Viseceradiology Update – Musculoskeletal FindingsC1 – C2 - Rheumatoid Spondylitis – Example of DC to MD CommunicationMichael J Vives, MD, Associate Professor, Department of Orthopedics, Division of Spine Surgery, New Jersey Medical School, University of Medicine and Dentistry of New JerseySteven R Garfin, MD, Professor, Chair, Department of Orthopedics, University of California at San Diego Medical Center

Updated: Aug 26, 2008

Introduction

History of the Procedure

The most common sites of rheumatoid arthritis (RA) are the metatarsophalangeal joints, followed by the metacarpophalangeal joints and the cervical spine (ankylosing spondylitis, rheumatoid spondylitis). Much of the understanding of spinal afflictions in RA was advanced by studies published in the 1950s and 1960s.[1 ]In 1951, Davis and Markley detailed medullary compression as a cause of death in patients with RA.[2 ]In 1969, Mathews reported that 25-30% of patients with RA who were admitted to the hospital had radiographic evidence of cervical spine involvement.[3 ]

Problem

Rheumatoid spondylitis (ankylosing spondylitis) primarily affects the cervical spine. Affliction of the thoracic or lumbar spine is rare. The anatomic abnormalities occur as a consequence of the destruction of synovial joints, ligaments, and bone. Abnormalities of the rheumatoid cervical spine generally can be grouped into 3 categories. Atlantoaxial instability (AAI) or atlantoaxial subluxation (AAS) is the most common. AAS can be a fixed deformity or can be partially or fully reducible. Superior migration of the odontoid (SMO) is the next most common abnormality and has alternately been referred to as cranial settling, pseudobasilar invagination, or vertical/upward translocation of the odontoid.[4 ]The third and least commonly seen deformity is subaxial subluxation. This may be seen at multiple levels, producing a stepladder deformity. The 3 deformities may be seen in isolation, or combined involvement may occur.

Frequency

Rheumatoid arthritis (RA) affects 0.8% of the white population in the United States and Europe. Neck pain is reported in 40-88% of patients with RA. The prevalence of cervical spine involvement (rheumatoid spondylitis, ankylosing spondylitis) in RA ranges from 25-80%, depending on the diagnostic criteria applied.[5 ]However, only 7-34% of patients with RA have a neurologic deficit. A substantial number of patients with radiographic instability or neck pain do not develop neurologic deficits.[6,7,8 ]

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Involvement of the cervical spine typically begins early in the disease process and often parallels the extent of peripheral disease. Of the 3 types of involvement, AAI is the most common, occurring in up to 49% of patients.[9 ]While most of these subluxations are anterior, approximately 20% are lateral and approximately 7% are posterior. SMO is seen in up to 38% of patients with RA. Subaxial subluxation is seen as a discrete pathologic entity in 10-20% of patients.

Subaxial subluxation also develops after previous upper cervical fusions.[10,11 ]In one series of 79 patients, 36% developed subaxial subluxation an average of 2.6 years following occipitocervical fusion, and 5.5% experienced subaxial subluxation an average of 9 years following atlantoaxial fusion.[10 ]

Pathophysiology

Recent theories on the pathogenesis of rheumatoid arthritis (RA) suggest that the synovial cells of these patients chronically express an antigen that triggers the production of rheumatoid factor, an immunoglobulin molecule directed against other autologous immunoglobulins. An inflammatory response is initiated, involving immune complex formation, activation of the complement cascade, and infiltration of polymorphonuclear leukocytes. The proliferating fibroblasts and inflammatory cells produce granulation tissue, known as rheumatoid pannus, within the synovium. The pannus produces proteolytic enzymes capable of destroying adjacent cartilage, ligaments, tendons, and bone. The destructive synovitis results in ligamentous laxity and bony erosion with resultant cervical instability and subluxation.[12,13 ]

Atlantoaxial subluxation results from erosive synovitis in the atlantoaxial, atlanto-odontoid, and atlanto-occipital joints and the bursa between the odontoid and the transverse ligament (see image below).

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3

Rheumatoid spondylitis. Depiction of anterior subluxation of C1 on C2, retrodental pannus, and osseous erosions; the spinal

cord is compressed between the pannus anteriorly and the posterior arch of the atlas.

The superior migration of the odontoid is attributed to erosion and bone loss in the occipitoatlantal and atlantoaxial joints (see image below).

4

Rheumatoid spondylitis. Depiction of superior migration of the odontoid into the foramen magnum with compression of the

spinal cord.

Subaxial subluxation results from destruction of the facets, intervertebral discs, and interspinous ligaments. Unlike degenerative disease, involvement of C2-C3 and C3-C4 is common, and osteophytes seldom are seen.

Presentation

Rheumatoid involvement of the cervical spine (rheumatoid spondylitis, ankylosing spondylitis) is just one element in a systemic disease process. Cervical involvement often correlates with the degree of hand and wrist erosion. Cervical involvement also has been associated with the presence of rheumatoid nodules and the use of corticosteroids. Classically, craniocervical neck pain often is associated with occipital headaches.

Compression of the C2 sensory fibers supplying the nucleus of the spinal trigeminal tract can cause facial pain. Compression of the C2 sensory fibers supplying the greater auricular nerve may result in ear pain. Occipital neuralgia results from compression of the C2 sensory fibers supplying the greater occipital nerve. A history of myelopathic symptoms should be sought carefully. Patients may experience weakness, decreased endurance, gait difficulty, paresthesias of the hands, and loss of fine dexterity. Patients with involvement may experience urinary retention and, eventually, incontinence.

Vertebrobasilar insufficiency may be found, particularly in patients with atlantoaxial instability (AAI). Complaints may include vertigo, loss of equilibrium, visual disturbances, tinnitus, and dysphagia. Similar symptomatology can also be caused by mechanical compression of the brainstem. In some patients, neck motion can elicit shocklike sensations through the torso or into the extremities (ie, Lhermitte sign).

