Sensible advice for aches, pains & injuries
A bone scan of patellefemoral pain, showing the faint grainy shapes of thigh and shin bones, even fainter outlines of soft tissue, and very dark kneecaps standing out boldly.

Bone scan of “hot” (metabolically active) kneecaps.

Patellofemoral Pain Diagnosis with Bone Scan

If you have anterior knee pain, should you bother x-ray, MRI, CT scan, or bone scan?

by Paul Ingraham, Vancouver, Canadabio
I am a science writer and a former Registered Massage Therapist with a decade of experience treating tough pain cases. I was the Assistant Editor of for several years. I’ve written hundreds of articles and several books, and I’m known for readable but heavily referenced analysis, with a touch of sass. I am a runner and ultimate player. • more about memore about

“Curiously, neither the widespread use of arthroscopy nor the advent of new diagnostic tests such as CT scanning and magnetic resonance imaging have cast much light on the enigma of patellofemoral pain,”1 and MRI in particular is not of much use diagnostically except to eliminate some diagnoses that can usually be made pretty easily without MRI.2

X-rays and bone scans, however, are a different matter — they are worthwhile, and potentially quite interesting. It’s been suggested since Dye et al in 1986 that increased metabolic activity can be imaged using bone scans.3 An initial study confirmed that this was true for PFPS Hejgaard et al.4 Any patient with stubborn, severe and/or atypical patellofemoral pain syndrome should consider pursuing these diagnostic options. There are significant diagnoses that simply cannot be made without them.

In more recent science, that was the main finding of Näslund et al’s 2006 study of diagnosing PFPS. In 75 patients that were clinically indistinguishable from each, they found 17 cases of disease — quite a lot.5 Quite a few more (29) had “hot,” metabolically active kneecaps,6 where bone is busily remodelling. In a similar study the year before, the same researchers found 48 hot knees out of 109 cases.7

All patients and 48 healthy subjects without any knee pain were then interviewed and examined by a surgeon and a physical therapist. They could not diagnose the pathologies without the scans! All patients with pain tested roughly the same, and their symptoms were indistinguishable.

In 2003, Lorberboym et al investigated the PFPS-detection power of a SPECT scintigram — a bone scan with a better camera, basically.8 They compared SPECT bone scanning to arthroscopy — literally looking at the inside of the knee with surgery — and it performed very well, with some caveats.9

All of this gives good support to Dr. Dye’s theory of metabolic distress.

X-rays are commonplace, but bone scans are a bit of a big deal, expensive and not always easy to get, especially SPECT. Your physician or surgeon may be puzzled by a request for a bone scan. In this case, you should respectfully refer them to a scientific paper: perhaps Dr. Dye’s 2005 paper about patellofemoral pain syndrome, or perhaps Näslund et al’s paper, which has a well-written overview.

The case for getting a bone scan: Any condition which results in a change in the metabolism of the bone will result in a change in the appearance of the bone scan. Lesions like fractures, infections, tumors, and arthritis can be recognized on a bone scan long before they can be seen with plain radiographs. More importantly, the technique has been proven to be useful in confirming a diagnosis of patellofemoral pain syndrome, and in helping to isolate the distressed tissues — exactly which bone is stressed.

If a bone scan clears you of disease, and shows that you’ve got a hot kneecap, then you have a much clearer idea of what you’re dealing with.

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About Paul Ingraham

Headshot of Paul Ingraham, short hair, neat beard, suit jacket.

I am a science writer, former massage therapist, and I was the assistant editor at for several years. I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook or Twitter.

Related Reading

This article is a free chapter from’s huge patellofemoral pain syndrome (PFPS) tutorial, one of 96 chapters in all. There are also several other articles on about patellofemoral pain and related topics:


  1. Insall JN. The patella. Springer Verlag; 1995. BACK TO TEXT
  2. Quibble: MRI can be helpful in confirming tendinosis. However, it’s fairly rare for tendinosis to be confused with PFPS in the first place. BACK TO TEXT
  3. Dye SF, Boll DA. Radionuclide imaging of the patellofemoral joint in young adults with anterior knee pain. Orthop Clin North Am. 1986;17(2):249–262. BACK TO TEXT
  4. Hejgaard N, Diemer H. Bone scan in the patellofemoral pain syndrome. Int Orthop. 1987;11(1):29–33. PubMed #3557753. BACK TO TEXT
  5. They didn’t say which diseases. 15 cases of pathology were identified by X-ray, and many or all of these were probably minor, and simply results a new and more specific diagnosis than PFPS. 2 cases were identified by bone scan …which can identify tumors. BACK TO TEXT
  6. What exactly does that mean? It means that the bone is busily adapting to stress, making and/or breaking down bone tissue. Näslund et al: “Bone metabolism and bone remodelling can be evaluated by specific bone seeking radionuclides in a scintigraphic measurement. A positive bone scintigraphy indicates an increase in bone metabolism, but the method cannot determine whether the final result will be a net loss or a net gain in bone. A pathophysiologically increased bone scintigraphy indicates an aetiological relationship between the area with increased bone metabolism and the patient’s symptoms.” BACK TO TEXT
  7. Näslund JE, Odenbring S, Naslund UB, Lundeberg T. Diffusely increased bone scintigraphic uptake in patellofemoral pain syndrome. Br J Sports Med. 2005;39:162–165. PubMed #15728696. PainSci #56679. BACK TO TEXT
  8. Lorberboym M, Ami DB, Zin D, Nikolov G, Adar E. Incremental diagnostic value of 99mTc methylene diphosphonate bone SPECT in patients with patellofemoral pain disorders. Nucl Med Commun. 2003 Apr;24(4):403–10. PubMed #12673169. BACK TO TEXT
  9. SPECT was super sensitive — 100%, actually — in detecting patellofemoral abnormalities! Alas, it was only 64% specific, meaning it didn't just detect PFPS, but other conditions like patellar arthritis. Hopefully the future will bring techniques with more specificity for PFPS specifically. BACK TO TEXT