Degenerative Disk Disease Treatment & Management
- Author: Stephen Kishner, MD, MHA; Chief Editor: Mary Ann E Keenan, MD more...
Medical Therapy
Conservative treatment includes back education and back school, exercise, medications, physical modalities, and injections.
Back education and back school
The goal is to teach patients how to help themselves manage their back pain. First, knowledge of normal spine anatomy and biomechanics is taught, together with the mechanisms of injury. Then, the diagnosis is explained to the patient, making use of spine models. The neutral or balanced position, which differs from patient to patient, is sought.
Back school teaches the patient basic body mechanics, such as the correct posture for standing, standing at a desk or drawing board, sitting, brushing teeth, washing the face, pushing and pulling a weight, lifting a weight, getting in and out of bed, sleeping, getting into a car, and sitting in a car. Back school also teaches patients the proper and improper approaches for sitting, bending forward, lying down, coughing, or sneezing when their back is painful.
Exercise
Different types of exercises are prescribed, depending on each patient's diagnosis. Floor exercises consist of abdominal bracing, modified sit-ups, double-knee-to-chest or low back stretches, seat lifts, mountain and sag exercises, knee-to-elbow exercises, hamstring stretches, extension exercises, and extension flexibility exercises. Swimming exercises are some of the best activities for back pain. Aerobic exercises improve endurance if performed regularly (ie, ≥ 3 times/wk). Relaxation exercises are good for relieving muscular tension that may aggravate back pain.
Medications
These include muscle relaxants, nonsteroidal anti-inflammatory drugs, and analgesics.
Physical modalities
These include the use of ice packs, heating pads, electrical stimulation, phonophoresis, iontophoresis, relaxation, and biofeedback.
Injections
Epidural steroid injections are most commonly used for therapeutic purposes. The type and dosage of steroid varies widely. Methylprednisolone (80-120 mg) mixed with normal saline to achieve a volume of 8-10 mL is an effective and safe dosage and volume. In some centers, 2-3 injections are given over a 1- to 2-week course, but long-term results do not appear to be any different from those achieved with a single injection.
The response to epidural injections is variable, and many authorities believe the injections are only of short-term value. Even if a favorable response occurs, no more than 4 injections should be given annually. Immediate pain relief may be achieved by adding 4-6 mg of preservative-free morphine to the epidural steroid injection. Pruritus is a reliable sign of epidural placement.
Patients should be observed for 24 hours for respiratory depression or urinary retention following morphine epidural steroid injections, even though these are uncommon adverse effects. If morphine is to be avoided, lidocaine or bupivacaine can be used in combination with the steroid to achieve immediate pain control, albeit of short duration.
Surgical Therapy
Surgical treatment is used in approximately 5% of patients and includes lumbar surgeries and cervical surgeries.
Lumbar Surgeries
The most common lumbar surgical procedures for degenerative disk disease fall into 2 categories. The first, decompression, involves removal of bone or disk material from around a compressed nerve root to relieve pinching of the nerves and provide more room for their recovery. This procedure is performed through laminectomy and diskectomy. The second, spinal fusion, involves using a bone graft to fuse one or more vertebrae and stop motion at a painful vertebral segment. This, in turn, should stop or decrease the pain generated from the joint.
