STRESS FRACTURES OF THE LOWER BACK: a common cause of back pain in young athletes
Updated: Jan 18, 2021
Teenage and young athletes have a surprisingly high rate of lower back stress fractures. Some sports have very high incidences of stress fractures, with around 50% of low back pain in adolescent athletes being due to a stress fracture. In Australia, cricket fast bowlers are well known for this type of injury, but any sport which involves extension and rotation of the spine can cause stress fractures as these movements place the bones of the spinal column under repetitive loads. Athletes in team sports such as soccer and basketball, and individual sports like gymnastics and athletics are at risk. The adolescent spine appears especially vulnerable to repetitive loading since it is not yet fully developed to withstand high loads. The medical term given to lower back stress fractures is a “pars fracture” or “spondylolysis”. The image below shows the most common area for stress fractures known as the “pars interarticularis”. Stress fractures also occur in other nearby areas due to the same mechanism of repetitive loading without adequate recovery.
The risk factors, aside from a young age, that may contribute to development of a stress fracture are variable, and include:
· Having an increased postural arch in the low back (“hyper-lodotic”) whilst being hyper-flexible (think of dancers and gymnasts here);
· Being very muscular and tight during a rapid growth spurt (think of male team sport athletes and weight lifters);
· or athletes new to a sport who do “too much training too soon” coupled with poor core strength, poor flexibility and poor technique.
It cannot be emphasised enough that early diagnosis and rest are critical to successful treatment, so if your adolescent is an active sports person who develops low back pain then getting them to a Sports Physiotherapist or Sports Physician early is crucial. Diagnosis requires MRI or CT imaging which are more accurate than plain Xray. Early conservative treatment (meaning rest, +/- brace) show excellent healing results in the early stages of the injury. Life-long pain and failed healing do occur in more advanced stages of the condition which often result if the athlete is not diagnosed quickly and their fracture managed poorly in the first instance. Advanced stages see both sides of the vertebrae fracture, causing the vertebrae to slip forwards and never heal. This forward slip is known as "spondylolisthesis" and can cause ongoing symptoms.
Why rest? It’s a broken bone – it needs rest to heal. This means no sport or bending/twisting movements for around 3 months on average. It means avoiding any activities that cause pain until the pain resolves, and it means limiting physical activity beyond routine daily tasks.
Prior to the pain fully settling, some types of very low load rehab can begin under the guidance of your Physiotherapist, and once the pain has fully resolved, rehab can be progressed gradually. Initially all strength work is completed with the spine in a neutral position using low loads only. As the athlete develops good low and then medium load strength, with good posture and movement patterns, sports specific and higher load work can begin (typically after 3-4months). Restoring cardiovascular fitness specific to your sport is critical.
For many adolescents this injury may be their first ever injury. A teenagers awareness of their own body can be poor, and learning what excellent and terrible movement patterns look and feel like may be happening for the first time ever. They may never have done any meaningful resistance training before. All of these things take time to learn and master. My recommendation is to return to sport only once these aspects are significantly improved, otherwise returning to sport with the same poor technique, poor strength, poor flexibility and/or poor movement patterns can lead to recurrence. Similarly, the training loads need to be carefully monitored as ramping up training too quickly will likely cause the stress fracture to recur and the entire process of rest to be repeated. The research shows that around 25% of adolescent athletes who return to sport without thorough rehabilitation have their stress fracture recur (Sakai et al 2017).
For some athletes follow-up CT scans to assess bony healing may be required before progression of rehab is allowed. You will need to discuss this with your treating practitioner.
In returning to sport, there is a large overlap between coaching and sports medicine science, which means that your practitioner and coach need to talk to work out how to get you back into sport without breaking your back again. Recent research has focused on the amount of load an athlete actually does and shows that too much or too little load can lead to injury. In other words there is a “sweet spot” in the middle where less injury occurs. Cricket bowlers have been studied extensively, and the science shows that players with high “chronic training loads” (which is the long term load typically measured in number of balls bowled per week) typically have less injuries. You did read that correctly – LESS injury with HIGHER long term loads. The caveat here is that the high training load was achieved with a very gradual build up (or “ramp rate”) and the overall load for elite adult fast bowlers being less than 170 balls per week (Cricket Australia Guidelines).
If you are an adolescent or young athlete with a stress fracture, make sure you thoroughly address all of the following:
· EARLY professional diagnosis and treatment;
· Do your rehab thoroughly – no shortcuts!
· Address your individual risk factors including any technique issues, weakness, tightness or poor movement patterns;
· Build your training load back very gradually to a good regular training volume, including enough recovery between training sessions.
This approach is successful for returning to sport at high levels without re-injury.
Athletes who do little training, or who increase the ramp rate (build-up) of training load too quickly, or fail to do their rehab and eliminate their risk factors, are at higher risk of recurrence.
Although the return to sport and how training load is measured differ between sports, I have included the Cricket Australia guidelines for fast bowlers as a guide for what a sensible training load might look like. If you are coming back from injury, DON’T jump straight back into the maximum recommended balls / week – you will likely get injured! You have to build back up carefully over some months before you can safely bowl that many deliveries (bone takes 3-4 months to adapt to new loads). As a parent it is useful to coach your adolescent that it is the quality of bowling each session, rather than the quantity or sheer pace that will make the difference in their overall cricket ability. Research shows that accuracy rather than pace is what separates international bowlers from first class bowlers. So working on the technique concerns raised by your Physiotherapist and coach are more helpful for the aspiring pace bowler than simply trying to bowl really fast without thought for technique or accuracy. This type of guidance, modified according to the particular sport your adolescent or young adult plays, can assist a growing athlete shift their focus onto the important things and prevent a very long lay-off with repeated back injury.
Comment by Dr Toby Loch-Wilkinson (Neurosurgeon – Spine Brain Nerve Neurosurgery, Brisbane)
Thanks for the excellent synopsis Dave. When I worked at a children’s hospital I saw many elite young athletes who had developed pars stress fracturing. Some of the sports in particular associated with this were ice hockey, swimmers who did a lot of butterfly or breaststroke, gymnasts, tennis and cricket. Almost always over-training was a factor. A suitable period of rest and restriction or modification of the typically intensive training regimes patients described was essential in recovery. Almost all patients improved over 3 – 6 months and could make a graded return up to elite performance level provided they didn’t do “too much too soon”.
Patients may have a pre-existing structural defect of the pars in some instances that predispose to further injury of the pars. Pars defects can lead long term to accelerated disc damage and chronic instability of a motion segment. This usually occurs at L5/S1 or L4/5.
Back pain associated with discopathy and chronic instability can often be managed very effectively with physiotherapy. A trial of non-operative therapy should almost always precede any consideration of surgery unless there are significant neurological concerns. In my practice patients with symptomatic chronic pars defects and spondylolisthesis that require surgery have ranged in age from their early 20s into the mid 60s. Symptomatic spondylolisthesis from chronic pars defects causing radicular pain or back pain can be treated very effectively with spinal fusion surgery. Despite the negative press surrounding spinal fusion, this condition in particular has excellent outcomes with spinal fusion surgery. Functional improvement is on par with hip or knee replacement surgery. A few very highly selected young patients may occasionally be suitable for surgical repair of the pars rather than spinal fusion.
Sakai et al (2017): Conservative Treatment for Bony Healing in Pediatric Lumbar Spondylolysis. Spine 42:E716-720.