Gymnasts, cricket fast bowlers and divers and are prone to stress fractures of the lumbar spine, from repetitive extension and rotation. Incidence is up to 60% in these sports. The presenting feature is low, usually one-sided, back pain, worsened with activity and relieved by rest, usually with no referral of pain. Tenderness may be elicited, but can be absent.
Practitioners, coaches and athletes should have a low index of suspicion, as the window of opportunity for healing is small.
Investigation of suspected cases includes x-rays. This may show an established lesion, usually in the ‘pars interarticularis’, but sometimes in the pedicle, but really the athlete needs a bone scan (nuclear medicine test) that will show the presence of fracture (or not) and the level.
Once diagnosed, a CT scan will determine if the fracture is healing: either ‘early’, ‘progressive’ or ‘terminal’. Terminal lesions will not heal. Earlier lesions may heal, and require strictly no extension activities for up to 12 weeks.
Established, non-healed fractures are termed ‘pars defects’ (see image). These are present in about 5% of the community, 2/3 (without symptoms) at age 5, but a second peak is at 15, when the pars is still immature and activity levels are high.
Athletes with stress fractures need to be assessed for biomechanical factors that may be contributing, such as tightness in the pelvic/leg/lower back region; weakness in the ‘core’ and pelvic areas; leg length differences and so forth. This often involves physiotherapy and sometimes podiatry.
Return to sport is determined by absence of pain and correction of the biomechanical factors. Ideally athletes should be screened for risk, especially those at high-risk. Technique correction is often an important factor, such as cricket bowlers where ‘mixed action’ is a major risk for stress factor.
Some pars defects, if present on both sides can lead to slip of one vertebra on another.