eMedicine Specialties > Orthopedic Surgery > Spine

Os Odontoideum: Follow-up

Author: Eeric Truumees, MD, Consulting Surgeon, Department of Orthopedic Surgery, William Beaumont HospitalOrthopaedic Director, Gehring Biomechanics LaboratoryAdjunct Faculty, Bio-Engineering Center, Wayne State University
Contributor Information and Disclosures

Updated: Sep 12, 2008

Outcome and Prognosis

Outcome and prognosis data for os odontoideum patients is limited to scattered case reports and small case series. These series typically describe successful outcomes with both nonoperative and surgical management.

Spierings and Braakman described their management of 37 os odontoideum patients.  At a median 7-year follow-up, of the 16 patients with neck pain only, none developed neurologic deficits. Four patients who had mild or transient myelopathy and limited radiographic instability were also followed nonoperatively. With a maximum follow-up of 14 years, 3 of the 4 had no recurrence; one had stable monoparesis. Seventeen patients with myelopathy and more instability underwent surgery. These authors found no difference in neck pain in the surgical and nonsurgical groups.57

In a series by Dai et al, 5 patients with os odontoideum without symptoms were treated nonoperatively and were monitored for an average of 6.5 years. None of these patients had symptom progression during the follow-up period.55

In a study by Fielding et al, 27 of 35 os odontoideum patients were radiographically unstable. Of the 27 patients, 26 underwent successful Gallie fusion. They reported “solid” fusions after 2 months of immobilization in children and after 3 months in adults. The 27th unstable patient refused surgery and remained well at 2-year follow-up examination. The 8 stable patients were managed  nonoperatively and remained well at last follow-up. Symptomatically, two thirds of Fielding’s patients had only mechanical pain. These patients reported resolution after fusion.59

The neurologic outcome in patients with symptomatic cord compression is less clear. These patients can be divided into those with acute, incomplete cord syndromes and those with insidious myelopathic syndromes. Typically, transient neurologic signs following trauma are associated with a good prognosis. Rapid functional return parallels improvement in neurologic signs, and recurrence rates are low.

Myelopathic patients or those with cerebellar or medullary signs exhibit a more progressive course. Because these patients gradually worsen, surgery is most clearly indicated in this setting. Neurologic outcomes after surgery have been reported in small case series only, however.  Typically, symptomatic progression ceases, and most patients report significant symptomatic improvement.

Future and Controversies

There are 3 evolving and controversial aspects of os odontoideum: etiology, surgical indications, and optimal management. Hadley’s 2002 consensus report called for several studies32 :

  • Population-wide studies of the prevalence of os odontoideum as an incidental finding.
  • A follow-up of incidentally noted and untreated os odontoideum, even with C1–C2 subluxation.
  • A cooperative, multi-institutional natural history study of patients with os odontoideum without C1–C2 instability, to provide demographic and clinical factors predictive of the development of subsequent instability.
  • A multi-institutional prospective, randomized trial comparing posterior wiring and fusion techniques with rigid, C1–C2 screw fixation.

In years to come both posttraumatic and congenital forms of os odontoideum may be identified. Today, however, authors in each camp often write as if their hypothesis has been all but proven. Understanding the true etiology of this disorder may be helpful in terms of identifying high-risk patients through genetic testing. If posttraumatic, the increased use of advanced imaging modalities such as spiral CT and MRI may markedly decrease the incidence of os odontoideum in the future. Further, better explication of etiology may better delineate progression risk, leading to decreased x-ray exposure during follow-up and the limiting of operative intervention only to those patients at high risk for progression. These data may also support or eliminate the need for activity restriction during the observation phase.

In the presence of progressive neurologic compromise, surgery is clearly indicated. With asymptomatic atlantoaxial hypermobility alone, on the other hand, the decision to proceed with surgery is more debatable. Larger series comparing outcomes between operative and nonoperative management may more clearly support surgery in some patients. Certainly, a better-defined discussion of surgical risks and benefits could be expected.

