Abstract
Background: The purpose of this study was to evaluate the complications of anterior cervical corpectomy and arthrodesis in patients who had had a previous cervical laminectomy. The results of previous studies have suggested that these patients can be managed with anterior decompression and an arthrodesis with either plate fixation or immobilization in a halo vest. However, no studies that we are aware of have specifically focused on the complications of these types of procedures.Methods: The records and radiographs of eighteen patients who had been managed with a one to four-level corpectomy with strut-grafting were retrospectively reviewed. The reviews were independently performed by the three of us who were not involved in the original operation. The interval between the laminectomy and the corpectomy ranged from one month to twenty-two years (mean, eight years).Results: Eleven of the eighteen patients sustained a total of sixteen complications during the follow-up period, which averaged 2.7 years (range, seven months to six years and four months), and nine of the eleven had graft-related complications. Five grafts extruded or collapsed, or both. There were four reoperations. Immobilization in a halo vest did not prevent extrusions, as three of the four extrusions occurred while the patient wore a halo vest. Four patients had a pseudarthrosis. In three patients, the kyphosis increased by 10 degrees or more from the immediate preoperative period to the most recent follow-up evaluation. Two patients had respiratory distress that necessitated reintubation, one patient had a small dural tear, and one had transient dysphagia.Conclusions: Our data suggest that anterior cervical corpectomy without instrumentation in a patient who has had a previous laminectomy is associated with a great risk of graft-related complications despite the use of a halo vest. This previously unreported finding is relevant in that it contradicts the recommendation previously made by Zdeblick and the senior one of us, who advocated postoperative immobilization in a halo vest for these patients. Anterior cervical corpectomy should be performed with caution and knowledge of the potential complications in a patient who has had a previous laminectomy.
Patients who have had a decompressive cervical laminectomy may continue to have or may subsequently have anterior compression of the spinal cord or nerve roots, or both, necessitating anterior decompression. Etiologies of the residual anterior compression include ossification of the posterior longitudinal ligament, osteophytes, herniated discs, and kyphotic cervical alignment. A corpectomy in these patients, who no longer have most of the posterior elements, presents some unique challenges to the surgeon. After a laminectomy, the posterior part of the vertebral ring is disrupted. A subsequent corpectomy at the same level severs the ring anteriorly, dissociating the left and right halves of that segment (Figs. 1-A and 1-B). The result is a markedly destabilized spine, with substantially decreased resistance to torsion and flexion-extension forces7,17.
Spinal stability may be compromised further by the presence of kyphosis. The prevalence of cervical kyphosis after a laminectomy varies widely, depending on the age and condition of the patient and the extent of the laminectomy4,6,7,9,10,14-16,18. Kyphosis was reported to have occurred after a laminectomy in nine of nine patients who were less than fifteen years old6 and in zero of five patients who were adults18. Zdeblick and the senior one of us (H. H. B.)19 reported on fourteen patients who had cervical kyphosis and myelopathy, seven of whom had the kyphosis after a laminectomy. In two of these seven patients, the graft extruded after anterior cervical corpectomy and arthrodesis. Those authors recommended immobilization in a halo vest in order to prevent this type of complication. Herman and Sonntag5 reported on twenty patients, nineteen of whom had a cervical corpectomy and all of whom had anterior plate fixation for the treatment of kyphosis after a laminectomy. Six of their patients had a complication; in one, a screw dislodged. McAfee et al.8 reported on 100 patients who had a circumferential arthrodesis, a few of whom had kyphosis after a laminectomy. Those authors believed that a one-stage circumferential operation reduced the likelihood of perioperative complications.
To our knowledge, these are the only reports in the literature regarding cervical corpectomy and strut-grafting in patients who had had a previous laminectomy, and none focused on the complications. The purpose of the present study was to review our experience, concentrating specifically on the complications of this procedure in patients who had had a previous laminectomy.
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
†Department of Orthopaedic Surgery, Washington University School of Medicine, One Barnes-Jewish Hospital Plaza, Suite 11300, West Pavilion, St. Louis, Missouri 63110.
