Search
A previous pearl discussed Spondylolysis. Once clinical concern is sufficient, the question of appropriate imaging arises.
Traditionally, the addition of oblique radiographs was recommended because they showed the pathognomonic “Scotty dog” sign. Recent studies have shown there is no significant increase in diagnosing spondylolysis with the addition of these oblique views. These additional views carry added cost and radiation exposure (approximately double).
AP and lateral radiographs offer similar diagnostic sensitivity to the old four view series.
If plain films are negative and symptoms persist despite 2-3 weeks of rest from offending activities, advanced imaging can be pursued on an outpatient basis. This is also strongly considered if the patient wishes to return to sport.
Despite being primarily osseous pathology, studies have shown that MRI can have similar diagnostic sensitivity to CT particularly in cases of acute injury. MRI may also show signs of stress reaction before complete fracture occurs.
Communicate with radiology and MRI technicians that you are looking for spondylolysis as this may affect the MRI sequences.
If a positive finding occurs on plain film, ordering CT imaging for the entire lumbar spine should be deferred due to added radiation concerns especially in cases where MRI would be available.
If MRI is not practical, consider limiting CT to one level above and one level below the region of concern. This would decrease the radiation exposure by approximately 50%
If advanced imaging is not practical or available and patient has a positive plain film, consider recommending repeat imaging in 4-6 weeks as an outpatient with rest from all offending activities.