Finally, if surgery has been selected, the merit of each individual technique is debated. The advent of C1 lateral mass and C2 pars screw fixation has addressed the major concerns with Magerl screw fixation. The Harms technique allows rigid fixation in a wider range of patients, including many with a degree of vertebral artery ectopy or incomplete reduction for which transarticular screw placement would be too risky.

In the future, the current open method of Harms screw placement may be replaced by a more percutaneous approach. Individual “proof of concept” case reports have been published. For less unstable, but progressive, atlantoaxial instability, injections of bone morphogenetic protein (BMP) may avoid instrumentation altogether. Until there is evidence proving that the less-invasive approaches confer less operative risk, operative indications must not be relaxed.

 


More on Os Odontoideum

Overview: Os Odontoideum
Workup: Os Odontoideum
Treatment: Os Odontoideum
Follow-up: Os Odontoideum
Multimedia: Os Odontoideum
References
[ CLOSE WINDOW ]

References

  1. Lipson SJ. Dysplasia of the odontoid process in Morquio''s syndrome causing quadriparesis. J Bone Joint Surg Am. Apr 1977;59(3):340-4. [Medline].

  2. Stevens JM, Kendall BE, Crockard HA, Ransford A. The odontoid process in Morquio-Brailsford''s disease. The effects of occipitocervical fusion. J Bone Joint Surg Br. Sep 1991;73(5):851-8. [Medline].

  3. McRae D. The significance of abnormalities of the cervical spine. AJR. 1960;84:3-25.

  4. Shaffrey CI, Chenelle AG, Avel MF. Anatomy and physiology of congenital spine lesions. In: Benzel EC, ed. Spine Surgery: Techniques, Complication Avoidance and Management. Churchill Livingstone;1999:265.

  5. O'Rahilly R, Müller F, Meyer DB. The human vertebral column at the end of the embryonic period proper. 2. The occipitocervical region. J Anat. Jan 1983;136(Pt 1):181-95. [Medline].

  6. Yukata K, Katoh S, Sairyo K, Matsui Y, Hamada Y, Yasui N. Os odontoideum in achondroplasia: a case report. J Pediatr Orthop B. Mar 2008;17(2):103-5. [Medline].

  7. Bassett F, Goldner JL. Aplasia of the odontoid process. J Bone Joint Surg. 1968;50A:833-4.

  8. Chang H, Park JB, Kim KW, Choi WS. Retro-dental reactive lesions related to development of myelopathy in patients with atlantoaxial instability secondary to Os odontoideum. Spine. Nov 1 2000;25(21):2777-83. [Medline].

  9. Fielding JW, Griffin PP. Os odontoideum: an acquired lesion. J Bone Joint Surg Am. Jan 1974;56(1):187-90. [Medline].

  10. Gwinn J, Smith J. Acquired and congenital absence of the odontoid process. AJR. 1962;88:424-31.

  11. Hawkins RJ, Fielding JW, Thompson WJ. Os odontoideum: congenital or acquired. A case report. J Bone Joint Surg Am. Apr 1976;58(3):413-4. [Medline].

  12. Morgan MK, Onofrio BM, Bender CE. Familial os odontoideum. Case report. J Neurosurg. Apr 1989;70(4):636-9. [Medline].

  13. Stillwell WT, Fielding JW. Acquired os odontoideum. A case report. Clin Orthop. Sep 1978;(135):71-3. [Medline].

  14. Wollin D. The os odontoideum. Separate odontoid process. J Bone Joint Surg. 1963;45-A:1459-1471.

  15. Hukuda S, Ota H, Okabe N, Tazima K. Traumatic atlantoaxial dislocation causing os odontoideum in infants. Spine. May-Jun 1980;5(3):207-10. [Medline].

  16. Kuhns LR, Loder RT, Farley FA, Hensinger RN. Nuchal cord changes in children with os odontoideum: evidence for associated trauma. J Pediatr Orthop. Nov-Dec 1998;18(6):815-9. [Medline].

