Revision
Spine Surgery San Francisco

Salvage Spine Surgery

Fortunately, patients who received absolutely appropriate treatment and surgery, which is perfectly performed, have an excellent probability of returning to normal function and excellent symptomatic relief. Unfortunately, not every patient achieves such perfection. Some surgeries are performed by surgeons without the benefit of the most up-to-date and accurate diagnostic tools and treatment options, including surgery. What about the patients who are not able to recover fully from spine surgery? Are they simply relegated to persistent symptoms and decreased function? Sometimes the surgeon has not identified the exact origin of a patient’s symptoms through comprehensive history, thorough exam, most up-to-date diagnostic imaging, MRI or CT, electrodiagnostic studies, and other medical evaluation. We may fail to recognize which patients have low pain tolerance and high psychological overlay. We may fail to provide appropriate postoperative rehabilitation and psychological support. When a patient fails to achieve the desired result of spine surgery, it is important to take a fresh look at problems that exclude other causes of postoperative symptoms. Possible causes for persistent symptoms or worsening of the preoperative condition include recurrent disc herniation after discectomy and microdiscectomy; overlooked or persistent spinal stenosis; instability not recognized or increased following surgery, especially after wide decompression; postoperative infection; epidural fibrosis; adhesive arachnoiditis; nerve injury caused by the original pathology or nerve injury occurring during surgery; a sacroiliac joint problem that was missed; and improper patient selection. One of the most common complications of spine surgery is wrong-level surgery. Technical errors during surgery include missed disc fragment and missed stenosis. Spinal fusion may fail. This includes failure of fusion or nonunion, implant failure, and breakdown of adjacent motion segments. Sagittal imbalance can occur when the fusion mass is either kyphotic or hypolordotic with motion segments above or below the fusion that have degenerated. The four most common presentations include patients who have a long fusion for scoliosis with subsequent degenerative changes proximally or distally, patients with degenerative sagittal imbalance with fusion performed in the distal lumbar spine in kyphotic or hypolordotic position with subsequent breakdown of adjacent motion segment, patients with post-traumatic kyphosis, and patients with ankylosing spondylitis.

The surgical solution for sagittal spinal imbalance involves a combination of osteotomies through the fusion mass and extension of fusion to include the degenerated segment. For patients with ankylosing spondylitis, the correction is achieved entirely with osteotomies. The goal is to normalize the regional segmental spinal alignment as much as possible and achieve global balance. The global balance is confirmed when the C7 plumb line falls over the lumbosacral disc on the long-cassette lateral radiograph taken with the patient standing with the knees fully extended in a natural, comfortable position. Three types of osteotomies can be performed.   Using a Smith-Petersen osteotomy, about 10% of the correction can be achieved. The second type involves pedicle-subtraction osteotomy, and this produces 30-35% of correction. The third method is to perform vertebral column resection, which is powerful for obtaining correction in both sagittal and coronal planes. Vertebral column resection is indicated for the most severe deformities. With long fusions, failure occurs in the proximal end of the fusion. Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) can occur. This problem would include increased kyphosis at the proximal end of the fusion and instrumentation, screw or rod breakage or failure, screw pullout, disc herniation, fracture, or breakdown adjacent to the end of the fusion and the instrumentation. The reported incidence of proximal junctional failure ranges widely from 5% to 46% in patients undergoing spinal instrumentation and fusion. The other causes for symptoms after surgery include altered joint mobility, muscle deconditioning, facet joint degeneration, sacroiliac joint degeneration, etc. Treatment for problems after surgery include physical therapy, nerve blocks, medications, injections, chronic pain management, and psychological support. Injections may include epidural block, selective nerve root block, facet block, and facet joint or sacroiliac joint rhizotomy. Sometimes spinal cord stimulation or a narcotic pump may be necessary to control the pain.

