An arteriovenous malformation (AVM) of the leg is an uncommon but important cause of leg pain and swelling. Because they can resemble an ordinary sports injury, these lesions sometimes present first to a musculoskeletal or sports medicine practitioner. So what is an AVM of the leg, how does it present, and how is it managed?

What is an arteriovenous malformation?

Normally, blood flows from an artery through a network of tiny capillaries into a vein. Those capillaries slow the flow and lower the pressure. An arteriovenous malformation is an abnormal, direct connection between an artery and a vein, without the capillaries in between — so high-pressure arterial blood flows straight into the veins.

Veins aren’t built to handle that pressure, so over time the vessels enlarge and weaken. AVMs are usually present from birth (congenital), though they may only become obvious later in life, sometimes after a growth spurt, injury, or hormonal change.

How does an AVM of the leg present?

An AVM can mimic a musculoskeletal problem, which is exactly why it matters. Features can include:

  • Leg pain and swelling
  • A warm area, sometimes with a visible or pulsating lump
  • A reddish or bluish skin discolouration over the area
  • A “buzzing” sensation (a thrill) or a sound (a bruit) the doctor can feel or hear over the lesion
  • Symptoms that don’t behave like a typical muscle or tendon injury, or that fail to settle as expected.

In more significant cases, the high flow can cause skin changes, poor healing, or — rarely, with a very large AVM — strain on the heart.

Why an AVM must not be mistaken for a sports injury

This is the important part. An AVM is a vascular lesion, not a muscle, tendon, or joint problem — and it is emphatically not something to inject or treat as a routine sports injury. Two things follow:

  • The pattern often doesn’t fit a straightforward musculoskeletal diagnosis — persistent, unexplained leg pain and swelling, a pulsatile lump, skin discolouration, or a bruit are all clues.
  • Because an AVM is high-flow and the vessels are fragile, it carries a risk of bleeding, so it needs proper vascular assessment rather than a needle or injection into the area.

Recognising the possibility and arranging the appropriate imaging and referral is the key role of the sports medicine doctor here.

How is an AVM of the leg diagnosed?

Imaging makes the diagnosis and maps the lesion:

  • Doppler ultrasound — often the first test, showing the abnormal high-flow blood movement
  • MRI and MR angiography — to define the size, depth, and extent of the AVM and its feeding vessels
  • CT angiography or catheter angiography — for detailed mapping, usually as part of planning treatment

How is an AVM of the leg treated?

A vascular team typically manages an AVM —vascular surgeons and interventional radiologists—not musculoskeletal injections. Options depend on the size, location, and symptoms:

  • Monitoring — small, symptom-free AVMs may be watched
  • Embolisation — the main treatment: an interventional radiologist blocks off the abnormal vessels from the inside, using a catheter
  • Surgery — sometimes combined with embolisation, to remove the malformation
  • Compression and supportive care — to help with swelling and symptoms

The role of the sports medicine doctor is to recognise the possibility of an AVM, arrange initial imaging, and promptly refer to the vascular team.

Frequently asked questions about an AVM of the leg

Can an AVM be mistaken for a sports injury?

Yes — that’s one of the main reasons it matters. An AVM of the leg can cause pain and swelling that look like a muscle or tendon problem, so it sometimes presents to a sports practitioner first. Clues that it’s something different include a pulsatile lump, skin discolouration, a warm area, a buzzing sensation, or pain that doesn’t fit a typical injury.

Is an AVM in the leg dangerous?

Most are manageable, but they’re not something to ignore. Because the vessels are fragile and high-flow, there’s a risk of bleeding, and large AVMs can cause skin problems, poor healing, or — rarely — strain on the heart. This is why proper vascular assessment and treatment matter, rather than treating the area as a routine sports injury.

Can you inject or massage an AVM?

No — an AVM should not be injected, and treating the area as an ordinary sports injury isn’t appropriate. It’s a high-flow vascular lesion with a bleeding risk, and it needs assessment and treatment by a vascular team. This is exactly why recognising it is so important.

How is an AVM treated?

Usually by embolisation — an interventional radiologist blocks the abnormal vessels from the inside using a catheter — sometimes combined with surgery. Small, symptom-free AVMs may just be monitored. A vascular surgeon and interventional radiologist direct treatment

Final word from Sport Doctor London about an AVM of the leg

An arteriovenous malformation of the leg is a rare vascular cause of leg pain and swelling that can masquerade as a sports injury. The key is to recognise it — a pulsatile lump, skin discolouration, warmth, or a buzzing sensation over persistent, unexplained leg symptoms — arrange the right imaging, and refer to a vascular team. It’s a lesion to recognise and refer, not to inject.

If you have persistent, unexplained leg pain or swelling, Dr Masci can assess you in London, arrange the right imaging, and refer you on where needed. Contact the team here or call +44 (0) 203 488 0350.

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