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ALIF

ALIF (anterior lumbar interbody fusion) resembles PLIF (posterior lumbar interbody fusion).

However, there is a difference; in ALIF, in order to achieve disc space fusion, the spine is approached through the abdomen and not through the lower back like in PLIF.

An anterior approach might not suffice to achieve a more rigid fixation.

In this case, ALIF and a posterior approach can be conjointly deployed.

Yet, if there is sufficient stability, ALIF alone can suffice.

This often happens when patients suffer from one-level degenerative disc disease which implies great disc space collapse.

The following series of steps are performed to complete an ALIF procedure:

• the surgeon makes a 3-5 inches incision in the left side of the patient’s abdomen
• he works around the stomach muscles and abdominal organs
• the surgeon removes the affected disc and replaces it with a large spacer (typically made of plastic or bone) and bone graft (or a synthetic substitute)
• pedicle screws, which may add more stability and help fusion, are inserted into the bone

The spacers inserted in ALIF are typically twice as big as the spacers used in TLIF or PLIF, both of which are performed from the patient's back side. The larger spacers:

• provide increased stability
• increase the disc height in order to restore alignment
• increase the chance of successful fusion

The spine can also be reached through the abdomen by using a transperitoneal approach. However, this technique would add a lot of morbidity to the operation and this is why surgeons don’t use it very often. Doctors often perform this surgery together with a vascular surgeon who can mobilize the large blood vessels (aorta and vena cava) which lay atop of the spine and continue to the legs. The surgeon removes the disc material once the blood vessels are pulled aside. Then, the bone graft or the graft and the anterior interbody cage can be inserted.

ALIF surgery has the following advantages:

• it doesn’t disturb the back muscles or the nerves like PLIF or a posterolateral gutter approach
• for a better fusion, the bone graft can be placed in front of the spine, creating compression
• opting for an anterior approach allows surgeons to insert a significantly larger implant, leading to more stability for the fusion construct

ALIF is performed in the area where the large blood vessels which go to the legs are located. This poses significant risks because if these vessels are affected, the patient may suffer excessive blood loss. Statistically, the risk rates are 1 to 15%. Nonetheless, an experienced surgeon will know how to avoid this risk.

Male patients who undergo ALIF are exposed to additional risk; the intervention can lead to retrograde ejaculation if L5-S1 disc space is approached frontally. This doesn’t cause impotence because the nerves from that area don’t play a part in the erection. Moreover, statistics point out that retrograde ejaculation is registered in less than 1% of interventions and it heals within the next months.

Here is an example of a patient who underwent an ALIF procedure with pedicle screw placement. The patient suffered from back and bilateral leg pain for two years. His condition was not improved although he tried oral medication, therapy, spinal injection, as well as adapted his activities. He then decided to go through ALIF; the procedure deployed a PEEK spacer, decompression, and posterior pedicle screws. The patient’s pain was reduced from 9 out of 10 pre-op to 3 out of 10 post-op (he had the last follow-up after 18 months).

Preoperative Lateral X-Ray
L4-L5 had spondylolisthesis on the pre-op lateral x-rays
stenosis was caused by L4 slipping forward on L5.

Postoperative Lateral X-Ray
The patient’s x-rays proved that the PEEK spacer had increased the disc height, the normal curvature (lordosis) was restored and the stenosis was relieved by reducing the slip of L4 on L5.
Fusion success was increased with the aid of pedicle screws that provided more stability.

This is an example of ALIF performed with an anterior plate. The advantage of using an anterior plate is that the surgeon can rely on the muscle-sparing anterior approach (frontal), without disrupting the posterior back muscles. The patient felt back pain and pain in his left leg. He had gone through an intensive program of physical exercises for trunk stabilization and he had taken spinal injections as well. He then tried to find a solution for his stenosis and degenerative disc disease by opting for fusion at L5-S1 via ALIF, decompression, and pedicle screws. After this treatment option, his pain diminished from 8/10 to 3/10 and his last follow-up examination was two years after the intervention.

Preoperative X-Ray
The lateral x-ray the patient had before the operation pointed out a loss of disc height (L5-S1).

Preoperative MRI
The patient had an MRI before the intervention and this showed a dark disc (L5-S1) with height loss and encroachment on the spine’s canal which led to his stenosis.

Postoperative X-Ray
After the operation, the patient’s x-rays showed that there was a bone graft spacer located in the disc space. This graft managed to restore the disc’s height and the lordosis (the lumbar spine’s normal curvature), as well as the anterior plate and the screws.

Postoperative AP X-Ray
The post-op AP x-ray shows the plate and screws.