Carreon et al evaluated 25 prospective, randomized clinical studies of patients who underwent spinal fusion or nonsurgical treatment for lumbar degenerative disk disease, chronic low back pain, and spondylolisthesis, comparing results after 1-year follow-up. They found substantial improvement in patients who underwent fusion for degenerative disk disease or spondylolisthesis. Not as much improvement was found in patients with chronic low back pain, but these patients also had lower baseline disability.[9]
A Cochrane Database of Systematic Reviews article reviewed 33 randomized comparative studies on various fusion techniques, including discectomy alone, addition of interbody fusion, and addition of anterior plates, for patients with single- or double-level degenerative disc disease. The analysis found that few studies reported on pain, and thus little or no difference was noted in pain relief between the different procedures. Moderate quality evidence was found for the following outcomes: for iliac crest autograft and metal cage techniques, no significant different was found in Odom’s criteria; fusion with bone graft was more effective than discectomy alone; complication rates were not significantly different for iliac crest autograft and discectomy alone.[10]
Lumbar diskectomy
During surgery, the affected level is identified through a posterior midline approach. The incision in the ligamentum flavum is started in the midline, where it is tented away from the dura. The ligamentum flavum is excised in 1 piece to expose the interlaminar space on 1 side. The opening is widened by excising portions of lamina. Difficulty in retracting the root suggests that it is compressed by a disk herniation or entrapped in a narrowed lateral recess.
Once the nerve root is identified, it is retracted and a cruciate incision is made in the bulging annulus. The loose fragments of the disk are extracted with pituitary rongeurs. The nerve root should be freely mobile and easily retracted, otherwise it may still be compressed or lateral stenosis may be present. In the latter case, the lateral recess and the neural foramen should be enlarged (see below, Lumbar laminectomy for 1-level central and lateral stenosis). A free fat graft is placed over the exposed dura to prevent adhesions.
After surgery, a neurological examination is performed in the recovery room, and the findings serve as a baseline. A urinary catheter is used if difficulties with micturition arise. Postoperatively, the patient may stand and walk for increasing periods. The patient can usually go home 1-5 days after surgery. Some surgeons also perform the lumbar diskectomy as an outpatient procedure.
Low back exercises (pelvic tilting and half sit-ups) are started at this point. Follow-up initially occurs at 2- to 6-week intervals. Light work is started at 2-8 weeks and heavy work at 12-16 weeks.
Lumbar laminotomy for 1-level central and lateral stenosis
The operation involves an approach to the stenotic level through a 1-level bilateral minimal partial laminotomy. A gauge is inserted into the lateral canal to determine its size. The medial third of the inferior articular process is removed with an osteotome or rongeur. The medial and anterior parts of the superior articular process are removed with a power tool, a Kerrison rongeur, or an osteotome and mallet. For lateral stenosis, removal of more of the superior articular process until the lateral canal diameter is 6 mm usually is necessary. At the end of the procedure, a free fat graft is placed between the dura and the posterior muscles to prevent adhesions.
Lumbar laminectomy for central and lateral stenosis at several levels
If conservative measures fail, the operation is essentially the same as for 1-level stenosis. The dura often is exposed just above or just below the lesion through a normal interlaminar space. The aperture is then widened as described above, and the medial portions of inferior and superior facets are removed. The exposure is then lengthened longitudinally with a Kerrison rongeur, taking care to not injure the dura. The laminectomy should be as short as possible. However, a long laminectomy does not make the spine unstable, provided the lateral two thirds of all the facet joints are preserved.
Postoperative care is the same as after diskectomy, but these patients usually experience less postoperative discomfort.
Approximately 70-80% of patients who undergo laminectomies have significant improvement in their function and markedly reduced levels of pain and discomfort. Laminectomy results are much better for relief of leg pain caused by spinal stenosis than for relief of lower back pain.
The risks and complications of laminectomies are (1) nerve root damage (1 per 1,000 cases); (2) bowel/bladder incontinence (1 per 10,000 cases); (3) cerebrospinal fluid leakage (1-3%); (4) infection (1%); (5) postoperative instability at the operated level (5-10%); and (6) general anesthetic complications, such as myocardial infarction, blood clots, stroke, pneumonia, or pulmonary embolism.
Lumbar spinal posterolateral gutter fusion
This type of spinal fusion involves placing bone graft material in the posterolateral portion of the spine (a region just adjacent to the spine).
During surgery, a bone graft is harvested from the posterior iliac crest. The posterior articular and transverse processes are completely denuded of periosteum with an elevator. The additional stripping provides more bare bone and stimulates more new bone formation. A sharp, curved gouge is used to raise "shingles" of corticocancellous bone on the posterior surface of the transverse process.
