Back Injuries of the immature spine

Most cases of back pain in children and adolescents are caused by benign musculoskeletal conditions and trauma. Non-specific musculoskeletal pain accounts for at least half of all cases in this age group. There are however, some specific musculoskeletal causes of back pain that present in childhood that will be further described here.

Spondylolysis (pars stress fracture)

Spondylolysis is commonly known as a pars stress fracture. The pars interarticularis is an area on the ring part of the vertebrae (vertebral arch), which is prone to stress reaction and fracture. These stress reactions occur more often in the athletic population and are 2-3 times more likely to occur in males. 80% of the time they occur on both sides of the vertebrae and the lowest lumbar vertebrae (L5) is affected at least 85% of the time.

Localised, repetitive loading which exceeds the threshold that the bone is able to withstand causes bone stress in the vertebral arch. This part of the vertebrae is loaded during trunk extension, side flexion and rotation. The pain may present as a gradual onset and be related to changes in training loads and volumes. The pain is localised in the lumbar spine but may radiate to the buttock or posterior thigh. It is most common in adolescents who play sports with repetitive spinal loading such as cricket fast bowlers, tennis players, gymnasts, divers and soccer and volleyball players.

The diagnosis is made with a combination of clinical examination and imaging (MRI). It is important to determine whether the bone stress injury is new (acute) or old (chronic) because they are managed differently.

Pars stress fractures are prone to non-union and are considered high-risk stress fractures. They need to be managed well in the acute stages to give the bone the best chance of healing. Chronic lesions are filled with fibrocartilaginous tissue that may give the bone enough stability to return to full pain-free activity, but they are prone to reinjury if the scar tissue is disrupted by mechanical loading so the best option is to diagnose the injury early enough to enable the bone to heal.

In order to allow the bone to heal adequately in an acute bone injury, the adolescent must stop their sport for at least 6-9 months and sometimes up to 12 months is needed. Surgery not indicated as first line treatment and bracing is rarely needed but is sometimes used (Boston Brace). The first 8 weeks of management is directed towards allowing the bone to heal, the next 8 weeks of rehabilitation involves protected reloading of the lumbar spine and the following stages of rehabilitation after the first 4 months are for transition to full function and return to sport.

Spondylolisthesis (slipped vertebrae)

Spondylolisthesis occurs when a vertebral body slips forward relative to the vertebra below it. There are 5 subtypes with type 1 and 2 affecting children and adolescents. Type 1 is a congenital malformation of the sacrum (S1) that allows the L5 vertebrae to slip forward on it. Type 2 is acquired and associated with bilateral pars defects that usually develop in early childhood. Having pars stress fractures on both sides of the vertebra allows the vertebrae to slip forward if the fractures separate. This type accounts for approximately 85% of cases in children and adolescents.

Spondylolisthesis is most commonly seen in children between 9 and 14 and the majority of cases are the L5 vertebrae slipping forward on S1.
Only 4% of pars stress fractures that result from athletic participation progress to spondylolisthesis. Children with pars stress fractures who progress to a slip usually do so during the adolescent growth spurt and there is minimal change after 16 years of age.

There is no evidence that active sports participation increases the risk of a slip and progression of a spondylolysis to a slip in adolescence can be asymptomatic. Symptomatic cases present with pain that spreads across the lumbar region and the pain can also radiate to the buttocks and the back of the thigh.

There are 4 grades of spondylolisthesis depending on how far forward the vertebra has slipped on the one below. Treatment of athletes with grade 1 or 2 symptomatic spondylolisthesis is usually non-operative with rehabilitation exercises effective in management. If ongoing symptoms persist despite 6 months of appropriate rehabilitation then a surgical review is appropriate.

Athletes with grade 3 or 4 spondylolisthesis should avoid high-speed or contact sports. Indications for surgery include growing children with a grade 3 or 4 slip, a slip that is progressing or one that involves neurological signs.

Scoliosis

Scoliosis is a lateral curvature of the spine. There are many causes however adolescent idiopathic scoliosis (AIS) is the most common type and makes up 80 – 85% of cases. Scoliosis affects males and females equally but females are 10 times more likely to have a progression of their curve needing treatment.

Adolescents may present with asymmetry of their spine, the height of their shoulders or the level of their shoulder blades. The asymmetry can become more obvious when bending forward. A diagnosis is made using a combination of clinical findings and measuring the angle of the spine on full length standing x-ray. A 10 degree curvature is needed to be considered a scoliosis (cobb angle) but most do not need treatment or cause symptoms until they get closer to 40 degrees.

The curve progresses in approximately two thirds of skeletally immature children and adolescents and is more likely to progress in girls under 12 years who start with a cobb angle greater than 20 degrees. Management options are observation, bracing and surgery and the goal of treatment is to have a cobb angle less than 40 degrees at skeletal maturity (determined by the ossification of the iliac crest apophysis).

If your child has back pain that doesn’t respond to rest from any aggravating activities, a consultation at Shire Sports Medicine can be beneficial to get an accurate diagnosis, to help guide management and to ensure the prevention of further complications.