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 back pain for a failed spine surgery can be sought.
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.
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.
Wrong level surgery is performed.
This situation is highly unusual but not unheard of. There are five vertebrae in the lumbar spine, twelve in the thoracic spine and seven in the cervical spine. Most of them look the same. To identify these vertebra, careful observation of the intraoperative X-rays need to be performed but there are many factors that can make vertebral levels appear distorted. Parallax of the image, very large body habitus making visualization difficult, poor x-ray technique and malfunction of equipment can occur to conceal the levels. Some patients have congenital anomalies that can put the count off in determining levels. Hopefully, these errors are caught in the operating room. If the surgery was not a success, a new MRI or CT scan can reveal the error of the incorrect level.
The wrong initial diagnosis originally was made
If a number of potential pain generators exist and the history and physical examination does not lead to a specific diagnosis, an error of wrong diagnostic site can occur. Without an obvious source of pain, pain generators should be investigated,
Careful identification of the pain generators using diagnostic injections can make the proposed surgical success rate higher. For example, a nerve could have been compressed at one level but not causing pain and at another level the painful pinched nerve is not recognized and not surgically addressed.
A careful work-up after an unsuccessful surgery can reveal this condition.
The original surgery was not performed perfectly
There are rare times that problems can occur during surgery. A screw could be placed in a position that can irritate a nerve and cause arm or leg pain. An inadvertent tear of the dura could expose nerve roots that can be damaged by subsequent rough handling. Fusion failures can occur from incomplete preparation of the fusion surfaces, improper placement of graft or of the wrong choice of graft material.
MRI and CT scans can potentially reveal some of these problems and the use of an intraoperative CT scan (the O-arm- see website) and intraoperative monitoring can prevent some of these errors.
The patient did not listen to or was not given the post-operative expectations (expectations too high)
Certain spine surgeries come with limitations that need to be understood and abided by. For example, while a one level fusion of the lumbar spine comes with no restrictions, a two level lumbar fusion has restrictions of impact and load. Three levels and more have further restrictions. Not following these restrictions can possibly cause further degeneration at levels higher in the spine.
Fusion of the lumbar spine does typically relieve pain but does not commonly relieve all pain. Pain is typically reduced by about 2/3rds. If the patient does not understand that fact and is disappointed regarding the results, he or she might not have been educated sufficiently and expectations were too high.
The patient did not follow immediate post-operative restrictions (smoking cessation, activity restriction, activity overstimulation)
There is a responsibility that the patient needs to embrace to undergo spine surgery. Patients need to quit smoking as the nicotine in tobacco retards fusion cells. Patients that do not listen to restrictions or go back to hard work/ lift and bend too soon after lumbar fusion can disrupt the healing of the bone cells. Patients that mountain bike or ski immediately after cervical ACDF can reduce the chance of healing.
Individual Examples of Failed Lower Back Surgery Syndrome and Corrections