Injury, Int. J. Care Injured (2006) 37, 659—662

www.elsevier.com/locate/injury

CASE REPORT

Spontaneous odontoid process fracture inrheumatoid arthritis: Diagnostic difficulties,pathology and treatment

A. Al khayer a,*, N. Sawant b, P. Emberton a, P.J. Sell a

a Spinal Unit, Queens Medical Centre, University Hospital NHS Trust, Derby Road, Nottingham NG7 2UH, UKbRoyal United Hospital, Bath, UK

Accepted 8 December 2005

Introduction

We report a case of spontaneous odontoid processfracture as a complication of rheumatoid arthritis.We aim to illustrate the diagnostic difficulties thatare faced in dealing with this unusual complication.We also present the possible underlying pathologyand the recommended treatment for this fracture.

Case report

A 69-year-old man presented with sudden onset ofsevere neck and occipital pain. He had suffered fromseropositive rheumatoid arthritis for 15 years, andhad synovitis of many joints and other stigmata ofrheumatoid arthritis. There was no recent head orneck injury and no cervical myelopathy. Plain ante-roposterior and lateral cervical spine flexion andextension radiographs showed anterior atlanto-axialsubluxation and possible osteolysis of the odontoidprocess (Figs. 1 and 2). MRI showed a pannus aroundthe odontoid process; no cord impingement, frac-ture or dislocation was noted (Fig. 3). Neck pain

* Corresponding author. Tel.: +44 115 9249924.E-mail address: hamadafirst@yahoo.com (A. Al khayer).

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persisted, and 2 months later CTrevealed a fracturethrough the base of the odontoid process, withanterior atlanto-axial subluxation. There was nosignificant increase in the atlanto-dental interval,as the odontoid process moved forward with thearch of the atlas (Fig. 4). A retrospective review of

Figure 1 Lateral plain radiograph of the cervical spinein flexion.

rved.

660 A. Al khayer et al.

Figure 2 Lateral plain radiograph of the cervical spinein extension.

Figure 4 CTshowing the odontoid fracture with anteriordisplacement.

the MRI revealed that the fracture was obscured bythe pannus.

The patient underwent surgical stabilisation witha posterior occipital-C5 fusion (Fig. 5). He wore ahard collar for 6 weeks, and had an uneventfulrecovery. At 3 months postoperatively, the neckand occipital pain had resolved completely.

Discussion

Cervical spinal lesions are common in rheumatoidarthritis. The most frequent rheumatoid abnormal-

Figure 3 MRI showing the pannus arou

ity of the cervical spine is anterior atlanto-axialsubluxation, with a prevalence of 19—70%.3 This isfollowed by vertical atlanto-axial impaction andsubaxial subluxations, with frequencies of 4—35%and 7—29%, respectively.3 Spontaneous fracture ofthe odontoid process has been very rarely reported,as a complication in rheumatoid arthritis; a litera-ture review found 10 documented cases.1,8,7,9 Thecommon symptom in all those cases was the suddenincrease of neck and occipital pain.

Adequate radiological examination is essentialfor diagnosis. Conventional radiographs are notalways reliable in this condition, as they may failto show the fracture because of the degenerationand osteopenia that accompany the disease.10 Inthe case we report, conventional radiographs didnot show the odontoid process fracture, which wasalso missed by MRI of the cervical spine. Subse-quent CT, however, revealed the fracture clearly,10

with anterior displacement. As the odontoid was

nd the base of the odontoid process.

Spontaneous odontoid process fracture in rheumatoid arthritis 661

Figure 5 Postoperative lateral plain radiograph of thecervical spine showing posterior occipital-C5 fusion.

not displaced on the MRI, it is probable that thedisplacement occurred over time rather than as aresult of positioning in the CT scanner. This issupported by the absence of neck pain and the factthat no clinical deterioration occurred. The undis-placed fracture might have been obscured by thepannus on the MRI, but CTwould have revealed it atthis stage.

At the time of the initial MRI, neither short tauinversion recovery (STIR) nor fat-saturated T2-weighted sequence were considered necessary, asno history of trauma was reported. In retrospect,these sequences could have revealed the fracture.

Several underlying pathological processes havebeen suggested as causes of the development of apathological fracture of the odontoid process inrheumatoid arthritis. Storms et al. suggested thatthe erosive changes at the base of the odontoidprocess decrease the base resistance to minorinjuries or even to normal biomechanical forces.8

Crellin et al. and Kennedy et al. hypothesised thatboth osteoporosis and synovial proliferation mightlead to the destruction of the odontoid process, theoccipital condyles and the lateral masses of theatlas.2,4 Konttinen et al. proposed that the chronicfocal inflammation resulting from pannus infiltra-tion may destroy the stabilising osseous and liga-

mentous structures, which would increase thestress on the remaining structures.5,6 Trippi et al.argued that the critical vascularisation of the odon-toid process might play an important part in thelysis and fracture of this bony structure.10 In thecase presented, we believe that the pannus infil-tration played a significant role in graduallydestroying the odontoid process andmaking it moresusceptible to fracture. We assume that the liga-mentous structures, including the transverse andthe alar ligament, remained intact, as the frac-tured odontoid process stayed immediately behindthe arch of the atlas. Nevertheless, the exactpathology of the odontoid process fracture is likelyto be multifactorial.

Indications for surgery in rheumatology caseswith cervical lesions are pain, instability andactual or impending myelopathy. The surgicaloptions are multiple and include cervical arthrod-esis, occipito-cervical fusion and C1—C2 fusion by adirect screw. In the case presented, the presenceof the odontoid fracture had led to anterioratlanto-axial subluxation, subaxial instability andsevere cervical and occipital pain. Occipito-cervi-cal fusion effectively addressed our patient’ssymptoms.

Conclusions

The progression of cervical spine lesions in rheu-matoid arthritis is normally slow. Changes in thesymptoms, such as sudden increase in neck andoccipital pain without apparent trauma, shouldraise suspicion of the possibility of an otherwiserare spontaneous odontoid process fracture. A pan-nus around the odontoid process on MRI may hidethe fracture. We emphasise the importance of CT,and we believe that this should be the gold-stan-dard investigation whenever a spontaneous odon-toid process fracture is suspected. The exactpathology of odontoid process fracture in rheuma-toid arthritis is yet to be determined, and is mostlikely to be multifactorial. Surgery that achievescervical arthrodesis and stability is the treatment ofchoice.

References

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2. Crellin RQ, MacCabe JJ, Hamilton EB. Severe subluxation ofthe cervical spine in rheumatoid arthritis. J Bone Joint SurgBr 1970;52(2):244—51.

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