The principal risk from a fusion is that it does not heal. In general, allograft bone does not heal quite as well as autograft bone, but both yield good results when used in the anterior cervical spine.

The procedure is performed in close proximity to the large blood vessels that go to the legs (I have figures to show this). Damage to these large blood vessels may result in excessive blood loss. Quoted rates in the medical literature put this risk at 1% to 15%. There is also a small risk of injury to the bowel or ureter, since they are in the proximity of the lower lumbar discs.

For males, another risk unique to this approach is that approaching the L5-S1 (lumbar segment 5 and sacral segment 1) disc space from the front has a risk of creating a condition known as retrograde ejaculation.

In males, there is a small risk of retrograde ejaculation with anterior approaches at L5-S1. The nerves that control ejaculation lay over the front of the L5-S1 disc. They are very sensitive, and therefore even with retraction the normal coordination of ejaculation can be disrupted resulting in the ejaculation occurring backward into the bladder. It should be noted that erection and sex drive are not affected. Fortunately, retrograde ejaculation happens in less than 1% of cases (but in some studies is higher) and tends to resolve over time (a few months to a year).

If a graft is used without instrumentation, there is a small chance (1% to 2%) of a graft dislodgment or extrusion. If this happens, another operation may be necessary to reinsert the bone graft, and instrumentation (plates) can then be used to hold it in place.

The principal disadvantage with using autograft bone is that another incision needs to be made over the hip to harvest the bone graft. Possible complications associated with taking out bone graft include:

• Graft site chronic pain (which happens 10% to 25% of the time)
• Infection
• Hip fracture
• Bleeding
• Damage to the lateral femoral cutaneous nerve (a sensory nerve that supplies sensation to the front of the thigh)

The chances of a graft-related complication increase with the size of the bone graft. The bone graft is an important part of the procedure, and many patients find the bone graft harvest site to be more painful than the lumbar surgery itself.

If allograft is used, there is a theoretical risk of transmission of an infection from a donor. The risk of contracting HIV from a graft has been estimated to be between 1 in 200,000 to 1 in 1 million.

In skilled hands, this is a very safe procedure. Possible reported risks and complications of anterior lumbar fusion may include:

• Non-union
• Bleeding
• Retrograde ejaculation (in men)
• Injury to the ureter
• Injury to the bowel
• Incisional hernia
• Injury to the diaphragm or kidney
• Damage to the spinal cord or nerve roots
• Bleeding
• Continued pain
• Adjacent disc disease
• Stroke
• Graft extrusion
• Paralysis
• Infection
• Death