  17. Brecknell JE, Malham GM. Os odontoideum: report of three cases. J Clin Neurosci. Mar 2008;15(3):295-301. [Medline].

  18. Schuler TC, Kurz L, Thompson DE, et al. Natural history of os odontoideum. J Pediatr Orthop. Mar-Apr 1991;11(2):222-5. [Medline].

  19. Garg A, Gaikward S, Gupta V, et al. Bipartite Atlas With Os Odontoideum: Case Report. Spine. January 2004 15;29(2):E35-E38.

  20. Mintken PE, Metrick L, Flynn TW. Upper cervical ligament testing in a patient with os odontoideum presenting with headaches. J Orthop Sports Phys Ther. Aug 2008;38(8):465-75. [Medline].

  21. Crockard HA, Stevens JM. Craniovertebral junction anomalies in inherited disorders: part of the syndrome or caused by the disorder?. Eur J Pediatr. Jul 1995;154(7):504-12. [Medline].

  22. Sankar W, Wills B, Dormans J, Drummond D. Os Odontoideum Revisited: The Case for a Multifactorial Etiology. Spine. 2006;31:979-984.

  23. Dyck P. Os odontoideum in children: neurological manifestations and surgical management. Neurosurgery. Mar-Apr 1978;2(2):93-9. [Medline].

  24. Rowland L, Shapiro J, Jacobson H. Neurological syndromes associated with congenital absence of the odontoid process. Arch Neurol Psych. 1958;80:286-291.

  25. Watanabe M, Toyama Y, Fujimura Y. Atlantoaxial instability in os odontoideum with myelopathy. Spine. Jun 15 1996;21(12):1435-9. [Medline].

  26. Bhatnagar M, Sponseller PD, Carroll C IV, Tolo VT. Pediatric atlantoaxial instability presenting as cerebral and cerebellar infarcts. J Pediatr Orthop. Jan-Feb 1991;11(1):103-7. [Medline].

  27. Sasaki H, Itoh T, Takei H, Hayashi M. Os odontoideum with cerebellar infarction: a case report. Spine. May 1 2000;25(9):1178-81. [Medline].

  28. Minderhoud JM, Braakman R, Penning L. Os odontoideum, clinical, radiological and therapeutic aspects. J Neurol Sci. May-Jun 1969;8(3):521-44. [Medline].

  29. Satte A, Ech-Cherif El Kettani N, El Quessar A, El Hassani MR, Chakir N, Boukhrissi N, et al. [Os odontoideum: clinical and radiological aspects]. Rev Neurol (Paris). Feb 2008;164(2):177-80. [Medline].

  30. Surov A, Hess S, Spielmann RP, Kunze C. A delayed diagnosis of an unstable os odontoideum. Eur J Med Res. Mar 31 2008;13(3):136-8. [Medline].

  31. Holt RG, Helms CA, Munk PL, Gillespy T 3rd. Hypertrophy of C-1 anterior arch: useful sign to distinguish os odontoideum from acute dens fracture. Radiology. Oct 1989;173(1):207-9. [Medline].

  32. Hadley MN. Os Odontoideum. Neurosurgery. March 2002;50(3) Supplement:S148-S155.

  33. Aksoy FG, Gomori JM. Symptomatic cervical synovial cyst associated with an os odontoideum diagnosed by magnetic resonance imaging: case report and review of the literature. Spine. May 15 2000;25(10):1300-2. [Medline].

  34. Hughes TB Jr, Richman JD, Rothfus WE. Diagnosis of Os odontoideum using kinematic magnetic resonance imaging. A case report. Spine. Apr 1 1999;24(7):715-8. [Medline].

  35. shellock FG. Functional Assessment of the Joints Using Kinematic Magnetic Resonance Imaging. Seminars in Musculoskeletal Radiology. Dynamic and Functional Musculoskeletal Imaging. 2003;7(4):249-276.