The physical inventory of these patients frequently is confounded by the severity of their peripheral rheumatoid involvement. Weakness in these patients can also be due to tenosynovitis, tendon rupture, muscular atrophy, peripheral nerve entrapment, or articular involvement, making neurologic impairment less obvious. Signs of myelopathy should raise suspicion of cervical involvement. Rarely, cranial nerve dysfunction can occur secondary to compression of the medullary nuclei by the odontoid. Other rare findings in patients with advanced brainstem compression include vertical nystagmus and Cheyne-Stokes respirations.

The Ranawat classification can be used to categorize patients with rheumatoid myelopathy based on their clinical history and physical findings (see below).[14 ]This classification has some utility in determining potential for neurologic recovery following surgery.

The Ranawat classification of neurologic deficit is as follows:

Class I - No neural deficit Class II - Subjective weakness, dysesthesias, and hyperreflexia

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Class IIIA - Objective weakness and long-tract signs; patient remains ambulatory

Class IIIB - Objective weakness and long-tract signs; patient no longer ambulatory

Indications

Numerous investigators have attempted to elucidate the natural history of rheumatoid arthritis (RA) as it affects the cervical spine (rheumatoid spondylitis, ankylosing spondylitis), with wide variation in their findings.[15,16,17,18,19 ]Depending on the diagnostic criteria applied, the prevalence of cervical involvement in RA ranges from 25-80%. The likelihood of cervical involvement appears to increase with the duration of rheumatic disease. Because neurologic deficit is seen only in 7-34% of cases, many patients with pain and radiographic criteria for instability do not develop neurologic sequelae. However, 10% of patients with RA may die from brainstem compression that is unrecognized before their sudden death.[20 ]

The identification of a subset of patients with impending neurologic deficit has been elusive due to the poor correlation of neurologic symptoms with radiographic indicators of instability. Therefore, universally accepted surgical indications have been slow to develop.

Contraindications

Contraindications to surgery for rheumatoid spondylitis (ankylosing spondylitis) include medical conditions that suggest the patient would not tolerate the stress of surgery, such as unstable angina or a recent myocardial infarction or stroke. Active infection with likely bacteremia would also be a relative contraindication to surgery, especially in the setting of planned instrumentation. The patient's medical condition should be optimized prior to proceeding with any planned surgical intervention.

Workup

Laboratory Studies

Rheumatoid factor seropositivity has been correlated with more extensive cervical involvement (rheumatoid spondylitis, ankylosing spondylitis). The use of the rheumatoid factor as a predictor of neurologic involvement has not been established; therefore, it does not have a role in the surveillance of patients with rheumatoid arthritis (RA) with cervical involvement.

Imaging Studies

All patients with rheumatoid arthritis (RA) should have radiographic examination of the cervical spine because cervical involvement (rheumatoid spondylitis, ankylosing spondylitis) can remain asymptomatic. While prediction of the onset of myelopathy in any particular patient is difficult, studies of large populations of patients have sought to establish parameters for predicting neurologic involvement.[6,21,22 ]

Plain radiography

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The initial imaging assessment should consist of plain radiographs of the cervical spine, including lateral flexion and extension views. Several measurements that can help direct management can be made on plain radiographs.

Traditionally, the anterior atlantodental interval (AADI) has been used to monitor patients with RA over time. This measures the interval from the posterior margin of the anterior ring of C1 to the anterior surface of the odontoid. An interval of more than 3 mm in an adult or 4 mm in a child is considered abnormal. Various authors have recommended surgery for values of more than 8 mm, 9 mm, or 10 mm.

Anterior atlantoaxial subluxation may also be assessed by measurement of the posterior atlantodental interval (PADI), as measured from the posterior aspect of the odontoid to the anterior margin of the lamina of C1. Because the synovial pannus may occupy 1-3 mm of the retro-odontoid space, this interval does not represent the true space available for the cord.

While the AADI was used commonly to monitor patients with cervical involvement, a number of investigations have shown that the AADI does not reliably discriminate patients who are neurologically intact from those with neural deficit.[23 ]This is due in part to the 3-dimensional changes that take place with progressive subluxation. As the deformity progresses, the anterior arch of the atlas displaces in an anteroinferior direction as superior migration of the odontoid (SMO) combines with atlantoaxial instability (AAI). With continued SMO, the AADI decreases, although this vertical translocation is associated with a more unfavorable prognosis.

Boden and associates demonstrated this pitfall by examining the sensitivity, specificity, accuracy, and positive and negative predictive values of the AADI in predicting paralysis based on varying critical intervals (see Table at the end of the imaging section).[24 ]For example, raising the cut-off value for the AADI from 8 mm to 10 mm increases the specificity from 58% to 90%. However, the sensitivity with such a change in threshold value decreases from 59% to 35%. More recently, the PADI has been recommended as a more reliable predictor of whether neurologic compromise will develop.

The PADI was compared with the traditional anterior interval in a long-term series involving 73 patients.[24 ]Using a critical PADI of less than or equal to 14 mm resulted in a sensitivity (ability to detect those with paralysis) of 97%, a level superior to that using the AADI. More important, the negative predictive value, using a critical PADI of 14 mm, rises to 94%. Therefore, if the PADI is more than 14 mm, there is a 94% chance that the patient will not have paralysis. Such a high negative predictive value makes the PADI extremely reliable as a screening test.

A variety of measurements have been used to assess SMO. All of these measurements attempt to identify and grade the degree of odontoid encroachment on space normally occupied by the spinal cord and brainstem. Unfortunately, many of these are difficult to reproduce. The image below depicts pertinent measurements.

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8

Rheumatoid spondylitis. Pertinent measurements of superior migration of the odontoid; cranial migration distance

(CMD).

The Ranawat index targets disease in the C1-C2 segment by utilizing a lateral radiograph. A line is drawn from the pedicles of C2 superiorly along the vertical axis of the odontoid until it intersects a line connecting the anterior and posterior arches of C1. A value less than 13 mm is diagnostic of vertical settling.

The McRae line connects the front of the foramen magnum to the back. The upper tip of the odontoid process should not project above this line and should normally be 1 cm below the anterior margin of the foramen magnum.

