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Preliminary experience with anterior cervical microdiscectomy and interbody titanium cage fusion (Novus CT-Ti) in patients with cervical disc disease
Spine
Preliminary Experience With Anterior Cervical Microdiscectomy and Interbody Titanium Cage Fusion (Novus CT-Ti) In Patients With Cervical Disc Disease Giovanni Profeta, M.D.,* Raffaele de Falco, M.D.,* Giuseppina Ianniciello, M.D.,* Luca Profeta, M.D.,* Alfredo Cigliano, M.D.,* and Ali I. Raja, M.D.† *Department of Neurosurgery, Cardarelli Hospital, Naples, Italy †Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois
Profeta G, de Falco R, Ianniciello G, Profeta L, Cigliano A, Raja AI. Preliminary experience with anterior cervical microdiscectomy and interbody titanium cage fusion (Novus CT-Ti) in patients with cervical disc disease. Surg Neurol 2000;53:417–26. BACKGROUND
Although the use of intervertebral fusion after anterior microdiscectomy in cervical disc disease remains controversial, a new surgical device is proposed for use in intervertebral fusion instead of bone graft. METHODS
This retrospective study at the Department of Neurosurgery, Cardarelli Hospital, Naples, from January 1993 to December 1998, compares the results of surgery on 58 patients with anterior microdiscectomy and intervertebral bone graft fusion (Group A) (ADIBG) with a group of 52 patients who underwent anterior microdiscectomy and intervertebral titanium cage fusion (Group B) (ADITC) in cervical radiculopathy and spondylotic myelopathy. In both groups a “radical discectomy” was performed under the operating microscope. In group A, interbody fusion was performed with autologous tricortical bone graft. In group B, a new type of titanium device (Novus CT-Ti) was used (Sofamor Danek Group). RESULTS
There was no collapse or extrusion of the device and no complications at the donor site (the bone fragments used to fill the cage were taken from osteophytes or vertebral body fragments). The use of this device provides immediate stabilization, reduces or eliminates pain, promotes bone fusion between the vertebrae adjacent to the cage by allowing bone growth through the cage, reestablishes and maintains the intervertebral space, reduces the average hospitalization time, and allows a quicker return to work.
Address reprint requests to: Prof. Giovanni Profeta, Via Petrarca 175, 80122 Napoli, Italy. Received October 11, 1999; accepted February 14, 2000. © 2000 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
CONCLUSIONS
Patients who underwent ADITC did well and benefited from the surgery. Those who underwent ADITC did better than those who underwent ADIBG in regard to function, relief from pain, and complications. Early and good stability of the cervical spine seems to be the main advantage of using titanium cages. © 2000 by Elsevier Science Inc. KEY WORDS
Anterior cervical discectomy with fusion, threaded titanium cage, cervical disc disease.
he clinical benefit of combining anterior cervical discectomy with interbody graft placement versus performing anterior cervical discectomy alone in cervical radiculopathy and spondylotic myelopathy remains controversial [4,6,10,13]. We have always been in favor of intervertebral fusion after anterior microdiscectomy. In our opinion, the advantages of fusion are stability of the cervical spine and preservation of the physiological lordosis. Procedures that do not employ fusion rely on nature to compensate for the defect. The consequent shortening of the interbody space makes narrowing of the intervertebral foramina unavoidable. Through distraction with an appropriately shaped bone graft, the intervertebral foramina become wider [7] and additional posterior decompression may be achieved by stretching the ligamentum flavum, enlarging the spinal canal [14]. Thorell described a group of 525 patients who underwent anterior cervical discectomy; 290 without interbody fusion and 235 with graft placement. The patients who underwent surgery with inter-
T
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stops spur formation, prevents the buckling of ligament flavum and decreases postoperative pain. The purpose of this study was to determine the clinical advantages of intervertebral graft placement using a titanium device (Novus CT-Ti) instead of autologus bone graft.
Patients and Methods
Intraoperative photograph of the completed resection of the vertebral margins and posterior longitudinal ligament. The dura is widely exposed.
1
body fusion reported fewer problems with pain than those who underwent surgery without interbody fusion [11]. Moreover, interbody fusion
Interbody fusion with autologus tricortical bone graft. (A) Graft taken from the iliac crest; (B) Graft modelled to a “roman nail” morphology; (C) Final interbody placement.
