Case 4. Medial femoral condyle lesions

Two patients with similar findings.

Case first posted Fri, Nov 15, 2002; by John Hunter

From Eva Escobedo:

Two cases of pathology high and posterior on the medial femoral condyle: we have assumed that this was an area with minimal weight bearing because of location. Yet these cases and another like them recently seem to suggest otherwise. Any thoughts on mechanisms? Any similar cases?

Patient 1:

History: Left knee pain in a 54 y/o obese female. In May when she was moving furniture, she developed some left knee pain. Since that time, it has been swollen.The pain is on the medial aspect and it is worse when she is going up and down stairs. It can pretty much hurt at any time. No improvement with rest.

Sag T2W FSE fat satSag PD

Sagittal T2W FSE fat sat and PD images

Ax T2W FSE fat satAx GRE

Axial T2W FSE fat sat and GRE images

Other than mild OA changes, no other findings noted on MR or plain films.

Patient 2:

21 y/o male with fall on hyperflexed knee and medial joint line tenderness. The mechanism is more apparent in this case.

Sag T2W FSE fat sat 2Cor T2W FSE fat sat

Sagittal and coronal T2W FSE fat sat images

Ax T2W FSE fat sat

Axial T2W FSE fat sat image

Medial femoral condyle contusion was only MR finding.

These lesions are in different areas of the medial femoral condyle posteriorly, but appear to indicate that this is an area under potential stress. In patient 1, the pathology seems to be OA, in patient 2, direct trauma.

Comments (5)

Michael Tuite, M.D. Mar 14, 2007 09:05 PM

I’ve seen that before. I wonder if the subchondral bone plate has relatively weak underlying trabecula, which would explain pt. 2. For pt 1, if there’s been no prior chondral injury there, I don’t know what’s unique about that area to cause the focal OA.

Andy Sonin Mar 14, 2007 09:07 PM

I see this all the time, and frankly, I’ve never generated a really intelligent explanation for it. The arthroscopist can’t see it because it’s too posterior.

It probably has to do with transferred shear stress, or perhaps trauma to the extreme posterior aspect of the condyles when in flexion. I probably see 2-3 cases/day of this. The more you look, the more you see.

Tom Martin, M.D. Mar 14, 2007 09:08 PM

I too see this all the time. It is my understanding that the stresses placed across the posterior femoral condyles are much greater with the knee in flexion then in the standard extended position in which we image patients. I’ve always wondered if this finding was more common in people who either had occupations with a lot of knee flexion (eg a plumber) or in certain sports (eg skiing) – I think there is a paper in the offing.

Chris Beaulieu, M.D. Mar 14, 2007 10:33 PM

I’ve always assumed that these areas are loaded with things like stairclimbing, so chalk it up to DJD. On the lateral side one sometimes sees fabello-femoral DJD manifest as such. It would seem unusual to have such a small, and deep, contusion in this location, so I’d be wondering about “edema suggesting invisible overlying cartilage degeneration”.

cb

Kirk Davis, M.D. Mar 14, 2007 10:34 PM

The Rosenberg radiographic position was developed because of the concept that cartilage wear and degeneration in “osteoarthrosis” (as some surgeons say) most commonly develops first in the 30-60 degree range, assuming the inferior tip of the femoral condyles is 0 and the back margin is 90. Thus, placing the knee in 45 degrees of flexion is more likely to show earlier joint space loss than the fully extended position. If that’s true, it’s not a stretch to expect degenerative changes at the most posterior aspect of the femoral articular surface in a few patients, especially with some activities as some of the commentors have mentioned.

Besides, we were given articular cartilage there, so why shouldn’t we be able to break it down?

I have a beautiful case to contribute if someone writes this up, with extensive subchondral change medially at “90 degrees” and a focal subchondral cyst/geode in the same spot on the LFC.