Alternatively, a high-speed burr can be used to achieve decortication. The same technique is used for shingling and denuding the upper and posterior surface of the sacrum, for obtaining a free cancellous bone graft. The graft is then placed over and between the denuded surfaces. The large back muscles that attach to the transverse processes are elevated to create a bed on which to lay the bone graft. The back muscles are then laid back over the bone graft, and the tension created holds the bone graft in place. Finally, a free fat graft is placed and sutured over the exposed dura to prevent encroachment onto the bone graft.
Postoperative care is for approximately 5-10 days. A back brace usually is applied.
The 2 key factors under a patient's control that determine whether a fusion solidifies are (1) smoking cessation and (2) limited motion.
The risks of this type of surgery are nonunion, infection, bleeding, and solid union with no reduction of back pain. The nonunion rates are 10-40%. Risks of nonunion are prior surgery, smoking, obesity, multilevel fusion surgery, and previous radiation therapy for cancer. Infection and bleeding have an occurrence rate of 1-3%.
Posterior lumbar interbody fusion
The advantage of posterior lumbar interbody fusion (PLIF) over anterior interbody fusion is that either decompression or diskectomy can be performed through the same approach. Unlike posterolateral gutter fusion, PLIF achieves spinal fusion by inserting a bone graft directly into the disk space. An oversized bone graft is harvested from the posterior iliac crest through a transverse incision. The ligamentum flavum is excised completely.
When the operation is for disk disease, the interlaminar space is widened by removal of the superior and inferior margins of the adjacent laminae, partial medial facetectomy, and retraction with a laminar spreader. A rectangle of annulus is excised. The bony ledge of the superior margin of the lower vertebral body is removed, clearing the way to the diseased disk. The endplates and disk material are then removed. Blocks of corticocancellous bone taken from the iliac crest are cut to the measured size of the disk space and jammed into place. The same maneuver is repeated on the opposite side. Finally, a free fat graft is sutured to the nearby soft tissues to cover the dura.
Postoperatively, braces are optional.
PLIF has several disadvantages. First, not as much of the disk space can be removed with a posterior approach. Second, an anterior approach provides for a much more comprehensive evacuation of the disk space and, hence, increased surface area available for fusion. Third, a much larger bone graft can be inserted from an anterior approach. Fourth, in cases of spinal deformity (eg, isthmic spondylolisthesis), a posterior approach alone is more difficult to reduce the deformity. Finally, although the risk is small, insertion of a bone graft posteriorly may allow it to retropulse back into the canal and create neural compression.
The major risk for this type of surgery is nonunion. The rates of nonunion are 5-10%, lower than that for posterolateral gutter fusion.
Anterior lumbar interbody fusion
Anterior lumbar interbody fusion (ALIF) is similar to PLIF, except that in ALIF the disk space is fused by approaching the spine through the abdomen instead of through the back.
An anterior retroperitoneal or transperitoneal approach is made, and the main vessels are retracted to the side. A flap of the anterior longitudinal ligament and anterior annulus fibrosus is raised with a scalpel. The disk material is removed piecemeal with curettes and pituitary rongeurs as far as the posterior longitudinal ligament. When the disk is completely cleared posteriorly and laterally, the endplates are excised to bleeding cancellous bone with osteotomes. When bleeding is controlled, iliac crest grafts are punched into the space. The flap of anterior ligament and annulus is replaced and sutured.
Postoperatively, oral intake is delayed until bowel sounds return or flatus is passed. Care is similar to that for other fusions.
The ALIF approach has the advantage that, unlike the PLIF or the posterolateral gutter approaches, both the back muscles and nerves remain undisturbed. Another advantage is that placing the graft in the front of the spine puts it in compression, and bone in compression tends to fuse better, according to the Wolff law. However, because of the reliance on compression for achieving solid fusion, osteoporosis is a contraindication for ALIF.
