The Journal of Bone & Joint Surgery

The Journal of Bone & Joint Surgery, Volume 87, Issue 3

Scientific Articles | March 01, 2005

Development of Adjacent-Level Ossification in Patients with an Anterior Cervical Plate

Jong-Beom Park, MD, PhD¹; Yong-Sun Cho, MD¹; K. Daniel Riew, MD¹

¹ Department of Orthopaedic Surgery, Barnes-Jewish Hospital at Washington University School of Medicine, One Barnes-Jewish Hospital Plaza, Suite 11300 West Pavilion, St. Louis, MO 63110. E-mail address for K.D. Riew: riewd@wustl.edu

View Disclosures and Other Information

The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

Investigation performed at the Cervical Spine Service, Department of Orthopaedic Surgery, Barnes-Jewish Hospital at Washington University School of Medicine, St. Louis, Missouri

The Journal of Bone and Joint Surgery, Incorporated

J Bone Joint Surg Am, 2005 Mar 01;87(3):558-563. doi: 10.2106/JBJS.C.01555

5 Recommendations (Recommend) | 3 Comments | Saved by 3 Users Save Case

Article

Comments (1)

text A A A

Abstract

Background: It has been our experience that ossification occurs adjacent to anterior cervical plates. Our hypothesis was that the closer the plate is to the adjacent disc space, the greater the ossification.

Methods: We retrospectively reviewed the lateral radiographs of the cervical spine of 118 patients who had a solid fusion following an anterior cervical arthrodesis with a plate for the treatment of a degenerative cervical condition; none of the patients had had cervical spine surgery prior to the index arthrodesis. The plate-to-disc distance was measured on the postoperative lateral radiograph and was used to divide the patients into two groups for each of the two adjacent disc spaces. In group A the plate-to-disc distance was <5 mm, and in group B it was =5 mm. The mean duration of follow-up was 25.7 months. The severity of the ossification at the two adjacent disc spaces was classified on a scale ranging from grade 0 (no ossification) to grade 3 (complete bridging). Eighteen patients were excluded from the measurement of the severity of the caudal ossification because overlapping by the bone of the shoulder precluded adequate visualization of the caudal level.

Results: Ossification developed in seventy (59%) of the 118 cephalad adjacent disc spaces and twenty-nine (29%) of the 100 caudal adjacent disc spaces (p < 0.001). The mean cephalad plate-to-disc distance was shorter than the mean caudal plate-to-disc distance (p < 0.001). The rate of ossification was higher in group A than in group B, both at the cephalad adjacent disc spaces (67% compared with 24%) and at the caudal adjacent disc spaces (45% compared with 5%) (both p < 0.001). In addition, 93% (twenty-six) of the twenty-eight cases of moderate-to-severe ossification developed in group A.

Conclusions: We found a positive association between adjacent-level ossification following anterior cervical plate procedures and the plate-to-disc distance. We now strive to place anterior cervical plates at least 5 mm away from the adjacent disc spaces in order to decrease the likelihood of moderate-to-severe adjacent-level ossification.

Level of Evidence: Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

Figures in this Article

Anterior cervical plates are effective in achieving immediate stability, restoring the normal lordotic curve, and increasing fusion rates^1-4. However, the development of late adjacent-level degenerative changes, such as anterior osteophyte formation or ossification of the anterior longitudinal ligament, has been reported following anterior cervical arthrodesis^5-11. Furthermore, there have been few studies concerning the association of anterior cervical plates and late degenerative changes. Goffin et al. found late degenerative changes at the disc levels adjacent to the fused area in fifteen of twenty-five patients with fractures and/or dislocations of the cervical spine, and they recommended the use of the shortest plate possible to avoid extending the plate into adjacent discs¹². Mähring described two types of anterior spondylophyte formation—"noses" and "bridges"—at segments adjacent to the fusion and stressed that careful operative technique can decrease postoperative spondylophyte formation at segments adjacent to a fusion¹³.

It has been the experience of the senior author (K.D.R.) that ossification commonly occurs at the motion segments adjacent to anterior cervical plates used to treat degenerative cervical disc conditions, especially when the plates were placed close to an adjacent disc space. To our knowledge, however, no one has previously examined the relationship between plateto-disc distance and peri-plate ossification. We therefore undertook the current study to analyze that relationship.