  36. Hosono N, Yonenobu K, Ebara S, Ono K. Cineradiographic motion analysis of atlantoaxial instability in os odontoideum. Spine. Oct 1991;16(10 Suppl):S480-2. [Medline].

  37. Hensinger RN. Congenital anomalies of the cervical spine. In: Herkowitz HN, Garfin SR, Balderston RA, et al, eds. The Spine. Lippincott-Raven;1999:242-243.

  38. Hensinger RN. Osseous anomalies of the craniovertebral junction. Spine. May 1986;11(4):323-33. [Medline].

  39. Hensinger RN, Fielding JW, Hawkins RJ. Congenital anomalies of the odontoid process. Orthop Clin North Am. Oct 1978;9(4):901-12. [Medline].

  40. An H, ed. Congenital anomalies of the cervical spine. In: Principles and Techniques of Spine Surgery. 1st ed. Lippincott Williams & Wilkins;1997:165.

  41. Callahan RA, Lockwood R, Green B. Modified Brooks fusion for an os odontoideum associated with an incomplete posterior arch of the atlas. A case report. Spine. Jan-Feb 1983;8(1):107-8. [Medline].

  42. Brockmeyer DL, York JE, Apfelbaum RI. Anatomical suitability of C1-2 transarticular screw placement in pediatric patients. J Neurosurg. Jan 2000;92(1 Suppl):7-11. [Medline].

  43. Jun BY. Complete reduction of retro-odontoid soft tissue mass in os odontoideum following the posterior C1-C2 tranarticular screw fixation. Spine. Sep 15 1999;24(18):1961-4. [Medline].

  44. Prabhu VC, France JC, Voelker JL, Zoarski GH. Vertebral artery pseudoaneurysm complicating posterior C1-2 transarticular screw fixation: case report. Surg Neurol. Jan 2001;55(1):29-33; discussion 33-4. [Medline].

  45. Reilly CW, Choit RL. Transarticular screws in the management of C1-C2 instability in children. J Pediatr Orthop. Sep-Oct 2006;26(5):582-8. [Medline].

  46. Motosuneya T, Hirabayashi S, Yamada H, Kobayashi Y, Sekiya S, Sakai H. Posterior atlantoaxial subluxation due to os odontoideum combined with cervical spondylotic myelopathy: a case report. Eur Spine J. Sep 2008;17 Suppl 2:S275-9. [Medline].

  47. Wang J, Vokshoor A, Kim S, et al. Pediatric atlantoaxial instability: management with screw fixation. Pediatr Neurosurg. Feb 1999;30(2):70-8. [Medline].

  48. Takakuwa T, Hiroi S, Hasegawa H, et al. Os odontoideum with vertebral artery occlusion. Spine. Feb 15 1994;19(4):460-2. [Medline].

  49. Stulík J, Vyskocil T, Sebesta P, Kryl J. [Harms technique of C1-C2 fixation with polyaxial screws and rods]. Acta Chir Orthop Traumatol Cech. 2005;72(1):22-7. [Medline].

  50. Lamas E, Estevez J, Castillo R, Esparza J. Os odontoideum removed by a transoral approach. Surg Neurol. May 1977;7(5):312-4. [Medline].

  51. Laus M, Pignatti G, Malaguti MC, et al. Anterior extraoral surgery to the upper cervical spine. Spine. Jul 15 1996;21(14):1687-93. [Medline].

  52. Chang H, Park JB, Kim KW. Synovial cyst of the transverse ligament of the atlas in a patient with os odontoideum and atlantoaxial instability. Spine. Mar 15 2000;25(6):741-4. [Medline].

  53. Park J, Huhn SL, Lee M, et al. A Definitive Surgical Option without a Halo or Occipital Fusion. Neurosurgery. August 2005;57(2):437.

  54. Juhl M, Seerup KK. Os odontoideum. A cause of atlanto-axial instability. Acta Orthop Scand. Feb 1983;54(1):113-8. [Medline].