‡Rothman Institute, 925 Chestnut Street, Fifth Floor, Philadelphia, Pennsylvania 19107.
§Department of Orthopaedic Surgery, Brown University School of Medicine, 2 Dudley Street, Suite 200, Providence, Rhode Island 02905.
#Department of Orthopaedic Surgery, University Hospitals Spine Institute, University Hospitals of Cleveland and Case Western Reserve University School of Medicine, 11100 Euclid Avenue, Cleveland, Ohio 44106.
We retrospectively reviewed the records and radiographs of patients who had been managed with an anterior cervical corpectomy and strut-grafting after a previous cervical laminectomy, at one institution, from 1974 to 1995. All of the operations were performed by the senior one of us (H. H. B.) or under his supervision, and the reviews were independently performed by the three of us (K. D. R., A. S. H., and M. A. P.) who were not involved in these operations. We were able to locate a total of eighteen patients who had complete medical records and radiographs. There were eleven men and seven women, and the ages ranged from thirty-one to seventy-nine years (mean, fifty-four years) at the time of the index corpectomy. The indications for the anterior procedures were persistent, recurrent, or increased neurological deficits. Seven patients had myelopathy or myeloradiculopathy; four, quadriparesis; four, radiculopathy; one, quadriplegia; one, Brown-Séquard syndrome; and one, torticollis. Preoperative neck pain, increasing deformity, and instability on flexion and extension radiographs of the cervical spine were not specifically noted as an indication for the operation in any of these patients. The preoperative neurological status was graded with the system described by Nurick11,12 (Table I). According to this classification, grade 0 indicates a neurologically intact individual and grade 5 indicates an individual who is wheelchair-dependent or bedridden. Of the eighteen patients, five had a grade-5 neurological status; three, grade-4; four, grade-3; three, grade-2; one, grade-1; and two, grade-0. Seventeen of the eighteen patients had cervical kyphosis preoperatively, and the remaining patient had a swan-neck deformity. Preoperative kyphosis, which was measured on a lateral radiograph made with the neck in neutral position, ranged from 4 to 54 degrees (mean, 22 degrees).
All eighteen patients had previously had a laminectomy of two, three, or four levels (mean, 3.5 levels). The interval between the laminectomy and the anterior cervical procedure ranged from one month to twenty-two years (mean, eight years). Of the eighteen patients, five had a four-level corpectomy; eight, a three-level corpectomy; three, a two-level corpectomy; and two, a one-level corpectomy. Seven patients had a five-level arthrodesis; seven, a four-level arthrodesis; two, a three-level arthrodesis; and two, a two-level arthrodesis. Typically, the arthrodesis involved one more level than did the corpectomy; nonetheless, there were some discrepancies. All five patients who had a four-level corpectomy had a five-level arthrodesis. However, two patients who had a three-level corpectomy had a total of five levels included in the arthrodesis, with a combination of anterior and posterior procedures. One patient had a hemicorpectomy of the sixth and seventh cervical vertebrae. This was considered a two-level corpectomy. This patient also had an anterior cervical discectomy and an arthrodesis at the seventh cervical and first thoracic vertebrae. Because only two disc levels were involved, even though major portions of both the sixth and the seventh cervical vertebral body were removed, only two levels were included in the arthrodesis. One patient had a single-level anterior corpectomy but then had a four-level posterior arthrodesis from the fifth cervical to the second thoracic vertebra. In the remaining patients, the levels of the arthrodesis coincided with those of the corpectomy, with one additional level included in the arthrodesis.