Major risks of ALIF are blood loss from damage to major blood vessels (eg, aorta, vena cava), with quoted rates of 1-15% and, in men, retrograde ejaculation. The other risks are nonunion (5-10%), infection, and bleeding (1-3%).
Transforaminal lumbar interbody fusion
Transforaminal lumbar interbody fusion (TLIF) has become an increasingly popular treatment for lumbar degenerative disk disease, spondylolisthesis, degenerative adult scoliosis, spinal stenosis, and recurrent disk herniation.[11]
TLIF was developed by Harms; the approach to the spine is posterior, with access to the disk via a path through the far lateral portion of the vertebral foramen. This allows complete removal of the disk and placement of an interbody support transforaminally, with reduced risk of nerve injury, while permitting posterior decompression and interbody fusion.
TLIF is a modification of PLIF that has been used since the 1940s for degenerative disk disease. It offers good exposure with decreased risk, especially in repeat cases of spine surgery in which the presence of scar tissue makes PLIF very difficult. PLIF permits good posterior decompression; however, the disk is not removed and the segment is not immobilized efficiently. TLIF is also a viable alternative to anteroposterior circumferential and anterior lumbar interbody fusion. The approach is either unilateral or bilateral laminectomy with an inferior facetectomy, diskectomy, arthrodesis, pedicle screw fixation, and insertion of titanium or carbon fiber cages with autologous bone. The fusion can be single-level or multilevel. The goal is anterior column support and fusion.
The results in a number of published series have shown excellent outcomes with few complications. Complications include cerebrospinal fluid leaks, transient neurological complications, and minor wound infections. In some series, radiographic fusion was demonstrated in 74-93% of patients, with no deaths or major hardware failure. Of these patients, 90% said they would have the procedure again. TLIF has become a safe technique for interbody support with good clinical outcome.
Preoperative care and postoperative care are the same as for PLIF.
Spine fusion instrumentation
Bone tends to fuse better in an environment with as little motion as possible. The role of spine fusion instrumentation is to decrease motion at the segment undergoing fusion and to provide additional spinal stability.
The 3 major types of spine surgery instrumentation are pedicle screws, anterior interbody cages, and posterior lumbar cages. Pedicle screws provide a means of gripping onto a vertebral segment and limiting its motion. Anterior interbody cages are devices inserted into the lumbar disk space through an anterior approach. They can be made of allograft bone, titanium, or carbon/polyetheretherketone (PEEK) (radiolucent cages). Posterior lumbar cages are also made to be inserted into the lumbar disk space, but they are modified to be inserted through a posterior approach. They can be made from the same materials as the anterior cages.
Total disk arthroplasty
This procedure has been used for lumbar diskogenic pain, with and without radicular symptoms. The ProDisc prosthesis has been used for both single-level and multilevel degenerative disease. Bertagnoli et al, in a 2-year study of patients older than 60 years, showed a 94% satisfaction rate with the ProDisc therapy. Patients also showed a decrease in radicular pain. Patients with decreased bone mineral density underwent a vertebroplasty before insertion of the ProDisc.[12, 13] However, the accuracy of certain studies on ProDisc is currently being challenged.[14]
One study compared the results of surgical intervention with the ProDisc II prosthesis with nonsurgical rehabilitation in patients with chronic low back pain after 2-year follow-up. While both methods achieved substantial improvement, the surgical group experienced improved low back pain, patient satisfaction, SF-36 physical component score, and self-efficacy for pain over the nonsurgical group; however, the improvement did not surpass the study’s predetermined “minimally important clinical difference” between the 2 groups. Surgical risks should be considered in deciding a course of treatment.[15]
Tropiano et al showed that the sex of the patient and whether surgery was multilevel did not affect the outcome, but prior lumbar surgery or age younger than 45 years was associated with slightly worse outcomes.[16]
Complications were very few, and included a unilateral foot drop, implant subsidence, and loss of vibration and proprioception. These complications were seen mainly in patients with circumferential spinal stenosis.
