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# Tibiofibular joint capsule

The tibiofibular joint capsule encloses the small joint between the tops of the [tibia](https://durgical.com/en/anatomy/tibia/) and [fibula](https://durgical.com/en/anatomy/fibula/), just below the outer knee.

Official name: Capsule of superior tibiofibular joint

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## What it is

The capsule of the small joint between the top of the tibia and fibula.

## What it does

Holds that joint together.

## Key points

- The common fibular nerve winds round the fibular neck just below the joint: at risk in dislocation and surgery, and ganglion cysts from the joint can track into it
- Its cavity communicates with the knee joint through the [popliteus](https://durgical.com/en/anatomy/popliteus-muscle/) recess in a minority of adults (often quoted around 10%)
- Dislocation is rare and easily missed; the anterolateral type is the most common, from a twisting fall on a bent knee

## Key facts

**Where**
Proximal tibiofibular joint: plane synovial joint between fibular head and lateral tibial condyle

**Attaches**
Margins of articular facets of fibular head and lateral tibial condyle

**Function**
Encloses the joint; reinforced by ligaments of fibular head; sometimes communicates with knee joint

## Relations

**In front**
Anterior ligament of the fibular head (the stronger of the two), reinforced by expansions of the [biceps femoris tendon](https://durgical.com/en/anatomy/tendon-of-biceps-femoris/)

**Behind**
Posterior ligament of the fibular head, crossed by the [popliteus tendon](https://durgical.com/en/anatomy/tendon-of-popliteus/) on its way to the knee

**Above**
Lateral collateral ligament and biceps femoris inserting on the fibular head; the knee joint just above

**Below**
Fibular neck, where the [common fibular nerve](https://durgical.com/en/anatomy/common-fibular-nerve/) divides into the superficial and deep fibular nerves

## How to find it

The fibular head is felt at the posterolateral knee, just below the level of the lateral joint line, at the end of the biceps femoris tendon. The joint lies in front of and medial to it, against the lateral tibial condyle. With the knee bent to 90° the fibular head can be gripped and glided forward and back.

## Examination

- Fibular head glide: with the knee bent to 90°, the head is moved forward and back; more movement or pain than on the other side suggests instability or dislocation

## On imaging

AP and lateral knee radiographs show the fibular head overlapping the tibia; comparison with the other knee helps detect subtle dislocation, and CT confirms it. A small avulsion from the fibular head (arcuate sign) marks a posterolateral corner injury. MRI shows ganglion cysts and their tract along the articular branch to the nerve.

## Clinical notes

- Intraneural ganglion: joint fluid tracks up the articular branch into the common fibular nerve, causing foot drop
- A missed dislocation causes lateral knee pain, clicking and instability, sometimes with fibular nerve symptoms
- Posterolateral corner reconstruction, high tibial osteotomy and fibular head fixation work beside this joint and the nerve

## Anatomical variants

- The joint surface may be near-horizontal or steeply oblique; the oblique type moves less and is said to be more prone to instability (texts differ on the cut-off angle)

## Test yourself

Think of the answer, then tap the question to see it.

## Which nerve is at risk next to the proximal tibiofibular joint?

The common fibular nerve, which winds round the fibular neck just below the joint; it is at risk in dislocation and surgery.

## How can a ganglion from the proximal tibiofibular joint cause foot drop?

Joint fluid tracks up the articular branch into the common fibular nerve, forming an intraneural ganglion.

## What is the most common type of proximal tibiofibular dislocation, and how does it occur?

Anterolateral dislocation, from a twisting fall on a bent knee; it is rare and easily missed.

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Educational information, not medical advice. For any symptom, see a health professional.

## Its names

**Official Latin (TA2)**
articulatio tibiofibularis TA2 1909

**Official Spanish (DeCS)**
Cápsula de la articulación tibiofibular superior

**English (TA2)**
Capsule of superior tibiofibular joint

**Also called**
articulus tibiofibularis

## Related

- [Fibula](https://durgical.com/en/anatomy/fibula/)
- [Tibia](https://durgical.com/en/anatomy/tibia/)

Sources: Terminologia Anatomica (TA2); [Anatomy, Bony Pelvis and Lower Limb: Fibula](https://www.ncbi.nlm.nih.gov/books/NBK470591/).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/anatomy/capsule-of-superior-tibiofibular-joint/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/capsule-of-superior-tibiofibular-joint/