Three patients were managed with internal fixation. The decision to use an anterior cervical plate was arbitrarily made by the surgeon at the time of the operation. In one patient, an anterior cervical plate was inserted after a single-level corpectomy. Two patients were managed with a posterior cervical arthrodesis and wiring of the facets after the anterior procedures. One of these patients had had a laminectomy of the third and fourth cervical vertebrae eight years before the index procedure. He then had myelopathy secondary to compromise of the spinal cord posterior to the fifth, sixth, and seventh cervical vertebrae, and he was managed with corpectomy of all three levels. Because it was believed that kyphosis might develop at the third and fourth cervical levels, where the previous laminectomy had been performed, the patient was managed with a posterior arthrodesis with wiring of the facets from the second to the fifth cervical vertebra. The second patient had had a laminectomy of the third through the sixth cervical levels. He then was managed with a corpectomy of the fourth, fifth, and sixth cervical levels and with a posterior arthrodesis from the second to the seventh cervical level with wiring of the facets.
Only autogenous grafts from the iliac crest and the fibula were used. The two patients who had a one-level corpectomy were managed with a graft from the iliac crest. Of the three patients who had a two-level corpectomy, two had reconstruction with an iliac-crest graft and one, with a fibular graft. A fibular graft alone was used in the patients who were managed with a three or four-level corpectomy. The senior one of us routinely uses a graft from the iliac crest for two-level corpectomies. Occasionally, if the iliac crest appears difficult to remove (for example, in an obese individual) or if the corpectomy is so long that the curve of the iliac crest precludes its use, a fibular graft is used.
The grafts were so-called keyed in, as previously described18. Briefly, the central portions of the remaining end plates were burred until a rounded three or four-millimeter-deep crater was made. The ends of the graft were then rounded off so that the graft would fit into this crater under skull-tong traction. Once the traction was released, the crater helped to prevent displacement of the graft.
Of the two patients who had a one-level corpectomy, one was managed with a plate anteriorly and with postoperative immobilization in a molded head-cervical orthosis and the other was managed with immobilization in a two-poster rigid cervical orthosis. All three of the patients who had a two-level corpectomy were managed with a two-poster orthosis, and all of the patients who had a three or four-level corpectomy were managed with a halo vest.
The follow-up period ranged from seven months to six years and four months (mean, 2.7 years). Because the present report concerns the short-term postoperative complications of these procedures, a two-year follow-up period was not believed to be necessary for all of the patients. One patient died of a cardiac cause twenty months after the spinal operation. We analyzed the data to determine whether there were significant risk factors for these complications. Because of the small number of patients involved, Fisher's exact test was used for statistical analysis.
We measured the cervical kyphosis with Cobb's method1 on a lateral radiograph. The lines were drawn parallel to the inferior end plates of the most cephalad and caudad vertebrae of the kyphotic segment. The angle formed by these two lines was defined as the kyphotic angle. We arbitrarily picked a change of 10 degrees or more from the alignment immediately preoperatively to that at the time of the most recent follow-up evaluation as being substantial. Any change of less than 10 degrees was believed to be within the error of measurement or not clinically relevant.
There were a total of sixteen complications in eleven patients. Nine of the eleven patients had graft-related problems: extrusion or collapse of the graft, pseudarthrosis, or progressive kyphosis. Other complications included respiratory distress necessitating reintubation in two patients, a small dural tear in one patient, and transient dysphagia in one patient.
Extrusion of the graft occurred in four patients, two of whom had a partial extrusion. One patient was managed with a halo vest, and healing was uneventful. Another patient was managed with a two-poster brace and, at eleven months, the graft was stable but still had not fused. The third patient was managed with repositioning of the graft and stabilization with an anterior buttress plate (Figs. 2-A and 2-B), and the fourth patient was managed with posterior facet grafting and wiring until the strut graft healed, followed later by an anterior cervical discectomy and an arthrodesis at the next caudad level (Figs. 3-A and 3-B). No attempts were made at reduction with traction in a halo vest. All of the extrusions occurred at the inferior end of the construct. The grafts had been keyed in as previously described18, and the extrusions were associated with fracture of the anterosuperior corner of the inferior vertebra. Three of the four extruded grafts were fibular, and the remaining one was from the iliac crest. With the numbers available, no significant difference could be detected between the two types of grafts with regard to the rate of extrusion (p < 0.09). Two patients, including one of the four who had extrusion, had collapse of an osteopenic iliac-crest graft. As already mentioned, one of these patients was managed with a halo vest until a solid fusion was achieved. In the second patient, as the graft collapsed, it fractured the anterior portion of the inferior vertebral body, necessitating the removal of this vertebral body and replacement with a fibular graft.
