Spondylolysis is a fracture in one of the vertebrae, in an area known as the pars interarticularis. This can occur without any injury, or can occur in younger people who participate in sports leading to repetitive strain on the lower back – such as fast bowling in cricket, gymnastics, weightlifting and football. It can also occur in older people who have degenerative changes of the lumbar spine.
Most people will present with lower back pain. This can be a mild ache or severe pain that can worsen with activity, and may cause shooting/radiating pain into the buttocks or legs. Some people do not have any obvious symptoms, and only have the condition diagnosed when having imaging for another unrelated reason.
If the fracture in the pars interarticularis separates, this can allow for the vertebrae to slide forward in relationship to the vertebrae below it. This is most common at the L5/S1 and L4/L5 levels. Most commonly this is a low grade slip (less than 50% of the vertebral body), but can rarely be a high grade slip (50-100% of the vertebral body) or even spondyloptosis (more than 100% slip).
Although some patients with spondylolisthesis can be asymptomatic and only be diagnosed due to imaging for other unrelated issues, others can have lower back pain, tight hamstrings, and pain and numbness in the leg(s) caused by compression/stretch of the affected nerve root.
Xray is the first line examination as it is shows the overall alignment of the spine. It can reveal spondylolisthesis and will often show the spondylolysis (fracture in pars interarticularis).
CT scan and bone scan can be used if there is uncertainty around the diagnosis, because these scans are accurate in the diagnosis of the fracture if it is undisplaced. However, they do have more ionizing radiation that xray and MRI scan, so they should only be used where necessary, particularly in younger patients.
MRI scan is particularly useful if there are pains that radiate into the buttocks or legs, or if surgery is being considered. This is the most accurate imaging study to assess for compression of nerve roots.
Most patients with back pain will improve with symptomatic non-surgical treatment only. These include rest, anti-inflammatory medications, physical therapy and possibly short periods of bracing.
Surgery may be recommended for patients who do not respond to non-surgical treatment, or who present with high grade slippage and/or severe nerve root compression with leg pains. The goals of surgery are to reduce pain, achieve a solid fusion and correct the overall correct of the spine. The slippage is not always possible or safe to be completely reduced.
A number of different surgical options exist, and the best option in each case depends on a number of factors that will be discussed with your doctor. The surgery can be performed via an anterior, lateral, posterior, or a combination of the above approaches.