One brief window to prevent a lifetime of back pain
A few weeks ago, I had a bit of a rant on my facebook page about over-reliance on radiological images. Although there are certainly conditions that are over-scanned, the rant was more about inappropriate ordering and interpretation of scans. Importantly though, there are also times when scans are under-utilised.
Spinal (pars interarticularis - PI) stress fractures in adolescents is one such condition.
Clinicians have all seen the studies that show spinal MRIs can be both unhelpful and counterproductive as there can be poor correlation between reported abnormalities and symptoms. This is very true in non-radiculopathic chronic back pain in adults but it is not at all the case in acute adolescent back pain.
We should consider the following to be a spinal stress fracture until proven otherwise
Active adolescent with lower back pain that is at its worst during activity (particularly on each impact with running foot-strike and jumping)
Other factors that increase suspicion are:
- Unilateral well localized pain
- Undergoing a period of rapid growth
- Tall stature
- High risk sports: cricket fast bowler, jumping sports (basketball, volleyball), running ball sports, athletics, gymnastics, rowing
- Worse with arching backwards. Or with combined arching and rotating.
- Worse with arching backwards. Or with combined arching and rotating.
Why Scan?
This is a serious condition that is commonly missed and missing it can lead to life-long implications. The pars interarticularis is not very good at healing. Persistent lifelong instability in this area can lead to a number of degenerative and irreversible conditions involving the surrounding joints, discs and nerves. Early diagnosis can make a massive difference.
What type of scan?
X-rays are unhelpful. If a PI fracture is seen, there is no way of knowing if it is congenital, old or a new injury. If it is not seen, it isn’t useful in ruling anything out.
Ultrasounds are unhelpful.
CT scans are unhelpful as a first investigation as, although a CT is fantastic at looking at bone in high resolution (better even than MRI), it can’t tell us if there is bone stress and weakening before it leads to a crack in the bone.
MRIs and Bone scans are the only investigations that will show bones that are under stress. Although Bone Scans are slightly more sensitive in picking up even the lowest grade bone stress, MRI is usually the preferred initial option. This is because it is still highly sensitive and, unlike bone scans, there is no ionizing radiation involved which is an important consideration in young people.
Take home message
In my clinic, any active adolescent with unilateral back pain that hurts primarily while running, arching or jumping is a stress fracture until proven otherwise and is sent for an MRI as a first line investigation.
