedius and can add a layer to the tendon; texts differ on how often
Development
The patella develops inside this tendon as the body's largest sesamoid bone; it starts as cartilage and ossifies in early childhood. Failure of one ossification centre to fuse leaves a bipartite patella, usually at the upper outer corner.
Test yourself
Think of the answer, then tap the question to see it.
What are the three layers of the quadriceps tendon?
Rectus femoris superficial, vastus medialis and lateralis in the middle, vastus intermedius deep.
Where does the quadriceps tendon usually rupture, and which conditions raise the risk?
Just above the patella; kidney disease, diabetes and steroid use raise the risk, and both sides may tear.
Why is a complete quadriceps tendon rupture often missed?
If the retinacula are intact, some active knee extension may remain.
What does a lateral knee X-ray show after quadriceps tendon rupture?
A low-riding patella (patella baja), soft-tissue swelling above it and sometimes small bone flecks from the upper pole.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- tendo musculi quadricipitis femoris TA2 2621
- Official Spanish (DeCS)
- Tendón del músculo cuádriceps femoral DeCS D013710
- English (TA2)
- Tendon of quadriceps femoris muscle
Related
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Bony Pelvis and Lower Limb: Thigh Quadriceps Muscle; 8.4 Bones of the Lower Limb (OpenStax (Rice University), 2022) · adapted, CC BY 4.0.
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Representative model, for educational purposes only.