2
We analyzed the clinical outcome in a group of 58 patients (Group A) who underwent anterior cervical discectomy with interbody graft fusion (ADIBG) for cervical disc disease, versus a group of 52 patients (Group B) who underwent anterior cervical discectomy with interbody fusion using titanium cages (Novus CT-Ti) (ADITC) at the Department of Neurosurgery, Cardarelli Hospital, Naples. In Group A the patients underwent surgery between January 1993 and June 1997 (mean follow-up of 2 years). In group B the patients underwent surgery between July 1997 and May 1999 (4 –26 months follow-up; mean 16 months). We followed the patients with X-rays and CT for the assessment of stability, fusion, and degree of lordosis and with MRI for the evaluation of spinal cord decompression. We measured the postoperative lordosis in our patients who underwent surgery (Group B). We drew a straight line from the posterior circumference of the dens to the posteroinferior border of C7 and another line from the postero-inferior border of C4 perpendicular to the first line; its length measures the degree of lordosis in millimeters.
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Surgical Technique
Instrumentation set (Novus CT-Ti). (A) Guide protection sleeve; (B) Implant inserter; (C) Cage; (D) Reamer; (E) Graft impactor.
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4
In both groups surgical discectomy was performed under the operating microscope. The posterior longitudinal ligament was opened and resected. Thereafter we performed an additional removal of disc fragments penetrating the posterior longitudinal ligament, which are seen in the majority of ruptured discs. Furthermore, this procedure makes the removal of osteophytes much easier. Foraminal resection of uncovertebral joints was performed when clinical radiculopathy was present. This technique was defined as “radical” by Vise [12] (Figure 1). In Group A the interbody fusion was performed with autologous tricortical bone graft taken from the iliac crest. The graft was shaped according to a “roman nail” morphology (Figure 2 A, B). The purpose of this shape is to increase its stability, preventing collapse and extrusion. This was possible because the head of the bone graft was tricortical and therefore resistant to axial compression, and also because it was placed in the anterior part of the superior and inferior bodies (Figure 2 C). In Group B a new type of metallic device (Novus CT-Ti threaded titanium cage) was used (Sofamor
(A) Correct position of cage on X-ray (lateral view at C4-C5 level); (B) antero-posterior view at C5-C6 level.
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(A) Preoperative MRI showing multilevel spondylosis (C4-C5 and C5-C6); (B) Postoperative MRI: note anterior and posterior decompression; (C) Postoperative lateral X-ray after 12 months: good position of the cages and lordosis.
Interbody Titanium Cage Fusion
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Patient Demographics and Presentation
GROUP A 58 PATIENTS
GROUP B 52 PATIENTS
49 32/26
51 31/21
30 28
26 26
Average age in years Male/female Presentation: Radiculopathy Myelopathy
Danek Group, Memphis, Tennessee). The aim of this device is to maintain the cervical interbody geometry, to preserve the physiological lordosis during fusion, preventing collapse, and to eliminate complications at the donor site. The cage is available in various lengths and diameters and has a threaded conical shape. It is inserted between the cervical bodies and provides support and good stabilization after radical microdiscectomy (Figure 3). The size of cage to be inserted is determined intraoperatively according to the height of the disc space distraction. We performed intervertebral distraction and discectomy using standard anterior cervical instruments. The end plates are prepared by removing the cortical cartilaginous layers. This step is important to ensure good contact between the cage and vertebral bodies and thus stability of the implant. The sleeve diameter is chosen according to the diameter of the cage to be used. It is introduced between the end plates as perpendicular as possible to their surfaces and the spikes are impacted into the upper and lower vertebral bodies. The spikes will maintain the vertebral bodies in place during reaming. Once the reamer corresponding to the diameter of the space is selected, it is inserted in the sleeve and drilling is performed until the stop is reached. After reaming, the sleeve and bone fragments are removed. The graft impacter is used to gently compact the bone fragments into the implant to ensure that it is completely filled with bone prior to insertion. Autogenous bone fragments are taken
2
Number of Levels Involved
LEVELS
GROUP A
GROUP B
C3-C4 C4-C5 C5-C6 C6-C7 Total
4 12 22 20 58
5 21 36 15 77
Total Levels Operated Upon Through Radical Microsurgical Anterior Discectomy
Total levels operated on Total operation Number of patients: with radiculopathy with myelopathy Spine level of operation one level two levels three levels Level reoperated
GROUP A 58 PATIENTS
GROUP B 52 PATIENTS
58 58
77 52
30 28
26 26
58 0 0 1
30 19 3 0
from pathological bone osteophytes at the vertebral margins and from the drilling of the bodies. At the end of the insertion process the handle must be perpendicular to the spine and parallel to the disc space, to have a well positioned hole (Figure 4 A, B). One cage is used for each level. When grafting is performed at multiple levels, all the discectomies must be completed before the cages are implanted (Figure 5 A, B, C).
