An Overview of Failed Back Surgery of the Lumbar Spine
Many individuals undergo spinal surgery with excellent results. The success rate with most surgeries is about 90%. When surgical results are not what they should be, a new workup needs to be completed to find out the source of the continuing symptoms. Once the exact cause of the back pain has been found, treatment for pain for a failed spine surgery of the lumbar spine can be sought.
Common Causes of Failed Back Surgery
Failure of fusion surgery is a failure of the bones to unite. This is called a pseudoarthrosis or “false joint.” Pseudoarthrosis can occur even in the best of circumstances and in the best hands but should be uncommon. This failure of fusion however can occur as a higher percentage under some circumstances.
Instrument fixation of the two bones to be united using screws and plates or rods is critical to prevent motion. Motion prevents the bone cells from uniting the two surfaces. A construct that is flexible or weak can contribute to pseudoarthrosis.
Paramount in fusion surgery is preparation the graft bed or the bone surfaces so that nothing impairs the fusion. Poor preparation can lead to fusion failure.
The choice of graft materials is important. Use of allograft (donor bone) has a lower fusion success rate than autograft (your own bone). The use of PEEK spacers (plastic spacers) can be useful or detrimental depending upon the circumstances. The use of bone morphogenic protein can significantly increase the fusion rate and the speed to fusion under the right circumstances.
The CT scan (on a 64 slice or greater scanner) and the flexion-extension x-rays are the mainstay to diagnose a pseudoarthrosis. In correctly chosen cases, surgical repair can remedy the problem.
Incomplete or recurrent compression of a nerve has occurred
Surgery to relieve buttocks, arm and shoulder or leg pain is called a decompression surgery. It may or may not be accompanied by a fusion surgery. If buttocks pain, leg pain, arm pain or posterior shoulder pain is still present after surgery or is relieved only temporarily after surgery, the nerve may not be fully decompressed or may have developed recurrent compression.
An example is a foraminotomy either in the neck or the lower back. A complete decompression will yield pain relief but if the vertebral level collapses after the decompression, the nerve will be compressed again and the pain will recur. Another example is a microdiscectomy for disc herniation. Pain relief for three weeks and then return of pain could indicate a recurrent disc herniation.
An MRI should reveal this condition.
Neuropathic pain is present but is unrecognized
Neuropathic pain is pain generated as a result of internal injury to the nerve root. This condition occurs from compression or stretch of a nerve. This is the most common surgical diagnostic dilemma that spine surgeons face. Diagnosis can only be confirmed by a successful surgical decompression with continued nerve pain and no further compression based upon a new post-operative MRI.
Before the initial surgery, a physical examination can typically identify the nerve involved. Imaging (X-ray, CT scan or MRI) will confirm the nerve compression. A nerve root block will even relieve the pain generated by the injured nerve. A successful surgery to decompress the nerve can be performed. A post-operative MRI will note a successful surgery where the nerve is free from compression. In spite of all of this, the pain remains
This is an unfortunate case of neuropathic pain. The nerve was damaged by the original compression (herniated disc, lateral recess or foraminal compression) and the surgery successfully decompressed the nerve but the nerve itself did not heal.
An injection can temporarily relieve the pain, as even an injured nerve will stop pain conduction under the proximity of a numbing agent like Lidocaine or Marcaine.
Treatment is chronic pain management, which would include medications and therapy and might include neurostimulation.