Artificial disk replacement has shown results similar to fusion in the short term, but long-term results are not known.
Smoking versus not smoking and the risk of pseudoarthrosis (surgical nonunion) after fusion procedures
Smoking is well known to impede bone and wound healing. Brown et al investigated the rate of pseudoarthrosis in persons who smoke and in persons who do not smoke who had undergone a 2-level laminectomy and fusion of the lumbar spine over a 1-year period. Of 100 patients, 40% of those who smoked and 8% of those who did not smoke developed a pseudoarthrosis. The results clearly show that smoking causes a significant increased risk for pseudoarthrosis in spine fusions and is a major contraindication for surgery.
Cervical Surgeries
The goal of surgery for cervical radiculopathy is to adequately decompress the nerve roots. The options available are (1) anterior cervical diskectomy (ACD), (2) ACD and fusion (ACDF), (3) ACDF with internal fixation (plating), and (4) posterior foraminotomy. The choice of the appropriate procedure depends on a number of factors, including the location of the neural compression, the presence of deformity or instability, and potential morbidity. In general, anterior pathology, such as a centrally herniated disk and anterior osteophytes, is treated anteriorly, and posterior pathology, such as posterolateral osteophytes/disk herniations, may be treated with a posterior approach.
The goal of surgery for degenerative cervical disk disease with myelopathy is to decompress the spinal cord adequately. Literature regarding spondylotic myelopathy does not demonstrate clearly the superiority of either the anterior approach or the posterior approach. Options for surgery include (1) single- or multiple-level ACDFs, (2) single- or multiple-level anterior corpectomy with fusion, (3) laminectomy with or without fusion, and (4) laminoplasty. The choice of approach is based on the location of the pathology, the risks and benefits of each procedure, and the geometry of the spinal canal.
Anterior cervical diskectomy
ACD involves performing a decompression of the nerve roots through an anterior diskectomy. An area of controversy is whether an interbody fusion is necessary after a single-level ACD. Although initially ACD involved fusion procedures, complications, including graft and donor-site complications, prompted some surgeons to perform a simple diskectomy. Diskectomy may be considered for patients with normal cervical lordosis, minimal axial pain, and abnormalities limited to 1 level. A high frequency of improvement has been reported in the literature with diskectomy alone, although most surgeons now routinely use fusion.
Possible risks and complications of ACD include (1) nerve root damage, (2) damage to the spinal cord (approximately 1 per 10,000 cases), (3) bleeding, (4) infection, (5) graft dislodgment, (6) damage to the trachea or esophagus, and (7) continued pain. Damage to the recurrent laryngeal nerve during the procedure may cause hoarseness, and retraction of the esophagus sometimes causes temporary difficulty with swallowing.
ACD and fusion
An interbody fusion usually avoids recurrent radiculopathy from foraminal narrowing and the possibility of developing late kyphosis from disk-space collapse. A combination of diskectomy and fusion should be performed in all patients, especially if multiple levels are involved or if instability is documented at any level. The complications involved with not performing a fusion are much higher than the small risk of complications associated with fusion.
For single-level fusion, autologous bone results in a fusion rate of 95%. To prevent donor-site complications, alternatives include the use of allograft bank bone, bovine cancellous bone, and synthetic materials. The main risk of a fusion surgery is that it does not result in fusion. 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.
If a graft is used without instrumentation, the risk of graft dislodgment or extrusion is 1-2%. If this happens, another operation is performed to reinsert the bone graft, and instrumentation (plating) can be used to hold it in place.
ACDF with internal fixation (plating)
Plating can be helpful in patients who require procedures in multiple levels, with documented instability, in persons who smoke, patients with a prior history of nonunion, and those with a previous fusion adjacent to the level to be fused. In addition, with a plate, no brace is needed, allowing an earlier return to work and resumption of daily activities.