Results From January 1993 to May 1999 two different groups of patients underwent surgery for cervical spondylotic disease with anterior radical microdiscectomy
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Postoperative Evaluation Criteria and Results
Improvement of radiculopathy Neck and arm pain Neurological deficit: Recovered Moderate improvement Unimproved Improvement of myelopathy: Recovered Moderate improvement Unimproved Maintenance of disc height Physiological lordosis Hospitalization time (mean)
GROUP A 58 PATIENTS
GROUP B 52 PATIENTS
24/30
24/26
23/30 5/30
23/26 2/26
2/30
1/26
15/28 8/28
18/26 5/26
5/28 48/58
3/26 49/52
30/58 8 days
44/52 4 days
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COMPLICATIONS
GROUP A 58 PATIENTS
GROUP B 52 PATIENTS
Dysphagia Infection Graft extrusion Space collapse Change in voice At donor site Postoperative instability Slight local deformity
4 0 0 3 1 12 1 6
4 0 0 0 0 0 0 3
and fusion. Group A (58 patients) underwent fusion with tricortical bone graft; Group B (52 patients) underwent interbody fusion with the titanium Novus CT-Ti cage. Demographic and clinical data are provided in Table 1. The clinical disc disease was defined as intractable radiculopathy or myelopathy due to nerve root or spinal cord compression. The most common level involved was C5-C6. Other levels commonly involved were C6-C7 in
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Radiological Results of Surgery at 19 Months in 52 Patients with Single or Multilevel Cervical Anterior Discectomy and Titanium Cage Fusion
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Postoperative Complications
Cage position Stability Lordosis Fusion Decompression
GOOD
FAIR
49 52 46 52 52
3 0 6 0 0
Group A and C4-C5 in Group B. Table 2 summarizes the number of levels involved. Table 3 summarizes the total levels operated upon through radical anterior microdiscectomy. The postoperative assessment criteria for the evaluation of patient outcome were: decrease in pain, variation in neurological condition, maintenance of disc height, restoration of physiological lordosis, and time of hospitalization (Table 4). Postoperative complications and radiological findings are shown in Tables 5 and 6. In Group A bone graft resorption was seen with a space narrowing of 15%, and in three cases we
(A) Preoperative lateral X-ray shows the disappearance of normal cervical lordosis; (B) Same case: good lordosis and correct alignment after two-level microdiscectomy (C4-C5 and C5-C6) and Novus CT-Ti fusion.
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Scheme for evaluation of lordosis. We drew a straight line from the posterior circumference of the dens to the posterior-inferior border of C7 and another line from the posterior-inferior border of C4 perpendicular to the first line. Its length is the measurement of lordosis in millimeters. If the latter is 0, the cervical spine is straight and no lordosis is present. A negative measurement indicates cervical kyphosis.
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observed collapse of the interspace (Table 5). These events were seen in the initial few months after the operation (there was no space change after 6 months in our series). In the cases with space narrowing we saw a 22.4% rate of cervical symptom recurrence (neck pain) and in the three patients with space collapse (complete loss of the disc space) cervical symptoms recurred in all cases and arm pain only in one. In Group B we have seen neither space narrowing nor collapse and the rate of cervical symptom recurrence was 5.7%. Most of the patients who had radiculopathy are free from pain, and many patients who had myelopathy have made a good recovery.
Discussion The anterior cervical discectomy is considered the procedure of choice for the treatment of segmental
Linear Measures of Cervical Lordosis in 52 Patients With Interbody Titanium Cage Fusion
NO. OF PATIENTS
LORDOSIS
3 22 21 3 3
16 mm 9–13 mm 6–8 mm 4–5 mm 0 mm
degenerative disease of the cervical spine without spinal canal stenosis. Cloward, Robinson and Smith, and Baryley first described an anterior discectomy combined with bone graft placement [1,3,9]. There is no doubt that anterior discectomy with interbody fusion removes the source of compression and immediately relieves pain in most patients. Murphy has shown that the bone graft distracts the disc space, increases the size of intervertebral foramina at the appropriate level and prevents postoperative settling [7]. The segmental distraction eliminates abnormal stimuli coming from stretch receptors in the muscles, joint capsules and skeletal structures of the cervical spine, that produce an increase in muscle tone involving adjacent segments. The removal of this stimulation decreases the muscle tone and reestablishes the cervical lordosis [8] (Figure 6 A, B). Boreadis examined the cervical lordosis in 90 men and 90 women ranging in age from 21 to 80 years. In 98% the lordosis measured 11.8 mm and the limits were ⫾5 [2]. The linear measures of the postoperative lordosis calculated in our patients with the method previously described (Figure 7) are provided in Table 7 (Figure 8 A, B). In our series, the use of the titanium cage post discectomy has offered further advantages including the absence of complications at the donor site, easier implantation technique, and good immediate and long-term stabilization. Although fusion through the cage is difficult to show with the usual radiological techniques, signs of osseous consolidation can be detected around the cage. Furthermore, it may be deduced from the long-term stability and absence of bone rarefaction around the cage (Figure 9). An interesting question is whether complete corpectomy is necessary in cervical spondylotic myelopathy with segmental multilevel compression and whether multilevel radical discectomy and osteophytectomy might achieve the same results [5]. We have performed in three cases, with good results, multilevel discectomy for spondylotic my-
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(A) Preoperative lateral X-ray: note the absence of lordosis; (B) Two-level microdiscectomy (C3-C4 and C4-C5) and Novus CT-Ti cage fusion achieved 10 mm of lordosis.