The Chamberlain line is drawn from the posterior margin of the hard palate to the posterior margin of the foramen magnum. Projection of the tip of the odontoid 6 mm above this line is considered pathologic. However, the margins of the foramen magnum frequently are difficult to delineate without a tomogram.

The McGregor line has become the most consistent reference because it connects the posterior margin of the hard palate to the most caudal point of the occiput. Vertical settling is defined here by migration of the odontoid more than 4.5 mm above this line.

The Redlund-Johnell value assesses the occiput-to-C2 complex. The value measures the distance between the midpoint of the inferior margin of the body of the axis to the McGregor line. Values less than 34 mm in males and 29 mm in females are considered abnormal and correlate with increased risk of neurologic injury.[25 ]

Plain radiographs also are useful in detecting subaxial vertebral subluxations. These subluxations may be quantitated on lateral cervical radiographs as translation forward in millimeters or as a percentage slip of the total anteroposterior diameter of the inferior vertebral body. Historically, focus was directed on the number of millimeters of listhesis or the percentage of vertebral slip. However, recent demonstrations show that the sagittal diameter of the subaxial canal correlates with the presence and degree of paralysis more often than does the percentage of vertebral slip. Patients with canal diameters of 13 mm or less are at higher risk for neurologic involvement.

Magnetic resonance imaging

Magnetic resonance imaging (MRI) has provided an increased ability to visualize the extent of spinal cord compression, particularly when due to pannus.[26 ]

Dvorak and colleagues showed that two thirds of patients with AAS have a pannus of more than 3 mm in diameter.[27 ]Therefore, the bony canal diameter measured on plain radiographs may not represent the true space available for the cord.

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Kawaida et al demonstrated spinal cord compression in all patients with RA when the space available for the cord (as measured on MRI) was less than or equal to 13 mm.[28 ]

Using MRI, the cervicomedullary angle is an effective indicator of cord distortion from SMO. This angle incorporates lines drawn along the anterior aspects of the cervical cord and along the medulla. The normal range is 135-175°. Angles less than 135° indicate basilar invagination and have been associated with myelopathy. See image below for a patient example.

10

Rheumatoid spondylitis. MRI of a patient with superior migration of the odontoid and subaxial subluxation. Courtesy of

Steven R. Garfin.

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Dynamic cord compression can be detected with functional MRI scans obtained in flexion and extension.[29 ]

Polytomography and computed tomography

Historically, tomograms were useful for quantitating the degree of basilar invagination and to measure AADI and PADI more accurately in patients with abnormal radiographs.

Computed tomography (CT) scan with sagittal and coronal reformatting largely has supplanted biplanar tomography. A CT scan combined with intrathecal contrast provides excellent bony detail and the ability to detect spinal cord compression from synovial pannus.

While the noninvasive nature of MRI has made it the preferred modality for this type of evaluation, CT myelography is useful for patients with contraindications to MRI.

Reliability of the Anterior (AADI) and Posterior (PADI) Atlantodental Intervals in Predicting Paralysis in Patients with Rheumatoid Arthritis

Test SENS* SPEC† ACC‡ PPV§ NPV||

AADI  8 59 58 58 61 56

AADI  9 41 77 58 67 55

AADI  10 35 90 62 80 56

AADI  11 18 97 55 86 52

PADI  12 76 90 83 90 78

PADI  13 91 71 82 78 88

PADI  14 97 52 75 69 94

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Note that all values are expressed as percents. These numbers were calculated from a series of 73 patients.*SENS = Sensitivity†SPEC = Specificity‡ ACC = Accuracy§PPV = Positive predictive value||NPV = Negative predictive valueReprinted with permission from Boden SD, Dodge LD, Bohlman HH, and Rechtine GR.[24 ]

Treatment

Medical Therapy

An approach to surgical and nonsurgical management for rheumatoid arthritis (RA) and for rheumatoid spondylitis (ankylosing spondylitis) can be developed based on the natural history of rheumatoid involvement of the cervical spine and radiographic predictors of paralysis. As suggested by Boden, 3 goals should be kept in mind.[30 ]The first goal is to avoid the development of an irreversible neurologic deficit, as patients with more severe deficits have less recovery and higher morbidity. A second goal is to prevent sudden death from unrecognized neural compression, as has been reported in up to 10% of deaths in RA. Finally, as half of patients with RA with radiographic evidence of instability remain asymptomatic, it is best to avoid surgery if the patient can be identified as being one who will most likely not develop neurologic problems.

Nonsurgical treatment

Nonoperative treatment of rheumatoid involvement of the cervical spine (rheumatoid spondylitis, ankylosing spondylitis) is supportive. Early aggressive medical management is important in the global sense, as cervical involvement has been correlated with disease activity.[31 ]Collars can be used for comfort purposes. Rigid cervical collars most likely do not prevent subluxation; however, they may prevent reduction of a deformity by limiting extension.[32,33 ]Skin sensitivity in this population also causes problems with rigid orthoses. Patients being monitored need careful surveillance for long-tract signs or for radiographic findings suggesting impending neurologic compromise.

Surgical Therapy

Patients with rheumatoid arthritis (RA) or, particularly, rheumatoid spondylitis (ankylosing spondylitis) who have refractory pain, clearly evident neurologic compromise, or intrinsic spinal cord signal changes on MRI generally are candidates for surgical intervention. Controversy surrounds treatment for patients with little or no pain, no neural deficit, and radiographs suggestive of instability. To facilitate understanding of the operative indications and perioperative details, categorization of these patients by their pathologic lesion is helpful.[34,35,36,37 ]

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Atlantoaxial subluxation - Preoperative details

Patients with AAS and no symptoms or signs of myelopathy can be observed when the posterior atlantodental interval (PADI) on the lateral cervical radiograph is more than 14 mm. Those who have a PADI that measures less than 14 mm should have an MRI scan to determine the true space available for the cord. MRI findings of less than 13 mm of space available for the cord and a cervicomedullary angle of less than 135° generally are indications for surgical stabilization.

