Popliteofibular Ligament

For Medical Students

What It Shows

The popliteofibular ligament runs from the popliteus tendon to the fibular styloid. 2.10.3 covers the popliteofibular ligament.

It is small and is visualised inconsistently, even on a dedicated study. 5.5.9 covers the ligaments.

It matters because it is a principal restraint to external rotation, so it has more functional weight than visibility. 3.10.5 covers the popliteofibular ligament function.

How It Is Acquired

Use thin coronal and axial images through the fibular styloid. 5.5.2 covers the sports knee protocol.

Trace it from the popliteus tendon towards the styloid. 2.10.2 covers the popliteus tendon.

Accept that it may not be identifiable, and say so rather than omitting it. 5.20.1 covers structured reporting.

Assess the fibular styloid for avulsion, which reports the ligament indirectly. 2.3.2 covers the attachments.

Assess the rest of the corner, since this ligament rarely fails alone. 5.10.3 covers PLC injuries.

What Normal Looks Like

A short band between the popliteus tendon and the fibular styloid where it can be seen. 2.10.3 covers the popliteofibular ligament.

An intact fibular styloid with no marrow change. 5.13.1 covers bone marrow oedema.

An intact popliteus tendon, which the ligament depends on. 2.10.2 covers the popliteus tendon.

The rest of the corner intact. 2.10.4 covers the posterolateral corner.

What Abnormal Looks Like

Discontinuity where the ligament is visible. 2.10.3 covers the popliteofibular ligament.

Avulsion of the fibular styloid, which is the reliable indirect sign. 2.3.2 covers the attachments.

Marrow change at the styloid with no visible fragment. 5.13.1 covers bone marrow oedema.

Injury of the popliteus tendon, which the ligament arises from. 5.10.2 covers popliteus injuries.

Oedema around the styloid with the ligament not identifiable. 5.5.9 covers the ligaments.

MRCS Level

How It Is Acquired

In a viva the expected answer admits the ligament may not be seen.

The expected points are the thin images, the trace from the tendon, the admission of non visualisation, the styloid, and the rest of the corner.

Say that not visualised is a legitimate finding and that omission is not. 5.20.8 covers common reporting errors.

Say that the styloid is where this ligament is reported from. 2.3.2 covers the attachments.

Say that the dial test reports the function this ligament carries. 4.13.5 covers the dial test.

What Abnormal Looks Like

The reasoning expected is that the ligament connects a tendon to a bone rather than bone to bone, so its function depends on the popliteus being intact, and the two are assessed together. 3.10.5 covers the popliteofibular ligament function.

Its small size and oblique course mean a standard protocol may not resolve it, which is why the indirect sign carries the weight. 5.5.2 covers the sports knee protocol.

A styloid avulsion is specific, because the structures attaching there are this ligament and the capsule rather than the collateral ligament. 2.10.4 covers the posterolateral corner.

That makes the fibular head and styloid the most informative bone in the lateral knee. 2.3.3 covers the clinical importance.

How Good It Is

Magnetic resonance imaging identifies this ligament inconsistently and reports it reliably through the fibular styloid.

Its best contribution is the styloid avulsion and the state of the popliteus it arises from. 2.3.2 covers the attachments.

It is limited because the ligament itself is often not resolvable, so the report depends on an indirect sign. 5.5.9 covers the ligaments.

No figures appear for accuracy on this page, under decision 028, and no visualisation rates or dimensions appear either: those are published quantities from particular series and this environment cannot check them.

FRCS Level

How Good It Is

At decision level a styloid avulsion is treated as a corner injury. 5.10.3 covers PLC injuries.

Non visualisation of this ligament does not downgrade the injury. 5.20.8 covers common reporting errors.

The dial test and the recurvatum test carry the functional question. 4.13.7 covers the external rotation recurvatum test.

A reconstruction of the corner addresses this ligament's function whether or not the ligament was seen. 3.10.8 covers the PLC reconstruction biomechanics.

A combined posterior cruciate injury changes the operation. 3.10.9 covers the combined PCL and PLC injury.

Where It Misleads

The commonest error is omitting the ligament rather than reporting it as not visualised. 5.20.1 covers structured reporting.

Non visualisation is read as absence. 5.5.9 covers the ligaments.

A styloid avulsion is reported as an avulsion of the collateral ligament. 2.10.1 covers the LCL.

Styloid marrow change with no fragment is overlooked. 5.13.1 covers bone marrow oedema.

The popliteus is reported separately, as though the two were unrelated. 5.10.2 covers popliteus injuries.

Fellowship Level

Where It Misleads

At fellowship level this ligament is the one most often absent from the report and most often relevant to the operation. 3.10.5 covers the popliteofibular ligament function.

A knee with external rotation laxity and a structurally normal looking lateral side is the common presentation. 4.13.5 covers the dial test.

The original study is worth re-reading for the styloid rather than re-scanning for the ligament. 2.3.2 covers the attachments.

After a corner reconstruction this ligament's function is carried by a graft that does not reproduce it, so the post-operative appearance is of a different structure. 5.10.6 covers the post-operative PLC imaging.

Cadaveric work defines this ligament's role better than any imaging series does, which is unusual and worth saying. 3.10.6 covers the posterolateral corner function.

The useful report states whether the ligament was visualised, the styloid, the popliteus and the rest of the corner. 5.20.1 covers structured reporting.