elopathy with titanium cage fusion (Figure 10 A, B), although it is argued that the possibility of pseudoarthrosis is increased with multiple bone fusion [10,13]. In our experience with multilevel discectomy, we have obtained good stability and adequate decompression by osteophyte removal. Therefore, it is our personal preference to perform, when possible, multiple discectomies rather than corpectomies in segmental multilevel cervical disease.
Conclusions In conclusion, a new type of metallic device, the Novus CT-Ti threaded cage, has been designed to provide stabilization and promote bone fusion during the normal healing process following surgical correction of cervical disc disease. The goal of this device is to maintain the cervical interbody geometry during fusion and to prevent disc space collapse. Our early experience has shown immediate postoperative stability and preservation of the intervertebral space until fusion has occurred. This procedure avoids the need to take a bone
graft from the anterior iliac crest and allows a shortened hospital stay. It is still to be verified in a longer follow-up if there is a possibility of recurrent pain, if the lordosis is stable over time, and if spondylosis or disc extrusion can arise at a level adjacent to the fusion.
REFERENCES 1. Baryley RW, Badgley CE. Stabilization of the cervical spine by anterior fusion. J Bone Joint Surg Am 1960; 42:565–94. 2. Boreadis AG, Rechtman AM, Gershon–Cohen J. The normal cervical lordosis. Radiology 1960;74:806 –9. 3. Cloward RB. The anterior approach for removal of ruptured cervical discs. J Neurosurg 1958;15:602–17. 4. Cuatico W. Anterior cervical discectomy without interbody fusion: An analysis of 81 cases. Acta Neurochir (Wien) 1981;57:269 –74. 5. Fessler RG, Steck JC, Giovanini MA. Anterior cervical corpectomy for cervical spondylotic myelopathy. Neurosurgery 1998;43:257– 67. 6. Hankinson HL, Wilson CB. Use of operating microscope in anterior cervical discectomy without fusion. J Neurosurg 1975;43:452– 6. 7. Murphy MA, Trimble MB, Piedmonte MR, Kalfas IH. Changes in the cervical foraminal area after anterior
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9. 10. 11.
12.
13. 14.
schmerz. In: Hohmann D, Ku ¨ gelgen B, Liebig K. ¨ bergangs. Erkrankungen des zervikookzipitalen U Spondylolisthesis. Wirbelsa¨ule in arbeit und beruf. Berlin Springer, 1988:83–101. Smith GW, Robinson RA. Anterolateral cervical disc removal and interbody fusion for cervical disc syndrome. Bull Johns Hopkins Med Soc 1955;96:223–24. Sonntag VKH, Klara P. Controversy in spine care: is fusion necessary after anterior cervical discectomy? Spine 1996;21:1111–3. Thorell W, Cooper J, Hellbusch L, Leibrock L. The long term clinical outcome of patients undergoing anterior cervical discectomy with and without intervertebral bone graft placement. Neurosurgery 1998; 43:268 –74. Vise WM. Anterior discectomy without fusion for soft cervical disc herniation. In: Origitano TC, Al Mefty O. Controversies in neurosurgery. New York, Thieme, 1996:228 – 45. Watters WC III, Levinthal R. Anterior cervical discectomy with and without fusion: results, complications, and long-term follow-up. Spine 1994;19:2343–7. White AA, Panjabi MM. Clinical biomechanics of the spine ed. 2. Philadelphia, JB Lippincott, 1990.
COMMENTARY
Postoperative lateral cervical x-ray after 15 months: note the fusion around the cages.
The collapse of a cervical interbody graft is a problem which can result in the recurrence of a patient’s symptoms. The use of a metal device such as that employed by the authors in the present study may prevent that from happening. Additional follow-up in their group of patients would be of interest.
discectomy with and without a graft. Neurosurgery 1994;34:93– 6. 8. Pfafferath V, Dandekar R. Der zarvikogene kopf-
Franklin C. Wagner, Jr., M.D. Department of Neurosurgery University of Illinois at Chicago Chicago, Illinois
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(A) Preoperative lateral x-ray showing multilevel spondylosis: note the cervical kyphosis; (B) After three-level radical microdiscectomy and fusion with Novus CT-Ti cages. Note the restoration of lordosis.