Atlantoaxial subluxation - Intraoperative details

The type of procedure performed is determined by whether or not the subluxation is reducible, the individual surgeon's preference and experience, and the patient's condition.

If the deformity is reducible, posterior atlantoaxial fusion can be accomplished by a variety of techniques.[38 ]Gallie reported a technique for posterior atlantoaxial arthrodesis in 1939, a technique that has been used with different modifications since that time.[39 ]In essence, the procedure consists of a block of autologous bone graft fixed by wire loop to the posterior arch of the atlas and the spinous process of the axis. While technically straightforward to perform, rotational stability and translational stability are inferior to other techniques. The image below depicts modified Gallie fusion.

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Rheumatoid spondylitis. Modified Gallie fusion. Note the H-shaped bone block wired over the spinous process of C2.

The Brooks fusion uses 2 posterior paramedian autologous structural grafts, usually attached with sublaminar wires. The bilateral fixation improves rotational stability. Multistrand titanium cables are increasingly favored over monofilament stainless steel wires because of improved strength and

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ease of contouring, as well as postoperative MRI and CT scan imaging qualities. All techniques using sublaminar wire or cable fixation have the potential risk of spinal cord injury during passage or from late failure of the implants. Additionally, the posterior arch of the atlas may be osteoporotic or partially deficient, thereby limiting its use. The image below depicts Brooks-type fusion.

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Rheumatoid spondylitis. Brooks-type fusion. Rectangular structural grafts are beveled to fit between the arches of C1 and C2;

then they are secured by bilateral doubled-twisted wires.

Immediate multidirectional stability can be achieved by C1-C2 transarticular screw fixation (see image below).[40 ]

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Rheumatoid spondylitis. C1-C2 transarticular screw fixation. Courtesy of Steven R. Garfin.

The screws are inserted posteriorly by entering the inferior aspect of the facet of C2, crossing the C1-C2 facet joint, and then entering into the lateral mass of C1. Safe insertion requires thorough understanding of the upper cervical anatomy and exposure of the medial border of the C2 pedicle.[41 ]A preoperative CT scan should be reviewed carefully because some C2 pedicles may have a small diameter, the lateral mass may be partially resorbed, or the vertebral artery may course superomedially. These conditions preclude safe transarticular screw placement. If there is good bone in the lateral masses, the patient may require only a cervical collar. However, patients with poor fixation may require a halo device postoperatively.

Patients with irreducible deformity and posterior compression can be treated with a C1 laminectomy and transarticular stabilization. Patients who have irreducible deformity and bony anterior compression may be decompressed by an anterior transoral approach, particularly in end-stage conditions.[42,43 ]This route has several difficulties, such as limited opening of the mouth in patients with concomitant temporomandibular disease, postoperative infection, and pharyngeal mucosal edema. However, several authors have reported good results using this procedure. This technique generally is followed by posterior stabilization as a 2-stage same-day procedure.

Patients who are healthier (Ranawat class I and class II) may be treated adequately with atlantoaxial stabilization and fusion alone, even in the presence of irreducible deformity. Some authors recommend that patients with anterior cord compression from proliferative retrodental pannus be treated with ventral transoral decompression. However, recent data have documented resorption of retrodental pannus if a stable posterior fusion is achieved.[44 ]Of these options, initial treatment with a posterior fusion followed by MRI and clinical follow-up is the most common. If the pannus does not resorb and neurologic deficit persists, late transoral decompression can be performed.

Superior migration of the odontoid - Preoperative details

Even in the absence of neurologic deficit, patients with any degree of basilar invagination should have an MRI in flexion to evaluate spinal cord compression. Surgical treatment should be considered in any patient with cord compression or neurologic deficit. Preoperatively, cervical traction can be used to attempt a gradual reduction.

Superior migration of the odontoid - Intraoperative details

Occipitocervical fusion is the procedure of choice in patients with SMO. Several devices have been described, ranging from wire loops securing tricortical bone graft supplemented with cement or metal mesh, contoured rods, and more recently, plates and screws (see image below).[45,46 ]

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Rheumatoid spondylitis. Occipitocervical fusion combined with lateral mass plating for a patient with combined superior

migration of the odontoid and subaxial subluxation. Courtesy of Steven R. Garfin.

The more rigid fixation afforded by plating has been associated with a lower pseudarthrosis rate when compared with wiring techniques.[47 ]Occipitocervical fusion with plating generally involves screw placement into the C2 pedicles under fluoroscopic guidance through a precontoured plate. This allows easier subsequent placement of subaxial screws in the lateral masses and in the occiput. Screws usually are not placed above the inion to avoid the intracranial venous sinuses.

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While the inner table can be thin in places, holes drilled 2-3 cm from the midline, halfway between the foramen magnum and the transverse sinus, generally are safe. No matter which implant technique is used, autologous bone grafting should always be performed. If the deformity is irreducible in traction, decompression either posteriorly or anteriorly (based on the location of the compression) should be considered as an adjunct to the fusion, as discussed above. Anterior compression in these patients is predominantly osseous, not from synovial pannus. Therefore, a ventral route provides more reliable decompression.

Subaxial subluxation - Preoperative details

Patients with subaxial subluxation and no evidence of neurologic deficit can be observed. Plain radiographs are sufficient for surveillance. Patients with a bony canal diameter less than 14 mm should have an MRI to evaluate the true space available for the cord. If the space available for the cord is less than 13 mm or if significant segmental hypermobility is present, surgical consideration is warranted.

Subaxial subluxation - Intraoperative details

Most patients with subaxial subluxation can be treated with posterior cervical fusion using autograft bone. Internal fixation with wires, plate-screw, or rod-screw constructs allows for earlier mobilization and increased rates of fusion. Patients with irreducible subluxations or significant neurologic deficit may best be treated with anterior decompression and fusion alone or in concert with posterior fusion.[48 ]

Combined subluxations - Preoperative details

Some patients may have upper cervical involvement as well as early subaxial subluxation. In these instances, the fusion should be extended to include the involved subaxial segments to avoid early deterioration of borderline subluxations below a rigid upper cervical fusion (see image below).

