Spondylolisthesis is a condition of the spine when one of the vertebra slips forward or backward compared to vertebra above or below. Forward slippage of one vertebra on another is referred to as anterolisthesis, while backward slippage is referred to as retrolisthesis. Anterolisthesis is a spine condition in which the upper vertebral body, the drum-shaped area in front of each vertebrae, slips forward onto the vertebra below. The amount of slippage is graded on a scale from 1 to 4.
There are various anterolistheis treatments but they vary depending on the intensity and severity of the condition. The doctor will in most cases need the X-ray image to determine the degree of anterolisthesis. If the X-ray does not give the required detail the doctor may need a Magnetic Resonance Imaging (MRI) or a Computer Tomography (CT) scan.
It is important to note that the patient may not be able to regain the physique and fitness that was there before the event that caused anterolisthesis.
The following are the available Anterolisthesis treatments:-
Conservative treatments:
This refers to the non–invasive medical procedures. Most doctors will want to try the conservative measures if the anterolisthesis does not present very severe symptoms. It’s main advantage is that it is less costly and it actually offers complete recovery if it is professionally offered by qualified medical professional like physiotherapist.
The common conservative treatments for Anterolisthesis include:-
Rest: 
The anterolisthesis patient is put to bed rest. Note that this is not strict bed rest because there is need for some mild exercises of the spine and spinal cord. The patients are advised to avoid engaging in activities or events that may cause further slippage or straining of the vertebrae.
All patients suffering from anterolisthesis are advised to take several days off from work and then spend the following few days or weeks on bed rest that is in most cases coupled with mild exercises for anterolistheis.
The patient may undertake this treatment at home or at the hospital depending on the severity of the condition. If the patient is unable to control the urine and bowel movements as a result of the condition, he or she should seek advice on the diets to take and those to avoid.
Physical Therapies
This is in most cases accompanied by bed rest. The patient is put on physical therapies by well trained physiotherapists. It will in most cases involve exercises for anterolisthesis so as to improve the movement of the discs and relieve the pain. The physiotherapists will first assess the muscoskeletal dysfunctions before deciding on the best therapy.
The duration of therapy may take several weeks or months depending on the intensity and severity of anterolisthesis. It may involve postural training, heat massage, electronic simulation and various other non-invasive procedures that are aimed at reliving the pain. Back stretchers may also be used in the therapy.
The patient may also be given anti inflammatory medications either orally or through injection to prevent the inflammation. Pain killers are also given orally or through injections so as to alleviate the severe pain that characterizes anterolisthesis.
Note that these conservative treatments are only likely to work in grade I anterolisthesis and in some grade II anterolisthesis cases. If these treatments do not work or they do not produce the worthwhile or expected results, the patient has no option but to undertake surgery.
Like all the other surgeries, this is an invasive procedure that has various risks. In most cases however, the surgery is successful and the patient will get relief. The surgery for treatment of anterolisthesis is referred to as interbody fusion.

How is the interbody fusion surgery carried out?
In interbody fusion, the surgeon will make an incision in the patient’s back. The incision will be done through the mid layers of those ligaments and muscles which are positioned on both sides of the spine. Note that the ligament is the tough tissues that lie between the joints. It attaches the joints, holds them and separates them from each other. The joint is that place in which two bones connect to each other. It allows for bone movement thus causing general body movements like bending and twisting.
After the surgeon has cuts the already mentioned areas, the attachments to the laminae and the spinuos processes will be freed. The laminae refer to the flat and thin parts of the human vertebral arch. The vertebral arch refers to rings of bones that surround the human spinal cord. These rings of bones surround the spinal cord with other vertebral bodies. The spinuos processes refer to the bony parts which project from the vertebrae’s back.
The surgeons use special instrument to remove the small pieces of bones from the lamina such that the nerves are now visible. The nerves will then moved very slightly so that the
Intervertebral discs are clearly exposed. By use of special medical instruments, the surgeon will remove the disc through the left or right side of the patient’s spinal canal. Note that the spinal canal refers to the space that is between bony structure (which surrounds the spinal cord) and the spinal cord.
Once the surgeon has removed the disc, he or she must align the patient’s vertebra. The empty space that remains after the disc has been removed will be filled with a bone. This bone is in most cases taken from any other part of the body of the patient. The surgeon may also use a bone clock (an artificial bone) to fill the space that used to be occupied by the disc that has been removed.
After filling of the space that is in between the vertebrae, the patient’s vertebrae are now fused together. The fusion should be done very carefully to ensure that the bone can never slide or slip forwards again thus causing another incidence of anterolisthesis. To ensure this, the surgeon can stabilize the fused vertebrae by fastening it with screws or other hardware.
Nowadays, surgeons conducting anterolisthesis surgery have entrenched the practice of implanting spinal cage after removing the disc that lies in between the vertebrae that had slipped over the other. The spinal cage is basically a small cage that is threaded and filled with tiny natural bone pieces. The surgeon will cap and implant this packed cage in between the vertebrae.
Permanent stability and fusion will be accomplished when the natural bone will grow through the holes that are in the cage such that it fuses with the tiny natural bone pieces.

Yes, I have already had a fusion done from l4-s1, the anterolisthesis is happening at the l4-l5 level where it is already fused. I was wondering why this would be happening?