Lower Back Pain In The Adolescent Athlete

After spending the last few posts on ACL and PFJ injuries, I am now going to turn my attention to low back pain in the active teenage athlete. It has been documented that between 26% - 50% of the entire pediatric population will experience low back pain by the age of 15 (reference). The rise in incidence has been linked to either increased sedentary activity, or higher levels of organised sporting activity compared to previous generations. With organised sport, injuries unfortunately can be a by-product. As mentioned in previous blogs, most non-contact and overuse injuries that occur during adolescence, can and should be avoided. Low back pain is no different, and if ignored, can have long term detrimental effects on function and quality of life.

In the active teenager, most will present to their health care provider with a gradual onset of worsening low back pain and declining performance (usually >3weeks). Their pain is exacerbated by repetitive lumbar flexion/extension/rotation movements and/or high impact exercise. During the subjective assessment, one must keep an open-mind and VERY, VERY importantly attempt to rule out “red flag” conditions such as:

• malignancy
• inflammatory diseases
• spinal cord compression
• cauda equina
• infection
• diabetes
• traumatic fracture
• rheumatoid conditions

There are a few potential causes of mechanical low back in this adolescent age group, but once "red flags" have been ruled out, the treating health professional should have a high degree of suspicion that the young athlete has an injury to the pars interarticularis, also known as spondylolysis or pars defect. Muscle strain can also be considered, but it is a diagnosis of exclusion, with studies reporting that 47% of LBP in athletic adolescents is due to spondylolysis, while only 6% is due to “lumbosacral” strain (reference).

The pars interarticularis is a narrow section of bone on the lumbar vertebrae that sits between the inferior and superior facet joints. A diagram of the pars interartcularis can be found here. In the general population pars defects are observed in 2-6% of the population, but in the athletic adolescent population that number grows to between 8-15% and that number can grow as high as 47% (dependent on sport). High risk sports for this type of injury are; cricket (fast bowlers), gymnastics, dancing, tennis, rowing, golf and diving, which all involve repetitive lumbar flexion/extension/hyper-extension +/- rotation. Like all bone stress-related injuries, it is accepted that spondylolysis occurs when the repeated lumbar spine stress is greater than the capacity of the bone to heal and remodel adequately. Although less common, acute traumatic pars interarticularis fractures can occur and have been noted to occur in 40% of overall cases (reference).

Injury to the pars interarticularis has been classified into 4 different stages and it is crucial to understand the stage of injury as it will guide rehabilitation and return to sport (reference):

• Grade 0 (normal pars interarticularis): MRI = normal marrow signal and intact cortical margins.
• Grade I (stress reaction): MRI= bone marrow oedema of the pars. Intact cortical margins.
• Grade II (incomplete stress fracture): MRI = bone marrow oedema in the pars and cortical fracture incompletely extending through the pars. No fracture line.
• Grade III (acute complete fracture): MRI = complete spondylolysis with bone marrow oedema of the pars. Fracture line present.
• Grade IV (chronic fracture, non-union): MRI = complete spondylolysis without bone marrow oedema of the pars. Fracture line present.

MRI is the imaging option of choice when one is suspicious of spondylolysis, as it will pick up the early stages of stress fracture (Grade I). It is comparable to CT imaging, and has the bonus of no radiation exposure (reference). 

In this adolescent age group, early diagnosis and management is crucial as it increases the possibility of full bone healing, rather than progressing to chronic non-union. Once a diagnosis has been made, the athlete must stop high impact exercise and sport for at least 3 months, as this has been shown to be crucial for healing and recovery, with the athlete having a 16x more likely chance to have an “excellent” outcome when this management plan is enforced (reference).

In my experience a carefully crafted rehabilitation plan, looking at addressing internal and external factors for the increased pars interarticularis bone stress, in conjunction with avoidance of high impact exercise for 3 months is a more proactive way to treat the condition rather than saying to the athlete “rest for the next 3 months”. In my opinion, advising to “rest” will not address any biomechanical errors, or training errors, that have lead to the injury occurring in the first place. Furthermore, 3 months off exercise will de-condition the athlete in other areas of the body, including the cardiovascular system, to the point that when they do return to sport they have a high risk of picking up a subsequent injury elsewhere.

The other thing to watch out for in this active teenage group is prolonged complaints of “soreness” in the lower back. “Soreness” can be easily brushed off as "growing pains", but in the active teenager, it is typically a symptom of early bone stress reaction. It is thought that playing through “soreness”, can lead to stress fracture and a longer period out of sport (reference).

So there you have it, a brief overview of lumbar spondylolysis. Like most blogs that I write, I’ve tried to keep this clinically relevant in terms of management and treatment, rather than go into the nitty gritty about clinical assessment. Obviously that’s important, and its nice to have an accurate diagnosis through clinical tests and imaging, but what I feel is equally important is an evidenced based approach to treating/managing the condition, and I hope that I have provided you with some useful information today. Once again, if you feel like that I have missed something please comment and let me know, or feel free to share this blog with your colleagues/friends/family who may find this information useful.

Cheers,

Mick