Materials and Methods

Materials and Methods | Results | Discussion | References

One hundred and eighteen patients who had a solid fusion following an anterior cervical arthrodesis with a plate for the management of a degenerative cervical condition, who had had no previous cervical spine surgery, and who had been followed for a minimum of one year were identified from a database for inclusion in this study. Patients who had had preoperative anterior osteophytes cephalad or caudad to the level subsequently treated with the anterior cervical plate were excluded from the study. All of the surgical procedures were performed by the senior author (K.D.R.). The criteria used to define fusion were no radiolucency between the graft and the vertebral body, bridging osseous trabeculae, and <1 mm of motion between the tips of the posterior spinous processes of the fused segments on flexion and extension lateral radiographs of the cervical spine. Sixty-four of the patients were men, and fifty-four were women. The mean age at the time of surgery was 51.8 years (range, thirty-two to seventy-six years). The mean duration of postoperative follow-up was 25.7 months (range, twelve to seventy-six months). The diagnosis was cervical spondylotic radiculopathy in forty-eight patients, cervical disc herniation in twenty-two, a combination of cervical spondylotic radiculopathy and cervical disc herniation in twenty-eight, and cervical spondylotic myeloradiculopathy in twenty. Thirty-six patients underwent the arthrodesis at one level; forty-seven, at two levels; thirty-two, at three levels; and three, at four levels.

The radiographs of the cervical spine were made with the standard tube-to-film distance (1.8 m) for all patients. All of the radiographic analyses were performed independently by two experienced spine surgeons who were not involved in the patients' care. The distances between the tips of the plate and the caudal as well as the cephalad adjacent disc (plate-to-disc distance) were measured on the immediate postoperative lateral radiograph of the cervical spine (Figs. 1-A and 1-B). The distances were used to divide the patients into two groups for each of the cephalad and caudal adjacent disc spaces. In group A the plate-to-disc distance was <5 mm, and in group B it was =5 mm. The severity of the ossification at the cephalad and caudal adjacent disc spaces was classified, on the last follow-up lateral radiograph, as grade 0 (none) (Fig. 2-A), grade 1 (mild) if the ossification extended across <50% of the disc space (Fig. 2-B), grade 2 (moderate) if the ossification extended across =50% of the disc space (Fig. 2-C), or grade 3 (severe) if there was complete bridging of the adjacent disc space (Fig. 2-D). Eighteen patients were excluded from the grading of the ossification at the caudal adjacent level because overlapping by the bone of the shoulder precluded adequate visualization of that level. Each independent observer determined the grade of the adjacent-level ossification twice, and the average of the four measurements was used as the final grade.

View Large | Download Slide(.ppt)
Add to My JBJS

Fig. 1-A and Fig. 1-B: The plate-to-disc distances were measured from the tips of the plate to the cephalad (Fig. 1-A) and caudal (Fig. 1-B) adjacent disc spaces on the postoperative lateral radiograph of the cervical spine.

View Large | Download Slide(.ppt)
Add to My JBJS

Figs. 2-A through 2-D: Lateral radiographs of the cervical spine, made at the time of final follow-up, showing the different grades of adjacent-level ossification. Fig. 2-A Grade 0: no adjacent-level ossification.

View Large | Download Slide(.ppt)
Add to My JBJS

Fig. 2-B: Grade 1: ossification extending across <50% of the adjacent disc space.

View Large | Download Slide(.ppt)
Add to My JBJS

Fig. 2-C: Grade 2: ossification extending across =50% of the adjacent disc space.

View Large | Download Slide(.ppt)
Add to My JBJS

Fig. 2-D: Grade 3: complete bridging of the adjacent disc space.

Five different types of anterior cervical plates were used: forty-four C-TEK Anterior Cervical Plate Systems (Interpore Cross, Irvine, California), twenty-seven Cervical Spine Locking Plates (Synthes Spine, Paoli, Pennsylvania), twenty-three Atlantis and fourteen Orion Anterior Cervical Plating Systems (Medtronic Sofamor-Danek, Memphis, Tennessee), and ten Caspar Bicortical Anterior Cervical Plates (ABC Aesculap, Tuttlingen, Germany).

Statistical analyses were performed with use of the chi-square test, independent sample t test, and Spearman correlation test. A p value of <0.05 was considered to be significant.

Results

Materials and Methods | Results | Discussion | References

The correlation coefficients for intraobserver and interobserver variabilities of the technique for grading the severity of the adjacent-level ossification were r = 0.98 (p < 0.001) and r = 0.96 (p < 0.001), respectively. These findings validate the capacity of the grading system to measure the severity of adjacent-level ossification on a lateral radiograph of the cervical spine.

