Use of MRI to diagnose a knee injury: Jack’s story

Kathy was standing on the side of the rugby field when she saw her football-mad, 16-year-old son, Jack, twist and fall awkwardly as he was tackled by two players hitting him from different directions. Straight away it was obvious that something was wrong, and he was soon stretchered off the field. The first-aid officer put an ice pack and bandage on Jack’s knee, which had already swollen up like a balloon.

Jack struggled out of the car with his mum's help and into the GP waiting room. After carefully examining Jack’s knee the doctor said, 'First up, we’ll definitely need to X-ray this. If it doesn't show a broken bone, I would like to see you in a few days. I need to look at it again once the swelling has gone down, to see if we need to do anything further.' Some crutches were organised and Kathy took Jack to the radiology practice. The X-rays didn't show anything broken, so on the doctor's advice over the next few days Jack applied ice packs, took regular paracetamol, kept his leg elevated when resting and used crutches for getting around.

A few days later, after re-examining the knee which remained swollen, the doctor said, 'The X-ray shows no obvious break but I don't like the look of that knee. I think we need to get an MRI of this — I’m suspicious he might have done something to his cruciate ligaments.' Turning to Jack, she continued, 'That’s not good Jack, it might put you off the field for the whole season, mate. Anyway, we’ll see what the scan shows and take it from there.'

'I thought they did CT scans of knees. Why are we doing a MRI?' Kathy asked.

'Well, CTs can be used, but generally MRIs have taken over as the preferred option in this situation now they’re becoming more available. They give excellent pictures of the ligaments and other tissues. And the other thing, MRIs have no radiation. This is especially important for children,' the doctor explained.

‘But don’t MRIs cost a lot?’ Kathy asked. ‘Could we wait and see if he really needs a scan?’

‘They’re not cheap, but there is now a Medicare rebate for this sort of situation in children under 16, which will help. The cost to you depends on whether the local radiology practice bulk bills for this — we can look into this. As for waiting — sometimes that is a sensible option. But in this case we need to know whether those ligaments are damaged so we can treat him properly. I’ll organise a referral form.’

Jack’s MRI confirmed he had torn his anterior cruciate ligament, and the crestfallen Jack went off to see an orthopaedic surgeon to discuss his options.