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Rheumatoid spondylitis. Occipitocervical fusion combined with lateral mass plating for a patient with combined superior

migration of the odontoid and subaxial subluxation. Courtesy of Steven R. Garfin.

Combined subluxations - Postoperative details

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The type of orthosis used postoperatively often is best determined on an individualized basis. Many patients have porotic bone of both the posterior elements and of the structural graft harvested from the iliac crest. Upper cervical fusions in such patients may best be managed postoperatively in a halo. When rigid collars are used, careful surveillance of the skin is mandatory to avoid decubiti. Also, if temporomandibular joint (TMJ) involvement is present, eating (chewing) may be a problem in a cervical-thoracic orthosis (CTO).

Follow-up

Even after achieving a successful fusion, patients with rheumatoid spondylitis (ankylosing spondylitis) must continue to have long-term follow-up. Subaxial instability can develop below upper cervical fusions, so radiographic follow-up should be obtained periodically, even in patients who are asymptomatic.

For excellent patient education resources, visit eMedicine's Arthritis Center. Also, see eMedicine's patient education articles Rheumatoid Arthritis and Understanding Rheumatoid Arthritis Medications.

Complications

Rheumatoid arthritis (RA) is a systemic disorder, and patients may have varying degrees of generalized debilitation.[49 ]The postoperative course of such patients can be complicated by fragile skin and poor wound healing. Poor preoperative nutritional status and corticosteroid dependence may potentiate wound-healing problems and predispose toward infection. Some airways are difficult to intubate. Excessive trauma during intubation may be responsible for postoperative breathing problems. Wattenmaker et al reported a 14% incidence of upper airway obstruction after extubation in patients intubated without fiberoptic assistance, compared with a 1% incidence in patients intubated fiberoptically.[50 ]The perioperative mortality rate has been reported to be as high as 5-10%.

Outcome and Prognosis

Cervical fusion in patients with rheumatoid spondylitis (ankylosing spondylitis) has a clinical success rate of 60-90%.[51,52,53,54,55,56,57 ]This wide range is partly due to the definition of clinical success and by variation in disease severity at the time of surgery. Rates of neurologic improvement also vary widely, ranging from 27-100%.[51,52,53,54,55,58,59,60 ]Peppelman et al reviewed the neurologic recovery in 90 patients with neurologic deficits who underwent surgery for rheumatoid deformity of the cervical spine.[61 ]The investigators reported that 95% of patients treated for atlantoaxial subluxation (AAS) improved at least one Ranawat grade, 76% of patients with combined AAS and superior migration of the odontoid (SMO) improved, and 94% of those treated for isolated subaxial subluxation improved.

Age, gender, duration of paralysis, preoperative atlantodental interval (ADI), and percentage of slippage in subaxial subluxations all have been found to have no correlation with neurologic recovery. The degree of preoperative neurologic deficit has been shown to correlate with neurologic recovery. The results appear to be less favorable in patients with more advanced preoperative neurologic deficits. Casey and colleagues reported

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their results after surgery in patients classified as Ranawat Class III.[62 ]Fifty-eight percent of ambulatory patients (grade IIIA) attained a grade I or grade II after surgery. Conversely, only 20% of nonambulatory patients (grade IIIB) improved to grade I or grade II postoperatively.

Radiographic parameters also have been shown to predict postoperative neurologic recovery. Boden et al reported that patients with AAS whose posterior ADI (PADI)was less than 10 mm before surgery had poor return of motor function. With superimposed SMO, clinically significant neurologic recovery was seen only when the PADI was at least 13 mm prior to surgery. For patients with subaxial subluxations, less recovery was seen in those with a residual postoperative subaxial canal diameter of less than 14 mm.[24 ]

Nonunion rates in this population have been estimated at 5-20%. Many of these nonunions may be asymptomatic, so management should be individualized.

Multimedia

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Media file 1: Rheumatoid spondylitis. Depiction of anterior subluxation of C1 on C2, retrodental pannus, and osseous erosions;

the spinal cord is compressed between the pannus anteriorly and the posterior arch of the atlas.

24

Media file 2: Rheumatoid spondylitis. Depiction of superior migration of the odontoid into the foramen magnum with

25

compression of the spinal cord.

26

27

Media file 3: Rheumatoid spondylitis. Pertinent measurements of superior migration of the odontoid; cranial migration

distance (CMD).

28

Media file 4: Rheumatoid spondylitis. MRI of a patient with superior migration of the odontoid and subaxial subluxation.

Courtesy of Steven R. Garfin.

29

Media file 5: Rheumatoid sponylitis. Modified Gallie fusion. Note the H-shaped bone block wired over the spinous process of

C2.

30

Media file 6: Rheumatoid spondylitis. Brooks-type fusion. Rectangular structural grafts are beveled to fit between the arches

of C1 and C2; then they are secured by bilateral doubled-twisted wires.

31

Media file 7: Rheumatoid spondylitis. C1-C2 transarticular screw fixation. Courtesy of Steven R. Garfin.

Media file 8: Rheumatoid spondylitis. Occipitocervical fusion combined with lateral mass plating for a patient with combined

superior migration of the odontoid and subaxial subluxation. Courtesy of Steven R. Garfin.

References

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1. Bland JH. Rheumatoid arthritis of the cervical spine. Bull Rheum Dis. Oct 1967;18(2):471-6. [Medline].

2. Davis FW, Markley HE. Rheumatoid arthritis with death from medullary compression. Ann Intern Med. 1951;35:451-454.

3. Mathews JA. Atlanto-axial subluxation in rheumatoid arthritis. Ann Rheum Dis. May 1969;28(3):260-6. [Medline].

4. Menezes AH, VanGilder JC, Clark CR, el-Khoury G. Odontoid upward migration in rheumatoid arthritis. An analysis of 45 patients with "cranial settling". J Neurosurg. Oct 1985;63(4):500-9. [Medline].

5. Rajangam K, Thomas IM. Frequency of cervical spine involvement in rheumatoid arthritis. J Indian Med Assoc. Apr 1995;93(4):138-9, 137. [Medline].