Preliminary Experience With Anterior Cervical Microdiscectomy and Interbody Titanium Cage Fusion (Novus CT-Ti) In Patients With Cervical Disc Disease Giovanni Profeta, M.D.,* Raffaele de Falco, M.D.,* Giuseppina Ianniciello, M.D.,* Luca Profeta, M.D.,* Alfredo Cigliano, M.D.,* and Ali I. Raja, M.D.† *Department of Neurosurgery, Cardarelli Hospital, Naples, Italy †Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois
Profeta G, de Falco R, Ianniciello G, Profeta L, Cigliano A, Raja AI. Preliminary experience with anterior cervical microdiscectomy and interbody titanium cage fusion (Novus CT-Ti) in patients with cervical disc disease. Surg Neurol 2000;53:417–26. BACKGROUND
Although the use of intervertebral fusion after anterior microdiscectomy in cervical disc disease remains controversial, a new surgical device is proposed for use in intervertebral fusion instead of bone graft. METHODS
This retrospective study at the Department of Neurosurgery, Cardarelli Hospital, Naples, from January 1993 to December 1998, compares the results of surgery on 58 patients with anterior microdiscectomy and intervertebral bone graft fusion (Group A) (ADIBG) with a group of 52 patients who underwent anterior microdiscectomy and intervertebral titanium cage fusion (Group B) (ADITC) in cervical radiculopathy and spondylotic myelopathy. In both groups a “radical discectomy” was performed under the operating microscope. In group A, interbody fusion was performed with autologous tricortical bone graft. In group B, a new type of titanium device (Novus CT-Ti) was used (Sofamor Danek Group). RESULTS
There was no collapse or extrusion of the device and no complications at the donor site (the bone fragments used to fill the cage were taken from osteophytes or vertebral body fragments). The use of this device provides immediate stabilization, reduces or eliminates pain, promotes bone fusion between the vertebrae adjacent to the cage by allowing bone growth through the cage, reestablishes and maintains the intervertebral space, reduces the average hospitalization time, and allows a quicker return to work.
Address reprint requests to: Prof. Giovanni Profeta, Via Petrarca 175, 80122 Napoli, Italy. Received October 11, 1999; accepted February 14, 2000. © 2000 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
CONCLUSIONS
Patients who underwent ADITC did well and benefited from the surgery. Those who underwent ADITC did better than those who underwent ADIBG in regard to function, relief from pain, and complications. Early and good stability of the cervical spine seems to be the main advantage of using titanium cages. © 2000 by Elsevier Science Inc. KEY WORDS
Anterior cervical discectomy with fusion, threaded titanium cage, cervical disc disease.
he clinical benefit of combining anterior cervical discectomy with interbody graft placement versus performing anterior cervical discectomy alone in cervical radiculopathy and spondylotic myelopathy remains controversial [4,6,10,13]. We have always been in favor of intervertebral fusion after anterior microdiscectomy. In our opinion, the advantages of fusion are stability of the cervical spine and preservation of the physiological lordosis. Procedures that do not employ fusion rely on nature to compensate for the defect. The consequent shortening of the interbody space makes narrowing of the intervertebral foramina unavoidable. Through distraction with an appropriately shaped bone graft, the intervertebral foramina become wider [7] and additional posterior decompression may be achieved by stretching the ligamentum flavum, enlarging the spinal canal [14]. Thorell described a group of 525 patients who underwent anterior cervical discectomy; 290 without interbody fusion and 235 with graft placement. The patients who underwent surgery with inter-
T
0090-3019/00/$–see front matter PII S0090-3019(00)00207-X
418 Surg Neurol 2000;53:417–26
Profeta et al
stops spur formation, prevents the buckling of ligament flavum and decreases postoperative pain. The purpose of this study was to determine the clinical advantages of intervertebral graft placement using a titanium device (Novus CT-Ti) instead of autologus bone graft.
Patients and Methods
Intraoperative photograph of the completed resection of the vertebral margins and posterior longitudinal ligament. The dura is widely exposed.
1
body fusion reported fewer problems with pain than those who underwent surgery without interbody fusion [11]. Moreover, interbody fusion
Interbody fusion with autologus tricortical bone graft. (A) Graft taken from the iliac crest; (B) Graft modelled to a “roman nail” morphology; (C) Final interbody placement.
