Dynamic Tracking

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For Medical Students

What It Tests

Dynamic tracking is the patella's behaviour during a loaded movement, which is when the quadriceps is working and the limb is controlling itself.

It differs from the sitting tracking assessment because that is active and unloaded, and loading changes both the quadriceps' pull and the limb's alignment. 4.15.1 covers the unloaded version.

The assessment matters because the patient's symptoms occur under load, on stairs and in descent, and a patella that tracks acceptably sitting can track badly in a squat. 4.2.11 covers aggravating factors.

How It Is Performed

Watch the patient perform a double leg squat, from the front, at knee level.

Watch a single leg squat on each side, noting whether the knee falls medially as it loads. 4.4.9 covers single leg landing.

Watch a step down, which is the task most patients name as the one that hurts. 4.7.9 covers functional range.

Watch the patella itself as well as the knee, noting whether it moves laterally as the knee flexes under load.

Note the trunk and the pelvis, since proximal control determines the limb's alignment and therefore the patella's path. 4.4.5 covers that pattern.

What a Positive Means

A knee that falls medially under single leg load has dynamic valgus, which increases the lateral vector on the patella without any abnormality at the patella itself. 3.12.7 covers it.

A patella that deviates laterally under load and not when sitting has a dynamic tracking problem, and the proximal control is usually the treatable part. 4.4.10 covers functional screening.

Pain reproduced during the loaded task, in the arc the patient describes, is the most useful finding on this page. 4.7.6 covers the painful arc.

An inability to perform the task is a finding and should be recorded as the task attempted and not completed. 4.4.9 covers that argument.

A normal dynamic assessment in a patient with a clear complaint means the task is below the demand that fails, and the assessment has to be raised. 4.4.8 covers running gait.

Key Learning Points

Loading changes both the quadriceps' pull and the limb's alignment.
A patella can track acceptably sitting and badly in a squat.
A knee falling medially under load increases the lateral vector on the patella.
Pain reproduced in the arc the patient describes is the most useful finding.
A normal assessment with a clear complaint means the task is too easy.

MRCS Level

How It Is Performed

In a viva this is the answer to how you would assess patellofemoral pain functionally, and the single leg tasks are the mark.

The expected points are the double leg squat, the single leg squat, the step down, watching the patella as well as the knee, and the trunk and pelvis.

Say that you would watch the proximal segments, since dynamic valgus originates above the knee and is the treatable contributor. 4.4.5 covers it.

Say that you would ask the patient which task hurts and watch that one, which is more useful than a standard set.

Say that the loaded assessment correlates with the complaint better than the static patellar tests, which is the argument for performing it. 4.15.4 covers the static tests.

What a Positive Means

The reasoning expected is that the patella's path depends on the vector between the quadriceps and the patellar tendon, and that vector depends on the femur's rotation and the knee's alignment under load. 3.12.6 covers the Q angle.

Hip abductor and external rotator weakness allows the femur to adduct and internally rotate, which increases that vector dynamically. 3.12.7 covers dynamic valgus.

Patellofemoral contact pressure rises steeply with flexion under load, which is why a squat and a step down reproduce symptoms that walking does not. 3.12.3 covers contact pressures.

The proximal contribution is modifiable, which is why identifying it changes the treatment from a patellar problem to a control problem. 4.4.10 covers screening.

How Good It Is

Dynamic assessment correlates with the patient's complaint better than any static patellofemoral test and is less reproducible between examiners.

It identifies the proximal contribution reliably, which is its most valuable output because that contribution is treatable.

It is unsafe or impossible in an acutely painful knee, where the static assessment carries what it can.

Instrumented and video analysis measure what the eye estimates, and video on a phone is a practical improvement for little effort. 4.4.8 covers that argument.

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

Key Learning Points

The patella's path depends on a vector that depends on the femur's rotation under load.
Hip abductor and external rotator weakness increases that vector dynamically.
Patellofemoral contact pressure rises steeply with flexion under load.
The proximal contribution is modifiable, which is why identifying it changes the treatment.
It correlates better with the complaint and is less reproducible than the static tests.

FRCS Level

How Good It Is

At decision level the dynamic assessment decides whether a patellofemoral complaint is treated with rehabilitation or with an operation, and rehabilitation is the right answer far more often.

A patient with dynamic valgus, anterior pain and no instability has a control problem, and a programme addressing the hip and the landing mechanics is the treatment. 4.4.10 covers screening.

A patient with a structural maltracking visible both sitting and loaded, with instability episodes, is the surgical group, and the imaging decides which operation. 4.15.8 covers dysplasia.

A patient whose loaded assessment is normal and whose complaint is severe needs the task raised rather than an operation offered. 4.4.8 covers running gait.

After surgery the loaded assessment is the one that corresponds to the patient's experience, and following it is more useful than repeating the glide. 4.20.6 covers that assessment.

Where It Misleads

The commonest error is not performing it, which leaves a control problem undiagnosed.

The second is watching the knee and not the patella, or the reverse.

The third is attributing dynamic valgus to the patella.

The fourth is performing it in a knee too painful to load.

The fifth is treating a normal assessment as reassurance in a patient whose demand is higher than the task.

Key Learning Points

The assessment decides between rehabilitation and an operation, and rehabilitation wins more often.
Dynamic valgus with pain and no instability is a control problem.
Structural maltracking with instability episodes is the surgical group.
A normal loaded assessment with a severe complaint means raising the task.
After surgery it corresponds to the patient's experience better than the glide.

Fellowship Level

Where It Misleads

In referred practice the dynamic assessment is the step that explains the patellofemoral patient who has had everything else done.

A patient with normal imaging, a normal static examination and anterior pain on loading has a control or load problem, and the assessment is where it appears rather than on a further scan. 4.1.6 covers that relationship.

A patient with several previous patellofemoral procedures and persisting dynamic valgus has had the distal problem treated repeatedly and the proximal one never. 4.4.5 covers the pattern.

An athlete whose clinic tasks are normal and who fails in sport needs the assessment at the sport's intensity, which the clinic cannot supply. 4.23.2 covers those patients.

A patient with a tubercle osteotomy and persisting loaded maltracking may have a correction that was adequate statically and inadequate under load, which is an argument for assessing both. 4.6.7 covers the tubercle.

In medicolegal work a recorded loaded assessment is unusual and valuable, because it is the observation closest to the claimed functional limitation. 4.23.7 covers that setting.

Key Learning Points

It explains the patellofemoral patient who has had everything else done.
Normal imaging and a normal static examination with loaded pain is a control or load problem.
Several procedures with persisting dynamic valgus means the proximal problem was never treated.
An athlete needs the assessment at the sport's intensity.
A correction adequate statically can be inadequate under load.

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.