Four of the eighteen patients had a pseudarthrosis. Two patients, one of whom died at twenty months postoperatively, were asymptomatic. The third patient continued to have some pain at the time of the most recent follow-up (eleven months postoperatively). The fourth patient had persistent pain and was managed with a posterior facet arthrodesis and wiring. This patient eventually had healing without additional complications.
The kyphosis in three patients increased by 10 degrees or more from the immediate preoperative period to the time of the most recent follow-up. The kyphosis increased from 26 to 50 degrees in one patient, from 19 to 37 degrees in another patient, and from 15 to 26 degrees in the third patient. All of these increases were due to subsidence of a fibular graft. With the numbers available, no significant difference could be detected between fibular and iliac-crest grafts with regard to the development of postoperative kyphosis (p < 1.0, Fisher's exact test). Despite the radiographic appearance, the symptoms decreased in all of these patients and none of them had neck pain at the most recent follow-up evaluation. The kyphosis in the other patients in the series decreased, remained unchanged, or increased by less than 10 degrees. In eight of the eighteen patients, the kyphosis decreased by 10 degrees or more. In two patients, the kyphosis increased by less than 5 degrees, which we believe is within the error of measurement. The overall mean preoperative kyphosis was 22 degrees; this decreased to a mean of 9 degrees on the radiographs made immediately postoperatively but then increased to 16 degrees at the time of the most recent follow-up.
Of the eighteen patients, four needed a revision operation. As described, one was managed with a corpectomy at an additional level, with fibular strut-grafting, after collapse of an osteoporotic iliac-crest graft; one had repositioning of an extruded graft and placement of an anterior buttress plate; one had a posterior facet arthrodesis and wiring for the treatment of a pseudarthrosis; and one was managed with a posterior facet arthrodesis and wiring because of extrusion of the graft and, at a later date, with an anterior cervical discectomy with interbody grafting at the next caudad level.
Postoperatively, twelve of the patients improved neurologically by at least one Nurick grade and none of the patients worsened neurologically. The mean Nurick grade improved from 3.1 preoperatively to 2 postoperatively. There was a higher prevalence of complications in the patients who had had a three or four-level corpectomy than in those who had had only a one or two-level corpectomy. Two of the five patients who had had a one or two-level corpectomy subsequently had a complication compared with nine of the thirteen patients who had had a three or four-level corpectomy.
The purpose of the present study was to review the complications associated with anterior cervical corpectomy and arthrodesis in patients who had a previous cervical laminectomy. A combined corpectomy and laminectomy of a single cervical segment disrupts both the anterior and the posterior portion of the vertebral ring, producing dissociated left and right halves that are connected only by soft tissues. The result is a markedly destabilized spine, and the reconstruction of such a spine might reasonably be associated with a relatively high rate of complications. Perhaps because these are relatively rare procedures, there are only a few pertinent articles in the literature and none that we are aware of have specifically focused on complications.
We found that anterior-only reconstruction after circumferential decompression was associated with an unacceptably high rate of complications. Eleven of the eighteen patients had some type of complication, and nine of the eleven had graft-related complications, including extrusion or collapse of the graft, pseudarthrosis, and progressive kyphosis. Five patients sustained an extrusion or collapse of the graft, or both. Even immobilization in a halo vest was found to be inadequate protection against extrusion, as three of the four extrusions occurred in patients who were wearing a halo vest.
Despite the high rate of complications, the symptoms of most of the patients in the present study decreased after the operation. The kyphosis decreased by 10 degrees or more in eight of the eighteen patients, and it increased by 10 degrees or more in only three patients. In several patients, the kyphosis decreased in the immediate postoperative period but then increased as the graft subsided.