Ossification developed in 59% (seventy) of the 118 cephalad adjacent disc spaces and 29% (twenty-nine) of the 100 caudal adjacent disc spaces (p < 0.001). The severity of the ossification was grade 0 in forty-eight cephalad adjacent disc spaces, grade 1 in fifty-three, grade 2 in eight, and grade 3 in nine. The severity was grade 0 in seventy-one caudal adjacent disc spaces, grade 1 in eighteen, grade 2 in seven, and grade 3 in four. The mean cephalad plate-to-disc distance (and standard deviation) was 2.86 ± 1.78 mm, and the mean caudal plate-to-disc distance was 4.02 ± 1.89 mm (p < 0.001).

Ossification occurred in 67% (sixty-five) of the ninety-seven cephalad adjacent-level disc spaces in group A (cephalad plate-to-disc distance of <5 mm) and 24% (five) of the twenty-one cephalad disc spaces in group B (cephalad plate-to-disc distance of =5 mm) (p < 0.001). Of note is the fact that all nine cases of grade-3 cephalad adjacent-level ossification and all eight cases of grade-2 cephalad ossification developed in group A.

Ossification occurred in 45% (twenty-seven) of the sixty caudal adjacent-level disc spaces in group A and 5% (two) of the forty in group B (p < 0.001). All four cases of grade-3 caudal adjacent-level ossification developed in group A. Of the seven cases of grade-2 caudal ossification, five were in group A and two were in group B.

Discussion

Materials and Methods | Results | Discussion | References

Peri-plate ossification has been previously discussed as an incidental finding following arthrodesis with an anterior cervical plate and has been thought to be secondary to oversizing or improper placement of the plate^12,13. Our findings demonstrate that, if an anterior cervical plate is placed <5 mm from the cephalad or caudal adjacent disc space, there is an increased risk of moderate-to-severe cephalad or caudal adjacent-level ossification (p < 0.001). While twenty-six cases of grade-2 or 3 adjacent-level ossification developed in the patients with a plate-to-disc distance of <5 mm, only two cases of grade-2 ossification and no cases of grade-3 ossification developed in the patients with a plate-to-disc distance of =5 mm. Those results indicate that a plate-to-disc distance of <5 mm is strongly associated with the development of moderate-to-severe adjacent-level ossification.

The ossification occurred at a significantly higher rate and was more severe at the cephalad adjacent levels than at the caudal adjacent levels (p < 0.001). Because the mean cephalad plate-to-disc distance was shorter than the mean caudal plate-to-disc distance (p < 0.001), we attributed the higher rate and more severe extent of the cephalad adjacent-level ossification to the shorter cephalad plate-to-disc distance.

Mähring¹³ suggested that excessive dissection along the anterior longitudinal ligament can affect the development of late degenerative changes. However, in our series, all of the operative procedures were performed by the senior author (K.D.R.) using the same microscope-visualized surgical technique with minimum stripping of the anterior longitudinal ligament.

The exact mechanism of adjacent-level ossification was not identified in this study. Although it is our opinion that the association between the plate position and the extent of the adjacent-level ossification may be due to irritation of the anterior aspect of the adjacent disc space, we have no evidence to support that hypothesis at this time. In addition, we cannot exclude the possibility that adjacent-level ossification may develop as the result of the healing of a stripped anterior longitudinal ligament or anterior fibers of the annulus fibrosus.

In this paper, we use the term adjacent-level ossification to describe ossification that was observed at the disc spaces adjacent to an anterior cervical plate. In previous studies, this observation was referred to as late degenerative changes^12,13. While it is likely that many of those cases were simple degenerative changes, at least some may have been due to the plate irritating the anterior longitudinal ligament or the anterior annulus during flexion-extension movements. We are currently comparing adjacent-level ossification following arthrodeses performed with a plate with that following arthrodeses performed without a plate to determine if the plate itself is responsible for the increased rate and severity of adjacent-level ossification.

There is some controversy concerning the influence of adjacent-level ossification on clinical outcome. Goffin et al.¹² reported that late degenerative changes at adjacent levels were not associated with signs or symptoms of radiculopathy, myelopathy, or cervical instability. In their series, there were no reoperations due to these degenerative changes, but the duration of their follow-up was short. In contrast, Gore et al.⁸ found that patients with recurrent pain were more likely to have progression of spondylosis cephalad and caudad to the fused segments than were those without recurrent pain. Because we did not examine this issue in the current study, we believe that the association between adjacent-level ossification and clinical outcomes needs to be investigated in future studies.