2
We analyzed the clinical outcome in a group of 58 patients (Group A) who underwent anterior cervical discectomy with interbody graft fusion (ADIBG) for cervical disc disease, versus a group of 52 patients (Group B) who underwent anterior cervical discectomy with interbody fusion using titanium cages (Novus CT-Ti) (ADITC) at the Department of Neurosurgery, Cardarelli Hospital, Naples. In Group A the patients underwent surgery between January 1993 and June 1997 (mean follow-up of 2 years). In group B the patients underwent surgery between July 1997 and May 1999 (4 –26 months follow-up; mean 16 months). We followed the patients with X-rays and CT for the assessment of stability, fusion, and degree of lordosis and with MRI for the evaluation of spinal cord decompression. We measured the postoperative lordosis in our patients who underwent surgery (Group B). We drew a straight line from the posterior circumference of the dens to the posteroinferior border of C7 and another line from the postero-inferior border of C4 perpendicular to the first line; its length measures the degree of lordosis in millimeters.
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Surgical Technique
Instrumentation set (Novus CT-Ti). (A) Guide protection sleeve; (B) Implant inserter; (C) Cage; (D) Reamer; (E) Graft impactor.
3
4
In both groups surgical discectomy was performed under the operating microscope. The posterior longitudinal ligament was opened and resected. Thereafter we performed an additional removal of disc fragments penetrating the posterior longitudinal ligament, which are seen in the majority of ruptured discs. Furthermore, this procedure makes the removal of osteophytes much easier. Foraminal resection of uncovertebral joints was performed when clinical radiculopathy was present. This technique was defined as “radical” by Vise [12] (Figure 1). In Group A the interbody fusion was performed with autologous tricortical bone graft taken from the iliac crest. The graft was shaped according to a “roman nail” morphology (Figure 2 A, B). The purpose of this shape is to increase its stability, preventing collapse and extrusion. This was possible because the head of the bone graft was tricortical and therefore resistant to axial compression, and also because it was placed in the anterior part of the superior and inferior bodies (Figure 2 C). In Group B a new type of metallic device (Novus CT-Ti threaded titanium cage) was used (Sofamor
(A) Correct position of cage on X-ray (lateral view at C4-C5 level); (B) antero-posterior view at C5-C6 level.
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(A) Preoperative MRI showing multilevel spondylosis (C4-C5 and C5-C6); (B) Postoperative MRI: note anterior and posterior decompression; (C) Postoperative lateral X-ray after 12 months: good position of the cages and lordosis.
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Patient Demographics and Presentation
GROUP A 58 PATIENTS
GROUP B 52 PATIENTS
49 32/26
51 31/21
30 28
26 26
Average age in years Male/female Presentation: Radiculopathy Myelopathy
Danek Group, Memphis, Tennessee). The aim of this device is to maintain the cervical interbody geometry, to preserve the physiological lordosis during fusion, preventing collapse, and to eliminate complications at the donor site. The cage is available in various lengths and diameters and has a threaded conical shape. It is inserted between the cervical bodies and provides support and good stabilization after radical microdiscectomy (Figure 3). The size of cage to be inserted is determined intraoperatively according to the height of the disc space distraction. We performed intervertebral distraction and discectomy using standard anterior cervical instruments. The end plates are prepared by removing the cortical cartilaginous layers. This step is important to ensure good contact between the cage and vertebral bodies and thus stability of the implant. The sleeve diameter is chosen according to the diameter of the cage to be used. It is introduced between the end plates as perpendicular as possible to their surfaces and the spikes are impacted into the upper and lower vertebral bodies. The spikes will maintain the vertebral bodies in place during reaming. Once the reamer corresponding to the diameter of the space is selected, it is inserted in the sleeve and drilling is performed until the stop is reached. After reaming, the sleeve and bone fragments are removed. The graft impacter is used to gently compact the bone fragments into the implant to ensure that it is completely filled with bone prior to insertion. Autogenous bone fragments are taken
2
Number of Levels Involved
LEVELS
GROUP A
GROUP B
C3-C4 C4-C5 C5-C6 C6-C7 Total
4 12 22 20 58
5 21 36 15 77
Total Levels Operated Upon Through Radical Microsurgical Anterior Discectomy
Total levels operated on Total operation Number of patients: with radiculopathy with myelopathy Spine level of operation one level two levels three levels Level reoperated
GROUP A 58 PATIENTS
GROUP B 52 PATIENTS
58 58
77 52
30 28
26 26
58 0 0 1
30 19 3 0
from pathological bone osteophytes at the vertebral margins and from the drilling of the bodies. At the end of the insertion process the handle must be perpendicular to the spine and parallel to the disc space, to have a well positioned hole (Figure 4 A, B). One cage is used for each level. When grafting is performed at multiple levels, all the discectomies must be completed before the cages are implanted (Figure 5 A, B, C).