6. Taniguchi D, Tokunaga D, Hase H, Mikami Y, Hojo T, Ikeda T, et al. Evaluation of lateral instability of the atlanto-axial joint in rheumatoid arthritis using dynamic open-mouth view radiographs. Clin Rheumatol. Jul 2008;27(7):851-7. [Medline].

7. Zhu TY, Tam LS, Lee VW, Hwang WW, Li TK, Lee KK, et al. Costs and quality of life of patients with ankylosing spondylitis in Hong Kong. Rheumatology (Oxford). Jul 17 2008;[Medline].

8. Kjeken I, Dagfinrud H, Mowinckel P, Uhlig T, Kvien TK, Finset A. Rheumatology care: Involvement in medical decisions, received information, satisfaction with care, and unmet health care needs in patients with rheumatoid arthritis and ankylosing spondylitis. Arthritis Rheum. Jun 15 2006;55(3):394-401. [Medline].

9. Morizono Y, Sakou T, Kawaida H. Upper cervical involvement in rheumatoid arthritis. Spine. Oct 1987;12(8):721-5. [Medline].

10. Kraus DR, Peppelman WC, Agarwal AK, et al. Incidence of subaxial subluxation in patients with generalized rheumatoid arthritis who have had previous occipital cervical fusions. Spine. Oct 1991;16(10 Suppl):S486-9. [Medline].

11. Clarke MJ, Cohen-Gadol AA, Ebersold MJ, Cabanela ME. Long-term incidence of subaxial cervical spine instability following cervical arthrodesis surgery in patients with rheumatoid arthritis. Surg Neurol. Aug 2006;66(2):136-40; discussion 140. [Medline].

12. Tam LS, Gu J, Yu D. Pathogenesis of ankylosing spondylitis. Nat Rev Rheumatol. Jun 1 2010;[Medline].

13. Machado P, Landewé R, Braun J, Hermann KG, Baker D, van der Heijde D. Both structural damage and inflammation of the spine contribute to impairment of spinal mobility in patients with ankylosing spondylitis. Ann Rheum Dis. May 24 2010;[Medline].

33

14. Ranawat CS, O'Leary P, Pellicci P, et al. Cervical spine fusion in rheumatoid arthritis. J Bone Joint Surg Am. Oct 1979;61(7):1003-10. [Medline].

15. Fujiwara K, Yonenobu K, Ochi T. Natural history of upper cervical lesions in rheumatoid arthritis. J Spinal Disord. Aug 1997;10(4):275-81. [Medline].

16. Oda T, Fujiwara K, Yonenobu K, et al. Natural course of cervical spine lesions in rheumatoid arthritis. Spine. May 15 1995;20(10):1128-35. [Medline].

17. Paimela L, Laasonen L, Kankaanpaa E. Progression of cervical spine changes in patients with early rheumatoid arthritis. J Rheumatol. Jul 1997;24(7):1280-4. [Medline].

18. Pellicci PM, Ranawat CS, Tsairis P, Bryan J. A prospective study of the progression of rheumatoid arthritis of the cervical spine. J Bone Joint Surg Am. Mar 1981;63(3):342-50. [Medline].

19. Rana NA. Natural history of atlanto-axial subluxation in rheumatoid arthritis. Spine. Oct 1989;14(10):1054-6. [Medline].

20. Mikulowski P, Wollheim FA, Rotmil P. Sudden death in rheumatoid arthritis with atlanto-axial dislocation. Acta Med Scand. Dec 1975;198(6):445-51. [Medline].

21. Zochling J. Assessment and treatment of ankylosing spondylitis: current status and future directions. Curr Opin Rheumatol. Jul 2008;20(4):398-403. [Medline].

22. Younes M, Belghali S, Kriâa S, Zrour S, Bejia I, Touzi M, et al. Compared imaging of the rheumatoid cervical spine: prevalence study and associated factors. Joint Bone Spine. Jul 2009;76(4):361-8. [Medline].

23. Casey AT, Crockard HA, Geddes JF, Stevens J. Vertical translocation: the enigma of the disappearing atlantodens interval in patients with myelopathy and rheumatoid arthritis. Part I. Clinical, radiological, and neuropathological features. J Neurosurg. Dec 1997;87(6):856-62. [Medline].

24. Boden SD, Dodge LD, Bohlman HH, Rechtine GR. Rheumatoid arthritis of the cervical spine. A long-term analysis with predictors of paralysis and recovery. J Bone Joint Surg Am. Sep 1993;75(9):1282-97. [Medline].

25. Redlund-Johnell I, Pettersson H. Radiographic measurements of the cranio-vertebral region. Designed for evaluation of abnormalities in rheumatoid arthritis. Acta Radiol Diagn (Stockh). 1984;25(1):23-8. [Medline].

34

26. Castro S, Verstraete K, Mielants H. Cervical spine involvement in rheumatoid arthritis: a clinical, neurological and radiological evaluation. Clin Exp Rheumatol. Jul-Aug 1994;12(4):369-74. [Medline].

27. Dvorak J, Grob D, Baumgartner H, et al. Functional evaluation of the spinal cord by magnetic resonance imaging in patients with rheumatoid arthritis and instability of upper cervical spine. Spine. Oct 1989;14(10):1057-64. [Medline].

28. Kawaida H, Sakou T, Morizono Y, Yoshkuni N. Magnetic resonance imaging of upper cervical disorders in rheumatoid arthritis. Spine. Nov 1989;14(11):1144-8. [Medline].

29. Roca A, Bernreuter WK, Alarcon GS. Functional magnetic resonance imaging should be included in the evaluation the cervical spine in patients with rheumatoid arthritis. J Rheumatol. Sep 1993;20(9):1485-8. [Medline].

30. Boden SD. Rheumatoid arthritis of the cervical spine. Surgical decision making based on predictors of paralysis and recovery. Spine. Oct 15 1994;19(20):2275-80. [Medline].