Kaiser et al found the overall fusion rate for 522 patients for 1-level ACDF with allograft bone and anterior plate to be 96%. This rate decreased to 91% when performed over 2 levels. The rates for 1- and 2-level fusions without anterior fixation were, respectively, 90% and 72%. The improved fusion rates and low complications associated with anterior cervical plating are good arguments for its use in the treatment of degenerative cervical disk disease.[17]
Posterior cervical foraminotomy
Nerve root decompression may be accomplished posteriorly by performing a foraminotomy. The keyhole approach, developed by Scoville to decompress nerve roots, involves removal of 1 or more hemilaminae with removal of osteophytes and disk fragments. This is used most commonly in soft posterolateral disk herniations, thus obviating the need for a fusion. High success rates have been reported.
Single- or multiple-level ACDFs
ACDFs at single or multiple levels may be performed for myelopathy when the pathology is limited to the disk spaces and does not involve the vertebral bodies. Although multilevel corpectomy is also an option in these cases, multilevel ACDFs have the advantage of segmental fixation and restoration of lordosis.
Single- or multiple-level cervical corpectomy with fusion
A corpectomy is the removal of a vertebral body and the disk spaces at either end in an effort to completely decompress the cervical canal.
With multiple areas of spondylotic compression of the spinal cord, corpectomy with strut grafting may be performed. With multilevel corpectomy, anterior strut fusion is necessary to prevent kyphotic deformity and to restore stability. Anterior plating is recommended for corpectomy and multilevel procedures to reduce the risk of graft extrusion and pseudoarthrosis. As the length of the fusion increases, the rates of both graft- and instrumentation-related complications increase. In such cases, posterior stabilization is recommended to improve stability and fusion rates and reduce graft- and instrumentation-related complications.
A corpectomy is a more technically difficult surgery to perform. The risks are similar to those for diskectomies, but because a corpectomy is a more extensive procedure than a diskectomy, the risks are greater. The most worrisome risk is compromise of the spinal cord leading to quadriplegia. To decrease this risk, spinal cord function can be monitored during surgery using somatosensory evoked potentials.
Another risk is compromising the vertebral artery, which can cause a stroke.
Cervical laminectomy with or without fusion
Laminectomy is sometimes needed if patients have congenital cervical stenosis or if the disease process involves more than 3 levels or multiple discontinuous levels. In patients with kyphosis, anterior fusion may be needed to prevent further progression of the kyphotic deformity. If most of the compression of the spinal cord is posterior, laminectomy can sometimes be used.
As with cervical corpectomy, the main risk with cervical posterior laminectomy is deterioration in neurological function after surgery. Use of intraoperative somatosensory evoked potentials can decrease this risk. Other risks include dural tear, infection, bleeding, increased pain, and instability in the spinal column.
If a laminectomy is performed, a fusion is recommended to prevent kyphotic progression. Other indications for posterior fusion include evidence of instability on preoperative dynamic radiographs, failure of anterior fusion, or decompression involving bilateral facetectomy. Most of the experience with posterior fusion has been with autologous bone from spinous processes or the iliac crest, but allograft bone has been used.
Cervical laminoplasty
The laminoplasty technique was developed by the Japanese primarily for treatment of ossification of the posterior longitudinal ligament. It involves osteoplastic enlargement of the spinal canal by performing the laminectomy on one side to create a "door." The goal of this procedure is to reduce the postlaminectomy instability discussed previously. Although infrequently used, successful treatment of cervical spondylosis has been reported with this technique.
Cervical keyhole foraminotomy
Posterolateral keyhole foraminotomy is indicated for posterolateral disk herniations with radicular pain. It is an efficient way of decompressing a lateral soft disk without the risks of an anterior approach. A bone graft is not needed. Use of an operative microscope helps achieve good outcomes. Burke and Caputy describe a rigid endoscopic approach with a smaller incision, less postoperative pain, and fewer complications.