Results From January 1993 to May 1999 two different groups of patients underwent surgery for cervical spondylotic disease with anterior radical microdiscectomy
4
Postoperative Evaluation Criteria and Results
Improvement of radiculopathy Neck and arm pain Neurological deficit: Recovered Moderate improvement Unimproved Improvement of myelopathy: Recovered Moderate improvement Unimproved Maintenance of disc height Physiological lordosis Hospitalization time (mean)
GROUP A 58 PATIENTS
GROUP B 52 PATIENTS
24/30
24/26
23/30 5/30
23/26 2/26
2/30
1/26
15/28 8/28
18/26 5/26
5/28 48/58
3/26 49/52
30/58 8 days
44/52 4 days
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COMPLICATIONS
GROUP A 58 PATIENTS
GROUP B 52 PATIENTS
Dysphagia Infection Graft extrusion Space collapse Change in voice At donor site Postoperative instability Slight local deformity
4 0 0 3 1 12 1 6
4 0 0 0 0 0 0 3
and fusion. Group A (58 patients) underwent fusion with tricortical bone graft; Group B (52 patients) underwent interbody fusion with the titanium Novus CT-Ti cage. Demographic and clinical data are provided in Table 1. The clinical disc disease was defined as intractable radiculopathy or myelopathy due to nerve root or spinal cord compression. The most common level involved was C5-C6. Other levels commonly involved were C6-C7 in
6
Radiological Results of Surgery at 19 Months in 52 Patients with Single or Multilevel Cervical Anterior Discectomy and Titanium Cage Fusion
6
Postoperative Complications
Cage position Stability Lordosis Fusion Decompression
GOOD
FAIR
49 52 46 52 52
3 0 6 0 0
Group A and C4-C5 in Group B. Table 2 summarizes the number of levels involved. Table 3 summarizes the total levels operated upon through radical anterior microdiscectomy. The postoperative assessment criteria for the evaluation of patient outcome were: decrease in pain, variation in neurological condition, maintenance of disc height, restoration of physiological lordosis, and time of hospitalization (Table 4). Postoperative complications and radiological findings are shown in Tables 5 and 6. In Group A bone graft resorption was seen with a space narrowing of 15%, and in three cases we
(A) Preoperative lateral X-ray shows the disappearance of normal cervical lordosis; (B) Same case: good lordosis and correct alignment after two-level microdiscectomy (C4-C5 and C5-C6) and Novus CT-Ti fusion.
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Scheme for evaluation of lordosis. We drew a straight line from the posterior circumference of the dens to the posterior-inferior border of C7 and another line from the posterior-inferior border of C4 perpendicular to the first line. Its length is the measurement of lordosis in millimeters. If the latter is 0, the cervical spine is straight and no lordosis is present. A negative measurement indicates cervical kyphosis.
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observed collapse of the interspace (Table 5). These events were seen in the initial few months after the operation (there was no space change after 6 months in our series). In the cases with space narrowing we saw a 22.4% rate of cervical symptom recurrence (neck pain) and in the three patients with space collapse (complete loss of the disc space) cervical symptoms recurred in all cases and arm pain only in one. In Group B we have seen neither space narrowing nor collapse and the rate of cervical symptom recurrence was 5.7%. Most of the patients who had radiculopathy are free from pain, and many patients who had myelopathy have made a good recovery.
Discussion The anterior cervical discectomy is considered the procedure of choice for the treatment of segmental
Linear Measures of Cervical Lordosis in 52 Patients With Interbody Titanium Cage Fusion
NO. OF PATIENTS
LORDOSIS
3 22 21 3 3
16 mm 9–13 mm 6–8 mm 4–5 mm 0 mm
degenerative disease of the cervical spine without spinal canal stenosis. Cloward, Robinson and Smith, and Baryley first described an anterior discectomy combined with bone graft placement [1,3,9]. There is no doubt that anterior discectomy with interbody fusion removes the source of compression and immediately relieves pain in most patients. Murphy has shown that the bone graft distracts the disc space, increases the size of intervertebral foramina at the appropriate level and prevents postoperative settling [7]. The segmental distraction eliminates abnormal stimuli coming from stretch receptors in the muscles, joint capsules and skeletal structures of the cervical spine, that produce an increase in muscle tone involving adjacent segments. The removal of this stimulation decreases the muscle tone and reestablishes the cervical lordosis [8] (Figure 6 A, B). Boreadis examined the cervical lordosis in 90 men and 90 women ranging in age from 21 to 80 years. In 98% the lordosis measured 11.8 mm and the limits were ⫾5 [2]. The linear measures of the postoperative lordosis calculated in our patients with the method previously described (Figure 7) are provided in Table 7 (Figure 8 A, B). In our series, the use of the titanium cage post discectomy has offered further advantages including the absence of complications at the donor site, easier implantation technique, and good immediate and long-term stabilization. Although fusion through the cage is difficult to show with the usual radiological techniques, signs of osseous consolidation can be detected around the cage. Furthermore, it may be deduced from the long-term stability and absence of bone rarefaction around the cage (Figure 9). An interesting question is whether complete corpectomy is necessary in cervical spondylotic myelopathy with segmental multilevel compression and whether multilevel radical discectomy and osteophytectomy might achieve the same results [5]. We have performed in three cases, with good results, multilevel discectomy for spondylotic my-
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(A) Preoperative lateral X-ray: note the absence of lordosis; (B) Two-level microdiscectomy (C3-C4 and C4-C5) and Novus CT-Ti cage fusion achieved 10 mm of lordosis.
