Osteoarthritis of the facet joints can lead to instability of a vertebral segment. Typically, as continued degeneration weakens the facet joints, the L4 vertebral body slips forward on the L5 vertebral body. Since the L4-L5 segment has substantial flexion-extension type movement, this area is most likely to slip. The next most likely level is L3-L4, and rarely L5-S1. As the body tries to capture the unstable segment, the facet joints get bigger and place pressure on the nerve root (lumbar spinal stenosis). Therefore, both the symptoms and conservative treatment are essentially identical as for patients with lumbar spinal stenosis.
Besides medication and physical therapy, other choices to treat the spondylolisthesis would include epidural steroid injections or a one level spine fusion. Epidural injections are easier to go through, but the surgery may be more reliable. Besides medications you may want to consider physical therapy and/or chiropractics. If this does not improve the pain, and it is limiting your normal level of functioning, you may want to consider epidural injections. If these do not work, a spinal fusion may be a reasonable option. Usually, surgery is only considered for patients with significant functional limitations.