PVNS: experience and causes

I recently got diagnosed with the fairly rare condition called Pigmented villonodular synovitis (PVNS) a disorder which affects joints. In my case, it was my knee joint, as is often the case.

I'm posting this to help others better identify and understand this condition, and also to explore any possible causes.

PVNS is very easily misdiagnosed by GP's. It was misdiagnosed twice in my case, by two different doctors.

Because it's more common in the 30's and 40's age group, and the symptoms are similar to arthritis, it can be misdiagnosed as the early onset of arthritis of the knee/joint in people who are in the upper end of this age bracket.

In the case of the PVNS affecting the knee joint which results in a tumour growth at the back of the knee (as in my own situation), because the condition often arises after a trauma to the knee joint, the condition can be misdiagnosed as a simple lingering knee injury, leaking joint fluid, giving rise to a Bakers Cyst.

The symptoms of PVNS are both sporadic and very similar to both an ordinary knee injury and arthritis as the condition progresses. The joint becomes stiff and movement restricted. It's usually painless in the early stages but as it progresses it causes mild to moderate discomfort with a persistent burning pain around the joint area.

If left untreated, PVNS in its advanced stages, can render the joint completely unusable, requiring a complete joint replacement.

Here's my own experience of PVNS:

I was taking Tramadol (a painkiller) for back pain and was heavily into exercise and was also carrying a heavy bicycle every day up and down stairs. I injured my knee. This was due to the Tramadol I believe. My pain tolerance threshold was at a much higher level, so the injury didn't fully register and I continued exercising and carrying the bicycle, further straining the already injured knee.

Two years later, the knee joint gradually became stiffer and a lump appeared at the back of the knee. It became so stiff I could no longer crouch or bend down to tie my shoe laces. I went to the doctor and was misdiagnosed as mentioned. The second GP ruled out arthritis from an x-ray and to confirm his diagnosis of a leaking joint and Bakers Cyst, he requested an ultrasound scan of the joint. The scan showed an overgrowth on the lining of the knee joint and a tumour growth, resulting in a PVNS diagnosis by an orthopedic consultant.

A proof-positive diagnosis is carried out from sample by examining cells under the microscope from the joint which have the typical PVNS-like abnormal characteristic.

There's two forms of PVNS, localised and diffused. The localised version is what I have. It is a lot easier to treat using key-hole surgery with a better prognosis for recovery. Diffused PVNS affects the entire joint lining, requiring open surgery to remove all of the knee lining and it has a much higher risk (almost 50%) of returning, and requiring extensive physiotherapy.

PVNS is quite a rare condition as I mentioned. Therefore it's not encountered very much by GP's and there hasn't been much research done into the causes of the condition or why it returns in many sufferers. It's not thought to be hereditary, and as I mentioned, trauma to the affected joint is a common feature.

This leads me to wonder if certain medicines, or activities, may cause the condition. As I mentioned, in my own case I was taking Tramadol (at a normal dose of 50mg once daily) for several years, both prior to, and after my knee injury.

I'd be interested to hear from anyone else out there who suffers with PVNS and their backgrounds, in particular:

Anyone who has developed PVNS while being on Tramadol or similar drugs?

Anyone who has developed PVNS after a sports or work related injury, which they ignored?

How much time elapsed from any initial injury to PVNS symptoms and diagnosis?

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