31. van der Heijde D, Schiff MH, Sieper J, Kivitz A, Wong RL, Kupper H, et al. Adalimumab effectiveness for the treatment of ankylosing spondylitis is maintained for up to 2 years: long-term results from the ATLAS trial. Ann Rheum Dis. Aug 13 2008;[Medline].

32. Kauppi M, Anttila P. A stiff collar can restrict atlantoaxial instability in rheumatoid cervical spine in selected cases. Ann Rheum Dis. Apr 1995;54(4):305-7. [Medline].

33. Kauppi M, Anttila P. A stiff collar for the treatment of rheumatoid atlantoaxial subluxation. Br J Rheumatol. Aug 1996;35(8):771-4. [Medline].

34. Ito H, Neo M, Yoshida M, Fujibayashi S, Yoshitomi H, Nakamura T. Efficacy of computer-assisted pedicle screw insertion for cervical instability in RA patients. Rheumatol Int. Apr 2007;27(6):567-74. [Medline].

35. Schmitt-Sody M, Kirchhoff C, Buhmann S, Metz P, Birkenmaier C, Troullier H, et al. Timing of cervical spine stabilisation and outcome in patients with rheumatoid arthritis. Int Orthop. Aug 2008;32(4):511-6. [Medline].

36. Etame AB, Than KD, Wang AC, Marca FL, Park P. Surgical management of symptomatic cervical or cervicothoracic kyphosis due to ankylosing spondylitis. Spine. Jul 15 2008;33(16):E559-64. [Medline].

37. Ishii K, Matsumoto M, Takahashi Y, Okada E, Watanabe K, Tsuji T, et al. Risk Factors for Development of Subaxial Subluxations Following Atlantoaxial Arthrodesis for Atlantoaxial Subluxations in Rheumatoid Arthritis. Spine (Phila Pa 1976). Jan 12 2010;[Medline].

35

38. Grob D, Crisco JJ 3rd, Panjabi MM. Biomechanical evaluation of four different posterior atlantoaxial fixation techniques. Spine. May 1992;17(5):480-90. [Medline].

39. Gallie WE. Fractures and dislocations of the cervical spine. J Bone Joint Surg. 1939;46A:495.

40. Grob D, Magerl F. [Surgical stabilization of C1 and C2 fractures]. Orthopade. Feb 1987;16(1):46-54. [Medline].

41. Jun BY. Anatomic study for ideal and safe posterior C1-C2 transarticular screw fixation. Spine. Aug 1 1998;23(15):1703-7. [Medline].

42. Crockard HA, Calder I, Ransford AO. One-stage transoral decompression and posterior fixation in rheumatoid atlanto-axial subluxation. J Bone Joint Surg Br. Jul 1990;72(4):682-5. [Medline].

43. Menezes AH, VanGilder JC. Transoral-transpharyngeal approach to the anterior craniocervical junction. Ten-year experience with 72 patients. J Neurosurg. Dec 1988;69(6):895-903. [Medline].

44. Grob D, Wursch R, Grauer W. Atlantoaxial fusion and retrodental pannus in rheumatoid arthritis. Spine. Jul 15 1997;22(14):1580-3; discussion 1584. [Medline].

45. Heywood AW, Learmonth ID, Thomas M. Internal fixation for occipito-cervical fusion. J Bone Joint Surg Br. Nov 1988;70(5):708-11. [Medline].

46. Smith MD, Anderson P, Grady MS. Occipitocervical arthrodesis using contoured plate fixation. An early report on a versatile fixation technique. Spine. Oct 15 1993;18(14):1984-90. [Medline].

47. Grob D, Dvorak J, Panjabi MM, Antinnes JA. The role of plate and screw fixation in occipitocervical fusion in rheumatoid arthritis. Spine. Nov 15 1994;19(22):2545-51. [Medline].

48. An HS. Internal fixation of the cervical spine: current indications and techniques. J Am Acad Orthop Surg. Jul 1995;3(4):194-206. [Medline].

49. Heyde CE, Fakler JK, Hasenboehler E, Stahel PF, John T, Robinson Y, et al. Pitfalls and complications in the treatment of cervical spine fractures in patients with ankylosing spondylitis. Patient Saf Surg. Jun 6 2008;2:15. [Medline].

50. Wattenmaker I, Concepcion M, Hibberd P, Lipson S. Upper-airway obstruction and perioperative management of the airway in patients managed with posterior operations on the cervical spine for rheumatoid arthritis. J Bone Joint Surg Am. Mar 1994;76(3):360-5. [Medline].

36

51. Clark CR, Goetz DD, Menezes AH. Arthrodesis of the cervical spine in rheumatoid arthritis. J Bone Joint Surg Am. Mar 1989;71(3):381-92. [Medline].

52. Fielding JW, Hawkins RJ, Ratzan SA. Spine fusion for atlanto-axial instability. J Bone Joint Surg Am. Apr 1976;58(3):400-7. [Medline].

53. Larsson SE, Toolanen G. Posterior fusion for atlanto-axial subluxation in rheumatoid arthritis. Spine. Jul-Aug 1986;11(6):525-30. [Medline].

54. Santavirta S, Konttinen YT, Laasonen E, et al. Ten-year results of operations for rheumatoid cervical spine disorders. J Bone Joint Surg Br. Jan 1991;73(1):116-20. [Medline].

55. Wertheim SB, Bohlman HH. Occipitocervical fusion. Indications, technique, and long-term results in thirteen patients. J Bone Joint Surg Am. Jul 1987;69(6):833-6. [Medline].

56. Zoma A, Sturrock RD, Fisher WD, et al. Surgical stabilisation of the rheumatoid cervical spine. A review of indications and results. J Bone Joint Surg Br. Jan 1987;69(1):8-12. [Medline].

57. El Miedany Y, El Gaafary M, Youssef S, Palmer D. Towards a multidimensional patient reported outcome measures assessment: Development and validation of a questionnaire for patients with ankylosing spondylitis/spondyloarthritis. Joint Bone Spine. May 13 2010;[Medline].

