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Posterior spinal fusion with anterior interbody cage | One disadvantage of the posterior approach fusion is that if all the pain mediators are from the disc side then a posterior fusion may allow microscopic motion at the disc producing continued low back pain after the fusion. One newer technique is the anterior approach. This involves going in to the abdominal area and protecting its contents.
Then the vessels over the spine are carefully mobilized. The involved disc is then removed and replaced by a metallic, polymer or ceramic cage as well as bone graft, and growth factors. A one level anterior fusion is usually a stand alone construct. However, a two level anterior lumber interbody fusion or ALIF is often followed by a posterior instrumentation to help stabilize the spine. This often can be done through a percutaneous approach placing the rods and screws in the spine through small incisions and viewed by fluoroscopic X-ray imaging. This also allows less destruction of the posterior musculature which is also thought to possibly be a pain mediator.
Generally patients undergoing spinal fusion are slower to progress than those just undergoing a decompressive surgery. Hospital time is usually five (5) to seven (7) days and the patient is fully ambulatory and moderately independent. A soft lumbar brace is usually placed to limit motion and protect the muscles while healing. While the patient is mobilized quickly, lifting limits are set for several months and depending on the patient's job requirements they may be required to do "light duty" for three (3) to six (6) months post op. Sometimes employers do not allow this and the patient may not be able to return to work for this period of time. Healing of the fusion take six (6) to twelve (12) months to fully mature but patients often have complete relief of their pain within six (6) to twelve (12) weeks.
Risks of spinal fusion are varied like any surgery. They include death, heart attack, stroke, seizure, infection, paralysis, spinal fluid leak, and loss of bowel and bladder control. In addition to these things already described in detail previously there are several other risks that are slightly more prevalent. With mobilization of the anterior blood vessels going to the legs there is a risk of tearing one of the vessels. Generally a vascular surgeon is available to help repair any potential injury. Also with mobilizing the vessels a clot may form in the vein which may produce phlebitis and necessitate placement of a filter to prevent blood clots from reaching the lungs. Very rarely are pre-existing clots in the artery knocked loose producing lack of blood flow to the leg. Again vascular surgery would reconnect blood flow to the extremity. Sometimes long term blood thinners or anticoagulants may be necessary. One other risk of performing an anterior L5-S1 fusion is retrograde ejaculation. In small percentages, males may experience ejaculation into the bladder rather than in the normal path. This often is transient and self limiting but younger males not yet having completed their families often opt not to undergo the risk, and will chose a posterior approach.
SEE ALSO SCOLIOSIS (COMPLICATIONS OF SURGERY).
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