Lead Article – June 2021
What Would We Do Without MRI Scans?
We may well be better off!
I say that with only partial flippancy. MRI scan examinations obviously do add considerably to the ancillary investigative regimen that can assist with the diagnostic process.
Conversely, MRI scan examinations can “over-diagnose”.
For example, consider somebody falling onto the anterior aspect of a flexed knee joint. Local bruising to the skin will be noticed, sometimes there may even be a post-traumatic bursitis involving the small fluid sac in front of the knee cap, and of course there can also be some damage to the patellofemoral joint itself. Patellar fractures can similarly be a sequel.
In the absence of a fracture, a plane radiograph will show little or nothing. The bruising will be visible to the naked eye, but that should subside over a week or two. The changes to the chondral or cartilage surfaces of the patella and the neighbouring trochlear groove surface of the femur are invisible on plane radiographs and would only be apparent on an MRI scan. Even then, it may be some considerable time before the MRI scan examination shows any chondral loss.
In the days before MRI scans, we would simply say that the patellofemoral joint had been “bruised”. A post-traumatic chondromalacia patellae syndrome may ensue and the AMA 5 Guides (Table 17-31) would allow an examiner to quantify a loss of 2% of whole person function referable to that joint.
MRI scan examinations can demonstrate bone oedema and even undisplaced trabecular fractures within the osseous structures. The word “fracture” usually excites both patients and lawyers alike. Both groups attach great significance to this word. In reality, these microtrabecular fractures are of little or no significance. Like the skin bruising, they usually heal without ongoing sequelae.
In summary therefore, whilst MRI scan examinations can be very useful, they can give rise to unnecessary focus upon changes within the bone which are really of little or no significance.
The answer? Exercise caution with interpretation and rely upon your expert.