As a result of this study, we now routinely attempt to use the shortest plate possible. We drill fixation holes as close to the fused disc space as possible and angle the trajectory of the drill away from the fused disc both cranially and caudally. This allows the placement of the shortest possible plate, and we strive to insert the plate =5 mm away from the adjacent disc spaces. ?

References

Materials and Methods | Results | Discussion | References

Bose B. Anterior cervical instrumentation enhances fusion rates in multilevel reconstruction in smokers. J Spinal Disord.2001;14: 3-9.143 2001 [PubMed][CrossRef]

Kaiser MG, Haid RW Jr, Subach BR, Barnes B, Rodts GE Jr. Anterior cervical plating enhances arthrodesis after discectomy and fusion with cortical allograft. Neurosurgery.2002;50: 229-38.50229 2002 [PubMed]

Schneeberger AG, Boos N, Schwarzenbach O, Aebi M. Anterior cervical interbody fusion with plate fixation for chronic spondylotic radiculopathy: a 2- to 8-year follow-up. J Spinal Disord.1999;12: 215-21.12215 1999

Wang JC, McDonough PW, Kanim LE, Endow KK, Delamarter RB. Increased fusion rates with cervical plating for three-level anterior cervical discectomy and fusion. Spine.2001;26: 643-7.26643 2001 [PubMed][CrossRef]

Baba H, Furusawa N, Imura S, Kawahara N, Tsuchiya H, Tomita K. Late radiographic findings after anterior cervical fusion for spondylotic myeloradiculopathy. Spine.1993;18: 2167-73.182167 1993 [PubMed][CrossRef]

Braunstein EM, Hunter LY, Bailey RW. Long term radiographic changes following anterior cervical fusion. Clin Radiol.1980;31: 201-3.31201 1980 [CrossRef]

Fuller DA, Kirkpatrick JS, Emery SE, Wilber RG, Davy DT. A kinematic study of the cervical spine before and after segmental arthrodesis. Spine.1998;23: 1649-56.231649 1998 [PubMed][CrossRef]

Gore DR, Gardner GM, Sepic SB, Murray MP. Roentgenographic findings following anterior cervical fusion. Skeletal Radiol.1986;15: 556-9.15556 1986 [PubMed][CrossRef]

Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman HH. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am.1999;81: 519-28.81519 1999

Matsunaga S, Kabayama S, Yamamoto T, Yone K, Sakou T, Nakanishi K. Strain on intervertebral discs after anterior cervical decompression and fusion. Spine.1999;24: 670-5.24670 1999 [PubMed][CrossRef]

Wu W, Thuomas KA, Hedlund R, Leszniewski W, Vavruch L. Degenerative changes following anterior cervical discectomy and fusion evaluated by fast spin-echo MR imaging. Acta Radiol.1996;37: 614-7.37614 1996 [PubMed][CrossRef]

Goffin J, van Loon J, Van Calenbergh F, Plets C. Long-term results after anterior cervical fusion and osteosynthetic stabilization for fractures and/or dislocations of the cervical spine. J Spinal Disord.1995;8: 499-508.8499 1995

Mähring M. [Segment changes in the cervical spine following cervical spondylodeses of unstable injuries]. Unfallchirurgie.1988;14: 247-58. German.14247 1988 [PubMed]

Topics

bone plates ; osteogenesis

Username

Password

Access for Patients

Forgot Password?

Have a subscription to the print edition?

Not a Subscriber?

Buy this Article

Get online access for 30 days for $35

New to JBJS?

Subscribe to the online edition for 30 days for $75

Register for a FREE limited account to get full access to all CME activities, to comment on public articles, or to sign up for alerts.

Have a subscription to the print edition?

Current subscribers to The Journal of Bone & Joint Surgery in either the print or quarterly DVD formats receive free online access to JBJS.org.

Activate your online account now

Forgot your password?

Enter your username and email address. We'll send you a reminder to the email address on record.

Username:*

Email Address:*

Forgot your username or need assistance? Please contact customer service at subs@jbjs.org. If your access is provided
by your institution, please contact you librarian or administrator for username and password information. Institutional
administrators, to reset your institution's master username or password, please contact subs@jbjs.org

References

Accreditation Statement

These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.