elopathy with titanium cage fusion (Figure 10 A, B), although it is argued that the possibility of pseudoarthrosis is increased with multiple bone fusion [10,13]. In our experience with multilevel discectomy, we have obtained good stability and adequate decompression by osteophyte removal. Therefore, it is our personal preference to perform, when possible, multiple discectomies rather than corpectomies in segmental multilevel cervical disease.
Conclusions In conclusion, a new type of metallic device, the Novus CT-Ti threaded cage, has been designed to provide stabilization and promote bone fusion during the normal healing process following surgical correction of cervical disc disease. The goal of this device is to maintain the cervical interbody geometry during fusion and to prevent disc space collapse. Our early experience has shown immediate postoperative stability and preservation of the intervertebral space until fusion has occurred. This procedure avoids the need to take a bone
graft from the anterior iliac crest and allows a shortened hospital stay. It is still to be verified in a longer follow-up if there is a possibility of recurrent pain, if the lordosis is stable over time, and if spondylosis or disc extrusion can arise at a level adjacent to the fusion.
REFERENCES 1. Baryley RW, Badgley CE. Stabilization of the cervical spine by anterior fusion. J Bone Joint Surg Am 1960; 42:565–94. 2. Boreadis AG, Rechtman AM, Gershon–Cohen J. The normal cervical lordosis. Radiology 1960;74:806 –9. 3. Cloward RB. The anterior approach for removal of ruptured cervical discs. J Neurosurg 1958;15:602–17. 4. Cuatico W. Anterior cervical discectomy without interbody fusion: An analysis of 81 cases. Acta Neurochir (Wien) 1981;57:269 –74. 5. Fessler RG, Steck JC, Giovanini MA. Anterior cervical corpectomy for cervical spondylotic myelopathy. Neurosurgery 1998;43:257– 67. 6. Hankinson HL, Wilson CB. Use of operating microscope in anterior cervical discectomy without fusion. J Neurosurg 1975;43:452– 6. 7. Murphy MA, Trimble MB, Piedmonte MR, Kalfas IH. Changes in the cervical foraminal area after anterior
Interbody Titanium Cage Fusion
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schmerz. In: Hohmann D, Ku ¨ gelgen B, Liebig K. ¨ bergangs. Erkrankungen des zervikookzipitalen U Spondylolisthesis. Wirbelsa¨ule in arbeit und beruf. Berlin Springer, 1988:83–101. Smith GW, Robinson RA. Anterolateral cervical disc removal and interbody fusion for cervical disc syndrome. Bull Johns Hopkins Med Soc 1955;96:223–24. Sonntag VKH, Klara P. Controversy in spine care: is fusion necessary after anterior cervical discectomy? Spine 1996;21:1111–3. Thorell W, Cooper J, Hellbusch L, Leibrock L. The long term clinical outcome of patients undergoing anterior cervical discectomy with and without intervertebral bone graft placement. Neurosurgery 1998; 43:268 –74. Vise WM. Anterior discectomy without fusion for soft cervical disc herniation. In: Origitano TC, Al Mefty O. Controversies in neurosurgery. New York, Thieme, 1996:228 – 45. Watters WC III, Levinthal R. Anterior cervical discectomy with and without fusion: results, complications, and long-term follow-up. Spine 1994;19:2343–7. White AA, Panjabi MM. Clinical biomechanics of the spine ed. 2. Philadelphia, JB Lippincott, 1990.
COMMENTARY
Postoperative lateral cervical x-ray after 15 months: note the fusion around the cages.
The collapse of a cervical interbody graft is a problem which can result in the recurrence of a patient’s symptoms. The use of a metal device such as that employed by the authors in the present study may prevent that from happening. Additional follow-up in their group of patients would be of interest.
discectomy with and without a graft. Neurosurgery 1994;34:93– 6. 8. Pfafferath V, Dandekar R. Der zarvikogene kopf-
Franklin C. Wagner, Jr., M.D. Department of Neurosurgery University of Illinois at Chicago Chicago, Illinois
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(A) Preoperative lateral x-ray showing multilevel spondylosis: note the cervical kyphosis; (B) After three-level radical microdiscectomy and fusion with Novus CT-Ti cages. Note the restoration of lordosis.