58. McRorie ER, McLoughlin P, Russell T, et al. Cervical spine surgery in patients with rheumatoid arthritis: an appraisal. Ann Rheum Dis. Feb 1996;55(2):99-104. [Medline].

59. Casey AT, Crockard HA, Stevens J. Vertical translocation. Part II. Outcomes after surgical treatment of rheumatoid cervical myelopathy. J Neurosurg. Dec 1997;87(6):863-9. [Medline].

60. Ronkainen A, Niskanen M, Auvinen A, Aalto J, Luosujärvi R. Cervical spine surgery in patients with rheumatoid arthritis: longterm mortality and its determinants. J Rheumatol. Mar 2006;33(3):517-22. [Medline].

61. Peppelman WC, Kraus DR, Donaldson WF 3rd, Agarwal A. Cervical spine surgery in rheumatoid arthritis: improvement of neurologic deficit after cervical spine fusion. Spine. Dec 1993;18(16):2375-9. [Medline].

62. Casey AT, Crockard HA, Bland JM, et al. Surgery on the rheumatoid cervical spine for the non-ambulant myelopathic patient-too much, too late?. Lancet. Apr 13 1996;347(9007):1004-7. [Medline].

37

63. Braunstein EM, Weissman BN, Seltzer SE, et al. Computed tomography and conventional radiographs of the craniocervical region in rheumatoid arthritis. A comparison. Arthritis Rheum. Jan 1984;27(1):26-31. [Medline].

64. Brooks AL, Jenkins EB. Atlanto-axial arthrodesis by the wedge compression method. J Bone Joint Surg Am. Apr 1978;60(3):279-84. [Medline].

65. Bundschuh C, Modic MT, Kearney F, et al. Rheumatoid arthritis of the cervical spine: surface-coil MR imaging. AJR Am J Roentgenol. Jul 1988;151(1):181-7. [Medline].

66. Conaty JP, Mongan ES. Cervical fusion in rheumatoid arthritis. J Bone Joint Surg Am. Oct 1981;63(8):1218-27. [Medline].

67. Crockard HA. Anterior approaches to lesions of the upper cervical spine. Clin Neurosurg. 1988;34:389-416. [Medline].

68. Fang D, Leong JC, Fang HS. Tuberculosis of the upper cervical spine. J Bone Joint Surg Br. Jan 1983;65(1):47-50. [Medline].

69. Fielding JW, Cochran Gv, Lawsing JF 3rd, Hohl M. Tears of the transverse ligament of the atlas. A clinical and biomechanical study. J Bone Joint Surg Am. Dec 1974;56(8):1683-91. [Medline].

70. Lipson S. Rheumatoid disease of the cervical spine: surgical treatment. In: Camins M, O'Leary P, eds. Disorders of the Cervical Spine. Baltimore:. Lippincott Williams & Wilkins;1992:565-571.

71. Lipson SJ. Cervical myelopathy and posterior atlanto-axial subluxation in patients with rheumatoid arthritis. J Bone Joint Surg Am. Apr 1985;67(4):593-7. [Medline].

72. Lipson SJ. Rheumatoid arthritis in the cervical spine. Clin Orthop. Feb 1989;(239):121-7. [Medline].

73. Mandel IM, Kambach BJ, Petersilge CA, et al. Morphologic considerations of C2 isthmus dimensions for the placement of transarticular screws. Spine. Jun 15 2000;25(12):1542-7. [Medline].

74. Ransford AO, Crockard HA, Pozo JL, et al. Craniocervical instability treated by contoured loop fixation. J Bone Joint Surg Br. Mar 1986;68(2):173-7. [Medline].

75. Reiter MF, Boden SD. Inflammatory disorders of the cervical spine. Spine. Dec 15 1998;23(24):2755-66. [Medline].

76. Weissman BN, Aliabadi P, Weinfeld MS, et al. Prognostic features of atlantoaxial subluxation in rheumatoid arthritis patients. Radiology. Sep 1982;144(4):745-51. [Medline].

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Keywords

rheumatoid spondylitis, ankylosing spondylitis, Bekhterev arthritis, Marie-Strumpell spondylitis, rhizomelic spondylitis, rheumatoid arthritis, RA, atlantoaxial subluxation, AAS, subaxial subluxation, atlantoaxial instability, AAI, superior migration of the odontoid, SMO

Contributor Information and Disclosures

Author

Michael J Vives, MD, Associate Professor, Department of Orthopedics, Division of Spine Surgery, New Jersey Medical School, University of Medicine and Dentistry of New JerseyMichael J Vives, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons and North American Spine Society Disclosure: Nothing to disclose.

Coauthor(s)

Steven R Garfin, MD, Professor, Chair, Department of Orthopedics, University of California at San Diego Medical CenterSteven R Garfin, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Association, North American Spine Society, Orthopaedic Research Society, and Western Orthopaedic Association Disclosure: Nothing to disclose.

Medical Editor

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

Pharmacy Editor

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

Managing Editor

William O Shaffer, MD, Professor, Vice-Chairman and Residency Program Director, Department of Orthopedic Surgery, University of Kentucky at LexingtonWilliam O Shaffer, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic

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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; DePuySpine 2009 Consulting fee Design of Offset Modification of Expedium

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 HospitalDinesh Patel, MD, FACS is a member of the following medical societies: American Academy of Orthopaedic 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 PennsylvaniaMary 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.

Further Reading

Rituximab for the treatment of rheumatoid arthritis. National Institute for Health and Clinical Excellence (NICE) - National Government Agency [Non-U.S.]. 2007 Aug. 26 pages. NGC:005902

Abatacept for the treatment of rheumatoid arthritis. National Institute for Health and Clinical Excellence (NICE) - National Government Agency [Non-U.S.].  2008 Apr.  29 pages.  NGC:006483

Related eMedicine topics:

Ankylosing Spondylitis [Orthopedic Surgery]

Ankylosing Spondylitis [Radiology]

Ankylosing Spondylitis and Undifferentiated Spondyloarthropathy [Rheumatology]

Rheumatoid Arthritis, Spine [Radiology]

Psoriatic Arthritis [Rheumatology]

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