Fibular Head Tenderness

For Medical Students

What It Tests

The fibular head is the attachment of the lateral collateral ligament, the biceps femoris and part of the posterolateral corner, and the common peroneal nerve wraps around its neck just below it. 2.10.6 covers the nerve.

Tenderness there indicates an injury to one of those attachments or a fracture, and in either case the nerve has to be examined.

It is one of the few palpation findings in the knee that changes the order of the examination, because the nerve examination becomes urgent. 4.11.7 covers that sequence.

How It Is Performed

Find the fibular head on the lateral side of the knee, below the joint line, as a palpable prominence.

Palpate it directly and note tenderness, and palpate the lateral collateral ligament's attachment to it in the figure of four position. 4.13.2 covers that palpation.

Palpate the biceps femoris tendon as it inserts, and follow the iliotibial band separately, since the two are adjacent and distinct. 3.11.1 covers the band.

Examine the common peroneal nerve: ankle dorsiflexion, great toe extension and sensation over the dorsum of the foot.

Test for a Tinel sign over the nerve at the fibular neck, which can be positive in a nerve injury or in a compressive lesion.

What a Positive Means

Tenderness at the fibular head in an injured knee indicates an avulsion of the lateral collateral ligament, a biceps avulsion, a fracture, or a posterolateral corner injury. 4.13.4 covers the corner.

Tenderness with a bony fragment on the radiograph indicates an avulsion fracture, which changes the operation to a repair. 4.13.2 covers the ligament.

Tenderness with any nerve deficit indicates a corner injury with a nerve injury, which is a serious combination and a recognised one. 4.11.7 covers the sequence.

Tenderness with no injury history raises a lesion at the nerve, a proximal tibiofibular joint problem, or a cyst, which is a different differential. 4.6.10 covers the popliteal fossa.

A positive Tinel sign with sensory symptoms in the foot points at the nerve rather than at the bone or the ligaments. 2.10.6 covers it.

MRCS Level

How It Is Performed

In a viva the nerve is the answer, and a candidate who palpates the fibular head and does not examine the nerve has missed the point of the station.

The expected points are the position, the palpation of each attachment, the figure of four for the ligament, the nerve examination, and the Tinel sign.

Say the nerve examination without being prompted, and name what you would test.

Say that you would request a radiograph for a tender fibular head after an injury, because an avulsion fracture changes the operation. 4.1.6 covers that relationship.

Say that you would perform the corner assessment in full, since fibular head tenderness is a corner finding and the dial test is what grades it. 4.13.5 covers the dial test.

What a Positive Means

The reasoning expected is that several lateral structures converge on a small bony prominence, so a single tender point indicates injury to a complex rather than to one structure. 3.10.6 covers the corner.

The nerve's course around the fibular neck is fixed and superficial, which is why it is injured with corner injuries and why it is vulnerable in surgery there. 2.10.6 covers the nerve.

An avulsion from the bone heals differently from a mid substance tear, because the repair is bone to bone, which is why identifying it changes the operation. 4.13.2 covers the ligament.

Tenderness with no trauma raises the proximal tibiofibular joint and a ganglion arising from it, which can compress the nerve and present as a knee complaint. 4.6.10 covers the posterior examination.

How Good It Is

Palpation here is precise and the finding is specific for a lateral or corner problem, because few other things are tender at exactly that point.

Its value lies less in diagnosis than in prompting the nerve examination and the radiograph, both of which it reliably does.

It is insensitive for a corner injury, since most corner injuries are not tender at the fibular head, so the finding's absence excludes nothing. 4.13.4 covers the assessment that does not miss them.

It cannot distinguish an avulsion from a sprain, which the radiograph and the stress test do. 4.13.1 covers varus stress testing.

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 this finding contributes to the lateral operation and to the consent conversation.

An avulsion fracture identified here is repaired rather than reconstructed, and that is a better operation with a better result, so finding it matters. 4.13.2 covers the ligament.

A nerve deficit identified here changes what any reconstruction can achieve and belongs in the consent before the operation rather than in a discussion afterwards. 4.13.4 covers the corner.

A tender fibular head in a knee without an obvious injury raises a proximal tibiofibular problem or a ganglion, both of which are treatable and neither of which is an intra-articular diagnosis. 4.6.10 covers the posterior fossa.

In surgery on the lateral side the nerve's relationship to this point is the anatomical fact that governs the approach, which is why the examination and the operation share the landmark. 2.10.7 covers surgical anatomy.

Where It Misleads

The commonest error is palpating the fibular head and not examining the nerve.

The second is not obtaining a radiograph in an injured knee with tenderness here.

The third is reading a non tender fibular head as excluding a corner injury.

The fourth is attributing tenderness to the iliotibial band when the biceps is the tender structure, since the two are adjacent.

The fifth is attributing a foot drop to the knee injury without examining for a compressive lesion, since a ganglion at this point produces the same deficit.

Fellowship Level

Where It Misleads

In referred practice this point is most often relevant in a knee that has had lateral surgery and has either pain or a nerve deficit.

A patient with persisting tenderness over a fixation device at the fibular head after a corner reconstruction has prominent hardware, which is simple to address once it is localised. 4.3.7 covers surgical scars.

A patient with a partial nerve deficit after corner surgery has either an intraoperative injury or a compressive problem, and the examination plus the operation note separates them. 4.13.4 covers the corner.

A patient with a foot drop and no injury has a compressive lesion until proven otherwise, and a ganglion of the proximal tibiofibular joint is the one that presents as a knee problem. 4.6.10 covers the posterior examination.

A patient with a previous proximal fibular resection or osteotomy has altered lateral anatomy, and the attachments the examination expects may not be where they are palpated for. 4.2.30 covers previous surgery.

In medicolegal work an undocumented nerve examination in a knee with lateral injury is one of the most serious gaps in a record, and this page is where that examination is prompted. 4.23.7 covers that setting.