The neurological status of twelve patients improved by at least one Nurick grade, and no patient had a worse neurological status. Neurological improvement occurred even in association with residual or increased kyphosis postoperatively. This finding suggests that, with adequate decompression and placement of the graft in the anterior portion of the spine, the spinal cord can move anteriorly. This movement can occur even though the overall kyphosis measured from the cephalad end to the caudad end of the fused levels may remain the same or even increase.
To our knowledge, there are only three articles in the literature regarding anterior cervical corpectomy in patients who have had a laminectomy5,8,19. In the first study, Zdeblick and the senior one of us19 reported on fourteen patients with cervical kyphosis and myelopathy who were managed with anterior decompression and arthrodesis. Eight of the fourteen patients had had a previous laminectomy, and one of the eight had also had a posterior facet arthrodesis. Of the seven patients who had had a laminectomy only (none of whom were included in the present series), two had complications that were related to the graft. One patient had slippage of the graft, which was reduced and closed and then healed after immobilization in a halo vest. A second patient had dislocation of the graft, which necessitated replacement. This eventually healed in a halo vest also.
In the second study, Herman and Sonntag5 reported on twenty patients with kyphosis and myelopathy or radiculopathy after a laminectomy who were managed with anterior decompression and application of a plate for the treatment of an anterior compressive lesion. Nineteen of these patients were managed with a corpectomy, one had a discectomy and arthrodesis at multiple levels, and all had anterior plate fixation. Seven of these patients had a one-level corpectomy, ten had a two-level corpectomy, two had a three-level corpectomy, and one had a discectomy and arthrodesis at three levels. There were seven complications (in six patients), including paresis of the vocal cords (three patients, one of whom also had a wound dehiscence), pneumonia (two patients, one of whom needed reintubation), and pull-out of screws (one patient, who was managed with replacement of the screws and immobilization in a halo vest for two months). Although the authors stated that all of their patients had evidence of radiographic fusion, they did not describe the methods for determining this. Also, they did not report on the prevalence of subsidence.
In the third study, McAfee et al.8 reported on 100 patients who were managed with anterior decompression and arthrodesis followed by immediate posterior stabilization of the cervical spine. The indications for the operation included traumatic, neoplastic, and miscellaneous etiologies. Although the authors did not clearly state how many of their patients had had a previous laminectomy, they noted that ten patients had severe kyphosis or a chin-on-chest deformity or had had a previous cervical laminectomy or laminaplasty. It cannot be determined from a review of their article whether any of the patients who had had a previous laminectomy had any complications. Overall, however, only two of the 100 patients had a pseudarthrosis and there were only eleven severe complications (in ten patients). Those authors concluded that, in patients who have preoperative instability, a one-stage combined anterior and posterior operation reduces the likelihood of perioperative complications.
Our results were comparable with those of Zdeblick and the senior one of us19, who reported two extrusions of the graft in seven patients who had had a corpectomy after a previous laminectomy. They recommended immobilization in a halo vest in order to help to prevent such complications. In the present series, we found that patients who had had an anterior corpectomy without instrumentation after a previous laminectomy were at great risk for graft-related complications despite the use of a halo vest. With the posterior elements removed, the anterior graft is the only structure that resists the tendency for the spine to fall back into a kyphotic alignment after a corrective operation. The graft, therefore, is subjected to substantial axial forces, increasing the risk of collapse or extrusion. Because immobilization in a halo vest does not prevent axial loading, it appears to be inadequate for preventing extrusion of the graft in this population of patients. This finding has not been reported previously, to our knowledge, and it is relevant in that it contradicts the recommendation previously made by Zdeblick and the senior one of us19, who advocated arthrodesis without instrumentation followed by postoperative immobilization in a halo vest for these patients.