CME Activities Associated with This Article

Submit a Comment

Please read the other comments before you post yours. Contributors must reveal any conflict of interest.
Comments are moderated and will appear on the site at the discretion of JBJS editorial staff.

* = Required Field

Comment Author(s) * (if multiple authors, separate names by comma)

Example: John Doe

Affiliation & Institution*

Comment Title*

Comment*

Cancel

Rajkumar S. Amaravati

Posted on March 18, 2005

Indications for Anterior Cervical Plating and Fusion

assistant professor,department of orthopaedics,st.john's medical college and hospital,bangalore-

To the Editor:

I commend the authors on their efforts to classify and propose a probable cause of adjacent level ossificationfollowing arthrodesis with an anterior cervical plate. The prevalence of ossification in their series was rather high-- about 59% of 118 cephalad and 29% of 100 caudal adjacent disc spaces. It would have been helpful if they had assesed the clinical outcomes as well. I have a few questions for the authors.

Degenerative changes occur as part of the natural history of cervical spondylosis. After arhtrodesis, the unfused adjacent segments have more stress. It is also seen that new symptoms that develop after fusion in the adjacent disc levels resolve after Anterior cervical plating and fusion (1). As the disease can progress either way, what is the rationale for performing surgery?

There is a chance of developing adjacent level ossification after open surgery or after microscopic surgery. Are they an indication of imminent disc lesion?

It has been found in the literature that at 2-years follow up non- operative treatment gave good to excellent results for symptoms of cervical radiculopathy (2).Also a conflicting report found no difference in the rate of new radiculopathy that develops at adjacent level in patients who had Anterior cervical discectomy or Anterior cervical plating[ACP] with fusion (3).So we are at cross roads as what to tell our patients and how much to tell.Whether to go for conservative treatment or operative.

Finally, I would like to know whether the authors feel there a need to remove the posterior longitudinal ligament in all cases while doing ACP with fusion.If yes,then what are the do's and and dont's and how much does this influence the adjacent level ossification?

REFERENCES:

1.Hillbrand AS,Carlson GD,Palumbo MA,Jones PK, Bohlman HH. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis.J. Bone Joint Surg Am 1999;81:519- 528.

2.Saal JS, Saal JA,Yurth EF.Nonoperative management of herniated cervicalintervertebral disc with radiculopathy. Spine 1996;21:1877-1883.

3.Lunsford LD,Bissonette D,Janetta PJ,Sheptaak PE,Zorub DS.Anterior surgery for Cervical disc disease Part 1:Treatment of lateral cervical disc herniation in 253 cases.J Neurosurg 1980;53 :1-11.

Print
PDF
Email

Recipient(s) will receive an email with a link (good for 5 days) to 'Development of Adjacent-Level Ossification in Patients with an Anterior Cervical Plate'.
Your Name:*
Example: John Doe

Email Address:* CC Me:
Enter your valid email address. Example: jdoe@example.com

Recipient's Email Address:*

Separate multiple email address with semi-colons (up to 5).

Subject:* 's The Journal of Bone & Joint Surgery: 'Development of Adjacent-Level Ossification in Patients with an Anterior Cervical Plate'
Subject for your email.

Message:

(Optional, message will truncate at 1000 characters)

Processing your request... Please Wait...

Copyright © in the material you requested is held by The Journal of Bone & Joint Surgery, Inc. (unless otherwise noted). This email ability is provided as a courtesy, and by using it you agree that that you are requesting the material solely for personal, non-commercial use, and that it is subject to Journal of Bone & Joint Surgery, Inc.'s Terms of Use. The information provided in order to email this topic will not be used to send unsolicited email, nor will it be furnished to third parties. Please refer to The Journal of Bone & Joint Surgery Inc.'s Privacy Policy for further information.

Copyright © The Journal of Bone & Joint Surgery Inc. All rights reserved.
Share
Get Citation

Jong-Beom Park, Yong-Sun Cho, K. Daniel Riew; Development of Adjacent-Level Ossification in Patients with an Anterior Cervical Plate. The Journal of Bone & Joint Surgery. 2005 Mar;87(3):558-563.

Download citation file:

RIS (Zotero)

EndNote

BibTex

Medlars

ProCite

RefWorks

Reference Manager

Copyright © The Journal of Bone and Joint Surgery, Inc.
Rights & Permissions
Article Alerts

Processing your request... Please Wait.
Submit a Comment