Quadriceps Tendon, Tendon Examination

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Quadriceps Tendon

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For Medical Students

What It Tests

The quadriceps tendon joins the quadriceps to the upper pole of the patella, and examining it tests for tendinopathy and for rupture.

Rupture is the finding that matters. A complete tear makes the extensor mechanism discontinuous, so the patient cannot actively extend the knee, and that is a clinical diagnosis with an operative answer. 4.7.8 covers extension lag.

It is commoner in older patients and in those with systemic risk factors, and the mechanism is usually an eccentric load on a flexed knee. 4.2.9 covers onset.

How It Is Performed

Lay the patient supine with the leg exposed from the thigh down.

Look for a defect above the patella and for the patella sitting lower than the other side, both of which follow a complete rupture. 4.3.4 covers the sitting assessment.

Palpate the tendon from the upper pole of the patella upwards along its whole length, feeling for tenderness and for a gap. 4.6.6 covers tendon tenderness.

Ask the patient to straighten the knee, then to hold the straightened leg lifted against gravity, which is the test that identifies a rupture. 4.7.1 covers active motion.

Measure the active and the passive extension separately, since the difference is the finding. 4.7.2 covers passive motion.

What a Positive Means

A palpable gap above the patella with an inability to hold the leg straight indicates a complete rupture, and that is urgent.

Tenderness along the tendon with intact active extension indicates a tendinopathy or a partial tear, and the examination cannot separate those. 4.6.6 covers that limit.

A low lying patella compared with the other side supports a complete rupture and is easy to miss without the comparison. 4.3.4 covers the sitting assessment.

An extension lag with no gap and a tender tendon can be a partial tear, and in that situation the imaging decides. 4.1.6 covers that relationship.

Weakness without tenderness or a gap points at the muscle or the nerve rather than the tendon. 4.3.9 covers muscle wasting.

Key Learning Points

Rupture is the finding that matters, and it is a clinical diagnosis.
A complete tear makes the extensor mechanism discontinuous, so active extension fails.
Look for a defect above the patella and for a low lying patella.
Tenderness with intact active extension is a tendinopathy or a partial tear, and palpation cannot separate them.
Weakness without tenderness or a gap points at the muscle or the nerve.

MRCS Level

How It Is Performed

In a viva the straight leg hold is the answer, and a candidate who palpates and does not test active extension has missed the diagnosis the station is about.

The expected points are the inspection for a defect and the patellar height, the palpation of the whole tendon, the active extension, the straight leg hold, and both range measurements.

Say that you would test the straight leg hold in any patient with a tender tendon and a history of a sudden load, and say why. 4.7.8 covers the lag.

Say that you would ask about systemic risk factors and medication, since both change the likelihood of a rupture.

Say that a partial tear and a tendinopathy are not separable clinically and that imaging answers it. 4.1.6 covers that relationship.

What a Positive Means

The reasoning expected is that the extensor mechanism is a chain from quadriceps to tibial tubercle, so a break anywhere in it abolishes active extension while leaving passive extension intact. 4.6.7 covers the far end of the chain.

The tendon's blood supply is relatively poor near its insertion, which is where degenerative tears occur, and that is why spontaneous rupture happens in an older or systemically affected tendon. 2.4.1 covers the patellar anatomy.

A partial tear leaves the chain continuous, so active extension persists and the diagnosis becomes an imaging one rather than a clinical one.

The patella's position reflects the balance of the two tendons pulling on it, which is why a quadriceps rupture lets it sit low and a patellar tendon rupture lets it sit high. 4.16.2 covers the other tendon.

How Good It Is

The clinical diagnosis of a complete rupture is reliable and depends almost entirely on testing active extension against gravity, which takes seconds. 4.7.1 covers it.

Palpation for a gap is specific and less sensitive, particularly in a swollen or a heavy limb, so the functional test carries the diagnosis.

The examination cannot grade a partial tear or distinguish it from tendinopathy, and ultrasound or magnetic resonance imaging does. 4.1.6 covers that relationship.

Delayed diagnosis is a recognised problem with this injury, and the omission is almost always the straight leg hold rather than the palpation. 4.7.8 covers the lag.

No figures appear for any accuracy comparison on this page, under decision 023, and the comparison is the claim being made.

