History of Adult Isthmic Spondylolisthesis
The history is the patient’s story: how the symptoms began, where the symptoms are located, what is the interference in the quality of life, what relieves and what aggravates. Isthmic Spondylolisthesis is due to a fracture of the pars commonly due to repetitive stress on a growing , re-modeling skeleton. 
In adults, the fracture is usually old (having occurred as an adolescent) and other factors now produce symptoms. Those factors include degenerative changes in the disc between the slipped vertebra, instability of the spine due to abnormal motion between the slipped motion segments, pinching of the spinal nerve as it exits the spinal canal between the slipped vertebra. 
The major symptoms are low back pain and/or leg pain. Some patients will have numbness or weakness in the distribution of the affected nerve. 

Physical Exam of Adult Isthmic Spondylolisthesis
The physical exam is performed by the doctor to determine the effects of spondylolisthesis. Examination of the back may reveal tenderness, or reproduce the patient's pain when the patient tries to bend backwards. Numbness or weakness may be detected in the leg(s) if the spondylolisthesis pinches a spinal nerve(s).

Diagnostic Studies for Adult Isthmic Spondylolisthesis
The purpose of diagnostic studies is to answer the question, “where is the pain coming from.” Plain Xrays may reveal if one motion segment has slipped on another. Bone scan/spect scan is a test which shows whether a recent fracture has occurred. C.A.T. scan and/or M.R.I. may show if a fracture is present across the pars area connecting the motion segments together. M.R.I. may reveal degeneration of the disc between the slipped vertebra or pressure on the nerve exiting between the slipped vertebra. C.T. discograms may show that the pain is reproduced from the disc space between the slipped vertebra or above the slipped vertebra.. Myelogram and contrast C.A.T. scan may show nerve pressure in the area of the spondylolisthesis. 
Treatment of Adult Ishtmic Spondylolisthesis

Natural History
The natural history is the rate that nature cures a particular condition. Nature has been curing things for 3 billion years and a certain percentage of patients with a particular diagnosis are going to be healed by nature. Most patients with adult isthmic spondylolisthesis will improve and return to normal activities. 

Conservative Care
The purpose of conservative care is to relieve symptoms and improve function. Conservative treatment options include restriction of activity to alleviate pain, occasional bracing (far less common in adults) to reduce motion and activity, and exercise to strengthen the muscular perimeter of the trunk and injection therapy to relieve pain.  

Surgery
The goal of surgery is to stabilize the segment and decompress the affected spinal nerve(s). Different options exist to accomplish this goal. The basic surgical ideas are to fuse the two motion segments together and if nerve symptoms are present, to decompress the nerve.