  55. Dai L, Yuan W, Ni B, Jia L. Os odontoideum: etiology, diagnosis, and management. Surg Neurol. Feb 2000;53(2):106-8; discussion 108-9. [Medline].

  56. Taggard DA, Menezes AH, Ryken TC. Treatment of Down syndrome-associated craniovertebral junction abnormalities. J Neurosurg. Oct 2000;93(2 Suppl):205-13. [Medline].

  57. Spierings EL, Braakman R. The management of os odontoideum. Analysis of 37 cases. J Bone Joint Surg Br. 1982;64(4):422-8. [Medline].

  58. Smith MD, Phillips WA, Hensinger RN. Fusion of the upper cervical spine in children and adolescents. An analysis of 17 patients. Spine. Jul 1991;16(7):695-701. [Medline].

  59. Fielding JW, Hensinger RN, Hawkins RJ. Os Odontoideum. J Bone Joint Surg Am. Apr 1980;62(3):376-83. [Medline].

[ CLOSE WINDOW ]

Further Reading

[ CLOSE WINDOW ]

Keywords

os odontoideum, atlanto-axial instability, atlantoaxial instability, cervical instability, atlanto-axial joint, atlantoaxial joint, atlas bone, axis bone

[ CLOSE WINDOW ]

Contributor Information and Disclosures

Author

Eeric Truumees, MD, Consulting Surgeon, Department of Orthopedic Surgery, William Beaumont HospitalOrthopaedic Director, Gehring Biomechanics LaboratoryAdjunct Faculty, Bio-Engineering Center, Wayne State University
Eeric Truumees, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Orthopaedic Surgeons, American Orthopaedic Association, Cervical Spine Research Society, Michigan State Medical Society, Mid-America Orthopaedic Association, and North American Spine Society
Disclosure: Stryker Spine Consulting fee Consulting; DePuy Spine Consulting fee Consulting; Stryker Spine Royalty Other

Medical Editor

Lee H Riley III, MD, Chief, Division of Orthopedic Spine Surgery, Assistant Professor, Departments of Orthopedic Surgery and Neurosurgery, Johns Hopkins University
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

William O Shaffer, MD, Professor, Vice-Chairman and Residency Program Director, Department of Orthopedic Surgery, University of Kentucky at Lexington
William O Shaffer, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Association, International Society for the Study of the Lumbar Spine, Kentucky Medical Association, Kentucky Orthopaedic Society, North American Spine Society, Southern Medical Association, and Southern Orthopaedic Association
Disclosure: DePuySpine 1997-2007 (not presently) Royalty Consulting; DePuySpine 2002-2007 (closed) Grant/research funds SacroPelvic Instrumentation Biomechanical Study; DePuyBiologics 2005-2008 (closed) Grant/research funds Healos study just closed; No present Industry grants or funds. None None

CME Editor

Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital
Dinesh Patel, MD, FACS is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Association of Physicians of Indian Origin, American College of International Physicians, and American College of Surgeons
Disclosure: Nothing to disclose.

Chief Editor

Mary Ann E Keenan, MD, Professor, Vice Chair for Graduate Medical Education, Department of Orthopedic Surgery, University of Pennsylvania School of Medicine; Chief of Neuro-Orthopedics Program, Department of Orthopedic Surgery, Hospital of the University of Pennsylvania
Mary Ann E Keenan, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Orthopaedic Surgeons, American Orthopaedic Association, American Orthopaedic Foot and Ankle Society, American Society for Surgery of the Hand, and Orthopaedic Rehabilitation Association
Disclosure: Nothing to disclose.

 
 
HONcode

We subscribe to the
HONcode principles of the
Health On the Net Foundation

All material on this website is protected by copyright, Copyright© 1994- by Medscape.
This website also contains material copyrighted by 3rd parties.

DISCLAIMER: The content of this Website is not influenced by sponsors. The site is designed primarily for use by qualified physicians and other medical professionals. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.