Key Learning Points

A break anywhere in the extensor chain abolishes active extension and leaves passive extension intact.
The tendon's supply is poorer near its insertion, which is where degenerative tears occur.
A partial tear leaves the chain continuous, so the diagnosis becomes an imaging one.
A quadriceps rupture lets the patella sit low; a patellar tendon rupture lets it sit high.
Delayed diagnosis almost always traces to the missing straight leg hold.

FRCS Level

How Good It Is

At decision level the examination makes one time sensitive diagnosis and the imaging makes the rest.

A complete rupture is repaired, and an early repair has a better result than a late one, so the examination's job is to make the diagnosis on the day. 4.7.8 covers the finding.

A partial tear with intact active extension is usually managed non operatively, and the decision rests on the imaging and the patient's demand rather than on the examination.

A tendinopathy is a load management problem, and recognising it prevents an unnecessary investigation of the joint. 4.16.3 covers the equivalent at the other tendon.

In a patient with systemic risk factors and bilateral symptoms the possibility of bilateral degenerative rupture is worth holding, because the comparison with the other side then misleads. 4.1.2 covers the principle it undermines.

Where It Misleads

The commonest error is not testing active extension against gravity.

The second is relying on the gap, which is hard to feel in a swollen knee.

The third is comparing patellar height without the other knee in the same position.

The fourth is attributing an extension deficit to the joint when the tendon is the cause. 4.7.7 covers contractures.

The fifth is assuming a unilateral problem in a patient whose risk factors affect both sides.

Key Learning Points

The examination makes one time sensitive diagnosis and imaging makes the rest.
An early repair has a better result, so the diagnosis has to be made on the day.
A partial tear with intact extension is usually managed non operatively.
A tendinopathy is a load problem, and recognising it prevents investigating the joint.
With bilateral risk factors the comparison with the other side misleads.

Fellowship Level

Where It Misleads

In referred practice the quadriceps tendon appears as a missed rupture or as a problem after knee surgery.

A patient with an extension deficit weeks after a sudden load, a palpable defect and a low patella has a missed rupture, and the repair is harder and the result worse than it would have been. 4.7.8 covers the finding.

A patient with an extension lag after an arthroplasty may have a tendon problem rather than a quadriceps one, and the palpation separates them. 4.20.8 covers that assessment.

A patient with a previous quadriceps tendon harvest for a cruciate graft has a donor site that is tender and occasionally weak, which is not a failure of the reconstruction. 4.20.1 covers that assessment.

A patient with bilateral spontaneous ruptures has a systemic problem, and the examination's contribution is noticing that the pattern is not traumatic. 4.2.14 covers inflammatory pain.

In medicolegal work a missed quadriceps rupture is a recognised and avoidable failure, and the absence of a recorded active extension test is usually the point of criticism. 4.23.7 covers that setting.

Key Learning Points

A missed rupture gives a harder repair and a worse result.
An extension lag after arthroplasty may be a tendon problem, separated by palpation.
A quadriceps graft harvest leaves a tender donor site that is not a reconstruction failure.
Bilateral spontaneous ruptures mean a systemic problem.
A missed rupture traces to the absent active extension test.

Explore Further

Where this topic came from and where it goes next in the spiral.

References

No reference list is attached to this draft. Evidence verification has not run, because source retrieval was unavailable at generation time. Under the Operations Handbook a missing reference is acceptable and an invented one is a critical failure, so nothing has been cited and no citation marker appears in the text. This page carries no diagnostic accuracy figure, which is decision 023 rather than an omission. The comparative standing of these tests is standard teaching and a specific sensitivity written from memory is the same class of claim as an invented citation, so ACC-001 refuses the number and the page states the comparison. A reviewer with the literature can add the figures into How Good It Is without restructuring the page, and chapter 3.17 lists the studies the figures would come from. Any measurement here, including a flexion angle, is written from standard teaching, has not been checked, and is registered under decision 006 in pipeline/config/figures with a verification state of UNVERIFIED_FROM_MEMORY.

Safety. KneeSchool is educational and does not give individual medical advice. Seek urgent assessment for a knee that cannot bear weight after an injury, a hot swollen knee with a fever, or new numbness, weakness or coldness in the leg or foot.