Chen et al compared spine segment flexibility after the keyhole procedure with an ACDF and anterior foraminotomy with a diskectomy, and showed a minor increase in motion with the keyhole foraminotomy.[18]
Silveri et al in a 6-year long-term follow-up study showed excellent results with preoperative pain relief in all the patients and no significant complications. Preoperative and postoperative care is the same as with ACDFs.[19]
Complications
The complications of lumbar disk surgery are described above. Other complications include cauda equina syndrome, thrombophlebitis, pulmonary embolism, wound infection, pyogenic spondylitis, postoperative diskitis, dural tears, nerve root injury, cerebrospinal fluid fistula, laceration of the abdominal vessels, and injury to abdominal viscera. Paralysis, stroke, and death, although rare, are possible.
Two types of postfusion stenosis are described. The most common type is above the fusion, secondary to degenerative changes, and the second type is deep to the fusion, secondary to new bone formation. Degenerative stenosis above the fusion is relieved by decompression through a bilateral laminectomy. Stenosis beneath the fusion requires exposure of the dura above the fusion and removal of the central portion of the fusion mass in a caudal direction.
The most commonly seen lesions in the previously operated back are lateral spinal stenosis (58%), central spinal stenosis (7%), arachnoiditis (16%), recurrent disk herniation (12%), and epidural fibrosis (8%). Arachnoiditis, intraspinal fibrosis, and epidural adhesions may benefit from epidural steroid injections or from a caudal block. If an operation is undertaken again, the distortion of the anatomy, the scar tissue posterior to the dura, and the adhesions between the dura increase the risk of opening of the dura and damaging nerves or blood vessels.
The possible sources of pain in the previously operated spine are many, and they frequently coexist. Possibilities include persistent or recurring disk herniation, diskogenic pain, instability, pseudoarthrosis, lateral recess stenosis, painful motion segment adjacent to a fused motion segment, posterior joint syndrome, sacroiliac joint syndrome, myofascial syndrome, deconditioning of lumbar paraspinal muscles, arachnoiditis, epidural fibrosis, pain at the bone graft donor site, and psychological magnification and causation of pain.
A number of complications associated with ACD have been reported in the literature. Fortunately, the occurrence of serious complications is rare (3%). Injury to the recurrent laryngeal nerve, especially with right-sided approaches, is the most common complication, although it may be transient. Other structures at risk include the trachea, esophagus, carotid artery, sympathetic chain, and the vertebral artery, if the decompression is carried too far laterally. Spinal cord or nerve root injury is the most serious complication but is relatively rare (0.2%) in the hands of experienced surgeons. The C5 nerve root is sensitive to trauma. Other less frequent complications include infections, cerebrospinal fluid leak, and dural tears.
Graft complications after ACD and fusion include collapse, displacement, and pseudoarthrosis. The rate of graft displacement is reported to be as high as 8%. Graft placement under compression and use of plates may reduce this complication rate. Graft collapse is more frequent in patients with osteoporosis. Allograft is preferable if any question exists regarding the quality of the autologous bone. Pseudoarthrosis rates of 5% for 1 level and 12-15% for multiple levels have been reported.
Complications reported for ACDF with internal fixation (plating) include hardware failure, screw pullout, or breakage with esophageal perforation. The most serious complications of foraminotomy are nerve root injuries (4%).
Worsening of symptoms with laminectomy for myelopathy occurs in 3-5% of cases. Postlaminectomy instability and kyphosis have been reported in the range of 10-22%. The role of facetectomy in postoperative instability has been documented in the literature through laboratory and clinical data. Facetectomies of more than 50% cause a significant loss of stability in flexion and torsion compared with an intact spine. Progressive postlaminectomy kyphosis may require anterior corpectomy/strut grafting with instrumentation and, possibly, posterior instrumentation.
Future and Controversies
Chemonucleolysis with chymopapain or collagenase
The posterolateral extradural approach with a 2-plane image intensifier avoids penetrating the dura and causing leakage of chymopapain into the subarachnoid space. Because anaphylactic shock is a potential complication, cardiopulmonary monitoring is used. Additionally, an intravenous line is established; hydrocortisone, epinephrine, aminophylline, and diphenhydramine should be available, and an anesthetist should be present with intubation and ventilation equipment.
