Tibial Tubercle Tenderness

For Medical Students

What It Tests

The tibial tubercle is the patellar tendon's insertion, and tenderness over it indicates a problem at that insertion.

Which problem depends mostly on the patient's age: a growing adolescent, a skeletally mature athlete, and an adult with a previous surgery or injury each have a different diagnosis at the same tender point. 4.2.9 covers onset.

It is also a landmark the rest of the examination uses, for the drawer tests and for the rotational assessment, so finding it reliably matters beyond this page. 4.11.2 covers one of those tests.

How It Is Performed

With the knee flexed to about ninety degrees, find the tubercle as the bony prominence below the patella where the tendon inserts.

Palpate the tubercle itself, then the tendon immediately above it, then the bone below it. 4.6.6 covers the tendon.

Note whether the tubercle is enlarged, which it commonly is in a patient who had a traction problem in adolescence.

Ask the patient to extend the knee against resistance and note whether that reproduces the pain, which localises it to the insertion.

Look for a scar or a palpable screw, since a tubercle osteotomy or a fixation device sits exactly here. 4.3.7 covers surgical scars.

What a Positive Means

Tenderness with an enlarged tubercle in a growing adolescent indicates a traction apophysitis, which is self limiting.

Tenderness in a skeletally mature athlete indicates an insertional tendinopathy or, with the right history, an avulsion. 4.6.6 covers the tendon.

Tenderness with an inability to extend the knee after a sudden load indicates an avulsion of the tendon or the tubercle, which is urgent. 4.7.8 covers extension lag.

Tenderness over a palpable device after a tubercle osteotomy indicates prominent hardware, which is a common and treatable cause of persisting anterior pain. 4.3.7 covers scars.

Tenderness here with tenderness at the inferior pole of the patella suggests the whole tendon rather than one end of it. 4.6.5 covers the patella.

MRCS Level

How It Is Performed

In a viva the tubercle is usually a route into a question about the extensor mechanism or about an adolescent knee, and the age based differential is the answer.

The expected points are the position, the palpation of the tubercle and the tendon above it, the enlargement, the resisted extension, and the search for hardware.

Say that you would test active extension against gravity in any patient with tubercle tenderness and a history of sudden load. 4.7.1 covers active motion.

Say that an adolescent with this finding and an open apophysis has a different problem from an adult, and that the radiograph confirms the skeletal maturity. 4.1.6 covers that relationship.

Say that you would use the tubercle as a landmark for the rest of the examination deliberately, which is a practical point rather than a diagnostic one. 4.11.2 covers one such test.

What a Positive Means

The reasoning expected is that the patellar tendon transmits the whole extensor force to the tibia through this point, so it is a site of high stress and therefore of overload and avulsion injury. 2.4.3 covers patellar biomechanics.

In a growing skeleton the apophysis is the weakest part of the chain, which is why traction injury occurs there in adolescence and at the tendon in adults. 2.4.2 covers ossification.

The tubercle's position relative to the patella and the trochlea determines the tendon's line of pull, which is why a tubercle osteotomy is used to treat patellar instability and maltracking. 2.4.4 covers tracking.

Its lateral position relative to the trochlear groove is the basis of the measurement used in planning those operations, and the examination's estimate of it is the rotational assessment. 4.5.6 covers rotational alignment.

How Good It Is

Palpation here is precise, because the landmark is bony and superficial and the tenderness is focal.

Its specificity comes almost entirely from the age and the history rather than from the finding, which is unusual and worth stating.

It diagnoses an avulsion reliably when combined with the active extension test, which is the consequential use. 4.7.8 covers it.

It cannot distinguish an insertional tendinopathy from a partial avulsion, which imaging does. 4.1.6 covers that relationship.

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

FRCS Level

How Good It Is

At decision level the finding makes one urgent diagnosis and identifies one common and treatable cause of persisting pain.

The urgent diagnosis is an avulsion, which is operative and time sensitive, and the examination makes it. 4.7.8 covers extension lag.

The treatable cause is prominent hardware after a tubercle osteotomy, which is simple to address and frequently attributed to something else. 4.3.7 covers surgical scars.

In an adolescent the finding is reassurance rather than a decision, and the examination's contribution is confidence that nothing further is needed.

In a patient being planned for a tubercle osteotomy the examination's rotational assessment contributes to the question of whether the tubercle's position is part of the problem. 4.5.6 covers it.

Where It Misleads

The commonest error is not testing active extension in a patient with acute tenderness after a load.

The second is attributing adult tubercle pain to a childhood apophysitis, which has resolved.

The third is missing prominent hardware in a patient whose anterior pain followed an osteotomy.

The fourth is reading an enlarged tubercle as an active problem, when it is usually the healed remnant of an old one.

The fifth is attributing anterior pain to the tubercle without examining the patella and the tendon's whole length. 4.6.5 covers the patella.

Fellowship Level

Where It Misleads

In referred practice this point is most often relevant in the knee that has had a tubercle osteotomy and still hurts.

A patient with localised tenderness over a screw has prominent hardware, and removing it is a small operation with a reliable result, which makes it worth finding. 4.3.7 covers scars.

A patient with diffuse tenderness around a healed osteotomy and no palpable device has a different problem, and the examination has already distinguished them.

A patient with a previous bone patellar tendon bone graft harvest has a donor site at exactly this point, and donor site pain is common, under recognised and not a reconstruction failure. 4.10.11 covers post-reconstruction assessment.

A patient with a non union of a tubercle osteotomy has tenderness with movement at the site, and that is a finding the examination can detect before the imaging is reviewed.

In medicolegal work an avulsion diagnosed late is an avoidable failure, and the missing element is usually the active extension test rather than the palpation. 4.23.7 covers that setting.