The rate of complications in the present series was higher than the rate in the study by Herman and Sonntag5, who noted seven complications in six of their twenty patients. However, both studies included a relatively small number of patients, so the difference in the rates of complications may be insignificant. Also, most of their twenty patients were managed with a one or two-level corpectomy; only two of their patients had a three-level corpectomy, and none had a four-level corpectomy. In contrast, thirteen of our eighteen patients had a three or four-level corpectomy. The results of previous studies of cervical corpectomy in patients who had not had a previous laminectomy indicated that the rate of complications was associated with the number of levels included in the corpectomy2,13. Although it seems intuitive that the rate of complications will also be proportional to the number of corpectomies performed in patients who have had a previous laminectomy, with the numbers available in the present study no significant relationship could be detected (p < 0.3).
A second reason for the lower rate of complications in the series of Herman and Sonntag5 may be that an anterior plate was used in all twenty patients. Apparently, there were no graft-related complications, and all twenty patients had uneventful fusion. On the basis of the data of Herman and Sonntag, it seems that an anterior plate may provide enough stability to decrease the rate of graft-related complications after one-level and possibly two-level corpectomies in patients who have had a laminectomy. In these situations, the immediate enhancement of vertebral rigidity afforded by the plate may outweigh the risk of plate-related complications. However, anterior plate fixation of three or more levels presents its own set of complications2,3. In one report, seven of twenty-six patients who had plate fixation after a corpectomy of at least three levels subsequently had a pseudarthrosis2. The authors suggested that the plate prevented settling of the graft into the end plates, which, they hypothesized, might be necessary for fusion. In another series, Foley et al.3 reported four dislodged grafts and plates in thirty-nine patients who had been managed with a cervical corpectomy with anterior placement of a plate at multiple levels. In contrast, none of the eight patients in their series who were managed with a corpectomy and posterior cervical arthrodesis with instrumentation had displacement of the graft.
Because the spine is inherently even more unstable after a corpectomy preceded by a laminectomy than it is after a corpectomy only, a posterior cervical arthrodesis with instrumentation may help to decrease the prevalence of postoperative complications related to the graft. In the present study, two patients had a combined corpectomy and posterior facet arthrodesis and neither had extrusion or collapse of the graft. It is conceivable that the rate of complications might have been lower if all of our patients had been managed with posterior stabilization with use of a lateral-mass plate. Such an approach is supported by the results in the series of McAfee et al.8, in which a circumferential arthrodesis and posterior stabilization resulted in a far lower rate of graft-related complications.
One weakness of our study is the relatively short period of follow-up. With a longer follow-up period, there may actually have been a decreased rate of pseudarthrosis because patients who have had corpectomy and strut-grafting can continue to have consolidation of the graft for several years after the procedure. It is also possible that other complications, such as late fracture of the graft, infection, or failure of instrumentation, might have been identified if all of the patients had been followed for a minimum of two years. However, because we are reporting on the short-term complications of this procedure, we believe that the relatively short follow-up period is acceptable.
In conclusion, anterior cervical corpectomy and strut-grafting for patients who have had a laminectomy is associated with notable complications, including extrusion or collapse of the graft, or both, and pseudarthrosis. Immobilization in a halo vest appears to be inadequate for preventing extrusion after anterior procedures without instrumentation.
As a direct result of the present study, our approach to patients with these problems has changed. For a single-level corpectomy, augmentation with an anterior cervical plate, as advocated by Herman and Sonntag5, may be adequate. For reconstructions involving longer constructs, use of an anterior cervical plate may be associated with its own set of complications. On the basis of the findings of McAfee et al.8, our current approach to patients who need more than a single-level corpectomy and reconstruction after a previous laminectomy is to augment the construct with a posterior cervical arthrodesis and instrumentation. It is possible that this approach will decrease the risk of graft-related complications while increasing that of neurological or other complications, as the posterior aspect of the cord is no longer protected by laminae. Whether the overall rate and severity of complications will decrease remains to be determined. Although these procedures are challenging and fraught with potential complications, we believe that the final outcome may be worth the risks in most of these patients. Our finding, which we do not believe was reported previously, is relevant in that it contradicts the recommendation previously made by Zdeblick and the senior one of us19, who advocated postoperative immobilization in a halo vest for these patients.
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