The use of contrast material is kept to a minimum, and the chymopapain must be refrigerated until the time of use. The dose is 4000 U or 2 mL per disk.
Postoperatively, the patient should be as active as possible. A stiff canvas corset,[20] oral analgesics, and anti-inflammatory drugs are prescribed. Many patients require a few days of in-hospital care.
Because of complications and effectiveness problems, chymopapain injection is rarely performed in current practice.
Automated percutaneous lumbar diskectomy
Onik and associates introduced automated percutaneous lumbar diskectomy (APLD) in 1985. This procedure is safer than chymopapain intradiskal injection. It allows debulking of the central disk material by placement of a needle and the use of an automated suction/cutting device. At this time, no clear evidence suggests that APLD is more effective than noninvasive methods of treating disk herniation.
Arthroscopic microdiskectomy
With arthroscopic microdiskectomy (AMD), the surgeon can visualize the nerve root and annulus with an endoscope. Disk fragments in the posterior disk area can be removed using manual and automated instrumentation.[21] Biportal AMD has been attempted for improved surgical control (similar to joint arthroscopy), but this variant carries more risk of injury of the nerve root on the contralateral side.
APLD and AMD are recommended primarily for contained disk herniations when noninvasive methods have failed, although attempts have been made to address noncontained lateral disk herniations using AMD instead of the usual paralateral surgical approach.
Microendoscopic diskectomy
This diskectomy uses a posterior approach identical to standard lumbar diskectomy or microdiskectomy. A cannula is docked under the lamina under fluoroscopic guidance and laminotomy. Ligament removal and diskectomy are then performed using an endoscope. Migrated disk fragments are accessible with this technique.
Intradiskal electrothermal annuloplasty
Intradiskal electrothermal annuloplasty (IDET) is a minimally invasive outpatient surgical procedure. After the intervertebral disk is accessed under fluoroscopic guidance, an electrothermal catheter (heating wire) is passed into the posterior annulus of the painful lumbar disk.
Candidates for IDET include patients with back pain caused by small herniations, internal disk tears, or mild disk degeneration, limited to 1 or 2 levels. IDET is performed after 6 months of conservative treatment has failed.
Factors predicting successful outcome with IDET are (1) single-level disk disease, (2) good catheter placement at the time of the procedure, and (3) an absence of secondary gain issues (eg, financial gain from pending litigation or workers' compensation).
IDET is a very safe procedure with a very low risk of complications. Disk-space infection and nerve injury occur in less than 1% of the patients.
Artificial disks
The main objective of an artificial disk is to replace a painful disk while maintaining the natural anatomical structure of the spine. The procedure is an alternative to lumbar fusion. The Charite disk has recently been approved for use in the United States and has been used in a number of European countries for many years. Random enrollment for trials of the ProDisc are complete. However, the accuracy of certain studies on ProDisc is currently being challenged.[14] The Maverick and Flexicore lumbar disks are actively enrolling patients with single-level disease.
The current indications for implantation of an artificial disk are quite similar to indications for lumbar spine fusion and include (1) degenerative disk disease (typically at a single level), (2) age of 18-60 years, (3) major symptom of lower back pain rather than leg pain, (4) minimum of 6 months of conservative treatment, and (5) patient is a candidate for spine surgery (eg, lumbar fusion).
The 2 types of artificial disks are (1) a total disk prosthesis, designed to replace a full disk, and (2) a nuclear prosthesis, designed to replace the soft inner core of a disk.[22] The outer shell of the disk is made of metal, and the inner core is made of rubber polyethylene.
In some European countries, artificial disks have been used for approximately 10 years. The product used most commonly is the SB Charite prosthesis. Although no studies have examined the long-term effectiveness of this product, short-term and intermediate results have generally been favorable.
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