In diagnosing the cause of pain once a spinal fusion has failed makes “the water muddy.” It is harder to rehabilitate a patient in the face of pain. It is harder to sort out psychological subjective symptoms from organic physical symptoms. The revision or salvage surgery is more difficult to perform and more fraught with complications such as dural leaks, instability, and arachnoiditis. Although some surgeons attribute pain to scar tissue, scar tissue may not be the cause of pain. Sometimes MRI postoperatively shows only scar tissue, suggesting it is likely the cause of symptoms. Almost all postoperative MRIs show scar tissue. For most patients, scar tissue or epidural fibrosis is most likely not the cause of persistent symptoms. In addition to most advanced MRI, CT scan, motion x-rays, and electrodiagnostic studies, it is important to perform other medical diagnostic studies to pinpoint the responsible pathology. It is important that the physician or surgeon is persistent and performs due diligence to identify the exact origin of pain or persistent symptoms.

After the appropriate and thorough preoperative diagnostic studies, and if one can be absolutely certain of the source of pain, a small surgery with more direct approach should be used first. There is a tendency for surgeons to do more on “redo operations” to achieve more stability. There is a tendency to “leave no stone unturned.” We at St. Mary’s Spine Center have the most experienced spine surgeons who have been treating patients who have failed previous spine surgeries. We have the most up-to-date imaging studies, including the latest MRI, CT scan, x-rays, and fluoroscopy. We perform diagnostic injections at our facility at St. Mary’s Spine Center. We have excellent internal medicine, physical medicine and rehabilitation, and psychological support staff to help our patients achieve the symptomatic relief they need and to fully recover from their condition. We believe that surgery is part of the total rehabilitation effort to return our patients to complete symptomatic relief and full, normal function.

Revision spine surgery becomes complicated by altered or distorted previously normal anatomy, especially by obliterated tissue planes with scar tissue formation and/or epidural fibrosis. The surgeon must safely establish a plane between the neural tissue, the dura, and the scar tissue. It is safer and easier to work from normal, unscarred area to the abnormal, scarred area. The normal, unscarred area in the spine is characteristically defined by the surrounding bone, which should be carefully exposed. Usually, a midline incision is made. Dissection is carried through the scar tissue, or by excising the old scar, or bypassing it. The exposure is carried down to a safe 3-5 mm distance from the dura as determined by the exposure of adjacent structures such as the lamina. Exposure is then made laterally at the safe level, leaving the scar tissue overlying the dural sac (Figure 1).

The soft tissue is removed from the facets, and if necessary, exposure carried to the transverse process (Figure 2).

The scar tissue often encroaches on the laminectomy site and intervertebral foramen, making surgical dissection difficult and risking dural tear or nerve injury (Figure 3).

A sharp curette can be used to develop the plane between the soft scar tissue and facet (Figure 4).

Blunt dissection of the plane is then made between the dura and facet with great care (Figure 5).

The area of bone to be removed should be carefully defined around the previous laminectomy site (Figure 6).

This can be performed with a chisel to remove laterally 3-10 mm of what is left of the lamina, facet joint, or pars interarticularis (Figure 7).

A new plane of dissection is bluntly developed as the dura is gently retracted away (Figure 8).

Adherent bone fragment to the scar tissue can be used for traction as a new plane is developed (Figure 9).

Under the removed bone, the surgeon can find a nerve root with normal tissue plane. Then, the lateral recess and neural foramen can be enlarged and probed (Figure 10).

In recurrent disc herniation, the spinal nerve is often adherent to the underlying disc material and scar tissue. It is usually very difficult to retract the nerve from this dense scar. Care should be exercised to minimize trauma to the nerve root, and no further attempt should be made to create a plane. In this case, the disc is entered more laterally to the nerve, and the disc material is removed from under the nerve from inside the disc (Figure 11).

Down-going curette can be used for this purpose (Figure 12).

The same procedure can be done from the opposite side, which was not surgically entered before. The surgeon must make sure that all involved nerves are free from compression from disc, scar tissue, or bone. Any symptom-causing abnormality found should be corrected. All available information from patient history, physical examination, preoperative imaging studies, and electrodiagnostic studies should be used to make this decision.

Sometimes, excessive bones are removed, such as the facet joint or pars interarticularis, to cause instability. If there is instability, fusion should be considered. The decision regarding the type of fusion—posterior, posterolateral, anterior, or lateral—as well as use of internal fixation such as pedicle screw fixation, should be made.